Fluke 8000 Victoreen User Manual

Victoreen® 8000

NERO® mAx

Users Manual

Fluke Biomedical

Radiation Management Services

6045 Cochran Road Cleveland, Ohio 44139

440.498.2564

www.flukebiomedical.com/rms

Table of Contents

Section 1: General Information................................................................................... 1-1

1.1 Product Description ..................................................................................... 1-1

1.2 New Features of Firmware 2.3..................................................................... 1-3

1.3 Specifications............................................................................................... 1-4

1.4 Battery Operation and Charging.................................................................. 1-5

1.5 Printing......................................................................................................... 1-6

1.6 Scope Output............................................................................................... 1-6

1.7 Procedures, Warnings, and Cautions .......................................................... 1-7

1.8 Receiving Inspection.................................................................................... 1-8

1.9 Storage........................................................................................................ 1-8

Section 2: Operation.................................................................................................... 2-1

2.1 Description................................................................................................... 2-1

2.2 General........................................................................................................ 2-1

2.3 Using the NERO mAx.................................................................................. 2-5

2.3.1 LCD Backlight Control............................................................................ 2-6

2.3.2 Measured Quantities .............................................................................. 2-7

2.4 Quick Start................................................................................................... 2-9

2.5 Modes of Operation ................................................................................... 2-10

2.5.1 Radio Mode.......................................................................................... 2-12

2.5.2 Mammo Mode ...................................................................................... 2-17

2.5.3 Fluoro Mode......................................................................................... 2-20

2.5.4 AMSE Mode......................................................................................... 2-25

2.5.5 CT Exposure Mode............................................................................... 2-28

2.5.6 Exp Mode............................................................................................. 2-30

2.5.7 HVL Mode ............................................................................................ 2-32

2.5.8 Cal Mode..............................................................................................2-43

2.5.9 Setup Mode.......................................................................................... 2-44

2.5.10 Unit ID .................................................................................................. 2-46

Section 3: Calibration.................................................................................................. 3-1

3.1 General........................................................................................................ 3-1

3.2 Calibration Check ........................................................................................ 3-1

Section 4: Troubleshooting ........................................................................................ 4-1

4.1 General........................................................................................................ 4-1

4.2 Modes of Operation ..................................................................................... 4-2

4.2.1 Radio Mode............................................................................................ 4-2

4.2.2 Mammo Mode ........................................................................................ 4-5

4.2.3 Fluoro Mode ........................................................................................... 4-5

4.2.4 AMSE Mode........................................................................................... 4-6

4.2.5 Exposure Mode & CT Exposure Mode................................................... 4-6

4.2.6 HVL Mode .............................................................................................. 4-6

4.3 Error Messages ...........................................................................................4-7

4.4 Power Up Diagnostic Messages................................................................ 4-11

4.5 Waveforms - Overshoot............................................................................. 4-12

4.6 Waveforms - Partial kV Waveforms........................................................... 4-14

4.7 Waveforms - Self Rectified ........................................................................ 4-16

4.8 Waveforms - Dental with Filament Preheat................................................ 4-16

Section 5: Maintenance............................................................................................... 5-1

5.1 Fuse Replacement....................................................................................... 5-1

5.2 Battery Replacement ................................................................................... 5-1

5.3 Routine Cleaning......................................................................................... 5-2

Appendix A: Temperature and Pressure .......................................................................A-1

A.1 Temperature and Pressure..........................................................................A-1

Appendix B: mA Limits vs. kV........................................................................................B-1

B.1 mA Limits vs. kV..........................................................................................B-1

Appendix C: Exposure and Rate Resolution and Limits..............................................C-1

C.1 Exposure and Rate Resolution and Limits...................................................C-1

Appendix D: CT Exposure Resolution...........................................................................D-1

D.1 CT Exposure Resolution..............................................................................D-1

Appendix E: Ion Chamber of Sensitive Volume............................................................E-1

E.1 Ion Chamber of Sensitive Volume ...............................................................E-1

Appendix F:

Replacement Parts .................................................................................... F-1

F.1 Replacement Parts......................................................................................F-1

F.2 Accessories ................................................................................................. F-2

General Information

Product Description

Section 1

General Information

1.1 Product Description

To proceed directly to "Quick Start", go to Section

2.4. To proceed directly to "Setup Mode", go to Section

2.5.9.

The Victoreen NERO™ mAx Model 8000, Non-invasive Evaluator of Radiation Output, uses an innovative system of menus and softkeys to provide an intuitive, user friendly operating environment. All measurement modes and options are displayed on the NERO mAx’s LCD and all functions are controlled by the 5 softkeys beneath the display and the 3 keys to the right of the display.

NOTE

The NERO mAx consists of the NERO mAx control console, detector, detector cable, filter slides, AC adapter, HVL plates, manual, Microsoft® Excel Add-in and carrying case.

The NERO mAx control console is compact and easy to use. The sophisticated electronics necessary to provide highly accurate, reproducible measurements while maintaining an intuitive, user friendly operating system are in the NERO mAx control console. The NERO mAx’s rechargeable battery is also housed in the control console. The front panel of the control console contains a backlit 240 x 64 pixel, dot matrix LCD display and eight push buttons. Connectors for power input, RS-232, printer, scope output and the NERO mAx detector are located on the control console’s rear panel.

1-1

Victoreen 8000

Operators Manual

Figure 1-1.Control Console Front Panel

Figure 1-2. Control Console Rear Panel

The NERO mAx detector contains sensors for simultaneously measuring kV, exposure or rate and invasive mA or mAs. Solid-state detectors are used to measure kV. An ion chamber, located in the top of the detector, is used for exposure/rate measurements. In addition, connectors for an external ion chamber are provided on the rear panel of the 8000 detector. The NERO mAx detector’s interface connector is also located on the detector’s rear panel. The front panel has a keyed opening for the model 8000-filter slides and a connector for mAs leads.

1-2

General Information

Product Description

The NERO mAx filter cards contain the various filters needed to accurately measure kilovoltage. Each filter card is coded so that the NERO mAx “knows” which filter is in use and its position. The NERO mAx also verifies that the filter card is valid for the selected measurement mode. In addition, the filter cards are keyed so that they may only be inserted one way. The W/Al filter card is labeled with the kVp ranges for which it is calibrated. The Mammo filter card is labeled for the x-ray tube targets for which it is calibrated.

The serial numbers of the NERO mAx control console unit, detector and filter cards must be matched in order to obtain accurate results. Since the control console unit, detector and filter cards are calibrated together, they

must be used together for accurate measurements.

1.2 New Features of Firmware Release 2.3

This release adds several new features to the Radiographic mode that give the NERO mAx greater flexibility when making kV and exposure time measurements on all types of radiographic and dental x-ray machines.

1. The %kV setting provides more time measurement options:

• Time measurements from 90%, 80%, and 75% of the peak kV.

• Pulse counting and zero crossing settings for single-phase generator time measurements.

2. User settable measurement delay allows:

• kV overshoot portion of waveform to be excluded from kV analysis.

• Exclusion of x-ray generator preheat pulses from kV and time analysis.

More information on these new features may be found in “Using a Measurement Delay” and “Using %kV and Exposure Time Measurements” at the end of Section 2.5.1--Radio Mode.

1-3

Victoreen 8000

Operators Manual

1.3 Specifications

Kilovoltage

Measured during the first 480 ms of exposure

Accuracy: 0.5 kV or ± 1% Reproducibility: 0.5 kV or ± 1% Range: W/Al 30 - 60 kV 50 - 100 kV 80 - 160 kV Mo/Mo 22 - 35 kV Mo/Rh 22 - 40 kV Mo/Al 22 - 49 kV Rh/Rh 25 - 49 kV Rh/Al 25 - 49 kV

Time To Display

Radio & Mammo: 3 seconds for 0.1 second exposure 1 second for each 32 ms of exposure time Fluoro & AMSE: 15 seconds for all exposures

Time

Measured during entire exposure at 90% rise/fall of waveform.

Accuracy: 1 ms Range: 1 ms to 60 sec

Exposure/Exposure & Rate

Measured during entire exposure; kVp corrected.

Accuracy: ± 5% Reproducibility: (Radio & Mammo Modes) ± 2% or 2 mR Range: 1 mR minimum

mAs and mA

Measured during entire exposure

Accuracy: ± 2% Reproducibility: ± 1% or 0.2 mAs Range: 1 - 1000 mA

HVL

Accuracy: ± 5% Range: .1 - 99.9 mmAl

Physical

Display: 240 x 60 pixel, super twist LCD w/ccfl backlight Power: 115 or 230 VAC External Supply. Rechargeable internal batteries supply more than

4 hours of continuous service with overnight charge.

1-4

Size: Console: 9.00" x 9.12" x 3.25" (22.86 mm x 23.17 mm x 8.26 mm) Detector: 6.56" x 3.70" x 2.58" (16.66 mm x 9.4 mm x 6.55 mm) Slides Only: 2.4" x 6.25" x 0.31" (6.1 mm x 15.88 x 0.8 mm) Operating Conditions: 10° C to 40°C (50° F to 104° F) Maximum 90% relative humidity (non-condensing) Weight: Console: 4 lbs. 9.0 oz. (2.067 kg) Detector: 1 lb. 10.4 oz. (with slide) (.747 kg) Slides Only: 2.9 oz. & 3.2 oz. (.090 kg & .094 kg) HVL Set

2.30 mm, 1.0 mm, 0.3 mm

Calibration

W/Al calibrated with 4.5 millimeters of Aluminum total filtration Mo/Mo calibrated with 30 microns of Molybdenum filtration Mo/Rh calibrated with 25 microns of Rhodium filtration Mo/Al calibrated with 1 millimeter of Aluminum filtration Rh/Rh calibrated with 25 microns of Rhodium filtration Rh/Al calibrated with 1 millimeter of Aluminum filtration

General Information

Specifications

1.4 Battery Operation and Charging

The NERO mAx has an internal rechargeable battery which provides up to four hours of continuous operation depending upon usage. The NERO mAx draws twice as much power from its from its battery when it is actively making measurements than it does when in an idle state with its backlight off. To conserve and extend battery life, the NERO mAx incorporates several power saving features. The display backlight automatically turns off after one minute of inactivity. The backlight turns on when any key is pressed or an exposure is made while in any measurement mode. In addition, the NERO mAx exits from any measurement mode after five minutes of no activity. Pressing the ENTER key restores the NERO mAx to its previous measurement mode.

The NERO mAx utilizes two levels of protection to assure reliable operation when the battery charge becomes low. The first level of protection is a warning that is displayed when there is approximately 20 minutes of battery life remaining. During this time, the AC adapter may be plugged into the NERO mAx to continue operation without interruption. The second level occurs when the battery charge is insufficient to guarantee proper operation. When this occurs, the low battery indicator in the lower left corner of the front panel illuminates and the instrument shuts down, becoming inoperable. When this happens, the AC adapter can be plugged into the NERO mAx to restore operation. The NERO mAx “remembers” what mode it was in before it shut down and returns to that mode upon power up. Pressing the ENTER key returns the NERO mAx to its measurement mode.

The battery is charged whenever the NERO mAx is connected to its AC adapter and the adapter is plugged into a suitable power source. When the power switch is on, the battery is charged at a low rate that is enough to sustain the battery’s charge. When the power switch is off, the battery is charged at a high rate.

To fully charge the battery, make sure that the NERO mAx is turned OFF, plug the AC adapter into the rear of the NERO mAx console and plug the adapter into a suitable power source. The green battery

1-5

Victoreen 8000

Operators Manual

charge indicator on the front panel of the NERO mAx console illuminates when the battery is charging. When the battery charge indicator is off, the battery is charged. It may take up to 16 hours to fully recharge a severely discharged battery.

1.5 Printing

All of the exposure results displayed by the NERO mAx may be printed automatically if desired. The data that is sent to the printer includes the NERO mAx’s mode of operation and selected options, the current time and date, and the measured data. The NERO mAx uses a standard IBM compatible PC printer cable.

With the NERO mAx turned off, plug the computer end of a standard IBM compatible PC printer cable into the printer port at the rear of the NERO mAx then plug the printer end of the cable into the printer and turn the printer on. Plug the AC adapter into the 8000 if needed (see Section 1.4--Battery Operation and Charging) and turn the instrument on. From the readout menu, select setup screen and turn the automatic printing on as follows:

SETUP CLOCK − > OFF

CAL PRINT − > ON HVL UNITS − > R EXP AIR −−− > 20.5 C 734 mmHg CT EXP DATE −−> Oct. 10, 1996 AMSE TIME −−> 10 30 45

MODE SELECT ON/OFF

From the SETUP screen, use the SELECT softkey (under column 1) to select PRINT. When PRINT is selected, the print selection blinks and a highlight (reverse video) extends across the other display field. Press the ON/OFF softkey (under column 2) to turn automatic printing to ON. Now, whenever a measurement is made, all of the measured results that are displayed on the NERO mAx’s screen will also be sent to the printer.

If the printer is off line, out of paper or is otherwise non functional, the NERO mAx will display a printer error message and printing will be disabled. If the printer becomes functional and returns to an on line status with no errors, the NERO mAx will resume printing with the next exposure.

To turn automatic printing off, follow the procedure outlined above and toggle PRINT to OFF.

1.6 Scope Output

The NERO mAx scope output provides a real time output of the radiation waveform from the NERO mAx detector. This output is from the less filtered detector; “channel A”. This signal can have a maximum amplitude of approximately 5 volts. This signal is always available at the scope output BNC connector. The NERO mAx does not need to be in a kVp measurement mode to provide a real time scope output, but the NERO mAx detector must be in the beam.

To use the real time scope output, connect the NERO mAx’s scope output to an oscilloscope input using a suitable BNC cable. Set the oscilloscope horizontal deflection controls to the desired sweep period and adjust the scope to trigger on a positive slope. Some experimentation will be necessary to get the trigger level and the vertical deflection adjusted properly. Generally, exposures made at the top of the selected kV range will have signals above one volt and exposures made near the bottom of the selected kV range will have signals in the tens of millivolts.

1-6

General Information

Procedures, Warnings, and Cautions

1.7 Procedures, Warnings, and Cautions

The equipment described in this manual is intended to be used for the detection and measurement of ionizing radiation. It should be used only by persons who have been trained in the proper interpretation of its readings and the appropriate safety procedures to be followed in the presence of radiation.

Although the equipment described in this manual is designed and manufactured in compliance with all applicable safety standards, certain hazards are inherent in the use of electronic and radiometric equipment.

WARNINGS and CAUTIONS are presented throughout this document to alert the user to potentially hazardous situations. A WARNING is a precautionary message preceding an operation that has the potential to cause personal injury or death. A CAUTION is a precautionary message preceding an operation that has the potential to cause permanent damage to the equipment and/or loss of data. Failure to comply with WARNINGS and CAUTIONS is at the user’s own risk and is sufficient cause to terminate the warranty agreement between Fluke Biomedical and the customer.

Adequate warnings are included in this manual and on the product itself to cover hazards that may be encountered in normal use and servicing of this equipment. No other procedures are warranted by Fluke Biomedical. It shall be the owner’s or user’s responsibility to see to it that the procedures described here are meticulously followed, and especially that WARNINGS and CAUTIONS are heeded. Failure on the part of the owner or user in any way to follow the prescribed procedures shall absolve Fluke Biomedical and its agents from any resulting liability.

Indicated battery and other operational tests must be performed prior to each use to assure that the instrument is functioning properly. If applicable, failure to conduct periodic performance tests in accordance with ANSI N323-1978 (R1983) Radiation Protection Instrumentation Test and Calibration, paragraphs 4.6 and 5.4, and to keep records thereof in accordance with paragraph 4.5 of the same standard, could result in erroneous readings or potential danger. ANSI N323-1978 becomes, by this reference, a part of this operating procedure.

Warning Summary

The following WARNINGS are provided for your reference and may appear throughout the NERO mAx manual:

Extreme caution should be used when making connections to the mAs terminals of the X-ray generator or detector. Improper connections may result in injury, damage to the NERO mAx, and/or damage to the x-ray generator. Tube current (mA and mAs) measurements should only be made by persons familiar with the calibration and repair of xray machines.

An electric shock hazard exists between the ion chamber bias connector and ground.

WARNING

1-7

Victoreen 8000

Operators Manual

Caution Summary

The following CAUTIONS are provided for your reference and may appear throughout the NERO mAx manual:

Use extreme caution when connecting to the mAs terminal of the detector.

If line voltage surges beyond 15% of normal, a power line conditioner must be used, otherwise damage to the charging circuit will occur.

Note Summary

In the event of a transient induced lockup of the Model 8000 NERO mAx, it is necessary to reset the unit by cycling its power (turning it off then on). After reset, the unit will power up in its normal operating mode.

1.8 Receiving Inspection

CAUTION

NOTE

Upon receipt of the package:

1. Inspect the carton(s) and contents for damage. If damage is evident, file a claim with the carrier and notify Fluke Biomedical at 440.248.9300.

2. Remove the contents from the packing material.

3. Verify that all items listed on the packing list have been received and are in good order.

1.9 Storage

If the unit is to be stored prior to use, pack it in the original container, if possible, and store in an environment free of corrosive materials, fluctuations in temperature and humidity, and vibration and shock.

Prior to use, check the condition and functionality of the device. Also check that the calibration is still valid. Periodic recalibrations are usually required by individual radiation safety and/or quality assurance programs. Please consult your local radiation safety or quality assurance office if you have any questions.

1-8

Operation

Description

Section 2

Operation

2.1 Description

The NERO mAx consists of the NERO mAx control console, detector, detector cable, filter slides, AC adapter, HVL plates, manual, Microsoft Excel Add-in and carrying case.

The NERO mAx control console is compact and easy to use. The sophisticated electronics necessary to provide highly accurate, reproducible measurements while maintaining an intuitive, user-friendly operating system are contained in the NERO mAx control console. The NERO mAx’s rechargeable battery is also housed in the control console. The front panel of the control console contains a backlit 240 x 64 pixel, dot matrix LCD display and eight push buttons. Connectors for power input, RS-232, printer, scope output and the NERO mAx detector are located on the control console’s rear panel. The ON/OFF switch is located on the right side of the control console.

The NERO mAx filter cards contain the various filters needed to accurately measure kilovoltage. Each filter card is coded so that the NERO mAx “knows” which filter is in use and its position. The NERO mAx also verifies that the filter card is valid for the selected measurement mode. In addition, the filter cards are keyed so that they may only be inserted one way. The W/Al filter card is labeled with the kVp ranges that it is calibrated for. The Mammo filter card is labeled for the x-ray tube targets that it is calibrated for.

The serial numbers of the NERO mAx control console unit, detector and filter slides must be matched in order to obtain accurate results. The control console unit, detector and filter slides are calibrated together, and

must be used together for accurate measurements.

2.2 General

Positioning the Control Console

Position the NERO mAx control console on a stable, flat surface within 25 feet of the detector. If a printer is to be used with the NERO mAx it should also be placed on a stable, flat surface.

Positioning the Detector

Correct and reproducible positioning of the NERO mAx detector in the x-ray beam is very important in obtaining accurate and reproducible results from the NERO mAx. Fluke Biomedical has printed several alignment marks on top of the detector to assure correct, reproducible positioning of the detector.

The black circle is the minimum collimated beam size required for accurate exposure, rate and kVp measurements. This circle defines the diameter of the NERO mAx’s internal ion chamber.

2-1

Victoreen 8000

Operators Manual

NOTE

The dashed gray rectangle is the minimum collimated beam size required for accurate kVp measurements only. This rectangle outlines the NERO mAx’s kV detectors. Exposure and rate results from an x-ray beam collimated to this area will be incorrect because the beam is not illuminating all of the internal ion chamber.

The black square and the dashed black crosshairs are alignment marks to aid in positioning the NERO mAx detector in the x-ray beam.

The red arrows on the detector indicate the axis of the detector that should be aligned with the x-ray tube axis for the most accurate measurements. This minimizes any heel effect.

Radiographic

Install the W/Al filter slide in the detector and set the filter slide to the desired kVp range. Position the detector under the x-ray tube with the top of the detector facing up. Align the detector along the axis of the x-ray tube to minimize heel effect. Set x-ray tube SDD (normally 26 inches) and collimate the beam size to the round or square alignment marks on the top of the detector. Align the x-ray beam by making the light field crosshairs coincident with the crosshairs on the top of the detector.

Dental

Set the detector on a flat, stable surface and position the x-ray tube so that the cone is just above the detector's top surface.

2-2

Operation

General

NOTE

Do not rest the cone on the detector. This may depress the top of the ion chamber and cause incorrect exposure measurements.

Make sure that the detector is aligned along the axis of the x-ray tube and that the tube is perpendicular to the detector's top surface and is centered over the detector crosshairs.

Mammography

Install the Mammo filter slide in the detector and set the filter slide for the x-ray machine’s target material. Position the detector under the x-ray tube with the top of the detector facing up. Align the detector along the axis of the x-ray tube to minimize heel effect. Set x-ray tube SSD (normally 26 inches) and collimate the beam size to the square alignment marks on the top of the detector. Line up the front edge of the square alignment mark on the top of the detector with the front edge (toward the chest wall) of the collimated x-ray beam.

Fluoroscopy

Install the W/Al filter slide in the detector and set the filter slide to the desired kVp range. The kVp range is the range closest to the detector front panel.

Position the detector ray tube) and align the detector along the axis of the x-ray tube to minimize heel effect. Using the centering marks provided on the table (or other centering methods), center the detector over the x-ray beam. Don protective clothing and energize the fluoroscope to view the detector on the fluoro screen. Move the fluoroscope so that the lead shield containing the NERO mAx’s detector diodes (opaque rectangle) is centered on the screen.

upside down on the table (the top of the detector must be positioned toward the x-

Collimate to this area

X-Ray Tube Axis

Fluoro Detector Positioning

2-3

Victoreen 8000

Operators Manual

For automatic brightness control machines, place appropriate shielding over the detector to drive the output to its maximum. A folded lead apron, gloves or a lead sheet may be used. For manual systems, set the machine for its maximum output and use appropriate shielding to protect the image intensifier.

Other Applications

The basic principles are the same for other applications. In general, the detector should be located 18 to 40 inches from the x-ray source. The detector should be aligned with the x-ray tube axis with the top of the detector facing the x-ray source. The detector should be in the center of the x-ray beam and the beam should be collimated to the round or square alignment marks on the top of the detector.

For chest x-ray machines, the detector may be strapped or taped to the table in front of the film cassette. For panoramic dental machines, the detector may be strapped or taped to the film cassette holder.

Inserting the Filter Slide

The NERO mAx filter slides are inserted into the front of the detector. The filter slides are keyed so that they may only be inserted one way. To insert the filter slide, place the filter slide in the opening in the front of the detector and gently push. The slide will click into place at each of its positions. Move the filter slide until the desired kVp range (W/Al) or target material (Mammo) is closest to the detector front panel (below “kVp RANGE”).

Connections to the NERO mAx

The NERO mAx detector and control console are connected to each other via a 25-foot cable. The NERO mAx power should be turned an external ion chamber to the detector or connecting the mAs leads.

off when connecting the detector to the control console, connecting

mAs Connections

Extreme caution should be used when making connections to the mAs terminals of the X-ray generator. Improper connections may result in injury, damage to the NERO mAx, and/or damage to the x-ray generator. Tube current (mA and mAs) measurements should only be made by persons familiar with the calibration and repair of xray machines.

Two mAs cables are provided with the NERO mAx; 12-ft. long mAs leads and 12-ft. long mAs extension leads. The mAs leads are black, with a miniature phone plug at one end and alligator clips at the other end, the mAs extension leads have clear insulation with two banana plugs at one end and alligator clips at the other end. The miniature phone jack of the black mAs leads plugs into the mAs jack on the front panel of the NERO mAx detector. The alligator clips may then be connected to the generator’s mAs terminals. If the black mAs leads have insufficient length, the mAs extension leads may be used to provide additional length. The mAs extension leads may be used in two ways; the extension lead banana jacks may be plugged into the generator’s mAs terminals (if the generator has banana jacks) or the extension leads may be reversed and the alligator clips can be clipped to the generator’s mAs terminals.

WARNING

The opposite end of the mAs extension leads are to be connected to the alligator clips at the end of the black mAs leads. When using the mAs extension leads, care should be used to make sure that the leads are not shorted together when they are connected.

2-4

Operation

General

The mAs leads should always be connected in the ground return of the high voltage transformer. Damage to the generator or the NERO mAx or inaccurate measurements may result if the mAs leads are connected to any point other then the ground return of the x-ray tube current. Tube current measurements should only be made on generators providing open and short circuit protection of the metering circuit and where the circuit operates near ground potential. The polarity of the mAs input signal is not important because a full wave bridge is used in the NERO mAx mAs input circuit.

Printer Connections

When using the NERO mAx with a printer, both the printer and the NERO mAx should be turned off prior to connection. The NERO mAx uses a standard IBM PC printer cable. For more information on printing with the NERO mAx, see Section 1.5--Printing.

AC Adapter

The AC adapter may be plugged into the NERO mAx at any time. For more information on using the AC adapter with the NERO mAx, see Section 1.4--Battery Operation and Charging.

Scope Output

The NERO mAx’s scope output may be connected to a suitable oscilloscope at any time. For more information regarding the real time scope output, see Section 1.6--Scope Output.

2.3 Using The NERO mAx

The NERO mAx uses an innovative system of menus and softkeys to provide an intuitive, user-friendly operating environment. All measurement modes and options are displayed on the NERO mAx’s LCD and all functions are controlled by the 5 softkeys beneath the display and the 3 keys to the right of the display.

2-5

Victoreen 8000

Operators Manual

The NERO mAx display is divided into 5 columns, each column corresponds to the push button (softkey) directly beneath it. The left most column is the “MODE” column that is used to select the NERO mAx’s operating mode. The remaining four columns (1 through 4) display various options for each mode.

A highlight (reverse video block) denotes the selected menu element in each column. A blinking highlight (reverse video block) locates the “active” menu column and highlights the selected menu element in that column.

Legends, which describe the function of each softkey, appear along the bottom of the display. These legends are separated from the rest of the display by a horizontal line. The time and date may be displayed in the upper right corner of the display.

There are eight push buttons on the front panel of the NERO mAx. The five buttons directly beneath the display are “softkeys”, their functions change according to the NERO mAx’s mode of operation. These softkeys are used to select the NERO mAx’s mode of operation and various options within each mode. These softkeys are also used to increment numerical values such as time or date. The “MODE” softkey has two functions. First, it may be used to select the NERO mAx’s operating mode. Second, it may be used to exit from any active measurement mode.

The “UP” and “DOWN” keys to the right of the display are also used to select the NERO mAx’s mode of operation and various options within each mode. The “UP” and “DOWN” buttons move the highlight up and down within each selected column to select various options. When the “UP” button is pressed, the highlight moves up one menu element and wraps around when it reaches the top of the column and returns to the bottom. When the “DOWN” button is pressed, the highlight moves down one menu element and wraps around when it reaches the bottom. If only two options are available, the highlight toggles between the two selections. In the calibration and setup modes, the “UP” and “DOWN” buttons are used to toggle between options or to increment and decrement numeric values.

The “ENTER” button to the right of the display is used to initiate data acquisition and measurement with options that have been selected. It also is used to accept numeric data in situations requiring data entry.

Each of the NERO mAx’s operating modes has a menu. All available menu options for each mode are displayed in columns 1 through 4 above each softkey. All menus are left justified. This means that changes made in columns on the left (such as the MODE column) may affect the columns of options to the right. Softkey legends appear along the bottom of the display and as the menu options change, the softkey legends change. The left most menu column is the ‘mode’ column, which displays the available operating modes. The legend above the “MODE” softkey never changes, as this key always selects the mode of operation of the NERO mAx.

Pressing the softkey under any column (MODE, 1 - 4) moves the blinking highlight into that menu column, thereby selecting that column, and moves the highlight up through the available options. The highlight wraps around when it reaches the top of the column and returns to the bottom. If only two options are available, the highlight toggles between the two selections. In the calibration and setup modes, some of the softkeys are used to toggle between options or to increment numeric values.

To make a measurement with the NERO mAx, simply highlight the desired measurement mode and options and press the enter button. For more information on a specific measurement mode, see the manual section that applies to that mode or x-ray generator type.

All of the NERO mAx’s operating modes are described in "Modes of Operation", following "Quick Start".

2.3.1 LCD Backlight Control

As a power saving feature, the NERO mAx LCD backlight turns off after one minute of no activity. The backlight turns back on when any button is pressed. When the NERO mAx backlight turns off while exposure results are being displayed, the backlight may be restored without affecting the displayed exposure results by pressing any key except the MODE key. Pressing the mode key exits from the active measurement mode and returns to the menu screen, erasing all exposure data.

2-6

Operation

Using the NERO mAx

2.3.2 Measured Quantities

The NERO mAx calculates kVp from the ratio between two differentially filtered detector channels (A&B). When an x-ray exposure is made, the NERO mAx samples the two detector channels simultaneously at a rate of 100,000 samples per second. The detector waveforms are digitized by a pair of 100 kHz 16 bit A/D converters and stored in memory.

The NERO mAx has sufficient memory to store up to 480 milliseconds of waveform data. For radiographic exposures that exceed 480 milliseconds in length, the NERO mAx stores the first 320 milliseconds of the waveform and the last 160 milliseconds. This method allows storage of both the rising and falling edges of the x-ray waveform. In the fluoro and AMSE modes, the NERO mAx stores a 480millisecond sample of the x-ray waveform after the SAVE key is pressed.

A delay of up to 999 milliseconds may be used to delay the start of kV data acquisition in the Radio and Mammo modes. This delay may be used to skip events that occur at the beginning of an exposure, such as an overshoot or undershoot. When a delay is used, only the kV data acquisition is effected. Exposure, mAs and time measurements are not delayed and are measured over the entire exposure.

After the exposure is complete, the NERO mAx searches the stored channel A and B waveforms for ratio peaks, when a peak is found it is stored. These peaks are then averaged and the average kVp is calculated. While the NERO mAx searches for ratio peaks, it also looks for the highest peak, when the highest peak is found it is stored and peak kV is calculated. Effective kV is calculated from the ratio of the integrated A and B waveforms which is analogous to the density ratio in the kVp film cassette.

When calculating kVp average in the radiographic mode, the NERO mAx only includes peaks that are above the selected %kV in its kVp average calculation. When ZERO or 1ØPULSE are selected, the NERO mAx includes all detected peaks in the kVp average calculation.

The NERO mAx calculates kV as a function (F) of the ratio between the two detector channels, A and B (r). The calculations used to calculate kV peak, kV effective and kVp average are summarized below:

kVp Average = F (r), where r is the average peak ratio B/A kV Peak = F (r), where r is the peak ratio B/A kV Effective = F (r), where r is the ratio

The calibration information that the NERO mAx uses to calculate kV is stored in nonvolatile memory in the NERO mAx control console.

∑

B/A

∑

Time

The NERO mAx measures exposure time by determining the time between the first and last passage through a preset percentage of kVp average. To accomplish this, the NERO mAx calculates the detector ratio that corresponds to the preset percentage of the exposure's kVp, then measures the time between those points on the rising and falling edges of the ratio waveform. In the Radiographic mode, the percentage of kVp average over which the NERO mAx measures radiographic exposure time may be selected using the %kV key. In the Mammographic mode, the percentage is fixed at 90% of kVp average.

In the radiographic mode, when 75%, 80%, or 90% kV is selected, the NERO mAx measures exposure time between the 75%, 80%, or 90% points on the kV waveform. When zero crossing (ZERO) is selected, the NERO mAx measures radiographic exposure time from the moment x-rays are detected until they are no longer detected. When 1ØPULSE is selected, the NERO mAx counts the number of xray pulses in a pulsed or single-phase radiographic exposure. This is primarily for use with single phase full and half wave rectified generators.

In pulsed and single-phase applications when time is measured in pulses (1ØPULSE), use of a measurement delay may introduce errors in the pulse count because the NERO mAx does not count pulses during the delay time. In pulsed and single-phase applications when time is measured at a

2-7

Victoreen 8000

Operators Manual

percentage of kV, use of a measurement delay can also introduce errors. If the delay terminates between pulses, when no x-rays are present, the NERO mAx waits until the beginning of the next pulse to begin timing. If the delay terminates during a pulse, when x-rays are present, the NERO mAx begins timing immediately.

When a delay is used in making measurements in the Radio and Mammo Modes, the NERO mAx calculates exposure time differently. If a positive measurement delay is used in making a measurement, the NERO mAx includes the delay time in its calculated exposure time. In addition, the exposure time may be slightly longer than the exposure time between the selected %kV points on the kV waveform. This is because the Model 8000 does not store the leading edge of the x-ray output waveform; it waits for the specified delay time before acquiring kVp data. Because of this, the %kV point on the rising edge of the kV waveform is not stored and the rise time of the waveform appears to be instantaneous. The difference between the actual and measured exposure times is the rise time between zero and the specified %kV. When a negative measurement delay is specified, the NERO mAx does not include the delay time in the measured exposure time. The measured exposure time is from the beginning of data acquisition or the %kV point on the first rising edge after the delay until passage through the %kV point on the falling edge of the kV waveform.

More information on using the %kV function or using a measurement delay may be found at the end of the Radio Mode section under "Using %kV and Exposure Time Measurements" or "Using a Measurement Delay".

Exposure and Exposure Rate

The NERO mAx measures exposure by integrating the signal from an ion chamber (either internal or external) and applying the proper conversion factor(s) to calculate exposure (R or Gy). Exposure rate is calculated by sampling the integrated charge from the ion chamber at one-second intervals and dividing the integrated charge by the sample period and applying the proper conversion factor(s). In the Pulsed Fluoro and AMSE modes, the NERO mAx calculates exposure per pulse or frame by sampling the integrated charge from the ion chamber at one second intervals and dividing by the number of pulses or frames that it counts in a one second interval and applying the proper conversion factor(s). The NERO mAx's ion chamber is internally vented and all exposure and rate measurements are corrected for air density based upon user entered temperature and pressure.

The NERO mAx’s internal ion chamber is factory calibrated to provide accurate exposure and rate measurements over the entire kVp range of the NERO mAx. These exposure and rate measurements are adjusted by applying energy dependent correction factors that are determined by comparison to applicable N.I.S.T. techniques.

In addition to the factory calibration, a user entered multiplier is available for exposure and rate measurements made with the NERO mAx’s internal ion chamber.

When using external ion chambers, exposure and rate are calculated using the user entered calibration factor (R/nC or Gy/nC) for the selected chamber. When making measurements in the CT Exposure mode with a CT chamber, user entered beam width is also used in calculating exposure and rate.

mAs and mA

The NERO mAx measures mAs by integrating the signal from the mAs input during an x-ray exposure. To calculate mA, the integrated signal from the mAs input is sampled at one-second intervals and divided by the sample period. In the Pulsed Fluoro and AMSE modes, the NERO mAx calculates mAs per pulse or frame by sampling the integrated signal from the mAs input at one second intervals and dividing by the number of pulses or frames that it counts in a one second interval. The mA(s) circuitry is factory calibrated using a calibrated current source and is not user adjustable.

HVL

2-8

Operation

Using the NERO mAx

ion chamber. HVL is calculated using a linear regression of the natural log of the normalized exposure versus absorber thickness in millimeters of aluminum. Below is the formula used by the NERO mAx to calculate half value layer.

()

BxAHVL +∗= ln

Where: x = Normalized dose at Half Value Layer (0.5)

A = Slope of ln(x) vs. mmAl B = Intercept of ln(x) vs. mmAl (Usually very close to zero)

2.4 Quick Start

Locate a suitable radiographic x-ray generator. Set the generator for approximately 80 kV, 100 mA, .1 seconds or 10 mAs.

CAUTION

Make sure the NERO mAx is turned off.

Plug the detector cable into the back of the NERO mAx at the connector marked DETECTOR. Plug the other end of the detector cable into the NERO mAx detector. Insert the W/Al filter slide into the front filter slot of the NERO mAx detector at the 50 - 100 kVp position.

The filter slide will click into place. Place the detector on the x-ray table at approximately 26” SDD. Make sure that the top of the detector is

facing the x-ray tube and the detector is aligned with the x-ray tube axis. Plug the AC adapter into the NERO mAx and plug the adapter into a suitable AC power outlet. Turn on the NERO mAx. After the NERO mAx performs its power up diagnostics, the main menu screen is displayed.

EXP CT EXP 1Ø PULSE AMSE ZERO FLUORO 75% MAMMO 80% LOW

RADIO 90% HIGH +10 ms

MODE %kV SENS DELAY

a. Press the MODE button, the reverse video highlight in the mode column of the display (far left

column above the mode key) will start blinking.

b. Press the down arrow key until RADIO is highlighted. c. Press the "1" key until 75% is highlighted. d. Press the "2" key to toggle sensitivity between high and low, set the sensitivity to LOW. e. Press the "3" key to change the measurement delay. Using the up and down arrow keys, set the

delay to +10 milliseconds.

f. Press the ENTER button.

Please wait a moment while the NERO mAx prepares to measure an exposure. When the NERO mAx beeps and displays MAKE EXPOSURE, make an exposure.

2-9

Victoreen 8000

Operators Manual

Wait a moment while the 8000 analyzes the exposure then displays the measured kVp, exposure, time and mAs (mAs will be zero because the mAs input was not used).

80.0

79.2

81.1

RADIO 75% LOW + 10 ms Please MODE %kV SENS DELAY Wait…

The 8000 will immediately display Please Wait… in the lower right corner of its screen while it prepares to take another exposure.

After the 8000 beeps and displays Make Exposure in the lower right corner of the display, another exposure may be made.

To stop making exposures and return to the main menu screen, press the MODE button.

kVp Avg kV Eff kV Peak

100 392

0.0

msec mR mAs

2.5 Modes of Operation

The NERO mAx Nero has ten modes of operation as listed below (in selection order):

1. RADIO

2. MAMMO

3. FLUORO

4. AMSE

5. CT EXP

6. EXP

7. HVL

8. CAL

9. SETUP

10. UNIT ID

The NERO mAx's mode of operation is controlled from the main screen. When the menu cursor (blinking reverse video) is moved to a mode selection, by pressing the mode key or using the up and down arrow keys, all of the options available for that mode are displayed. Pressing a softkey (1 thru 4) moves the menu cursor into the selected menu column and starts it blinking. Pressing the softkey again will move the blinking menu cursor up through the column of available options. Pressing the up and down arrow keys moves the blinking menu cursor up or down through the selected column of available options. After options have been highlighted, the enter key is pressed to start the selected mode with the selected options. Pressing the mode key at any time returns to the mode select screen.

UNIT SETUP CAL HVL

EXP CT EXP AMSE ZERO FLUORO 75% MAMMO 80%

RADIO 90%

MODE %kV

1Ø PULSE

LOW

HIGH 10 mS SENS DELAY

NERO mAx Operating Modes

Radio Mode

Radio mode is used to make measurements on tungsten target, aluminum filtered radiographic x-ray generators. Radio mode simultaneously measures kVp, exposure, exposure time and mAs from a single radiographic exposure. Radiographic mode may also be used to verify the NERO mAx’s kV calibration.

2-10

Operation

Modes of Operation

Mammo Mode

Mammo mode is used to make measurements on mammographic x-ray generators. Mammo mode simultaneously measures kVp, exposure, exposure time and mAs from a single mammographic exposure.

Fluoro Mode

Fluoro mode is used to make measurements on fluoroscopic x-ray generators. Fluoro mode supports both continuous fluoro and pulsed fluoro measurements. In the continuous fluoro mode, the NERO mAx measures kVp, exposure rate (R/min) and mA. In the pulsed fluoro mode, the NERO mAx measures kVp, exposure rate (R/min and mR/pulse) and mAs/pulse.

AMSE Mode

AMSE mode is used for Automated Measurement of Sequential Exposures. This mode is used to measure the output of CINE X-ray generators. In AMSE mode, the NERO mAx measures kVp, exposure rate (mR/frame), mAs/frame and time/frame (mS/frame).

CT Exposure Mode

CT Exposure mode is used to make CT exposure measurements using the Victoreen 6000-100 or 6000200 CT ion chamber. A CT probe must be connected to the NERO mAx detector’s external ion chamber input in this mode. The exposure is calculated using the user entered beam width (in mm) and the CT probe’s calibration factor (Rcm/nC). This mode functions in the same manner as the Exposure Mode with the addition of beam width entry.

Exposure Mode

Exposure mode is used to make exposure and rate measurements using the NERO mAx’s internal ion chamber or an external ion chamber. The exposure is calculated using the selected ion chamber’s stored calibration factor.

HVL Mode

In the HVL mode, the NERO mAx calculates half value layer based upon a series of exposure or rate measurements made with varying thicknesses of aluminum absorbers placed in the x-ray beam. A minimum of two exposures are required and up to ten exposures may be used. The exposure or rate measurements may be made using the NERO mAx’s internal ion chamber or an external ion chamber. Exposure and rate are calculated using the selected ion chamber’s calibration factor and when using a CT chamber, beam width.

Calibrate Mode

The Calibrate mode is used to enter and store calibration factors for ion chambers used with the NERO mAx. Calibration factors are available for the NERO mAx’s internal chamber and external chambers, including the Victoreen CT chamber.

Setup Mode

The Setup Mode is used to setup various features of the NERO mAx. From the setup screen the user can set the instruments internal real time clock, set the temperature and pressure used in air density correction of exposure measurements, select exposure units of either Roentgens or Grays, turn automatic printing on or off, turn the clock display on or off and select normal or reverse video on screen clock display.

Unit ID

Displays the NERO mAx’s serial number, firmware part number and revision.

2-11

Victoreen 8000

Operators Manual

2.5.1 Radio Mode

Radio mode is primarily used to make measurements on tungsten target, aluminum filtered radiographic x-ray machines. Radio mode simultaneously measures kVp, exposure, exposure time and mAs from a single radiographic exposure. A measurement delay of up to 999 milliseconds may be used to delay the start of kV data acquisition in order to skip over waveform anomalies at the beginning of an exposure. See "Using a Measurement Delay" (at the end of this section) for more information on using a measurement delay. The percentage of peak kV over which exposure time is measured may be selected from 90%, 80%, or 75% of the kV peak. In addition, exposure time may be measured between zero crossings or x-ray pulses may be counted (for single-phase generators). See "Using %kV and Exposure Time Measurements" (at the end of this section) for more information about using %kV.

Generally, to measure radiographic exposures, choose a filter card (kV) setting such that the measured (or expected) kV is in the upper end of the filter range. For instance, use the 50 - 100 kVp range instead of the 80 - 160 kVp range to make measurements at 80 kVp. Staying in the upper end of the filter's kVp range improves the signal to noise performance of the NERO mAx and allows the NERO mAx to "receive" more of the radiation output that improves its measurements accuracy. Also, start out in low sensitivity, if a channel A or B overrange occurs, switch to the next kVp filter range. If the NERO mAx does not respond to an exposure and displays "MAKE EXPOSURE", switch to high sensitivity.

Radio mode may also be used to make measurements on dental x-ray generators. When using the NERO mAx with dental x-ray machines, follow the instructions in section "Positioning the Detector" to properly locate the detector. Generally, low sensitivity should be used, however if the NERO mAx does not respond to an exposure, switch to high sensitivity. Select the proper %kV for the type of generator being tested, generally ZERO or 1ØPULSE modes are needed for self-rectified generators, 75%, 80%, or 90% may be needed for three phase and medium to high frequency generators. If necessary, use a measurement delay in order to disregard any filament preheat effects at the beginning of an exposure. See "Using a Measurement Delay" and "Using %kV and Exposure Time Measurements" at the end of this section for more information about using the %kV and measurement delay functions.

To make a radiographic measurement

Make sure that the Model 8000 is turned off. Plug one end of the Model 8000's detector cable into the Model 8000 detector. Plug the other end of the detector cable into the Model 8000's detector connector. Insert the W/Al filter card into the detector and place the filter card in the correct position for the kV range to be measured. Place the Model 8000 detector on the x-ray table with the top of the detector facing the x-ray tube. Position the detector so that the detector is centered in the beam and is aligned with the x-ray tube axis. If mAs measurements are to be made, plug the mAs cable into the 8000 detector's mAs input and connect the mAs leads to the generators mAs terminals. For more information on positioning the Model 8000 detector, see section "Positioning the Detector".

WARNING

If results are to be printed, plug the printer cable into the printer port at the rear of the Model 8000 then plug the other end of the printer cable into the printer and turn the printer on (see Section 1.5--Printing). Plug the AC adapter into the 8000 if needed (see Section 1.4--Battery Operation and Charging) and turn the instrument on.

2-12

Operation

Modes of Operation

EXP CT EXP 1Ø PULSE AMSE ZERO FLUORO 75% MAMMO 80% LOW

RADIO 90% HIGH 10 ms

MODE %kV SENS DELAY

Select the RADIO mode, %kV, high or low sensitivity and measurement delay, then press the ENTER key. To use a measurement delay, press the DELAY key to select and increment the delay. The delay may also be incremented or decremented by pressing the up or down keys when the delay is selected. Select the interval, as a percentage of kV peak, over which exposure time is measured, using the %kV key. ZERO selects measurement between the zero crossings on the rising and falling edges of the kV waveform. 1ØPULSE selects the single-phase pulse counting mode for exposure time measurement. The measurement delay and %kV settings are retained from one exposure to the next.

Please wait… FILTER = 50 - 100

RADIO 75% LOW 10 ms MODE %kV SENS DELAY

Please wait while the Model 8000 prepares to take an exposure. Note that the selected filter kV range is displayed. The kV filter range may be changed at any time without exiting from the measurement mode. If the Model 8000 detects a fault condition such as an invalid filter card or position, an error message is displayed and the user must correct the error to continue (see Section 4.3--Error Messages--for more information). When the Model 8000 is ready for an exposure, it will beep and prompt for an exposure.

MAKE EXPOSURE FILTER = 50 - 100

RADIO 75% LOW 10 ms MODE %kV SENS DELAY

Make an exposure. If nothing happens, there is insufficient x-ray intensity to make a measurement. To remedy this situation, switch to high sensitivity, switch to the next lower kVp filter range (if possible), increase mA or decrease the distance between the x-ray tube and Model 8000 detector.

ANALYZING DATA FILTER = 50 - 100

RADIO 75% LOW 10 ms MODE %kV SENS DELAY

Please wait while the NERO mAx analyzes the exposure data.

80.0

kVp Avg

100

msec

2-13

Victoreen 8000

Operators Manual

79.2

81.1

RADIO 75% LOW 10 ms Please MODE %kV SENS DELAY Wait…

After data analysis is complete, kV, exposure, time and mAs are displayed. If an overrange is detected an error message is displayed. If the calculated kV is above or below the selected filter kV range, "High" or "Low" is displayed instead of kV and measured time may be "----". If the NERO mAx cannot find the selected %kV on the kV waveform, a %kV TOO LOW message is displayed (see Section 4.3--Error Messages--for more information). Please wait while the Model 8000 prepares for the next exposure. If the Model 8000 detects a fault condition such as an invalid filter card or position, an error message is displayed and the user must correct the error to continue (see Section 4.3--Error Messages--for more information).

80.0

79.2

81.1

RADIO 75% LOW 10 ms MAKE MODE %kV SENS DELAY EXPOSURE

The Model 8000 is now ready to take another exposure. Pressing the mode key at any time exits from this measurement mode and returns to the mode selection screen.

kV Eff kV Peak

kVp Avg kV Eff kV Peak

392

0.0

100 392

0.0

mR mAs

msec mR mAs

As a power saving feature, the Model 8000's display backlight turns off after one minute of no activity. The backlight turns back on when any button is pressed or an exposure is made. In addition, after five minutes of no activity, the 8000 exits from any measurement mode and returns to the mode selection screen.

Using A Measurement Delay

A measurement delay may be used to postpone the start of data acquisition in order to skip over waveform anomalies (such as overshoots or preheat effects) that may occur at the beginning of an exposure.

When a delay is used, the NERO mAx waits for the specified delay time after its radiation threshold is exceeded before starting data acquisition. Data acquisition starts immediately after the delay time has elapsed if radiation is above the NERO mAx radiation threshold. If no radiation is detected after the delay time has elapsed, data acquisition is delayed for up to one second after the delay time has elapsed. If no radiation is detected for one second after the delay time has elapsed, the NERO mAx assumes that no exposure has occurred and displays the “DELAY TOO LONG” message.

The delay range is from -999 to +999 milliseconds, and the polarity of the measurement delay only affects how exposure time measurements are performed.

2-14

Operation

Modes of Operation

When a negative measurement delay is specified, the NERO mAx does not include the delay time in the measured exposure time. A negative measurement delay should be used in cases when x-ray generator filament preheat pulses or other waveform anomalies should be excluded from kV and exposure time measurements. In the example shown below, a 10-pulse exposure is preceded by 14 filament preheat pulses. Using a -230 millisecond delay to skip over the filament preheat pulses results in a measured

Negative Measurement Delay

Relative Radiation

120%

100%

80%

60%

40%

20%

0 50 100 150 200 250 300 350 400

A negative delay is used to skip over

filament preheat pulses

msec

Exposure time measured

with a negative delay

exposure time of 10 pulses.

An example showing this use of a measurement delay can also be found in troubleshooting Section 4.8-Waveforms - Dental With Filament Preheat.

When the measurement delay is positive, the NERO mAx includes the delay time in its measured exposure time. A positive measurement delay should be used in cases when the kV waveform contains leading edge overshoot or other waveform anomalies that should be excluded from kV measurements but included in the exposure time measurement. In the example shown below, an overshoot occurs in the first few milliseconds of a 50-millisecond exposure. Using a +10 millisecond delay to skip the overshoot results in a measured kVp of 72 versus 82 and an exposure time of approximately 50 milliseconds.

2-15

Victoreen 8000

Operators Manual

Positive Measurement Delay

120

A positive delay

100

is used to skip

overshoots

Exposure time measured with positive delay

10 mill isecond

delay

0 102030405060

msec

An example showing this use of a measurement delay can be found in troubleshooting Section 4.5-Waveforms - Overshoot.

When a positive measurement delay is used in making a measurement in the Radio or Mammo mode, the measured exposure time may be slightly longer than the exposure time between the selected %kV points on the kV waveform. This is because the Model 8000 does not store the leading edge of the x-ray output waveform when a measurement delay is used; it waits for the specified delay time before acquiring waveform data. As a result of this, the %kV point on the rising edge of the kV waveform is not stored and the time from exposure start to this point cannot be subtracted from the total time.

When exposure time is measured in pulses (1ØPULSE), use of a measurement delay may cause an error in the pulse count because no pulses are counted during the delay time. The polarity of the delay has no effect on pulse counting; for example, the number of pulses counted with a -10 millisecond delay is the same as the number counted with a +10 millisecond delay.

When using a measurement delay in pulsed and single-phase applications, care must be used in determining the correct delay period. If x-rays are detected at the end of the delay period, such as during a pulse, the NERO mAx begins timing immediately. If no x-rays are detected at the end of the delay period, such as between pulses, the NERO mAx waits up to one second for the beginning of the next pulse to begin timing. As a result of this, the delay period should terminate prior to the first x-ray pulse to be included in data analysis.

The NERO mAx Excel Add-In should be used to view radiation and kV waveforms to determine the optimum measurement delay to use. Information on using the NERO mAx Excel Add-In to view waveforms may be found in the NERO mAx Toolkit for Excel Instruction Manual. In addition, a digital storage oscilloscope may be connected to the scope output on the rear panel of the NERO mAx readout to view radiation output waveforms. Information on using the NERO mAx scope output may be found in Section 1.6 of the NERO mAx instruction manual.

2-16

Operation

Modes of Operation

Using %kV and Exposure Time Measurements

The %kV setting determines how the NERO mAx measures exposure time. When 75%, 80%, or 90% kV is selected, the NERO mAx measures exposure time between the 75%, 80%, or 90% points on the kV waveform. For best results when selecting 75%, 80%, or 90% kV, make sure that the percentage of the kV waveforms peak kV is within the selected filter range. If the %kV or the measured kV is too low, a "%kV TOO LOW" error message will be displayed.

When zero crossing (ZERO) is selected, the NERO mAx measures radiographic exposure time from the moment x-rays are detected by the NERO mAx until they are no longer detected. This corresponds to the time between first and last passage through the NERO mAx internal radiation detection threshold of the channel A radiation signal. When using zero crossing, measured exposure times may be lengthened by cable charging or by output filter capacitors used in some single phase generators to smooth the generator’s output waveform.

When 1ØPULSE is selected, the NERO mAx counts the number of x-ray pulses in a pulsed or singlephase radiographic exposure. Pulses are detected by counting each passage through the NERO mAx internal radiation detection threshold of the rising and falling edges of the pulses on channel A radiation signal. This is primarily for use with single-phase full and half-wave rectified generators. Pulse counting may not function properly on single-phase generators employing output filter capacitors to smooth the generator’s output because the generator’s output may not drop to zero between pulses. Additionally, use of a measurement delay may cause an error in the pulse count. For more information, see "Using a Measurement Delay".

When calculating kVp average, the NERO mAx only includes peaks that are above the selected %kV in the kVp average calculation. When ZERO or 1ØPULSE are selected, the NERO mAx includes all detected peaks in the kVp average calculation.

2.5.2 Mammo Mode

Mammo mode is used to make measurements on mammographic generators. Mammo mode simultaneously measures kVp, exposure time and mAs from a single mammographic exposure. Exposure time in the Mammo mode is measured between the first and last passage through the 90% points on the kV waveform. A measurement delay of up to 999 milliseconds may be used to delay the start of kV data acquisition in order to skip over waveform anomalies at the beginning of an exposure. See "Using a Measurement Delay" (at the end of this section) for more information on using a measurement delay.

To make a mammographic measurement

Make sure that the NERO mAx is turned off. Plug one end of the NERO mAx’s detector cable into the NERO mAx detector. Plug the other end of the detector cable into the NERO mAx’s detector connector. Insert the MAMMO filter card into the detector and place the filter card in the correct position for the x-ray tube target material. Place the NERO mAx detector on the x-ray table with the top of the detector facing the x-ray tube. Position the detector so that the detector is centered in the beam and is aligned with the x-ray tube axis. If mAs measurements are to be made, plug the mAs cable into the NERO mAx detector’s mAs input and connect the mAs leads to the generators mAs terminals. For more information on positioning the NERO mAx detector, see section "Positioning the Detector".

WARNING

2-17

Victoreen 8000

Operators Manual

If results are to be printed, plug the printer cable into the printer port at the rear of the NERO mAx then plug the other end of the printer cable into the printer and turn the printer on (see Section 1.5--Printing). Plug the AC adapter into the NERO mAx if needed (see Section 1.4--Battery Operation and Charging) and turn the instrument on.

EXP CT EXP AMSE FLUORO Mo 30μ

MAMMO LOW RHODIUM Rh 25μ

RADIO HIGH MOLY Al 1MM 0 ms MODE SENS TARGET FILTER DELAY

Select the MAMMO mode, high or low sensitivity, target and filter and shot delay, then press the ENTER key. To use a measurement delay, press the DELAY key to select and increment the shot delay. The measurement delay may also be incremented or decremented by pressing the up or down keys when the delay is selected. The measurement delay is retained from one exposure to the next and can only be reset to zero by the user.

Please wait… FILTER = 22 - 35

MAMMO HIGH MOLY Mo 30μ 0 ms MODE SENS TARGET FILTER DELAY

Please wait while the NERO mAx prepares to take an exposure. Note that the selected filter kV range is displayed. If the NERO mAx detects a fault condition such as an invalid filter card or position, an error message is displayed and the user must correct the error to continue (see Section 4.3--Error Messages-for more information). When the NERO mAx is ready to take an exposure it will beep and prompt for an exposure.

MAKE EXPOSURE FILTER = 22 - 35

MAMMO HIGH MOLY Mo 30μ 0 ms MODE SENS TARGET FILTER DELAY

Make an exposure. If nothing happens, there is insufficient x-ray intensity to make a measurement. To remedy this situation, switch to high sensitivity, increase mA or decrease the distance between the x-ray tube and NERO mAx detector.

ANALYZING DATA FILTER = 22 - 35

MAMMO HIGH MOLY Mo 30μ 0 ms MODE SENS TARGET FILTER DELAY

Please wait while the NERO mAx analyzes the exposure data.

2-18

+ 68 hidden pages

Fluke 8000 Victoreen User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual