Fluke 10100AT User Manual

10100AT

TRIAD™ TnT Field Service Kit

Operators 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 Introduction.................................................................................................. 1-1

1.2 Features....................................................................................................... 1-1

1.3 Manual Addenda.......................................................................................... 1-2

1.4 Before You Start – Safety Precautions ........................................................ 1-2

1.5 Safety Symbols and Terms.......................................................................... 1-2

1.6 Specifications............................................................................................... 1-3

1.7 Unpacking and Inspection............................................................................ 1-8

1.8 Getting Started............................................................................................. 1-9

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

2.1 Introduction.................................................................................................. 2-1

2.2 Front Panel Familiarization.......................................................................... 2-1

2.2.1 Control Buttons....................................................................................... 2-2

2.2.2 Display.................................................................................................... 2-3

2.3 Connector Familiarization............................................................................ 2-3

2.3.1 Ion Chamber Connector......................................................................... 2-4

2.3.2 kVp Divider Connectors.......................................................................... 2-4

2.4 Power-Up Self-Test and Display Messages................................................. 2-4

2.5 Using the Options Button............................................................................. 2-5

2.6 Basic Measurement Techniques.................................................................. 2-6

2.6.1 General Considerations.......................................................................... 2-6

2.6.2 Making Exposure Measurements........................................................... 2-9

2.6.3 Making Exposure Rate Measurements................................................... 2-9

2.6.4 Use of the Model 35050AT Dosimeter as a kVp Divider Readout........ 2-10

2.7 Simultaneous Measurement Mode............................................................ 2-13

2.7.1 Making Combined Exposure Rate and kVp Measurements ................. 2-13

2.7.2 Making Combined Exposure, kVp, and Time Measurements............... 2-13

2.7.2.1 Advanced Measurements Options .................................................. 2-14

2.7.2.2 Time Corrections............................................................................. 2-14

2.7.3 Making kVp and Time Measurements Without an Ion Chamber .......... 2-14

2.7.4 Making Exposure or Exposure Rate Measurements Without a Model

35080/80A/80B kVp Divider ................................................................. 2-15

2.7.4.1 Advanced Measurements Options .................................................. 2-15

2.8 Exclusive Measurement Mode................................................................... 2-16

2.9 Using the Ion Chamber Test Stand and Accessories ................................ 2-17

2.9.1 Using the Test Stand for Over-Table Tubes......................................... 2-18

2.9.2 Using the Test Stand for Under-Table Tubes....................................... 2-19

2.9.3 Using the Test Stand for Horizontal X-ray Beams................................ 2-21

2.9.4 Using the Test Stand for Mammo kVp Measurements......................... 2-21

2.10 Using the Ion Chamber Cable Stem .......................................................... 2-22

2.11 Measurement Considerations.................................................................... 2-22

2.11.1 Using Other Ion Chambers................................................................... 2-22

2.11.2 Using Air Density Corrections............................................................... 2-22

2.11.3 Using Exposure/Frame Units................................................................ 2-23

2.11.4 Making Mammo kVp Measurements.................................................... 2-24

2.11.4.1 Cadmium k-edge Filter Pack Use.................................................... 2-24

2.11.4.2 Linear Filter Pack Use..................................................................... 2-25

Section 3: Theory of Operation ...................................................................... 3-1

3.1 Introduction.................................................................................................. 3-1

3.2 Overall Functional Description..................................................................... 3-1

3.3 Power Supply............................................................................................... 3-2

3.4 Front Panel Switches................................................................................... 3-3

3.5 Microcomputer............................................................................................. 3-3

3.6 Display......................................................................................................... 3-3

3.7 Serial Communications Port ........................................................................ 3-3

3.8 Multiplexer/A-D Converter............................................................................ 3-4

3.9 kVp Input Signal Buffer/Divider.................................................................... 3-4

3.10 Ion Chambers.............................................................................................. 3-4

3.10.1 Basic Theory .......................................................................................... 3-4

3.10.2 Air Density Corrections........................................................................... 3-5

3.11 Electrometer/HV Isolator/Ranging Amplifier................................................. 3-5

3.12 300 Volt Electronic Bias Supply................................................................... 3-6

3-13 Measurement Technique............................................................................. 3-6

3.13.1 High Sensitivity Dose.............................................................................. 3-6

3.13.2 High Sensitivity Rate .............................................................................. 3-7

3.13.2.1 Very Low Dose Rate ......................................................................... 3-7

3.13.3 kVp/Dose/Time....................................................................................... 3-7

3.13.4 kVp/Rate................................................................................................. 3-7

3.14 Temperature and Pressure Sensor.............................................................. 3-8

Section 4:

Maintenance................................................................................. 4-1

4.1 Introduction.................................................................................................. 4-1

4.2 Cleaning the Instrument............................................................................... 4-1

4.3 Battery Replacement ................................................................................... 4-1

4.4 Fuse Replacement....................................................................................... 4-2

4.5 Replaceable Parts Information..................................................................... 4-3

4.6 Temperature / Pressure Sensor Adjustment................................................ 4-3

4.7 Recalibration and Repair Information/Technical Assistance........................ 4-4

4.8 Warranty Information ................................................................................... 4-4

Appendix A: Model 35050AT Default Ion Chamber Selection Screens...................A-1

A.1 Introduction..................................................................................................A-1

A.2 Model 96020C (150 CC) Ion Chamber ........................................................A-1

A.3 Model 96035B (15 cc) Ion Chamber............................................................A-2

Appendix B: Model 96020C Ion Chamber Specifications......................................B-1

B.1 Introduction..................................................................................................B-1

B.2 Physical Specifications ................................................................................B-1

B.3 Electrical Specifications...............................................................................B-2

B.4 Radiological Specifications..........................................................................B-2

B.5 Calibration and Verification..........................................................................B-3

B.6 Energy Correction Factors...........................................................................B-5

B.6.1 Attenuated Beam (Behind the Phantom)................................................B-5

B.6.2 Unattenuated Beam (In Front of the Phantom).......................................B-7

Appendix C: Model 96035B Ion Chamber Specification .......................................C-1

C.1 Introduction..................................................................................................C-1

C.2 Physical Specifications ................................................................................C-1

C.3 Electrical Specifications...............................................................................C-2

C.4 Radiological Specifications..........................................................................C-2

C.5 Calibration and Verification..........................................................................C-4

C.6 Energy Correction Factors...........................................................................C-5

C.6.1 Diagnostic – Unattenuated Beam (In Front of the Phantom)..................C-5

C.6.2 Diagnostic – Attenuated Beam (Behind the Phantom)...........................C-7

C.6.3 Mammographic Beam Qualities .............................................................C-8

iii

(Blank page)

General Information

Introduction

Section 1

General Information

1.1 Introduction

The TRIAD Service Kit can be used for government compliance testing, troubleshooting, repair of diagnostic x-ray equipment, installation and setup of new equipment, preventive maintenance, radiographic quality assurance measurements, and measurements required for JCAHO accreditation.

The TRIAD Service Kit performs measurements on all modalities: mammographic, cine, dental, radiographic, fluoroscopic, CT, and image intensifiers.

The Model 35050AT Dosimeter, as featured in the Model 10100AT TRIAD Field Service Kit, is both a sensitive, full-function dosimeter and a digital display for the Models 35080/80A/80B Non-invasive kVp Divider. It features a direct readout and simplified operator controls.

This manual contains all the information necessary for you to operate and service your Model 35050AT Dosimeter/kVp/Time Readout and the Model 10100AT TRIAD Field Service Kit components. This manual contains a description of usage of the Model 35080/80A/80B kVp Divider with the Model 35050AT Dosimeter as its readout. The operator is referred to the Model 35080/80A/80B kVp Divider Instruction Manual, though, for a complete coverage of specifications, general use, etc.

Some service kits may include a Model 35035 mA/mAs meter. The user is referred to its instruction manual for details of operation, specifications, and servicing.

Information on customizing the Model 35050AT Dosimeter using the Customization Software is contained in a separate manual (Model 35050A Customization Instruction Manual). Also, a separate Model 35050A Programmer's Instruction Manual contains a description of the protocol and commands used to operate the Model 35050AT Dosimeter via the RS-232 interface. The RS-232 interface also allows the user to capture kV waveforms obtained during simultaneous use of the Model 35050AT Dosimeter and the Model 35080/80A/80B kVp Divider. Refer to these instruction manuals as needed.

1.2 Features

Simplified Controls – automatic or manual exposure reset, autoranging, automatic offset and drift compensation, and automatic power down.

Battery or Line Current Operation - 6 AA alkaline batteries provide instrument power with an auto power-down feature to extend battery life and a 300 V electronic ion chamber bias. An AC adapter is provided which allows line current operation.

Direct Reading - readout in user-selected units: R, Gy, Sv, C/kg, A, C, /s, /min, /hr, /frame; pressure and temperature corrected readings. Temperature and pressure corrections may be made automatically using an internal temperature and pressure sensor or by manual entry.

Ion Chamber Flexibility - radiation units for any triaxial-BNC ion chamber with a known calibration factor, including CT ion chambers.

High Sensitivity -image intensifier measurements at 0.1 mR and 5 mR/min resolutions. kVp+Dose+Time - kVp, dose, and exposure time measurements when used with the Model

35080/80A/80B Non-Invasive kVp Divider. Exposure time may be displayed in seconds or pulses (for single phase or pulsed outputs).

1-1

10100AT

Operators Manual

RS-232 Interface - remote operation, waveform capture, digital calibration, custom display units, customer specified ion chamber calibration factors, and Model 35080/80A/80B kVp Divider filter packs.

Self-Checking - the Model 35050AT Dosimeter and Model 35080/80A/80B kVp Divider battery voltage level, bias voltage level, ion chamber/cable leakage, and hardware/software checks.

1.3 Manual Addenda

Any improvements or changes concerning the instrument or manual will be explained in an addenda included with the manual. Be sure to note these changes and incorporate them into the manual.

1.4 Before You Start - Safety Precautions

This instrument is intended for use by qualified personnel who recognize radiation hazards associated with use of x-ray equipment.

Always turn off unit prior to connecting or disconnecting ion chamber or triaxial cable. Failure to do so could result in electrical shock or damage to the equipment.

Beyond the battery and fuse, this unit contains no operator serviceable parts. The operator should not attempt to gain access beyond the battery access cover. High voltage is generated internally and may remain on internal parts even after the batteries have been removed.

1.5 Safety Symbols and Terms

The following symbols and terms are found on the instrument and used in this manual.

The located in the manual.

The standard safety precautions to avoid personal contact with these voltages.

The heading used in this manual explains dangers that might result in personal injury or death. Always read the associated information very carefully before performing the indicated procedure.

The heading used in this manual explains hazards that could damage the instrument. Such damage may invalidate the warranty.

symbol on the instrument indicates that the user should refer to the operating instructions

symbol on the instrument shows that high voltage may be present on the terminal(s). Use

WARNING

CAUTION

1-2

General Information

Specifications

1.6 Specifications

Exposure and Exposure Rate Accuracy

The basic accuracy of the Model 35050AT Dosimeter is ± 1% of reading ± 2 range resolution steps (see Table 1-1) over the range of 18 to 28° C and ± 2% of reading ± 2 range resolution steps over the full operating temperature range of 0 to 50° C. This accuracy is guaranteed for a period of 1 year and is exclusive of all ion chamber effects. A 3% NIST traceable calibration is provided with each system and includes the effects of the Model 35050AT Dosimeter, Model 96035B Ion Chamber, and Model 96020C Ion Chamber.

Temperature and Pressure Accuracy

Temperature Accuracy: ± 2°C (3.6°F) Pressure Accuracy: ± 5mm Hg

NOTE

The measured temperature is the internal temperature of the Model 35050AT, TRIAD TnT Dosimeter, which may not be the same temperature as the Ion Chamber that is in use. Adequate time must be allowed for the Dosimeter and Ion Chamber to reach thermal equilibrium before automatic temperature sensing is used.

At standard conditions of 22°C and 760mm Hg:

1°C ~ 0.36 % change in ADC 1 mm Hg ~ 0.13% change in ADC

1-3

10100AT

Operators Manual

Electrometer Measurement Ranges

Table 1-1. Electrometer Measurement Ranges

Ion

Chamber

15 cc R 100 μ to

R/s 100 μ to

R/min 5 m to

R/hr 100 m to

R/frame** 2 μ to

150 cc R 10 μ to 2 6 μ 0.1 μ Gy 0.1 μ to

R/s 10 μ to 2 6 μ 0.1 μ Gy/s 0.1 μ to

R/min 0.5 m to

R/hr 10 m to

R/frame** 0.2 μ to

150 cc

VLDR

R/min 0.1 m to

R/hr 2 m to

R/frame** 0.04 μ to

Electrical

Units

A 1 p to

Values for ion chambers are calculated using nominal sensitivities: 15 cc: 2.4 x 10 150 cc: 2.4 x 10 * Very Low Dose Rate effective range at 5% resolution steps ** At 60 frames/s (1 to 120 frames/ selectable). *** IEC 61674 effective range at 1% resolution steps

Units Effective

Range***

1200

72 k

333 m

120

7.2 k

33 m

R/s 2 μ to 2* N/A 0.1 μ Gy/s 0.02 μ to

120*

7.2 k*

33 m*

C 1 p to

100 n

R/C

Threshold Resolution

Step Size

60 μ 60 μ 1 μ Gy/s 1 μ to 0.2

3.6 m 50 μ Gy/min 50 μ to

216 m 1 m Gy/hr 1 m to

1μ 0.02 μ Gy/frame** 0.02 μ to

0.36 m 5 μ Gy/min 5 μ to 1.2 3.15 μ 0.05 μ

21.6 m 0.1 m Gy/hr 0.1 m to

0.1μ 0.002 μ Gy/frame** 0.002 μ

N/A 5 μ Gy/min 1 μ to

N/A 0.1 m Gy/hr 0.02 m to

N/A 0.002 μ Gy/frame** 0.4 n

0.5 pC 0.01 p

250 fA 0.01 p

1 μ Gy 1 μ to 0.2

Units

Effective Range***

720

3.33m

0.02

to 0.33 m

0.02*

1.2*

72*

0.33 m*

Threshold Resolution

Step Size

.52 μ

31.5 μ

1.89 m

.008 μ

.052 μ 0.001 μ

.189 m 0.001 m

0.8 n 0.02 n

N/A 0.001 μ

N/A 0.05 μ

N/A 0.001 m

N/A 0.02 n

0.01 μ

0.5 μ

0.01 m

0.2 n

1-4

General Information

Specifications

Measurement Modes

Dosimeter Operation Only: In use when the Model 35080/80A/80B kVp Divider is not connected or

turned on. Full-sensitivity Exposure: Automatic drift and offset compensation, and automatic post-exposure

display hold are performed in this mode. Measurement range covers a span from low-level image intensifier inputs to unattenuated direct beams. Autoranging over five decades. Display updates at the end of each exposure. When the Automatic Reset option is enabled, exposure start and end detection are based on the exposure rate level crossing a 0.25 pA threshold. When the Automatic Reset option is disabled, exposure start detection is based on the exposure rate level crossing a 0.25 pA threshold but the exposure measurement is only reset by pressing the Reset/Measure key.

Full-sensitivity Exposure Rate: Automatic offset compensation and nonlinear digital filtering are performed in this mode. Autoranging provides five decades of sensitivity ranges. The measurement range covers a span from low-level image intensifier inputs to unattenuated direct beams. Display updates once per second. Differentiation between exposure on and off condition based on 0.25 pA threshold.

Very Low Dose Rate (VLDR): This mode is only for making very low dose rate measurements. Nonlinear digital filtering and autoranging provide five decades of sensitivity ranges. Display updates once per second. In this mode, automatic current offset and drift compensation is disabled. As a result, the system leakage (includes dosimeter, cable and ion chamber) is displayed and must be compensated for. This option should only be used with ion chambers suitable for very low dose rate measurements.

Dosimeter with kVp and Time Readout Operation: In use when the Model 35080/80A/80B kVp Divider is connected and a filter pack is selected from the Model 35050AT Dosimeter's front panel.

Tri-measurement Exposure: A single shot, direct beam measurement of exposure, kVp, and time. Autoranging across three-decade ranges and auto reset between exposures. Display updates following each exposure. Exposure start and stop based on detection of voltage from the Model 35080/80A/80B kVp Divider in excess of minimum kV for selected pack. A measurement delay of up to 999 ms may be used to skip over unwanted portions of an exposure. To prevent measurement of spurious signals, the 35050AT Dosimeter can be set to ignore exposures of less than 5ms.

Dual-measurement Exposure Rate: A simultaneous measurement of kVp and exposure rate. The display updates once per second. Autoranging across three-decade ranges provide adequate sensitivity for direct beam measurements. Display updates approximately once each second.

Customization

A customization program, contained on a compact disk, is included as part of a Model 10100AT TRIAD Field Service Kit.

The customization program runs on any IBM-PC or compatible computer. A cable and adapters are also furnished with the kit and provide means of interconnecting the computer's and the Model 35050AT Dosimeter's serial communications ports.

The program allows the user to modify the contents of the Model 35050AT Dosimeter's non-volatile memory, and thus determine a number of important operating parameters for the Model 35050AT Dosimeter. These are listed below:

1. All electrical calibration factors

2. All unit, ion chamber, and kV filter pack descriptions and conversion factors

3. Temperature and pressure unit types for use with air density corrections: In degrees Fahrenheit, Celsius and Kelvin In inches of Hg, mm of Hg, milliBars, hectoPascal, feet relative to sea level, and meters relative to

sea level

1-5

10100AT

Operators Manual

4. Number of minutes to auto power-down, from 1 to 255

5. Optional Power-On and Test screen messages

Display

The display is a two-line, 20-character alphanumeric PLED (polymer light emitting diode) display with an approximate character height of 0.5 cm. The display shows all ion chamber/kV filter pack identification information, numerical measurement results, and other information such as battery level and calibration date.

Bias Voltage Supply

An electronic bias supply is fixed at a nominal 310 V. The bias voltage is removed from the triaxial input connector at instrument turnoff. Internal low and high bias voltage test limits are set at 300 and 325 V respectively.

Power

Continuous operational life of approximately thirty hours is provided by six “AA” alkaline batteries. Auto power-down feature turns off unit after user-selected period (1-255 min) of unattended operation.

An AC adapter allows line current operation. When the AC adapter is in use, no current is drawn from the batteries. When the AC adapter is in use, the auto power down feature is disabled, providing continuous operation. The AC adapter is an unregulated 9v, 200 mA adapter with a center negative, 2 .1 mm plug.

Note: before auto turnoff, unit stores selections of ion chamber, units, and kVp filter pack in nonvolatile memory. Eliminates manual reselection at next power-up. The default factory setting for the automatic power-down feature is 15 minutes.

Control Buttons

Power On/Off: initiates power-up and -down sequences Detector Select: selection of ion chambers, kV filter packs Units Select: selects measurement units, frame rates Reset/Measure: starts measurement, provides manual reset (auto reset function is also available in the

Model 35050AT Dosimeter)

Air Density: sets ambient temperature and pressure Options: selects measurement options and displays diagnostic information such as supply level, ion

chamber leakage, bias voltage, and other diagnostic information Up, Down: scrolls through list of screen selections, increments / decrements numeric entries. Holding

down the up or down key increases scroll speed.

1-6

General Information

Specifications

Connections

Model 35080/80A/80B kVp Divider Interface: A coaxial-BNC connector used for measurement of kVp and exposure time.

Computer Interface: RS-232-C Serial Port offers full duplex communication with XON/XOFF handshaking. Connector is RJ-45 (female) with DCE configuration. Data format is 8 bits, no parity, and one stop bit. Data rate is fixed at 9,600 baud. Interface provides full instrument control, calibration, and automation.

Ion Chamber Input: A triaxial-BNC input connector: collector and guard positive-biased relative to ion chamber body/dosimeter chassis.

Power: 2.1mm DC Power Jack, power input for an unregulated 9v, 200 mA adapter with a center negative, 2.1 mm plug.

Models 96035B, 96020C Diagnostic Ion Chambers

Energy Range:

96035B: 25 kVp to 150 kVp 96020C: 30 kVp to 150 kVp

Calibration: pair of ion chambers with NIST-traceable calibration and 3% system calibration with Model 35050AT Dosimeter. Ion chambers are calibrated for use at 22°C and 760 mm Hg. Real time measurement or front panel selection of ambient temperature and pressure allow for corrected readings at other conditions.

Nominal Sensitivity:

96035B: 2.35 x 10

radiography and mammography.

96020C: 2.1 x 10

measurements

Multiply values by 0.00876 to convert from R to Gy.

Construction:

96035B: Graphite-coated acrylic, parallel-plate, air-vented 96020C: Composite graphite-filled thermoplastic, parallel-plate, air-vented

Volumes:

96035B: --15 cc 96020C: --150 cc

R/C (2.06 x 106 Gy/C). Flat response is suitable for both conventional diagnostic

R/C (1.84 x 105 Gy/C), optimized for low-level image intensifier and cine

NOTE

See Appendix B and C in this instruction manual for complete specifications on the Models 96020C and 96035B Ion Chambers.

Kit Accessories

Cable: (38208) 20 ft (6.1 m) Coax/Triax Cable Test Stand: (37581) machined stainless steel upright rod with baseplate, ion chamber holder, Model

35080/80A/80B kVp Divider holder, and tray for HVL filters, which includes the ion chamber stem (32147).

1-7

10100AT

Operators Manual Customization Kit: (37594) includes software on CD and a 6 ft (2 m) RS-232 interface cable with adapters

for PC- and AT-type computers.

Instruction Manuals: Model 10100AT TRIAD Field Service Kit Operator's Instruction Manual (38651). HVL Filter Set: (37668) set of nine aluminum filters for half-value layer measurements: one -- 2 mm, two -

- 1 mm, two -- 0.5 mm, three -- 0.1 mm, and one -- 0.2 mm. Kit Carrying Case: (37500D) high-density polyethylene (HDPE) plastic absorbs impact to protect contents.

Molded parallel ribs for strength. Corrosion-resistant hardware and locks. Custom-cut, high-quality foam interiors surround and protect standard kit equipment and accessories. The case is gasketed to exclude dust and moisture.

Environment

Operating: 0° to 50°C; relative humidity 20% - 80% non-condensing Storage: -25° to 65°C

Kit Dimensions, Weight

Approximately 46 cm long x 33 cm wide x 15 cm deep (18 in x 13 in x 6 in); approximately 6.4 kg (14 lb).

kVp Measurement Accuracy and Method

The Model 35050AT Dosimeter will typically add an uncertainty of ± 2 mV to the voltage produced by the Model 35080/80A/80B kVp Divider for a well behaved (quiet and constant) voltage waveform. The accuracy of the peak detection method will be dependent upon both the shape of the kV waveform, and the amount of noise present in the signal produced by the kVp divider. Based on sampling the output of the kVp divider at a rate of 5 kHz, the peak voltage is determined by examining a 50 ms wide segment of these samples. In selecting the data segment to be analyzed, a delay of one-tenth of the total exposure time is inserted. When a measurement delay is used, this occurs after the measurement delay time elapses or with the first rising edge after the delay time elapses. Before peak detection occurs, the signal is passed through a digital filter with 1 ms time constant. The digital filter is not used with the Mobile filter pack

Exposure Time Measurement Accuracy and Method

When seconds are selected as exposure time units, the exposure time accuracy is ± 0.1% of reading ±

0.2 ms. The measurement method is based on a kV threshold crossing. The threshold is set at 75% of the kVp, or the minimum kVp for the filter pack in use, whichever is greater. The maximum exposure time is six seconds and the measurement resolution is 0.2 ms.

When pulses are selected as exposure time units, the exposure time accuracy is ± 1 pulse. The measurement method is based on a kV threshold crossing; pulses are counted by detecting each passage through a threshold on the rising and falling edges each pulse in the output waveform.

When a negative measurement delay is specified, the TRIAD TnT Dosimeter 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.

When the measurement delay is positive, the TRIAD TnT Dosimeter 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.

* Specifications subject to change without notice.

1-8

General Information

Unpacking and Inspection

1.7 Unpacking and Inspection

The Model 10100AT TRIAD Field Service Kit was carefully inspected before shipment. Upon receiving the service kit, carefully unpack all items from the shipping carton and check for any obvious signs of physical damage that might have occurred during shipment. Report any damage to the shipping agent at once. Retain the original packing material in case reshipment becomes necessary. The following items are included with every Model 10100AT Service Kit shipment.

Standard System Components

• Model 35050AT Dosimeter/kVp Readout

• Model 10100AT TRIAD Field Service Kit Operator's Instruction Manual (38651)

• System Carrying Case (37500D)

• 15 cc and 150 cc Ion Chambers (96035B and 96020C)

• Test Stand (37581)

• 6.1 m (20 ft) Coax/Triax Cable (38208)

• Ion Chamber Stem (32147)

• HVL Filter Kit (37668)

• Spare Battery Holder (87-3)

• Customization Software Kit includes a compact disk, 2 m (6 ft) RS-232 Interface Cable, and adapters

for PC- and AT-type computers (37594)

• AC Adapter

Optional Equipment

The Model 35080/80A/80B Non-invasive kVp Divider - is compatible with the Model 10100AT when used with the appropriate filter packs:

• Wide Range Filter Pack (37617)

• CT Filter Pack (33551)

• Cadmium K-Edge Mammo Filter Pack (37355)

• Linear Mammo Filter Pack (37351)

• Mobile Filter Pack Plus (37946)

• Low Range Filter Pack (38237)

Model 35035 mA/mAs Meter - measures anode current (mA) and anode current and time product (mAs) of x-ray generators.

TRIAD Toolkit for Excel (10500EXL) - is a complete software package for the TRIAD that includes an Excel Add-In, called TRIAD Tool and Excel templates that may be used to evaluate the performance of radiographic, mammographic, and fluoroscopic x-ray machines.

TRIAD QA Software (37978) - is a quality assurance software package for IBM-PC. It simplifies testing of exposure reproducibility, linearity, kVp, timer accuracy, and HVL.

Cable and Reel Assembly (38209) - is used to keep the 6.1 m (20 ft) coax/triax cable tangle free.

1-9

10100AT

Operators Manual

1.8 Getting Started

The Model 35050AT Dosimeter/kVp/Time Readout is a highly sophisticated instrument with many capabilities. Although there are a number of complex aspects about the instrument, you can use the following procedure to get your instrument up and running quickly. For more detailed information, you should consult section 2 of this manual.

1. Carefully unpack your Service Kit as described in section 1.7. a. Connect the supplied triaxial cable to the case side input jack. Connect an appropriate ion

chamber to the other end of the triaxial cable. Position the chamber where required.

To prevent electrical shock, the Model 35050AT Dosimeter should always be turned off when connecting or disconnecting an ion chamber or triaxial cable.

2. a. If use of the Model 35080/80A/80B kVp Divider is intended, connect its output to input of the Model 35050AT Dosimeter using the coaxial cable provided. Position the kVp divider in the beam.

Make certain that the color of the cable boot matches the color indicator around the connector of the instrument.

2. b. If using the AC adapter, plug the adapter into a suitable power outlet and plug the 2.1mm plug fully into the power jack on the side of the unit.

Only use the supplied AC adapter. Use of AC adapters other than the one supplied with the unit may damage the unit and void the warranty.

3. a. Depress the front panel POWER ON/OFF button for approximately one second to apply power to the instrument. The instrument will power-up through a series of screens.

b. If a kVp divider is in use, set its switch to the RUN position and plug in desired filter pack.

4. a. At the Detector Select screen, make sure the ion chamber in use is indicated. If not, press the UP or DOWN buttons until it is. If air density corrections are desired, find an ion chamber with ADC in its description. If very low dose rate measurements are desired, find an ion chamber with VLDR in its description.

b. If using a Model 35080/80A/80B kVp Divider, press the DETECTOR SELECT button and then

press the UP or DOWN buttons until the proper filter pack is selected.

c. If a kVp divider is not in use, press the DETECTOR SELECT button and then press the UP or

DOWN buttons until the filter pack selection displays “35080/80A Not Used”.

WARNIN

NOTE

1-10

General Information

Getting Started

5. Press the UNITS SELECT button if an integrated exposure is to be measured. Or, if exposure rate

is desired, these same units may be chosen with a timebase of seconds, minutes or hours. Additionally, per frame and amperes are available. Select desired units of measurement by pressing the UNITS SELECT button. Change the selection by pressing the UP or DOWN buttons. If exposure/frame units are selected, the user must set the frame rate at this screen.

6. If an ion chamber using air density corrections is selected, press the AIR DENSITY button to

display the Air Density screen. If the temperature & pressure mode has been set to Automatic Sense, the measured ambient temperature and pressure will be displayed. If the temperature & pressure mode has been set to Manual Entry, the last used temperature and pressure will be displayed. Set temperature and pressure to match ambient conditions.

NOTE

When air density corrections are in effect, a “ADC” annunciator will appear on the Measurement screen. In Automatic Sense mode the ambient temperature and pressure are updated each time RESET/MEASURE is pressed.

7. Press and release the RESET/MEASURE button to place the dosimeter in the measurement mode.

8. Make the exposure. Following an exposure, the display will be updated with measurement results

for the exposure. Additional exposures may be made at this point as the dosimeter will detect each exposure and automatically update the display.

Complete detailed operation concerning the Model 35050AT Dosimeter front panel operation may be found in section 2 of this manual, including the use of the Model 35080/80A/80B kVp Divider. If you wish to control these functions over the RS-232 Interface Cable, consult the Model 35050A Programmer's Instruction Manual.

1-11

10100AT

Operators Manual

(Blank Page)

Operation

Introduction

Section 2

Operation

2.1 Introduction

Operation of the Model 35050AT Dosimeter may be divided into two general categories: front panel operation and RS-232 bus operation. This section contains information necessary to use the instrument from the front panel. Note that many of these functions can also be programmed over the RS-232 bus, as described in the Model 35050A Programmer's Instruction Manual.

The following paragraphs contain a complete description of the Model 35050AT Dosimeter front panel operation. First a complete description of each front panel function is presented. Next the complete procedure for each of the measuring functions is presented.

2.2 Front Panel Familiarization

The front panel of the Model 35050AT Dosimeter is shown in Figure 2-1. The front panel may be divided into two sections: control buttons and display. The following paragraphs describe each of these items in detail.

Figure 2-1. The Model 35050AT Dosimeter Front Panel

2-1

10100AT

Operators Manual

2.2.1 Control Buttons

All front panel control buttons are momentary contact switches, but their functions are firmware latched once depressed for even a short period of time. They are membrane type switches that provide a definite tactile indication of operation.

Power On/Off

This button controls the power to the instrument. Depressing this button for approximately one second turns the power on. Depressing and releasing the button a second time turns the power off.

When the power-up screens sequence is still in progress, depressing any button will have no effect. Similarly, depressing any button during the powerdown sequence will have no effect.

In the event of no button depression, no exposure, no operating kVp divider connected, or no RS-232 communication for a user-defined period; the instrument will automatically save its current settings and turn its power off. Note that any measurement values displayed at power down will be lost. For additional details on power-up screens, see section 2.4.

At next power-up, the unit will resume operation with these same selections. In addition, at power-up, the unit will automatically advance through four basic status or self-test screens and then automatically invoke the DETECTOR SELECT screen before returning control to the front panel buttons. This screen is shown in Figure 2-1.

NOTE

Options

This button is used to select various measurement options and display of a series of test screens. For additional details on test screens, see section 2.5. The complete wraparound list may be examined by repeatedly pressing the Options button.

Air Density

This button causes display of the temperature and barometric pressure used for vented ion chamber corrections. When the temperature & pressure mode is set to Automatic Sense, pressing the Air Density button causes the ambient temperature and pressure to be displayed. When the temperature & pressure mode is set to Manual Entry, the button has a toggle function: momentarily depressing it selects whether temperature or barometric pressure may be adjusted. The current variable is indicated by the “greater than” symbol (>) as first character in the display line; hereafter, this is referred to as the cursor. The current variable may then be changed in value, if desired, by use of the UP and DOWN buttons. Air density corrections to the exposure and exposure rate displays will be made only if 1) radiological units (not A or C) have been selected, and 2) an ion chamber with air density corrections enabled has been selected. When air density corrections are in effect, an “ADC” annunciator will be displayed on the measurement screen. In the event that the temperature/pressure sensor becomes non functional, an error message, “Temp & Press Error Use Manual Entry” is displayed and only the manual temperature and pressure entry mode is available.

Units Select

This button causes display of the selected radiological or electrical units and cine frames per second. This button also has the toggle function to cursor select the units or frame rate for changing. Changes may then be made by means of the UP and DOWN buttons. The exposure and exposure rate displays will be affected by the frame rate setting only if units of exposure per frame (R/frame, Sv/frame, etc.) have been selected.

2-2

Operation

Front Panel Familiarization

Detector Select

This button causes display of the identity of the ion chamber and kVp filter pack last used. This button also has the toggle function to cursor select which chamber and/or filter pack is to be currently used. If different, changes may then be made by means of the UP and DOWN buttons. The filter pack selection is used only when a Model 35080/80A/80B kVp Divider is connected.

Reset/Measure

This button is used to both begin and reset the measurement process. When the Exposure Reset option is set to Manual, indicated by exposures to clear the display. When the Exposure Reset option is set to Automatic, this is not required because of the automatic reset feature of the Model 35050AT Dosimeter. The manual reset feature is only active in the Full-Sensitivity Exposure mode.

in the upper right corner, this button may be depressed between

2.2.2 Display

The display, located on the upper left-hand corner of the front panel, is a two line, twenty character per line, alphanumeric PLED (polymer light emitting diode) display module. This module performs all visual indications for the manual operator.

Annunciators

The battery/supply level and ion chamber bias potential are measured regularly by the instrument in a background mode. Should either level go outside of preset limits, an annunciator is displayed. The preset limits are given below.

Bias voltage limits 300 to 325 volts Power battery limits 5.9 to 9.6 volts

The low battery limit of 5.9 V has been chosen to provide approximately two hours of useful battery life following the initial display of the low battery annunciator.

NOTE

The battery voltage is measured at the input of the 5-volt regulator, after some drops in fuse, switch, wiring, etc. There will be a discrepancy of several tenths of a volt from the actual battery voltage.

2.3 Connector Familiarization

There are four external connectors provided on the Model 35050AT Dosimeter case sides. On the side left of the front panel (front view) are the ion chamber and kVp divider connectors (marked by a yellow ring). The following paragraphs detail the purpose and use of these connectors. On the side right of the front panel are the DC power jack and the RS-232 connector. Information on RS-232 communication is in the Model 35050A Programmer's Instruction Manual that is available upon request.

2-3

10100AT

CAUTIO

Operators Manual

2.3.1 Ion Chamber Connector

Never connect a coaxial-BNC type cable to the Model 35050AT Dosimeter's triaxial ion chamber input connector. Doing so may damage the ion chamber input connector.

WARNING

The central pin and inner shield shell of this connector are operated at 300 volts above the outer shell and instrument case. Although this potential is energy and current limited, care should be taken to avoid unnecessary and possibly hazardous shocks. Mating and unmating to this connector (or to the other end of a cable already connected to it) should be done only when the instrument is powered down. Within a few seconds of turnoff, the high voltage is internally discharged making such connections safe and convenient.

The connector is a triaxial-BNC female with dust cap and chain. It connects to the supplied coax/triax cable or other low-noise triaxial-BNC male cables. And, by means of which, the Models 96020C Ion Chamber, Model 96035B Ion Chamber, and other ion chambers can be operated with the Model 35050AT Dosimeter.

The connector is side-mounted to avoid contaminating spills and dust, but putting its dust cap in place whenever a cable is not connected will help assure long service without leakage problems.

2.3.2 kVp Divider Connectors

The connector is a BNC jack marked with a yellow ring. It is the opposite gender of the usual panel mounted BNC connector to prevent accidental connection of the triax cable to the BNC connector, and vice versa. Such a cable connector mix up will damage some or all connectors involved. The male to female BNC coaxial cable (as indicated by yellow boots) provides the connection between the Model 35080/80A/80B kVp Divider and the Model 35050AT Dosimeter / kVp Readout.

2.4 Power-Up Self-Test and Display Messages

When the instrument is powered up by pressing and releasing the POWER ON/OFF button on the front panel, the following sequence of screens will be displayed:

1. Pixel test

2. Last calibration and software revision date (5 seconds)

3. Instrument power level in volts and HI, LO or OK advisory (5 seconds). If the unit is operating on

battery power, the displayed battery voltage will be between 5.9 and 9.6 volts. If the unit is powered by its AC adapter, the displayed battery voltage will be between 10 and 13 volts.

2-4

Operation

Power-Up Self-Test and Display Messages

NOTE

If the AC adapter is plugged into the instrument, but is not plugged into an AC power source, the Supply Level will be reduced by several tenths of a volt. This is due to the additional components that are switched into the power circuit when the AC adapter is plugged into the unit. For best performance on battery power, unplug the AC adapter from the unit when not in use.

4. Optional power on screen displays user selected information (5 seconds):

This screen will be skipped if blank screen was specified using customization software.

During this opening screen sequence, pressing any front panel button will have no effect. The sequence ends in DETECTOR SELECT. The last selected detector will be displayed on the screen. Other functions or another detector may now be selected with the front panel buttons.

2.5 Using the Options Button

Pressing the OPTIONS button, when in any other function, will display one of the status/option screens. Repeatedly pressing the OPTIONS button again will move the display through twelve status/option screens as follows:

1. Last calibration and software revision dates

2. Optional test screen, can be skipped by customization

3. Supply Level in volts and HI, LO or OK advisory. When battery power is in use, the battery voltage

is displayed. When the AC adapter is in use, the AC adapter voltage is displayed.

4. System leakage current measuring mode without offset current subtraction. Enables operator to

directly see the ion chamber, cable, and dosimeter leakage current. See section 2.6.1 for more information.

5. System bias level in volts and HI, LO or OK advisory

6. Ion chamber calibration factor in use: 4 digits plus exponent, dimensioned in either

Roentgens/Coulombs or Grays/Coulombs depending on option chosen during customization. Factor also includes air density correction if applicable.

7. Voltage measured at Data Terminal Ready (DTR) line of RS-232 port

8. Temperature & Pressure Mode selection. Pressing the up or down button toggles between

Automatic Sensing of temperature and pressure or Manual Entry of temperature and pressure.

9. Short Exposure (< 5ms) selection. Pressing the up or down button toggles between Accept and

Ignore. Accept allows the 35050AT to measure exposures that are less than 5 milliseconds in duration. When ignore is selected, the 35050AT ignores exposures that are less than 5 milliseconds in duration. This is useful when spurious signals trigger unintended measurements. This feature is only active when the 35050AT is in the Tri-measurement Exposure mode (when the 35080 is used).

10. kV Measurement Delay entry. Pressing the up or down buttons increments or decrements the

measurement delay. The measurement delay range is –999 to +999 milliseconds and can be set in one-millisecond increments. The polarity of the measurement delay only affects how exposure time measurements are performed. When a negative measurement delay is specified, the 35050AT does not include the delay time in the measured exposure time. When the measurement delay is positive, the 35050AT includes the delay time in its measured exposure time. This feature is only active when the 35050AT is in the Tri-measurement Exposure mode (when the 35080 is used).

2-5

10100AT

Operators Manual

11. Exposure Reset selection. Pressing the up or down button toggles between Automatic and Manual.

When the Exposure Reset option is set to Automatic, Model 35050AT Dosimeter automatically resets between exposures; exposure start and end detection are based on the exposure rate level crossing a 0.25 pA threshold. When the Exposure Reset option is set to Manual, this button may be depressed between exposures to clear the display. A the display when the Manual Reset option is active. Exposure start detection is based on the exposure rate level crossing a 0.25 pA threshold but the exposure measurement is only reset by pressing the Reset/Measure button. The manual reset feature is only active in the Full-sensitivity Exposure mode.

12. Exposure Time Units selection. Pressing the up or down button toggles between Seconds and

Pulses. When Seconds are selected as exposure time units, exposure time is measured between the first and last passage through the kV threshold. The displayed units are milliseconds (ms) or seconds (s). The threshold is set at 75% of the kVp, or the minimum kVp for the filter pack in use, whichever is greater. When Pulses are selected as exposure time units, exposure time is displayed in pulses (P), and pulses are counted by detecting each passage through a threshold on the rising and falling edges each pulse in the output waveform.

symbol appears in the upper right corner of

2.6 Basic Measurement Techniques

2.6.1 General Considerations

It will be helpful to the user to understand the presence of several automatic compensations being performed during measurements and how they could affect the measurements under certain circumstances.

Automatic Voltage Offset and Drift Compensation

The instrument automatically measures the voltage offset of the electrometer and subtracts the value from the exposure and exposure rate measurement results.

Automatic Current Offset and Drift Compensation

In the usual situation, this feature is transparent and amounts to system leakage current being nulled from the measurements. In order to do this, both a short-term history of the leakage current and the establishment of a leakage/“real” current threshold must be made.

The threshold is set at 0.25 pA and only a few seconds are required for an accurate leakage level assessment. In the typical case, system leakage current is on the order of 10 fA and reasonably steady. It may be viewed at any time by going to the OPTIONS and scrolling to the System Leakage screen. When it approaches the current threshold level and/or becomes highly erratic, the system may improperly compensate the measurement value.

Another consideration of higher, but suppressed, leakage levels is that the automatic electrometer integrator reset frequency is raised. This increases the small, but finite possibility, that a reset may occur during an exposure and thereby lose some of its value. With low system leakage and manually resetting just before the exposure, this possibility is precluded. In the case where the Model 35050AT Dosimeter detects the start of an exposure immediately following an automatic reset, an error message will be displayed advising the user to repeat the exposure.

For several reasons, then, it is good operator practice to regularly check for a low system leakage level. Experience should serve as a guide to how often this needs to be done and in what circumstances.

Similarly, ten seconds or so should be allowed to elapse between the last triaxial cable or chamber movement or other disturbances to the high impedance part of the system before commencing an exposure--so that the “correct” history is applied to the measurement.

2-6

+ 56 hidden pages