TXR HF Series Generators Calibration

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Technical Publication

CA-1004R4

Calibration

HF Series Generators

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REVISION HISTORY

REVISION DATE REASON FOR CHANGE

0 APR 1, 2001 First edition

1 JUL 4, 2001 Software update

2 FEB 1, 2003 New RF Adaptation Board

3 NOV 2, 2004 AEC Calibration

HF Series Generators

Calibration

This Document is the english original version, edited and supplied by the manufacturer.

The Revision state of this Document is indicated in the code number shown at the bottom of this page.

APR 1, 2005 Text revision

ADVISORY SYMBOLS

The following advisory symbols will be used throughout this manual. Their application and meaning are described below.

DANGERS ADVISE OF CONDITIONS OR SITUATIONS THAT IF NOT HEEDED OR AVOIDED WILL CAUSE SERIOUS PERSONAL INJURY OR DEATH.

ADVISE OF CONDITIONS OR SITUATIONS THAT IF NOT HEEDED OR AVOIDED COULD CAUSE SERIOUS PERSONAL INJURY, OR CATASTROPHIC DAMAGE OF EQUIPMENT OR DATA.

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Advise of conditions or situations that if not heeded or avoided could cause personal injury or damage to equipment or data.

Note . Alert readers to pertinent facts and conditions. Notes represent

information that is important to know but which do not necessarily relate to possible injury or damage to equipment.

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HF Series Generators

Calibration

TABLE OF CONTENTS

Section Page

1 INTRODUCTION 1.........................................................

1.1 Generator Specifications 2.............................................

1.1.1 Minimum Current Time Product (mAs) 2..........................

1.1.2 Accuracy of Radiographic and Fluoroscopic Parameters 2..........

1.1.3 Duty Cycle 2..................................................

2 CALIBRATION PROCEDURES 3............................................

2.1 Filament Stand-by Current 4...........................................

2.2 Exposure Time Adjustment 5...........................................

2.3 kV Loop 6...........................................................

2.4 Digital mA Loop Closed 9..............................................

2.5 Digital mA Loop Open (X-Ray Tube Calibration) 12........................

2.5.1 Autocalibration of Digital mA Loop Open 12........................

2.5.2 Manual Calibration of Digital mA Loop Open 15.....................

2.6 AEC Calibration 21....................................................

2.6.1 Previous Checks 22.............................................

2.6.2 Balance Adjustment for Three Field Detectors 23...................

2.6.3 Optical Density Adjustment 24....................................

2.6.4 kV Compensation 30............................................

2.6.5 PhotoMultiplier R AD-AEC (Digital RAD) Adjustment (optional) 33......

2.6.6 AEC Optical Density Scale 35....................................

2.7 Fluoro Calibration 36...................................................

2.8 ABC Calibration 40....................................................

2.8.1 ABC System with PhotoMultiplier Tube 40..........................

2.8.2 ABC System with TV Camera 45..................................

2.8.2.1 ABC System Adjustment with ABC Signal from TV Camera

Compatible with the Generator 47.........................

2.8.2.2 ABC System Adjustment with ABC Signal from TV Camera

Not Compatible with the Generator 49.....................

2.8.2.3 ABC System Adjustment with No ABC Signal

from TV Camera 51.....................................

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2.9 Final Checks 54.......................................................

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HF Series Generators

Calibration

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SECTION 1 INTRODUCTION

This Calibration document provides information and procedures to perform all the adjustments required to establish an optimal performance of this Generator.

Calibrate the Generator immediately after Configuration is completed.

DO NOT SUPPLY THE MAIN POWER UNTIL SPECIFICALLY INSTRUCTED TO DO SO IN THIS DOCUMENT.

THE MAIN CAPACITORS OF THE HIGH VOLTAGE INVERTER RETAIN A LARGE PORTION OF THEIR CHARGE FOR APPROX. 3 MINUTES AFTER THE UNIT IS TURNED OFF.

HF Series Generators

Calibration

Note .

Calibration data is entered in digital form and stored in a non-volatile memory chip (U3-EEPROM) located on the HT Controller Board, thus no battery back-up is required.

Calibration procedures must be document. Perform only the sections required to calibrate this unit.

performed in the order listed in this

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1.1 GENERATOR SPECIFICATIONS

1.1.1 MINIMUM CURRENT TIME PRODUCT (mAs)

• Minimum Current Time Product obtained at 0.1 s is 1 mAs.

• Minimum Current Time Product within the specified ranges of

compliance for linearity and constancy is 0.1 mAs.

1.1.2 ACCURACY OF RADIOGRAPHIC AND FLUOROSCOPIC PARAMETERS

Note .

1.1.3 DUTY CYCLE

Specified accuracy does not include test equipment accuracy.

ACCURACY

±(3%+1kV)

±(4%+1mA)

±(2%+0.1ms)

±(3%+1kV)

± 10%

±(1%+20ms)

RAD

FLUORO

PARAMETERS

Exposure Time

(with 12 BITS HT Controller)

The Generator duty cycle is continuous, but limits should be set during installation depending on the capacity of the X-ray tube.

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SECTION 2 CALIBRATION PROCEDURES

HF Series Generators

Calibration

Note .

Enter and store calibration data in the Extended Memory Locations as described in Section 2.2 of the “Configuration” document.

Record all the calibration data in the Data Book.

Before calibration, bear in mind that:

• For calibration and measure the kVp it is needed a Non-Invasive kVp Meter.

• For calibration and measure mA or mAs it is needed a mAs Meter plugged to the banana connections on the H V Transformer (connect the mAs Meter for Digital mA Loops calibration).

Test points on the HT Controller Board can also be used to monitor the kV and mA readings but should not be used unit. These test points must be checked with scope:

- mA test point is TP-5 and the scale factor is:

- from10to80mA, 1volt=10mA

- from 100 mA, 1 volt = 100 mA

to calibrate the

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- kV test point is TP-7 and the scale factor is 1 volt = 33.3 kV (0.3 volt = 10 kV)

• Verify that dip switch 3024SW2-3 on the ATP Console CPU Board is in

“On” position to permit the service mode.

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HF Series Generators

Calibration

• Verify position of dip switches on the HT Controller Board during every calibration procedure:

DIP SWITCH OPEN (OFF) CLOSED (ON)

3000SW2-2

3000SW2-4 Position during operation -- Digital mA Loop Closed Digital mA Loop Open / Filament Current Constant

Position during operation -- Enables Filament and Rotor Interlocks

Note .

Only for Generators with Low Speed Starter (LF-RAC) (it does not

Disables Filament and Rotor Interlocks (this turns off the filament so no radiation will be produced during the exposure).

apply to Generators with High Speed Starter - LV-DRAC):

-- When the Digital mA Loop is open (dip switch 3000SW2-4 in “On”), the rotor runs for two minutes after releasing the handswitch button from “Preparation” position. After this time the rotor will brake (unless DC Brake is removed).

-- When the Digital mA Loop is closed (dip switch 3000SW2-4 in “Off”), the rotor will brake after releasing the handswitch button from “Preparation” position (unless DC Brake is removed).

• Be sure that X-ray Tubes configured in E02 and E18 Memory Locations correspond to X-ray Tubes installed (refer to Configuration document).

2.1 FILAMENT STAND-BY CURRENT

Note .

For RAD Only Generators, the Filament Stand-by value is auto-calibrated by the Generator and automatically stored into the respective Memory Locations (E01 and E17). Filament Stand -by values are not field changeable.

For RAD and Fluoro Generators, E17 Memory Location (”Fluoro Filament Setting”) sets maximum patient Entrance Skin Exposure Dose Rate. (Refer to Section 2.7 “Fluoro Calibration”).

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2.2 EXPOSURE TIME ADJUSTMENT

The values stored in these Extended Memory Locations only affect to Exposure Times for techniques below 20 ms. The Memory Locations which affect short exposure times are:

HF Series Generators

Calibration

FUNCTION

EXPOSURE TIME ADJUSTMENT - DELAY E13 E29

EXPOSURE TIME ADJUSTMENT - Ceq kV E15 E31

MEMORY LOCATION

TUBE-1 TUBE-2

The Generator has been optimized at the factory to produce correct exposures at the lower times (<20 ms.) Therefore do not change the value factory set for E13 and E29 Memory Locations and only adjust the value for E15 and E31 Memory Location according to the HV Cables length.

The Exposure Time adjustment is calibrated by performing the following steps:

1. Enter calibration mode.

2. Select the E13 (or E29) Memory Location. Value in this Memory Location adjusts the time delay of the exposure. It is factory set for a value of 17, 18 or 19 (default v alue is “18”). Only read this value, do not change it.

3. Selectthe E15 (or E31) Memory Location. Valuein this Memory Location is set in relation to the length in meters of one of the HV Cables (1 ft = 0.3048 m). Verify the HV Cable length in meters and set the following value:

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HV CABLE LENGTH VALUE TO SET IN MEMORY

4m 27

6m 31

9m 38

12 m 45

14 m 49

16 m 54

For another HV Cable length value = (2.2711 x cable length) + 17.744

4. Store the new value of each Memory Location.

5. Exit from calibration mode and record the new values in the Data Book.

6. Repeat the above calibration process for the second tube (memory locations E29 and E31).

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HF Series Generators

Calibration

2.3 KV LOOP

Extended Memory Location E06 contains the calibration factor for kV Loop. Each number above or below of the indicated in the E06 memory location increases or decreases respectively the kV gain value.

Note .

Value in E06 Memory Location is only related to the Generator performance (it is not related to the X-ray Tube(s) or another components installed), so value in this Memory Location is factory adjusted. Only perform this procedure if the HT Controller Board and/or HV Transformer have been replaced in the unit.

The kV Gain for kV Loop can be manually calibrated with a Non-Invasive kV Meter (recommended procedure) or Auto-calibrated with HV Bleeder.

Manual Calibration of E06 Memory Location

1. With the Generator power OFF:

G Set Dip switch 3000SW2-2 on the HT Controller Board in “Off”

position (enables Filament and Rotor Interlocks).

G Set Dip switch 3000SW2-4 on the HT Controller Board in “On”

position (Digital mA Loop Open / Filament Current Constant).

G Remove the link between the banana plug connections on the HV

Transformer. Connect the mAs Meter to the banana plug connections to measure mA or mAs.

G Place and center a Non-Invasive kVp Meter on the X-ray Tube

output at the required SID (refer to the Non-Invasive kVp Meter documentation).

2. Enter in calibration mode.

3. Select the E06 Memory Location and read the calibration value by pressing the “AEC Reset” push-button. Enter the value “200” and store it by pressing the “AEC Reset” push-button.

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4. Calibrate manually the Filament Current Number for 80 kV / 200 mA combination, as indicated in the following steps (if it has not been previously calibrated).

In calibration mode, Filament Current Numbers are shown on the kV Display by pressing the “AEC Reset” push-button after selecting the respective kV / mA combination. They can be changed by pressing the “Increase” and “Decrease” (or “+1” and “ -- 1 ”) density push-buttons and stored by pressing the “AEC Reset” push-button.

Select 80 kV, 200 mA and set value “344” on Filament Current Number. Make an exposure. The mAs read on the mAs Meter must be the same mAs displayed on the calibration screen with a tolerance of ±0.1 mAs (tolerance of the parameter and mAs Meter).

If the mAs is low, increase the filament number. If the mA is high (or “Generator Overload” Error is shown), decrease the filament number. Press the “AEC Reset” push-button before making a new exposure. Repeat until the mAs read is correct and the mA station is calibrated.

5. Exit from Calibration mode.

6. Select:80 kV, 200 mA, 100 ms. Make an exposure and note the kV value at the end of the exposure.

7. If calibration of the kV Loop is correct (80 ±1 kV), record value “200”in the Data Book.

8. If calibration of the k V Loop is not correct:

a. Enter in Calibration mode and select the E06 Memory Location.

Press the “AEC Reset” push-button to read the value stored.

b. Increase or decrease the value to increase or decrease the kV

respectively. Enter the new value and store it by pressing the “AEC Reset” push-button.

c. Exit calibration mode and repeat the exposure (step-6.)to

determine if the new value has had the proper effect, if not repeat step-8.

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d. When it is correct, record the new value for E06 Memory Location

in the Data Book.

9. After calibration of E06 Memory Location, remove the Non-Invasive kVp Meter.

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HF Series Generators

Calibration

Auto-Calibration of E06 Memory Location

1. With the Generator power OFF:

G Set Dip switch 3000SW2-2 on the HT Controller Board in “On”

position (disables Filament and Rotor Interlocks).

G Remove the HV Cables from the X-ray Tube and connect them to

the HV Bleeder, then connect a short couple of HV Cables from the HV Bleeder to the X-ray Tube.

2. Enter in Calibration mode and select the E06 Memory Location.

EACH TIME THAT AUTO-CALIBRATION IS ACTIVATED IN THIS MEMORY LOCATION, CALIBRATION DATA STORED IS DELETED AND A NEW CALIBRATION FOR IT WILL BE REQUIRED.

3. Enter in Auto-calibration mode pressing the “Power On” and “kV Increase” push-buttons. After releasing both push-buttons, code “222” is flashing on the Console accompanied of an alarm waiting confirmation for entering in Auto-calibration mode.

Keep pressed the “kV increase” and “Power On” push-buttons again until code “222” disappears on the Console to confirm Auto-calibration mode or press only the “Power On” push-button to leave Auto-calibration mode and return to manual calibration.

4. Make an exposure (technique parameters are pre-programmed at 100 kV, 200 mA and 32 ms and they can be shown when pressing the “Prep” button).

5. Read the kVp measured with the HV Bleeder and enter this value on the kV Display by pressing the “kV Increase” or “kV Decrease” buttons.

6. Exit from Auto-calibration mode pressing the “Power ON” and “kV Decrease” push-buttons. At this moment, the Generator will calculate and store the new value in E06 Memory Location. Auto-calibration is deactivated and the process is finished when “E06”is indicated on the Console again.

7. Read the new value stored in E06 Memory Location pressing the “AEC Reset” push-button. Record this value in the Data Book.

8. Exit calibration mode.

9. After calibration of E06 Memory Location:

G Switch the Generator power OFF.

G Remove the HV Bleeder and connect the HV Cables from the

Generator directly to the X-ray Tube.

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2.4 DIGITAL mA LOOP CLOSED

Extended Memory Locations E03 and E05 contain the calibration factor for Digital mA Loop Closed. Each number above or below the indicated in the memory locations increases or decreases respectively the mA gain value.

HF Series Generators

Calibration

Note .

Values in E03 and E05 Memory Locations are only related to the Generator performance (they are not related to the X-ray Tube(s) installed), so values in these Memory Locations are factory adjusted. Only perform this procedure if the HT Controller Board and/or HV Transformer have been replaced in the unit.

The mA Gain for Digital mA Loop Closed is calibrated by performing the following steps:

1. With the Generator power OFF, set:

G Dip switch 3000SW2-2 on the HT Controller Board in “Off” position

(enables Filament and Rotor Interlocks).

G Dip switch 3000SW2-4 on the HT Controller Board in “On” position

(Digital mA Loop Open / Filament Current Constant).

G Remove the link between the banana plug connections on the HV

Transformer. Connect the mAs Meter to the banana plug connections to measure mA or mAs.

2. Select one available workstation (eg. “No Bucky”).

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3. Calibrate E03 and E05 Memory Locations as described in the following pages.

EACH TIME THAT AUTO-CALIBRATION IS ACTIVATED IN ONE OF THESE MEMORY LOCATIONS, CALIBRATION DATA STORED FOR THAT MEMORY LOCATION IS DELETED AND A N EW CALIBRATION FOR IT WILL BE REQUIRED.

4. After calibration of E03 and E05 Memory Locations:

G Switch the Generator power OFF.

G Disconnect the mAs Meter to the banana plug connections.

G Re-install the link between the banana plug connections on the HV

Transformer.

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HF Series Generators

Calibration

For Low mA stations (from 10 mA to 80 mA) (E03 Memory Location):

1. Enter calibration mode and select the E03 memory location.

2. Enter Auto-calibration mode pressing the “Power On” and “kV increase” push-buttons. After releasing both push-buttons, code “222” is flashing on the Console accompanied of an alarm waiting confirmation for entering in Auto-calibration mode.

Auto-calibration is activated when the Console shows the value “3.5 mAs”.

3. Perform the following steps:

a. Make an exposure (technique parameters are pre-programmed at

80 kV, 32 mA and 100 ms and they can be shown when pressing the “Prep” push-button).

b. Read the mAs measured on the mAs Meter.

c. Read the Filament Current Number shown on the kV Display by

pressing the “Increase” and “Decrease” (or “+1” and “-- 1 ”) density push-buttons. Since these push-buttons are also used to increase or decrease the values one number should be added or subtracted from the reading to obtain the correct value.

d. Increase or decrease the Filament Current Number to determine

the correction needed to obtain a value between 3.00 and 4.00 mAs in the mAs Meter after making a new exposure.

e. Repeat the above steps until a proper mAs value is obtained in the

mAs Meter.

4. Enter the mAs value read in the mAs Meter (it must be a value between

3.00 and 4.00 mAs) in the mAs Display pressing the “mAs increase”or “mAs decrease” push-buttons.

5. Exit from Auto-calibration mode pressing the “Power On” and “kV decrease” push-buttons. At this moment, the Generator will calculate and store the new value in E03 memory location. Auto-calibration is deactivated and the process is finished when “E03”is indicated on the Console again.

6. Read the new value stored in E03 memory location pressing the “AEC Reset” push-button. Record this value in the Data Book.

7. Exit calibration mode.

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Calibration

For High mA stations (from 100 mA) (E05 Memory Location):

1. Enter calibration mode and select the E05 memory location.

Auto-calibration is activated when the Console shows the value “7.75 mAs”.

3. Perform the following steps:

a. Make an exposure (technique parameters are pre-programmed at

80 kV, 125 mA and 64 ms (

or 63 ms or 65 ms depending on Generator)

and they can be shown when pressing the “Prep” push-button).

b. Read the mAs measured on the mAs Meter.

c. Read the Filament Current Number shown on the kV Display by

d. Increase or decrease the Filament Current Number to determine

the correction needed to obtain a value between 7.00 and 8.50 mAs in the mAs Meter after making a new exposure.

e. Repeat the above steps until a proper mAs value is obtained in the

mAs Meter.

4. Enter the mAs value read in the mAs Meter (it must be a value between

7.00 and 8.50 mAs) in the mAs Display pressing the “mAs increase”or “mAs decrease” push-buttons.

5. Exit from Auto-calibration mode pressing the “Power On” and “kV decrease” push-buttons. At this moment, the Generator will calculate and store the new value in E05 memory location. Auto-calibration is deactivated and the process is finished when “E05”is indicated on the Console again.

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6. Read the new value stored in E05 memory location pressing the “AEC Reset” push-button. Record this value in the Data Book.

7. Exit calibration mode.

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HF Series Generators

Calibration

2.5 DIGITAL mA LOOP OPEN (X-RAY TUBE CALIBRATION)

To achieve the most accurate calibration, this procedure has to be automatically performed by the Generator (Auto-calibration). Calibration

procedure will be manually performed by the field engineer only if Auto-calibration is not possible.

Two different methods are described in this section: Auto-calibration and Manual Calibration.

Digital mA Loop Open is calibrated by performing the following steps:

1. With the Generator power OFF, set:

G Dip switch 3000SW2-2 on the HT Controller Board in “Off” position

(enables Filament and Rotor Interlocks).

G Dip switch 3000SW2-4 on the HT Controller Board in “On” position

(Digital mA Loop Open / Filament Current Constant).

2. Turn the Generator ON.

3. Enterin Calibration mode. Select the E17 Memory Location and store the value “086”. Press the “AEC Reset” push-button to read the value stored. Exit calibration mode.

4. Perform the Auto-calibration procedure as described in Section 2.5.1 for each X-ray Tube in the system.

2.5.1 AUTO-CALIBRATION OF DIGITAL mA LOOP OPEN

Auto-calibration of the Filament Current Numbers is divided in two separated procedures related to the mA stations configured for the Small or Large Focal Spots.

It is recommended to start with the Small Focal Spot (first group) and continue with the Large Focal Spot (second group).

EACH TIME THAT AUTO-CALIBRATION IS ACTIVATED IN A mA STATION (OR IN “E01” MEMORY LOCATION), ALL THE FILAMENT CURRENT NUMBERS OF THE SELECTED FOCAL SPOT ARE AUTOMATICALLY SET TO “344”. SO A NEW COMPLETE CALIBRATION OF THE FILAMENT CURRENT NUMBERS FOR THIS FOCAL SPOT WILL BE REQUIRED.

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HF Series Generators

Calibration

Auto-calibration starts with the minimum available mA station for the selected Focal Spot at 50 kV and follows with the other combinations of mA stations for the selected Focal Spot at 80 kV, 120 kV and 40 kV.

1. Select one available workstation for the X-ray Tube selected. This workstation has to be one of the previously configured as “Direct”.

2. Enter calibration mode and select one of the configured mA stations for the Small Focal Spot.

3. Enter Auto-calibration mode pressing the “Power On” and “kV increase” push-buttons. After releasing both push-buttons, code “222” is flashing on the Console accompanied of an alarm waiting confirmation for entering in Auto-calibration mode.

Note .

Auto-calibration is activated after releasing both push-buttons. At this moment, the Generator will check the mA stations available for the Small Focal Spot. A “double-beep” will sound when the verification is completed.

4. Check that the Heat Units available for the X-ray Tube are 100% (kV Display shows “H -- --” on the Console).

BEFORE MAKING ANY EXPOSURE IN AUTO-CALIBRATION, VERIFY THAT THE LINK BETWEEN THE BANANA PLUG CONNECTIONS ON THE HV TRANSFORMER IS INSTALLED.

5. Keep fully pressed the Handswitch push-button or use the Exposure Controls on the Console to perform continuous exposures.

In Auto-calibration mode, all technique parameters are factory pre-programmed and they can not be changed.

Auto-calibration can be paused momentarily by releasing the Handswitch push-button or the Exposure Controls. Do not exit f rom Auto-calibration before the procedure has been completed.

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Note .

Auto-calibration can be cancelled by pressing the “Power On” and “kV decrease” push-buttons. A double “double-beep” sound and new values displayed on the Console indicates Auto-calibration is deactivated.

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HF Series Generators

Calibration

If during Auto-calibration process, any error indication is shown momentarily on the Console (such as “Tube Overload”, etc.), it means that Generator can not calibrate in this moment the selected kV / mA combination (because anode overheated, space charge, Generator power limit, etc.). In this case, the Generator will continue with Auto-calibration of the following available kV / mA combinations for the selected Focal Spot. At the end of the process it will try to calibrate or calculate the combinations previously uncalibrated.

If the Heat Units available for the X-ray Tube are less than 40%, exposures are inhibited momentarily and code “111”will be flashed on the Console accompanied of an alarm. The alarm will stop when the X-ray Tubebegins to cool and recovers the Heat Units capacity, exposures can be performed again even though code “111” is shown on the Console.

At this point, it is r ecommended to wait until the Heat Units available are closed to the 80% of the X-ray Tube capacity without making any exposure.

Generator tries to calibrate each kV / mA combination for ten (10) attempts (maximum). If calibration is aborted (after ten attempts), code “888” will be flashing on the Console until press the “Power On” push-button. Calibration can be also aborted due to space charge during calibration of the lowest kV at the highest mA stations for the Focal Spot selected, so code “777” will be flashing on the Console until press the “Power On” push-button.

IF AUTO-CALIBRATION IS ABORTED (CODE “888” OR “777”), CONTINUE THE AUTO-CALIBRATION PROCEDURE FOR THE OTHER FOCAL SPOT. CHECK AT THE END OF THE AUTO-CALIBRATION PROCEDURE WHICH KV / MA COMBINATIONS HAVE NOT BEEN AUTO-CALIBRATED FOR EACH FOCAL SPOT (THESE COMBINATIONS HAVE THE FILAMENT CURRENT NUMBER SET TO “344”). MANUALLY CALIBRATE THESE KV / MA COMBINATIONS AS EXPLAIN IN SECTION 2.5.2.

When Auto-calibration is successfully performed, code “999” will be flashing on the Console until press the “Power On” push-button to exit from Auto-calibration mode. A double “double-beep” sound and new values displayed on the Console indicates Auto-calibration is deactivated.

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6. Repeat the s ame procedure for the Large Focal Spot selecting one of the configured mA stations for the Large Focal Spot previous to enter in Auto-calibration mode.

Before starting the exposures, it is recommended to wait until the Heat Units available are closed to the 80% of the X-ray Tube capacity.

7. After performing both procedures (for Small and Large Focal Spots), select in calibration mode each combination of the available mA stations at the kV break points (40, 50, 80 and 120 kV). Press the “AEC Rese t” push-button to read on the kV Display the new value of the Filament Current Number stored for each combination and record the new values in the Data Book.

Note that the highest mA station for Small Focal Spot may have numbers larger than the lowest mA station for Large Focal Spot. This is normal.

8. Exit calibration mode.

9. Repeat the above calibration process for the second tube.

10. Turn the Generator power OFF and set Dip Switch 3000SW2-4 on the

HT Controller Board in “Off” position (Digital mA Loop Closed).

2.5.2 MANUAL CALIBRATION OF DIGITAL mA LOOP OPEN

This procedure describes the Manual calibration of all the Filament Current Numbers. It has to be also used to calibrate the kV / mA combinations not performed during Auto-calibration procedure because it has not been completed. These combinations have the Filament Current Number set to “344”, so only these combinations have to be manually calibrated as described in this procedure.

Manual Calibration is initiated at the 80 kV break point by entering the appropriate Filament Current Number for the proper tube current at each selectable mA. Calibration at the other kV break points (40, 50, 80 and 120 kV) are obtained by adding or subtracting values as indicated in Table 2-1.

Although the suggested values (Table 2-1) could change depending on the X-ray tube used, entering those values will approximate accurate calibration without making excessive exposures.

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Table 2-1 mA Calibration Numbers Change

mA STATION

40 50 80 120

FILAMENT CURRENT NUMBERS AT kV BREAK POINT

10 A1+7 A1+6 A

12.5 A2+7 A2+6 A

16 A3+7 A3+6 A

20 A4+7 A4+6 A

25 A5+7 A5+6 A

32 A6+7 A6+6 A

40 A7+7 A7+6 A

50 A8+7 A8+6 A

64 (or63or65) A9+7 A9+6 A

80 A10+7 A10+6 A

100 A11+10 A11+8 A

125 A12+10 A12+8 A

160 A13+10 A13+8 A

200 A14+10 A14+8 A

A1-- 5

A2-- 5

A3-- 5

A4-- 5

A5-- 5

A6-- 5

A7-- 5

A8-- 5

A9-- 5

A10-- 5

A11-- 7

A12-- 7

A13-- 7

A14-- 7

250 A15+10 A15+8 A

320 A16+14 A16+11 A

400 A17+14 A17+11 A

500 A18+14 A18+11 A

640 (or 630 or 650) A19+14 A19+11 A

800 A20+14 A20+11 A

A15-- 7

A16-- 9

A17-- 9

A18-- 9

A19-- 9

A20-- 9

Note.-- The mA station values depends on the Generator model. Some models do not contain all the mA stations listed above.

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HF Series Generators

Calibration

In calibration mode, Filament Current Numbers are shown on the kV Display by pressing the “AEC Reset” push-button after selecting the respective kV / mA combination. They can be changed by pressing the “Increase” and “Decrease” (or “+1” and “-- 1 ”) density push-buttons and stored by pressing the “AEC Reset” push-button.

The kV Display shows again the kV when the “AEC Reset” push-button is released. Note that in calibration mode, only the mA stations and kV (at the break points) can be selected.

Note .

If an exposure is made while displaying a Filament Current Number, the kV of the exposure is the previously displayed kV.

1. With the Generator power OFF, set:

G Dip switch 3000SW2-2 on the HT Controller Board in “Off” position

(enables Filament and Rotor Interlocks).

G Dip switch 3000SW2-4 on the HT Controller Board in “On” position

(Digital mA Loop Open / Filament Current Constant).

G Remove the link between the banana plug connections on the HV

Transformer. Connect the mAs Meter to the banana plug connections to measure mA or mAs.

2. Turn the Generator ON and select one available workstation for the X-ray Tube selected. This workstation has to be one of the previously configured as “Direct”.

3. Check that the Heat Units available for the X-ray Tube are 100% (kV Display shows “H -- --” on the Console).

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HF Series Generators

Calibration

4. Enter calibration mode and according to X-ray Tube ratings or maximum Generator power, check which kV / mA combinations in Table 2-1 are allowed.

If error “Tube Overload” is shown on the Console after selection of a kV / mA combination, it means this combination is not allowed for the selected X-ray Tube. In calibration mode, if Generator power is exceeded by a kV / mA combination selection, error “E-16” is shown on the Console after “Preparation”. To reset this error, press “AEC Reset ” push-button.

Note which combinations in Table 2-1 can not be calibrated by making exposures (combinations not allowed due to Tube rating, maximum Generator power, space charge, etc.) and the Exposure Time assigned to these combinations in calibration mode.

Exit calibration mode and select the mA station and Exposure Time of each kV / mA combination not allowed. Increase or decrease the kV value as required to determine the kV value allowed nearest to the kV value of the combination. Note the kV value allowed in the respective cell of Table 2-1.

Note .

5. Enter calibration mode and select 80 kV and the lowest mA station available (first combination available). Enter a filament number of “344” for this combination.

6. Make an exposure. The mAs read on the mAs Meter must be the mAs displayed on the Console ±0.1mAs(tolerance of the parameter and mAs Meter). If the mAs read is close to zero, increase the filament number in big steps (a.e. increase values in 40). As the mAs read is close to the mAs displayed on the Console, increase (or reduce) the filament number in smaller steps (a.e. increase value in 30, 20, 10, ...).

If the mAs is low, increase the filament number. If the mA is high, decrease the filament number. Press the “AEC Reset” push-button before making a new exposure. Repeat until the mA station is calibrated.

Press the “AEC Reset” push-buttonto store the new data (filament number) before selecting the next kV or mA stations.

Calibration data (presently in memory) may or may not be close to your requirements. If it is not close, the potential exists to damage the X-ray tube (i.e. too much mA). Thus, as you start the mA calibration procedure note how close or how far off the mA break points are. If a large adjustment (more than 40 points) is required at the low mA stations, make estimated adjustments to the high mA stations before

those

exposures are made.

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Calibration

7. Select the next mA station at 80 kV. Before making any exposure, enter as filament number the value calibrated for the previous mA station increased in 10.

8. Complete the calibration process for all mA stations at 80 kV as described before. When select the first mA station for the Large Focal Spot, enter as a filament number the value calibrated for the first mA station for the Small Focal Spot. Note that the highest mA station for Small Focal Spot may have numbers larger than the lowest mA station for Large Focal Spot. This is normal.

Press the “AEC Reset” push-button to read on the kV Display the new value of the Filament Current Number stored for each mA station at 80 kV. Record the new values in the Data Book.

Note .

When highest mA stations of the Generator can not be calibrated at 80 kV due to insufficient filament current, perform the following modification in the equipment:

Insufficient filament current: reached the maximum number (999), replace on the Filament Board (A3004--05) the Resistor R26 for another resistor with

1.5

Ω /

5 W, and place Jumper JP1 in position “A”. Then rename

the Filament Board as A3004--06.

ATTENTION: After doing the above modification reduce the value of all the filament current numbers (column for 80 kV) at the 25% and perform the calibration procedure again (from step-4).

9. Completethe calibration process for the remaining kV / mA combinations using Table 2-1 as a guide. It is not necessary to make exposures to do this. Compute the value for all the kV break points of each available mA station although the Generator power can not reach all the kV / mA combinations. Select the corresponding kV / mA combination and enter the computed value.

If the filament current number has

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Calibration

10. Check calibration at all allowed kV / mA combinations by making exposures and correct any calibration points as needed.

Note .

If “Tube Overload” error is shown directly on the Console after selection of an allowed combination (refer to step-4.), wait until the X-ray tube anode cools down to permit the calibration of the mA station.

11. Recalculate the values of the non-allowed combinations in accordance to the new values obtained by the previous exposures. (Refer to Table 2-1).

12. Exit calibration mode.

13. Select the mA station, Exposure Time and kV value noted for each kV / mA combination not allowed (refer to step-4.). Check calibration at these kV / mA combinations by making exposures. If needed, enter in calibration mode and correct the Filament Current Number of the respective kV / mA combination not allowed.

14. Incalibration mode, select each combination of the available mA stations at the kV break points (40, 50, 80 and 120 kV). Press the “AEC Rese t” push-button to read on the kV Display the new value of the Filament Current Number stored for each combination. Record the new values in the Data Book.

Note that the highest mA station for Small Focal Spot may have numbers larger than the lowest mA station for Large Focal Spot. This is normal.

15. Exit calibration mode.

16. Repeat the above calibration process for the second tube.

17. After calibration of Filament Current Numbers:

G Switch the Generator power OFF.

G Disconnect the mAs Meter to the banana plug connections.

G Re-install the link between the banana plug connections on the HV

Transformer.

G Set Dip Switch 3000SW2-4 on the HT Controller Board in

“Off” position (Digital mA Loop Closed).

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Page 25

2.6 AEC CALIBRATION

This section describes the adjustments needed to calibrate the AEC according to the customer input. Therefore, AEC exposures will be made during the calibration process in order to insure AEC functionality.

The Optical Density is controlled by the values stored in the respective memory locations. These values are influenced by film speed, screen speed, dark room procedures and customer requirements.

Use a homogeneous Phantom with enough density to produce an exposure of 100 ms, the AEC will be calibrated to produce a density of 1.0 (or the customer preference Optical Density) at 70 kV, and then AEC tracking will be adjusted to produce the same density at 55 kV, 90 kV and 110 kV.

HF Series Generators

Calibration

Note .

For AEC calibration, use the same Film and Cassettes used by the customer. AEC calibration must be performed

using the Medium Film/Screen speed combination. The Medium Film/Screen speed has to be double of the Slow and half of the Fast (a.e. 200--Slow, 400--Medium, 800--Fast).

When using CR (Computer Radiography) or DR (Digital Radiography) instead of measuring Optical Density:

-- measure the Image Gray level by using the needed software

tools inside each application (refer CR or DR documentation).

-- or measure the Dose level:

-- For CR, placing the Dosimeter as close as possible to the

Cassette and centered with the Central Area of the Ion Chamber.

-- For DR, placing the Dosimeter as close as possible to the Panel, centered with the Central Area of the Ion Chamber and with the Grid removed.

The following table indicates the Memory Locations related to AEC Calibration.

FUNCTION MEMORY LOCATION

AEC-1 CALIBRATION E04

AEC-1 TRACKING E08

AEC-2 CALIBRATION E09

AEC-2 TRACKING E10

AEC-3 CALIBRATION E20

AEC-4 CALIBRATION / PHOTOMULTIPLIER AEC CALIBRATION E23

AEC-3 and AEC-4 TRACKING (equal value for both) E24

AEC DENSITY SCALE E12

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HF Series Generators

(

f1)

Calibration

Illustration 2-1 Automatic Exposure Control

Jumper

Adjustment (Potentiomer)

ATP Console CPU Microprocessor

EXP ORDER

Data Bus

Vref

DAC

V out

COMPARATOR

Reference

Ramp

(from Ion Chamber)

AEC STOP

to cut the exposure

STRT DR

DAC Vout (Reference) (calibration data setting)

Ion Chamber Output

EXP Start

AEC STOP (AEC CONTROL PCB)

2.6.1 PREVIOUS CHECKS

Make sure the automatic processor works correctly, and the concentration and temperature of the solutions comply with manufacturer specifications.

Obtain a sensitometric curve to determine gamma (γ) of the film and the solution quality. The procedure normally requires a sensitometer,but if it is not available proceed as follows:

1. Make two exposures using the same kV and Film/Screen combination

AEC Function Waveform

EXP Stop

(medium is recommended) but with different mAs settings, mAs(f1) and mAs(f2).

2. Develop and measure the Density (d) of each, d(f1) and d(f2).

3. Determine gamma (γ) by the formula:

d(f2) − d(f1)

γ =

log

mAs(f2) mAs

Gamma (γ) must be between 2 and 3, if not change or renew solutions.

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2.6.2 BALANCE ADJUSTMENT FOR THREE FIELD DETECTORS

HF Series Generators

Calibration

Note .

Some Ion Chambers does not provide balance potentiometers for Three Field Detectors. Continue calibration process in Section

2.6.3 “Optical Density Adjustment”.

1. Set the Master Gain potentiometer of the Ion Chambers to mid range (refer to Ion Chamber documentation).

2. Set the following jumper on the AEC Control Board in position A: JP3 for Board A3012--x1/x2/x5 or JP2 for Board A3012--x6/x7/x9.

3. Set SID at the Focal Distance of the Grid installed in the Table Bucky (usually 100 cm) or in the Vertical Bucky Stand (usually 150 cm).

4. Collimate the X-ray beam so that it completely covers all three fields but does not extend beyond limits of the phantom.

5. Place Copper plates (or equivalent homogeneous phantom) in the Collimator Filter Holder: 1.5 mm for SID of 100 cm, 1 mm for SID 150 cm. (1 mm Copper

6. Enter in calibration mode and verify that AEC Calibration number in E04, E09, E20 and E23 Memory Locations is 70. The range for AEC calibration numbers are from 20 to 120. Then exit from calibration mode.

≃

10 cm Plexiglass or Water).

7. Select on the Console:

G A Workstation configured for the Ion Chamber to be calibrated.

G RAD: 70 kV, 200 mA Large Focus (or the first mA station for Large

Focus if 200 mA station is set for Small Focus) and 1 second back-up time.

G AEC: “Central Area”,“Density 0” and “Medium Film/Screen”.

8. Make an exposure without film in the cassette and note the Exposure Time displayed on the Console, it should be approximately 100 ms. If necessary, change the Copper thickness or mA station and make the exposure again. (Last exposure parameters are displayed by pressing the “AEC Reset” button of the Console.)

9. Deselect “Center Area” and select “Left Area”. Make an exposure without film in the cassette and record the Exposure Time. If this time is not equal to the “Center Area”time(± 7%), check that the Ion Chamber is parallel to the X-ray Tube and make an exposure again. If it is parallel, adjust “Left Area” balance potentiometer to increase or decrease Exposure Time. Repeat this process until both Exposure Times for “Center Area” and “Left Area” are equal.

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Calibration

10. Deselect “Left Area” and select “Right Area”. Make an exposure without film in the cassette and record the Exposure Time. If this time is not equal to the “Center Area”time(± 7%), adjust “Right Area” balance potentiometer to increase or decrease Exposure Time. Repeat process until both Exposure Times for “Center Area” and “Right Area” are equal.

11. Check that the three scan Areas have equal Exposure Time (± 7%):

G “Center Area”with“Left Area”, “Center Area”with“Right Area”,

and “Left Area”with“Right Area”.

G All three Areas.

2.6.3 OPTICAL DENSITY ADJUSTMENT

Note .

The Film Optical Density must be measured always on the same point for all the X-ray Films developed during this procedure.

The recommended point is on the central axis of the Film with relation of the Anode and Cathode and as close as possible to center of the Film.

Illustration 2-2 How to measure the Film Optical Density

USEFUL BEAM

DENSITOMETER

FILM

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Calibration

ION CHAMBERS WITH DETECTOR GAIN SWITCHES OR WITH POTENTIOMETER

1. Set the Detector Gain switches (or gain potentiometer) of the Ion Chamber to mid range (refer to Ion Chamber documentation). (If the Ion Chamber is provided with the Generator, this adjustment is Factory set.)

The following tables indicate the switch position for the “Vacutec”Ion Chamber ( Factory set).

VACUTEC ION CHAMBER -- BAK 70 151 with Amplifier 70 901

SWITCH POSITION SW1 SW2 SW3 SW4

0.1 V / µGy (10 V≃ 100 µGy)

GAIN

OUTPUT SIGNAL

NORMAL FACTORY SELECTION: 1 V / µGy (10 V≃10 µGy) - Positive

VACUTEC DIGITAL ION CHAMBER -- BAK 70 151 with Amplifier 70 902

SWITCH POSITION SW1 SW2 SW3 SW4

GAIN

OUTPUT SIGNAL

0.5 V / µGy (10 V≃ 20 µGy)

1V/µGy (10 V≃ 10 µGy)

2V/µGy (10 V≃ 5 µGy)

Positive ON

Negative OFF

0.1 V / µGy (10 V≃ 100 µGy)

0.5 V / µGy (10 V≃ 20 µGy)

1V/µGy (10 V≃ 10 µGy)

2V/µGy (10 V≃ 5 µGy)

4V/µGy (10 V≃ 2.5 µGy)

Positive or Negative polarity of the ramp signal is selected with a switch at the Ramp Module.

The Ramp Module is a 9-pin Sub-D connector plugged to the Ion Chamber cable.

Positive polarity of the ramp signal is factory set.

OFF OFF OFF

ON OFF OFF

OFF ON OFF

OFF OFF ON

OFF ON OFF ON

OFF OFF OFF OFF

OFF OFF OFF ON

OFF OFF ON OFF

OFF ON OFF OFF

ON OFF OFF OFF

NORMAL FACTORY SELECTION: 1 V / µGy (10 V≃10 µGy) - Positive

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OFF OFF ON OFF

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Calibration

2. Set the following jumper on the AEC Control Board in position A: JP3 for Board A3012--x1/x2/x5 or JP2 for Board A3012--x6/x7/x9.

3. Set SID at the Focal Distance of the Grid installed in the Table Bucky (usually 100 cm) or in the Vertical Bucky Stand (usually 150 cm).

4. Collimate the X-ray beam so that it completely covers all three fields but does not extend beyond limits of the phantom.

5. Place Copper plates (or equivalent homogeneous phantom) in the Collimator Filter Holder: 1.5 mm for SID of 100 cm, 1 mm for SID 150 cm. (1 mm Copper

≃

10 cm Plexiglass or Water).

6. Enter in calibration mode and verify that AEC Calibration number in E04, E09, E20 and E23 Memory Locations is 70. The useful range for AEC calibration numbers is from 20 to 120. Then exit from calibration mode.

7. Select on the Console:

G A Workstation configured for the Ion Chamber to be calibrated.

G RAD: 70 kV, 200 mA Large Focus (or the first mA station for Large

Focus if 200 mA station is set for Small Focus) and 1 second back-up time.

G AEC: “Central Area”,“Density 0” and “Medium Film/Screen”.

8. Make an exposure without film in the cassette and note the Exposure Time displayed on the Console, it should be approximately 100 ms. If necessary, change the Copper thickness (or if needed change the mA station) and make the exposure again. (Last exposure parameters are displayed by pressing the “AEC Reset” button of the Console.)

9. Insert a cassette with the Medium Film/Screen combination used by the customer. Make an exposure, develop the film and check the Optical Density, it should be 1.0 (or the customer preference O. Density).

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10. To change the density:

HF Series Generators

Calibration

G For Ion Chamber with Gain switches

-- If the Optical Density obtained is 33% above of the desired density, increase the gain with the switches. Repeat step-9.

-- If the Optical Density obtained is 33% below of the desired density, decrease the gain with the switches. Repeat step-9.

-- If the Optical Density obtained is in between 33% of the desired density, change the AEC calibration number. Enter in calibration mode, set the new AEC calibration number for the respecetive Memory Location (E04, E09, E20 or E23). The Optical Density increases / decreases when the calibration number is increased / decreased. Then exit calibration mode. Repeat step-9.

G For Ion Chamber with Master Gain potentiometer

potentiometer until the desired density is obtained by repeating step-9. If the adjustment is not achieved with the Master Gain potentiometer, change the AEC calibration number. Enter in calibration mode, set the new AEC calibration number for the respecetive Memory Location (E04, E09, E20 or E23). The Optical Density increases / decreases when the c alibration number is increased / decreased. Then exit calibration mode. Repeat step-9.

, adjust this

Note .

The AEC accuracy is better in all the useful range as the AEC calibration number is closer to 70.

11. Repeat the above steps for all the Ion Chambers installed with the Generator.

12. Record these values in the Data Book.

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Calibration

ION CHAMBERS WITHOUT DETECTOR GAIN SWITCHES OR WITHOUT POTENTIOMETER

1. Set the following jumper on the AEC Control Board in position B: JP3 for Board A3012--x1/x2/x5 or JP2 for Board A3012--x6/x7/x9.

2. Set to mid range, the following potentiometer on the AEC Control Board: R10 for Board A3012--x1/x2/x5 or R22 for Board A3012--x6/x7/x9.

Note .

The density adjustment of ALL the Ion Chambers in the system are affected by this potentiometer.

3. Set SID at the Focal Distance of the Grid installed in the Table Bucky (usually 100 cm) or in the Vertical Bucky Stand (usually 150 cm).

4. Collimate the X-ray beam so that it completely covers all three fields but does not extend beyond limits of the phantom.

5. Place Copper plates (or equivalent homogeneous phantom) in the Collimator Filter Holder: 1.5 mm for SID of 100 cm, 1 mm for SID 150 cm. (1 mm Copper

7. Select on the Console:

G A Workstation configured for the Ion Chamber to be calibrated.

G RAD: 70 kV, 200 mA Large Focus (or the first mA station for Large

Focus if 200 mA station is set for Small Focus) and 1 second back-up time.

≃

10 cm Plexiglass or Water).

G AEC: “Central Area”,“Density 0” and “Medium Film/Screen”.

8. Make an exposure without film in the cassette and note the Exposure Time displayed on the Console, it should be approximately 100 ms. If necessary for that, change the Copper thickness (or if needed change the mA station) and make the exposure again. (Last exposure

parameters are displayed by pressing the “AEC Reset” button of the Console.) Take note of the final Copper thickness and mA station

selected.

9. Repeat the above steps for each Ion Chamber.

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HF Series Generators

Calibration

10. Insert a cassette with the Medium Film/Screen combination used by the customer. Make an exposure with each Ion Chamber (use the final Copper thickness and the selected mA station noted before), develop the film and take note of the Optical Density measured for each Ion Chamber.

11. Take the maximum and minimum value of the O. Densities measured before, sum them and divide the result by two. Subtract this value from density 1.0 (or the customer preference O. Density) to obtain the O. Density difference.

O.D. difference = O.D. customer preference --

O.D. max + O.D. min

Calculate the new O. Density b y adding the O. D. difference (with its sign + or --)to the value of the O. Density measured for the Ion Chamber closer to 1.0 (or the customer preference O. Density).

new O.D. = O.D. mesured + (O.D. difference)

For this Ion Chamber, adjust the potentiometer (turning it clockwise will decrease the O. Density) R10 for Board A3012--x1/x2/x5 or R22 for

Board A3012--x6/x7/x9 (at least one turn). Make another exposure, develop the film and check the Optical Density. Repeat this action (adjusting the potentiometer and making exposures) until the new Optical Density (calculated before) for this Ion Chamber is obtained.

12. The Optical Density for each Ion Chamber has to be adjusted to 1.0 (or the customer preference O. Density).

Enter in calibration mode, select the AEC calibration number for the respective Memory Location (E04, E09, E20 or E23). Change the AEC calibration number: the Optical Density increases / decreases when the calibration number is increased / decreased. Then exit calibration mode.

CA-1004R4

Note .

Make another exposure, develop the film and check the Optical Density. Repeat this action (changing the respective Memory Location and making exposures) until the desired Optical Density is obtained.

The AEC accuracy is better in all the useful range as the AEC calibration number is closer to 70.

13. Repeat step-12. until the desired Optical Density for each Ion Chamber is obtained.

14. Record all the values for the Memory Locations in the Data Book.

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HF Series Generators

Calibration

2.6.4 kV COMPENSATION

To maintain constant AEC Optical Density regardless of the kV at which a film is exposed, the Generator provides kV compensation. (Referto Illustration 2-3)

Perform the following steps to determine whether or not AEC Tracking of Optical Density must be adjusted.

1. Enter in calibration mode and verify that AEC Tracking number in E08, E10 and E24 Memory Locations is “0”. Then exit from calibration mode and Service mode.

2. Select on the Console:

G A Workstation configured for the Ion Chamber to be calibrated.

G RAD: 55 kV, 200 mA Large Focus (or the first mA station for Large

Focus if 200 mA station is set for Small Focus) and 1 second back-up time.

G AEC: “Central Area”,“Density 0” and “Medium Film/Screen”.

3. Make an exposure without film in the cassette and check that the Exposure Time is lower than 1 second. If necessary for that, change the Copper thickness (or if needed change the mA station) and make the exposure again. Take note of the final Copper thickness and mA station selected for 55 kV.

4. Select 90 kV. Make an exposure without film in the cassette and check that the Exposure Time is higher than 20 ms. If necessary for that, change the Copper thickness (or if needed change the mA station) and make the exposure again. Take note of the final Copper thickness and mA station selected for 90 kV.

5. Select 110 kV. Make an exposure without film in the cassette and check that the Exposure Time is higher than 20 ms. If necessary for that, change the Copper thickness (or if needed change the mA station) and make the exposure again. Take note of the final Copper thickness and mA station selected for 110 kV.

6. Insert a cassette with the Medium Film/Screen combination used by the customer. Make an exposure at 55 kV and 90 kV (use the final Copper thickness and the selected mA station noted before for each kV),develop the film and measure the Optical Density obtained with those exposures. Check that the film variation range is the same ±0.2 of the Optical Density (±20% of Image Gray Level / Dose Level with CR or DR) obtained before at 70 kV (Density Gain Adjustment -- Section 2.6.3).

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Calibration

7. If the variation value is not ±0.2 of the Optical Density (±20% of Image Gray Level / Dose Level with CR or DR) calculate the new value for the AEC Tracking number in each Memory Location in the following manner:

G If the Optical Density at 55 k V has to be decreased and the Optical

Density above 70 kV has to be increased then increase the Tracking value in one.

G If the Optical Density at 55 kV has to be increased and the Optical

Density above 70 kV has to be decreased then decrease the Tracking value in one.

Note .

AEC-kV

TRACKING

CURVE

VAL UE T O E NTER

IN THE MEMORY

LOCATION

A tracking value of 10 will have no effect on AEC density (used in solid state detectors).

a. Enter in calibration mode and select the respective Memory

Location (E08, E10 or E24).

b. Values for AEC Tracking range is from --10 to +10. Determine the

correct value for the needed AEC Tracking change.

+10 +9 +8 +7 +6 +5 +4 +3 +2 +1

10 9 8 7 6 5 4 3 2 1

c. Enter the new value and store it by pressing the “AEC Reset”

push-button. Exit calibration mode and repeat this process from step-6. until the desired density compensation is obtained.

8. Insert a cassette with the Medium Film/Screen combination used by the customer. Make an exposure at 110 kV (use the final Copper thickness and the selected mA station noted before for 110 kV), develop the film and measure the Optical Density obtained with those exposures. Check that the film variation range is the same ±0.2 of the Optical Density (or ±20% of Image Gray Level / Dose Level with CR or DR) obtained before at 70 kV (Density Gain Adjustment -- Section 2.6.3). If the variation value is not ±0.2 repeat step-7.

-- 1 -- 2 -- 3 -- 4 -- 5 -- 6 -- 7 -- 8 -- 9 -- 1 0

255 254 253 252 251 250 249 248 247 246

CA-1004R4

Note .

Calibration of AEC Tracking at 110 kV modifies the adjustment done at 55 kV and 90 kV. Repeat exposures of step-6. and check that they are correct.

In case that the AEC Tracking at 110 kV places the adjustment at 55 kV and 90 kV out of range, choose the AEC Tracking value more convenient for the application.

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HF Series Generators

Calibration

Illustration 2-3 AEC kV Tracking Curve

250

200

9. Record all the values for the Memory Locations in the Data Book.

10. Repeat the above steps for all the Ion Chambers installed with the Generator.

11. Record all the values for the Memory Locations in the Data Book.

150

100

DAC OUTPUT in byte (8 Bit) (U3-2 of AEC Control Board)

-- 2

-- 4

-- 6

-- 8

-- 1 0

-- 5 0

40 50 60 9070 80 100 110 120 130 140 150

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HF Series Generators

2.6.5 PHOTOMULTIPLIER RAD--AEC (DIGITAL RAD) ADJUSTMENT (OPTIONAL)

The Photomultiplier RAD--AEC (Digital RAD) adjustment can b e performed in two ways: one is the value stored in E23 Memory Location and the other is the high voltage applied to the Photomultiplier Tube.

The recommended procedure for this adjustment is to store a constant value in E23 Memory Location and adjust the high voltage applied to the Photomultiplier Tube.

Calibration

Note .

Value in E23 Memory Location is a common data used for Photomultiplier AEC Calibration or used for the Fourth Ion Chamber Calibration (AEC-4).

Perform the following procedure:

1. Enter in calibration mode. Select E23 Memory Location and set a value of “127”. Then exit from calibration mode and Service mode.

2. Set up a Dosimeter as close as possible to the Image Intensifier Radiation Input to measure the Entrance Image Intensifier Exposure Dose Rate. Position the Probe at the center of the primary beam with the entire active volume within the primary beam. Select the Field of View for the Image Intensifier to have 9” FOV.

Place the Tube-Collimator Assembly at the normal SID (1 meter). Collimate the X-ray beam so it completely covers the Image Intensifier field but does not extend beyond limits of the phantom.

CA-1004R4

3. Place 2 mm of Copper (or equivalent homogeneous phantom) in the Collimator Filter Holder. (1 mm Copper

4. Select on the Console:

G RAD: 70 kV, 200 mA Large Focus (or the first mA station for Large

Focus if 200 mA station is set for Small Focus) and 1 second back-up time.

G AEC: “Central Area”,“Density 0” and “Medium Film/Screen”.

≃

10 cm Plexiglass or Water).

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HF Series Generators

Calibration

5. According to software installed on the ATP Console CPU Board:

G for software V4Rx or V5Rx: Before “Prep” is activated on the

Console, select the Photomultiplier (--PT SEL / --SFC signal = GND on TS3-7 Generator Cabinet) and select Digital RAD (--DSI SEL signal = GND on J13--5 ATP Console CPU Board). Hold “Prep” and adjust the high voltage applied to the Photomultiplier Tube with the following potentiometer on the AEC Control Board: R12 for Board A3012--x1/x2/x5 or R23 for Board A3012--x6/x7/x9; until measure --400 VDC between TS1--39 and TS1--42 (GND) in the Generator Cabinet.

G for software V6Rx or greater: Select a Digital Workstation

configured for Device = DSI. Activate “Digital Prep”(--DIGITAL PREP signal = GND on TS3-7 Generator Cabinet). Hold “Digital Prep” and adjust the high voltage applied to the Photomultiplier Tube with the following potentiometer on the AEC Control Board: R12 for Board A3012--x1/x2/x5 or R23 for Board A3012--x6/x7/x9; until measure --400 VDC between TS1--39 and TS1--42 (GND) in the Generator Cabinet.

Note .

6. The Dose is affected in the following manner:

G Increases when the high voltage applied to the Photomultiplier

Tube is decreased. (Example: if 100

--400 VDC, 200

voltage to --300 VDC).

G Decreases when the high voltage applied to the Photomultiplier

Tubeis increased. (Example: if 100

VDC, 50

--450 VDC).

7. Make an exposure and adjust the following potentiometer on the AEC Control Board: R12 for Board A3012--x1/x2/x5 or R23 on for Board A3012--x6/x7/x9; until getting a typical Dose around 100 µR per frame (at 9” FOV)(for more information refer to the Image System

documentation).

If the photo tube voltage required is too low, decrease the AEC calibration number in the E23 Memory Location and repeat the process.

R Dose may be obtained decreasing the high

R Dose may be obtained increasing the high voltage to

R Dose is obtained with

R Dose is obtained with --400

8. Record the E23 Memory Location in the Data Book.

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2.6.6 AEC OPTICAL DENSITY SCALE

E12

AEC is calibrated with “Density 0” selected (Normal Optical Density). The Optical Density can be increased or decreased in several steps.

The variation percentage of the density scale is factory set at 25%. This variation can be set according to the customer preferences by changing the value stored in E12 Memory Location. This value applies to both tubes.

Depending on the Console model, the range of the scale is “from --2 to +2” or “from --4 to +4” (optional ).

The following tables show some examples for the variation percentage of the density scale with reference to the value stored in E12 Memory Location.

HF Series Generators

Calibration

E12

LUE

5 N x 0.90 N x 0.95 N N x 1.05 N x 1.10

10 N x 0.80 N x 0.90 N N x 1.10 N x 1.20

25 N x 0.50 N x 0.75 N N x 1.25 N x 1.50

NOTE: If the value stored in E12 Memory Location is 0, 25 or 255, the variation percentage is 25%.

E12

VAL UE

5 N x 0.82 N x 0.86 N x 0.91 N x 0.95 N N x 1.05 N x 1.10 N x 1.16 N x 1.22

10 N x 0.68 N x 0.75 N x 0.83 N x 0.91 N N x 1.10 N x 1.21 N x 1.33 N x 1.46

25 N x 0.41 N x 0.51 N x 0.64 N x 0.80 N N x 1.25 N x 1.56 N x 1.95 N x 2.44

NOTE: With scale from “--4 to +4” the useful range for the value stored in E12 Memory Location is from 1 to 25 .

DENSITY SCALE FROM --4 TO +4 (OPTIONAL) . VARIATION OVER NORMAL OPTICAL DENSITY (N)

-- 4 -- 3 -- 2 -- 1 0 +1 +2 +3 +4

DENSITY SCALE FROM --2 TO +2 . VARIATION OVER NORMAL OPTICAL DENSITY (N)

-- 2 -- 1 0 +1 +2

Record the value for E12 Memory Location in the Data Book.

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HF Series Generators

METERCALIBRATIO

Calibration

2.7 FLUORO CALIBRATION

This generator uses Pulsed Fluoro at fixed or variable rate. This technique is a series of short exposures at the TV frame rate (fixed rate) or at the selected PPS (variable rate).

Fluoro exposures are controlled by kV with a constant filament current. The kV values are manually (Manual mode) or automatically (ABC mode) adjusted to obtain the desired brightness (entrance dose rate) on the Image Intensifier.

The Fluoro calibration consists of setting values in the corresponding Extended Memory Locations for Fluoro use. The following table indicates the relationship between Fluoro and Extended Memory Locations.

Fluoro Filament Setting E17

FUNCTION MEMORY LOCATIONS

Maximum Fluoro kV E19

Fluoro mA Display Calibration at 50 kV E25

Fluoro mA Display Calibration at 80 kV E26

Fluoro mA Display Calibration at 120 kV E27

The functions of these extended Memory Locations are:

• E17 is used to store data that controls the Maximum Skin Dose Radiation at the following maximum levels (Regulation limits) (1 Rad = 8.7 mGy).

G 5 R/min (43.5 mGy/min) for systems working with Manual mode

(Non-ABC).

G 10 R/min (87 mGy/min) for systems working with Automatic mode

(ABC).

Note that in practice, the rejection limits for entrance exposure rate must be somewhat less than the maximum specified due to Dosimeter calibration accuracy. (RefertoTable2-2.)

Table 2-2 Rejection Limits Based on Meter Calibration Accuracy

METER CALIBRATION

ACCURACY

±5%

±10%

±15%

FOR 5 R/min (43.5 mGy/min) MAXIMUM FOR 10 R/min (87 mGy/min) MAXIMUM

4.75 R/min (41.3 mGy/min) 9.5 R/min (82.7 mGy/min)

4.50 R/min (39.2 mGy/min) 9.0 R/min (78.3 mGy/min)

4.25 R/min (37 mGy/min) 8.5R/min (74mGy/min)

REJECTIONS LIMITS

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HF Series Generators

Calibration

• E19 is used to set maximum Fluoro kV. This value is determined by the type of TV camera and type of images desired. For general fluoroscopic use with a conventional TV system, 120 kV is recommended. A lower maximum setting will produce more contrast on the TV system but less penetration for large patients.

• E25, E26, E27 are used to calibrate the Fluoro mA Display. These values will be shown on the Fluoro mA Display during Fluoro exposures whenever maximum PPS are selected.

Note .

The Fluoro mA Display values entered into the Extended Memory Locations E25, E26 and E27 are also used to calculate Heat Units. It is important to enter accurate values.

Fluoro functions are calibrated by performing the following steps:

1. Turn the generator ON.

Make sure that the Small Filament of the X-ray tube is properly warmed-up (at less 15 minutes).

2. Set up a Dosimeter to measure the Maximum Entrance Skin Exposure Dose Rate. Position the Probe at the center of the primary beam with the entire active volume within the primary beam.

Place the Tube-Collimator Assembly as close as possible to the Table-Top, fully open the Collimator Blades and align the Image Intensifier with the light beam. Block radiation input to Image Intensifier with a Lead Apron. (Refer to Illustration 2-4).

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3. Enter in Calibration mode and read the Filament Number at 120 kV / 10 mA. Divide this value by four (4) and enter it as starting value for E17 Memory Location (Fluoro Filament Setting).

4. Select E19 Memory Location and set the maximum Fluoro kV at120 kV or more if it is possible.

5. Exit calibration mode.

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HF Series Generators

Calibration

Illustration 2-4 Fluoro Entrance Exposure Rate Test Set-up

DIAGNOSTIC SOURCE

ASSEMBLY

OVERTABLE SOURCE

SET AS CLOSE

AS POSSIBLE

PROBE

(12”)

30 cm

IMAGE SYSTEM

USEFUL BEAM

LEAD APRON (BLOCKER)

SPOT FILM DEVICE

LEAD APRON (BLOCKER)

UNDERTABLE SOURCE

PROBE

DIAGNOSTIC

SOURCE

ASSEMBLY

TABLE TOP

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HF Series Generators

Calibration

6. Select the maximum PPS and Non-ABC mode. Make a Fluoro exposure at maximum kV that will be used in the system and measure the dose applied, it should not be over the Rejection Limits for 10 R/min (87 mGy/min) or 5 R/min (43.5 mGy/min) (refertoTable2-2.).

In case that the value is not acquired, change the Fluoro Filament Setting stored in E17 as required until it is correctly calibrated to that dose. Be in mind that radiation increases or decreases in accordance to value in E17 is increased or decreased.

7. ThemA values displayed during Fluoro exposures are stored in E25, E26 and E27 Memory Locations. The method used to obtain the Fluoro mA values is to measure the average mA using a mA meter in Fluoro.

During Fluoro exposure, mA values are read directly with a mA Meter in DC connected to the mA Test Points (banana plug connections) on the HV Transformer. Only for this purpose, remove the link between the banana plug connections on the HV Transformer.

Select the maximum PPS and Non-ABC mode. Make the following Fluoro exposures:

G Make a Fluoro exposure at 50 kV and take note below the mA

reading, this value will be used as Fluoro mA at minimum kV (E25).

G Make a Fluoro exposure at 80 kV and take note below the mA

reading, this value will be used as Fluoro mA at medium kV (E26).

G Make a Fluoro exposure at 120 kV and take note below the mA

reading, this value will be used as Fluoro mA at maximum kV (E27).

FL mA value at 50 kV

(E25)

FL mA value at 80 kV

(E26)

FL mA value at 120 kV

(E27)

8. Remove the Dosimeter and the Lead Apron (Blocker).

9. Enter in Calibration mode.

10. Select E19 Memory Location if it is required to reduce the value for the maximum Fluoro kV in the installation.

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11. Select the E25, E26 and E27 Memory Locations and store the respective mA values noted before multiplied by 10 (a.e. if the mA value noted is “3.2”, store the value “32” in the respective Memory Location).

12. Record the new values in the Data Book.

13. Exit calibration mode.

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HF Series Generators

Calibration

2.8 ABC CALIBRATION

The purpose of the ABC System is to maintain an optimum constant Image Tube Output Brightness by controlling the X-ray kV during Fluoro exams, regardless of changes in the patient opacity viewed on the TV monitor.

The closed-loop ABC System can monitor the Image Tube Output Brightness through two ways: Photomultiplier Tube or TV Camera.

2.8.1 ABC SYSTEM WITH PHOTOMULTIPLIER TUBE

Note .

This operation requires the AEC Control Board A3012--x6/x7/x9 (Digital version).

On this system the Photomultiplier current signal, which is proportional to the Image Tube Output Brightness, is used as brightness signal “PT Input”forthe ABC circuitry of the Generator. (Refer to Illustration 2-5).

This analogic signal is converted to a voltage signal in the Photomultiplier Amplifier Board and sent to a peak-detector in the AEC Control Board. The peak signal obtained is then held through a “Sample and Hold” circuitry after a synchronism pulse. The peak signal held is adapted to obtain finally the “ABC IN” signal which is so the Photomultiplier signal-peak held between synchronism pulses. This signal is then compared to a window reference.

Brightness error at the comparator output is sent as “kV Up” and “kV Down”to the Generator where is used to drive the Fluoro kV control. The closed-loop operation requires more or less brightness thru “kV Up” and “kV Down” demand signals respectively. Patient Entrance Dose is automatically varied so that optimum constant Image Tube Output Brightness is maintained.

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The optimum brightness level in ABC mode is set by adjusting Brightness Control Resistor R13 on the AEC Control Board, which controls the output of the Photomultiplier Tube High Voltage power supply on the Interface Control Board (“PT CRL” plus 5 volts programs the output to be 0 volts, and 0 volts programs the output to approximately --1200 volts). The window comparator requires an input range from 0 to +10 VDC for the “ABC IN” (the optimum brightness level will be achieved with a value between 5 and 7 VDC).

Illustration 2-5 ABC System for Photomultiplier Tube

HF Series Generators

Calibration

MONITOR

VIDEOLIGHT

CAMERA

IMAGE

TUBE

PATI EN T

X-RAY TUBE

PHOTOMULTIPLIER

(Brightness signal)

AMPLIFIER

PHOTOMULTIPLIER

BOARD (A3168-- xx)

X-RAY TABLE

PT INPUT

(Photomultiplier Voltage supply)

AEC CONTROL PCB

BRIGHT. LEVEL ADJ.

R13

I/V CONVERTER

U10

TRANSFORMER

PEAK DETECT.

PT SPLY

WINDOW ADJ.

R11 -- R14

BUFFER

SAMPLE

HOLD

CONTROL CONSOLE

HT CONTROL PCBHV

U12

WINDOW

COMPARATOR

KVUP&KVDWN

POWER MODULE

PT CRL

INTERFACE

CONTROL PCB

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HF Series Generators

Calibration

Window reference could be adjusted first to set mid-way the brightness level (+5 VDC), and second to increase or decrease the range of response and sensitivity of the kV control to input variations (brightness changes). If oscillation occurs during ABC fluoro exposure, increase the dead zone by adjusting Resistors R11 and R14 on the AEC Control Board. (Refer to Illustration 2-6 for ABC waveforms).

Illustration 2-6 ABC Waveforms in AEC Control Board

DWN PT reference (R11)

ABC IN

(U8--8)

UP PT reference (R14)

window reference

Brightness level

(Gain adj.)

-- kV Down (J1--19)

-- k V U P ( J 1 -- 6 )

High Logic

Command to drive

thefluorokVpDOWN

Command to drive

thefluorokVpUP

Adjust the ABC system for Photomultiplier Tube as follow:

1. Besure that the VideoSystem and the Image Intensifier are powered and

2. Set up a Dosimeter as close as possible to the Image Intensifier

Low

Logic

operating correctly.

Radiation Input to measure the Entrance Image Intensifier Exposure Dose Rate. Position the Probe at the center of the primary beam with the entire active volume within the primary beam.

Place the Tube-Collimator Assembly at the normal SID (1 meter), fully open the Collimator Blades and align the Image Intensifier with the light beam.

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HF Series Generators

Calibration

3. Adjust TV Camera gain for 1 volt peak-to-peak composite video output.

4. Select the maximum PPS and Non-ABC mode.

5. Place 2 mm of Copper (or equivalent homogeneous phantom) in the Collimator Filter Holder.

6. Calculate the value of the optimum radiation (that will give optimum brightness) usually is 2 μR/frame at 9” FOV (for more information refer to

Image System documentation).

Examples: For 25 frame/second optimum radiation is 3 mR/min. 2 μR/frame x 25 frame/s = 50 μR/s. 50 μR/s x 60 s/min = 3000 μR/min = 3 mR/min. For 30 frame/second optimum radiation is 3.6 mR/min. 2 μR/frame x 30 frame/s = 60 μR/s. 60 μR/s x 60 s/min = 3600 μR/min = 3.6 mR/min.

Note .

The optimum radiation value should be measured at Image Intensifier Radiation Input. Intensifier grid should be removed, if it can not be removed, this value should be multiplied by two or by the value specified as Grid Absorption Factor.

7. Make a Fluoro exposure at 70 kV and measure the radiation. Optimum radiation is obtained by modifying the Fluoro kV or the Copper thickness in the Collimator Filter Holder. First modify the Fluoro kV, if it is more than 80 kV or less than 60 kV modify the Copper thickness in 0.1 mm (or

0.2 mm). Note the value of Fluoro KV and Copper thickness used to obtain the optimum radiation.

Radiation increases when kV is increased or Copper thickness is reduced.

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HF Series Generators

Calibration

8. Perform the following adjustments in the AEC Control Board:

a. Adjust R13 in order to obtain 6 VDC on TP3 (ABC IN).

b. Select 70 kV (or the kV obtained in step-7.) and increase 2 kV and

check the increased value of voltage in TP3 (ABC-IN) (if this value has not been increased, increase 1 kV more). Note this value (consider it as KV-DOWN-SEL).

c. Select 70 kV (or the kV obtained in step-7.) and decrease 2 kV and

check the decreased value of voltage in TP3 (ABC-IN) (if this value has not been decreased, decrease 1 k V more). Note this value (consider it as KV-UP-SEL).

d. Obtain in TP1 the same voltage noted as kV-DOWN-SEL

(DOWN PT) by adjusting the Potentiometer R11.

e. Obtain in TP2 the same voltage noted as kV-UP-SEL (UP PT) by

adjusting the Potentiometer R14.

9. Select 70 kV (or the kV obtained in step-7.) and ABC mode.

10. Make a Fluoro exposure and check that the kV does not change.

11. Stop the Fluoro exposure and select 40 kV. Make a Fluoro exposure and check that the kV value goes to 70 kV (or the kV obtained in step-7.) ±2 kV without System problems.

12. Stop the Fluoro exposure and select 100 kV. Make a Fluoro exposure and check that the kV value goes to 70 kV (or the kV obtained in step-7.) ±2 kV without System problems.

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2.8.2 ABC SYSTEM WITH TV CAMERA

The ABC can be performed with an Analogic Signal Output (ABC OUT) proportional to the brightness or with the Composite Video Signal Output from the TV Camera.

The “ABC OUT” signal from the TV Camera is compatible with the Generator when the range is from 0 VDC (dark image) to 10 VDC (bright image) and the Optimum Brightness is achieved at around 6 VDC.

When a TV Camera without a direct “ABC OUT” signal is used, the Composite Video signal (which amplitude is proportional to the image tube output brightness) is sent to an RF Adaptation Board where it is transformed into an “ABC OUT” analogic signal. In this case, the brightness level is taken from a rectangular window from the center of the raster. (Refer to Illustration 2-7).

This analogic signal in the AEC Control Board (“PT Input” in Board A3012--x1/x2/x5 and “ABC OUT” in Board A3012--x6/x7/x9) is filtered, and compared to a window reference. Brightness error at the comparator output is sent as “kV Up” and “kV Down” to the Generator where is used to drive the fluoro kV control. The closed-loop operation requires more or less brightness thru “kV Up” and “kV Down” demand signals respectively. Patient entrance dose is automatically varied so that constant image tube output brightness is maintained.

HF Series Generators

Calibration

Illustration 2-7 ABC System for TV Camera

RF ADAPTATION BOARD

CAMERA

LIGHT

IMAGE

TUBE

PATI EN T

X-RAY TABLE

X-RAY TUBE

VIDEO OUTVIDEO IN

PT INPUT

(Brightness signal)

TRANSFORMER

MONITOR

AEC CONTROL PCB

ABC OUT

WINDOW ADJ.

FILTER

R5 -- C11

R11 -- R14

WINDOW

COMPARATOR

CONTROL CONSOLE

KVUP&KVDWN

HT CONTROL PCB

POWER MODULE

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HF Series Generators

Calibration

The optimum brightness level in ABC mode is set by adjusting the gain at R27 on the RF Adaptation Board. The “ABC OUT” signal requires an input range from 0 to +10 VDC (the stabilized value will be between 5 and 7 VDC).

Window reference could be adjusted first to set mid-way the brightness level (+6 VDC), and second to increase or decrease the range of response and sensitivity of the kV control to input variations (brightness changes). If oscillation occurs during ABC fluoro exposure, increase the dead zone by adjusting R11 and R14 on the AEC Control Board. (Refer to Illustration 2-8 for ABC waveforms)

For system interface, refer to RF Adaptation Board. Adjust ABC System according to the following procedures.

Illustration 2-8 ABC Waveforms in AEC Control Board

DWN PT reference (R11)

ABC IN

(U8--8)

-- kV Down (J1--19)

-- k V U P ( J 1 -- 6 )

UP PT reference (R14)

window reference

Command to drive

thefluorokVpDOWN

High Logic

Command to drive

thefluorokVpUP

Brightness level

(Gain adj.)

Low

Logic

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HF Series Generators

Calibration

2.8.2.1 ABC SYSTEM ADJUSTMENT WITH ABC SIGNAL FROM TV CAMERA COMPATIBLE WITH THE GENERATOR

1. Besure that the VideoSystem and the Image Intensifier are powered and operating correctly.

Place the Tube-Collimator Assembly at the normal SID (1 meter), fully open the Collimator Blades and align the Image Intensifier with the light beam.

3. Adjust TV Camera gain for 1 volt peak-to-peak composite video output.

4. Set Jumper JP21 in position B on the RF Adaptation Board.

5. Select the maximum PPS and Non-ABC mode.

6. Place 2 mm of Copper (or equivalent homogeneous phantom) in the Collimator Filter Holder.

7. Calculate the value of the optimum radiation (that will give optimum brightness) usually is 2 μR/frame at 9” FOV (for more information refer to

Image System documentation).

Examples:

For 25 frame/second optimum radiation is 3 mR/min. 2 μR/frame x 25 frame/s = 50 μR/s. 50 μR/s x 60 s/min = 3000 μR/min = 3 mR/min.

For 30 frame/second optimum radiation is 3.6 mR/min. 2 μR/frame x 30 frame/s = 60 μR/s. 60 μR/s x 60 s/min = 3600 μR/min = 3.6 mR/min.

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HF Series Generators

Calibration

8. Make a Fluoro exposure at 70 kV and measure the radiation. Optimum radiation is obtained by modifying the Fluoro kV or the Copper thickness in the Collimator Filter Holder. First modify the Fluoro kV, if it is more than 80 kV or less than 60 kV modify the Copper thickness in 0.1 mm (or

0.2 mm). Note the value of Fluoro KV and Copper thickness used to obtain the optimum radiation.

Note .

Radiation increases when kV is increased or Copper thickness is reduced.

9. Perform the adjustment for the window test as specified on the TV Camera manuals. This window defines the area of the image where the brightness will be captured for the ABC and it should be the 25% of the image area.

10. Adjust the TV Camera to obtain +6 VDC (or the voltage supplied by the TV Camera as optimum brightness) on TP3 (ABC IN) on the AEC Control Board (Refer the TV Camera manuals).

11. Perform the following adjustments in the AEC Control Board:

a. Select 70 kV (or the kV obtained in step-8.) and increase 2 kV and

check the increased value of voltage in TP3 (ABC-IN) (if this value has not been increased, increase 1 kV more). Note this value (consider it as KV-DOWN-SEL).

b. Select 70 kV (or the kV obtained in step-8.) and decrease 2 kV and

check the decreased value of voltage in TP3 (ABC-IN) (if this value has not been decreased, decrease 1 k V more). Note this value (consider it as KV-UP-SEL).

c. Obtain in TP1 the same voltage noted as kV-DOWN-SEL (DOWN

PT) by adjusting the Potentiometer R11.

d. Obtain in TP2 the same voltage noted as kV-UP-SEL (UP PT) by

adjusting the Potentiometer R14.

12. Select the 70 kV (or the kV obtained in step-8.) and ABC mode.

13. Make a Fluoro exposure and check that the kV does not change.

14. Stop the Fluoro exposure and select 40 kV. Make a Fluoro exposure and check that the kV value goes to 70 kV (or the kV obtained in step-8.) ±2 kV without System problems.

15. Stop the Fluoro exposure and select 100 kV. Make a Fluoro exposure and check that the kV value goes to 70 kV (or the kV obtained in step-8.) ±2 kV without System problems.

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HF Series Generators

Calibration

2.8.2.2 ABC SYSTEM ADJUSTMENT WITH ABC SIGNAL FROM TV CAMERA NOT COMPATIBLE WITH THE GENERATOR

1. Besure that the VideoSystem and the Image Intensifier are powered and operating correctly.

Place the Tube-Collimator Assembly at the normal SID (1 meter), fully open the Collimator Blades and align the Image Intensifier with the light beam.

3. Adjust TV Camera gain for 1 volt peak-to-peak composite video output.

4. Set on the RF Adaptation Board, Jumpers JP21 in position “A” and JP20 in position “B” (for negative ABC signal) or in position “C” (for positive ABC signal).

5. Select the maximum PPS and Non-ABC mode.

6. Place 2 mm of Copper (or equivalent homogeneous phantom) in the Collimator Filter Holder.

7. Calculate the value of the optimum radiation (that will give optimum brightness) usually is 2 μR/frame at 9” FOV (for more information refer to

Image System documentation).

Examples:

For 25 frame/second optimum radiation is 3 mR/min. 2 μR/frame x 25 frame/s = 50 μR/s. 50 μR/s x 60 s/min = 3000 μR/min = 3 mR/min.

For 30 frame/second optimum radiation is 3.6 mR/min. 2 μR/frame x 30 frame/s = 60 μR/s. 60 μR/s x 60 s/min = 3600 μR/min = 3.6 mR/min.

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HF Series Generators

Calibration

0.2 mm). Note the value of Fluoro KV and Copper thickness used to obtain the optimum radiation.

Note .

Radiation increases when kV is increased or Copper thickness is reduced.

10. Select the 70 kV (or the kV obtained in step-8.) and Non-ABC mode.

11. Adjust R29 (OFFSET) on the RF Adaptation Board to have 0 VDC in TP7.

12. Adjust gain at R27 (Gain) on the RF Adaptation Board to make the “ABC OUT” signal equal to +6 VDC. Measure “ABC OUT”inTP-7ofRF Adaptation Board or in TP3 (”ABC IN”) of the AEC Control Board.

13. Perform the following adjustments in the AEC Control Board:

a. Select 70 kV (or the kV obtained in step-8.) and increase 2 kV and

check the increased value of voltage in TP3 (ABC-IN). Note this value (consider it as KV-DOWN-SEL).

b. Select 70 kV (or the kV obtained in step-8.) and decrease 2 kV and

check the decreased value of voltage in TP3 (ABC-IN). Note this value (consider it as KV-UP-SEL).

c. Obtain in TP1 the same voltage noted as kV-DOWN-SEL (DOWN

PT) by adjusting the Potentiometer R11.

d. Obtain in TP2 the same voltage noted as kV-UP-SEL (UP PT) by

adjusting the Potentiometer R14.

14. Select the 70 kV (or the kV obtained in step-8.) and ABC mode.

15. Make a Fluoro exposure and check that the kV does not change.

16. Stop the Fluoro exposure and select 40 kV. Make a Fluoro exposure and check that the kV value goes to 70 kV (or the kV obtained in step-8.) ±2 kV without System problems.

17. Stop the Fluoro exposure and select 100 kV. Make a Fluoro exposure and check that the kV value goes to 70 kV (or the kV obtained in step-8.) ±2 kV without System problems.

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2.8.2.3 ABC SYSTEM ADJUSTMENT WITH NO ABC SIGNAL FROM TV CAMERA

1. Besure that the VideoSystem and the Image Intensifier are powered and operating correctly.

Place the Tube-Collimator Assembly at the normal SID (1 meter), fully open the Collimator Blades and align the Image Intensifier with the light beam.

3. Adjust TV Camera gain for 1 volt peak-to-peak composite video output.

Calibration

4. Set on the RF Adaptation Board, Jumpers JP21 in position “A” and JP20 in position “A”.

5. Select the maximum PPS and Non-ABC mode.

6. Place 2 mm of Copper (or equivalent homogeneous phantom) in the Collimator Filter Holder.

7. Calculate the value of the optimum radiation (that will give optimum brightness) usually is 2 μR/frame at 9” FOV (for more information refer to

Image System documentation).

Examples:

For 25 frame/second optimum radiation is 3 mR/min. 2 μR/frame x 25 frame/s = 50 μR/s. 50 μR/s x 60 s/min = 3000 μR/min = 3 mR/min.

For 30 frame/second optimum radiation is 3.6 mR/min. 2 μR/frame x 30 frame/s = 60 μR/s. 60 μR/s x 60 s/min = 3600 μR/min = 3.6 mR/min.

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Calibration

0.2 mm). Note the value of Fluoro KV and Copper thickness used to obtain the optimum radiation.

Note .

Radiation increases when kV is increased or Copper thickness is reduced.

9. Perform the adjustment for the window test. This window defines the area of the image where the brightness will be captured for the ABC.

a. Calculate the image area πr

(clear circle on the monitor). (r=circle

radius).

b. Calculate the 25% of the image area ( πr

c. Calculate the sides of the window: l = πr

/4).

∕4(I= side of square).

d. Mark the calculated area on the monitor (square).

e. Position jumper JP18 of RF Adaptation Board in “A”. A window will

be displayed on the monitor.

f. Adjust in the RF Adaptation Board the following potentiometers to

move the window under the frame marked on the monitor in step--d:

-- R1 potentiometer (vertical position)

-- R2 potentiometer (vertical width)

-- R3 potentiometer (horizontal position)

-- R4 potentiometer (horizontal width)

g. Once the window is configured, place JP18 in “B” again at RF

Adaptation Board.

10. Select the 70 kV (or the kV obtained in step-8.) and Non-ABC mode.

11. Adjust the gain at R27 on the RF Adaptation Board to make the “ABC OUT” signal equal to +6 VDC. Measure “ABC OUT”inTP7ofRF Adaptation Board or in TP3 (”ABC IN”) of the AEC Control Board.

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HF Series Generators

12. Perform the following adjustments in the AEC Control Board:

a. Select 70 kV (or the kV obtained in step-8.) and increase 2 kV and

check the increased value of voltage in TP3 (ABC-IN) (if this value has not been increased, increase 1 kV more). Note this value (consider it as KV-DOWN-SEL).

b. Select 70 kV (or the kV obtained in step-8.) and decrease 2 kV and

check the decreased value of voltage in TP3 (ABC-IN) (if this value has not been decreased, decrease 1 k V more). Note this value (consider it as KV-UP-SEL).

c. Obtain in TP1 the same voltage noted as kV-DOWN-SEL (DOWN

PT) by adjusting the Potentiometer R11.

d. Obtain in TP2 the same voltage noted as kV-UP-SEL (UP PT) by

adjusting the Potentiometer R14.

Calibration

13. Select the 70 kV (or the kV obtained in step-8.) and ABC mode.

14. Make a Fluoro exposure and check that the kV does not change.

15. Stop the Fluoro exposure and select 40 kV. Make a Fluoro exposure and check that the kV value goes to 70 kV (or the kV obtained in step-8.) ±4 kV without System problems.

16. Stop the Fluoro exposure and select 100 kV. Make a Fluoro exposure and check that the kV value goes to 70 kV (or the kV obtained in step-8.) ±4 kV without System problems.

CA-1004R4

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HF Series Generators

Calibration

2.9 FINAL CHECKS

Verify that all Configuration and Calibration data have been properly stored in memory.

1. Enter in calibration mode and check that the values noted for the “Filament Current Numbers” and “Extended Memory Locations” tables of the Data Book are the same that the values displayed and stored in memory. Press the “AEC Reset” button to read the stored values.

2. Exit from calibration mode and Service mode.

3. Turn the Generator OFF and verify position of dip switches on the HT Controller Board are:

G Dip switch 3000SW2-2 in “Off” position (enables Filament and

Rotor Interlocks).

G Dip switch 3000SW2-4 in “Off” position (Digital mA Loop Closed).

4. Set the Test dip switch 3024SW2-3 on the ATP Console CPU Board in

“Off” position to place the Generator in normal operating mode.

CA-1004R4