Fluke 90100 User Manual

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Model 90100

TRACKER™ System

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....................................................................................................... 1-2

1.3 Before You Start - Safety Precautions ......................................................... 1-3

1.4 Safety Terms ............................................................................................... 1-3

1.5 Manual Addenda.......................................................................................... 1-3

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

1.6.1 Model 35300A Detector.......................................................................... 1-3

1.6.2 Model 35360A Tracker Display .............................................................. 1-5

1.6.3 Interface Cable – Detector To Display.................................................... 1-6

1.7 Unpacking And Inspection ........................................................................... 1-6

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

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

2.2 Rear Panel Familiarization........................................................................... 2-2

2.2.1 Powering The System ............................................................................ 2-2

2.2.2 Detector Input......................................................................................... 2-2

2.2.3 RS-232 Computer Interface.................................................................... 2-4

2.3 Positioning The Model 35300A Detector In The Beam ................................ 2-4

2.4 Operation Instructions.................................................................................. 2-6

2.4.1 Front Panel Controls............................................................................... 2-6

2.4.2 Powering Up The Model 35360A Tracker Display.................................. 2-8

2.4.3 Powering Down The Model 35360A Tracker Display ............................. 2-8

2.4.4 Using The Test/Detector Button ............................................................. 2-8

2.4.5 Using The Units Select Button................................................................ 2-9

2.4.6 Using The Air Density Button ............................................................... 2-10

2.4.7 Using The Gain Select Button .............................................................. 2-10

2.4.8 Using The Measure Select Button........................................................ 2-11

2.4.8.1 Absolute Measurements ................................................................. 2-11

2.4.8.2 Percent-Of-Center Measurements .................................................. 2-12

2.4.8.3 Underranging And Overranging Conditions .................................... 2-13

2.4.9 Battery And Bias Annunciators............................................................. 2-13

2.4.10 Gain Setting Mode................................................................................ 2-14

2.4.10.1 Changing Front Panel Gain Factor’s From The Measurement ....... 2-15

2.4.10.2 Saving the FPGF Changes ............................................................. 2-15

2.4.10.3 Aborting the FPGF Changes........................................................... 2-15

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

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

3.2 Overall Function Description Of The Model 35360A TRACKER Display ..... 3-1

3.2.1 Power Supply ......................................................................................... 3-2

3.2.2 300 Volt Electronic Bias Supply.............................................................. 3-3

3.2.3 Front Panel Switches.............................................................................. 3-3

3.2.4 Processor ............................................................................................... 3-3

3.2.5 VFD Display ........................................................................................... 3-3

3.2.6 Serial Communications Port ................................................................... 3-4

3.2.7 Electrometer ........................................................................................... 3-4

3.2.8 Multiplexer and A/D Converter ............................................................... 3-4

3.3 Model 35300A Ion Chamber Detectors........................................................ 3-5

3.4 Air Density Corrections ................................................................................ 3-5

3.5 Basic Operating Equations .......................................................................... 3-6

3.5.1 Charge.................................................................................................... 3-6

3.5.2 Current ................................................................................................... 3-6

3.5.3 Absolute Dose ........................................................................................ 3-6

3.5.4 Absolute Dose Rate................................................................................ 3-6

3.5.5 Percent-of-Center ................................................................................... 3-6

3.6 Basic Operating Quantities .......................................................................... 3-7

Section 4: Maintenance and Service ............................................................................. 4-1

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

4.2 Troubleshooting ........................................................................................... 4-2

4.3 Line Fuse Replacement ............................................................................... 4-7

4.4 Interface Connector Cleaning ...................................................................... 4-9

4.5 Cleaning The Instrument.............................................................................. 4-9

4.6 Replaceable Parts Information..................................................................... 4-9

4.7 Recalibration & Repair Information/Technical Assistance.......................... 4-10

Section 5: Customization ............................................................................................... 5-1

5.1 Introduction .................................................................................................. 5-1

5.2 Make A Working Disk................................................................................... 5-2

5.3 Connection To The Computer...................................................................... 5-2

5.4 Starting The Customization Software........................................................... 5-2

5.5 Screen Formats ........................................................................................... 5-2

5.6 Definitions .................................................................................................... 5-5

5.7 Setting The Electrometer Gains And Offsets ............................................... 5-6

5.8 Usage Examples.......................................................................................... 5-8

5.9 Errors......................................................................................................... 5-10

Appendix A: Using Build-Up .......................................................................................... A-1

A-1 Build-Up, Peg, And Retainer Kit Options .....................................................A-1

General Information

Introduction

Section 1

General Information

1.1 Introduction

The Model 90100 TRACKER is a radiation measurement system intended for use in quality assurance programs for high-energy accelerators and Co daily checks of beam constancy, symmetry, and flatness, its portability makes it a good choice for field service engineers and consulting physicists. The two main components of the system are the Model 35360A TRACKER Display, and the Model 35300A Detector, see Figure 1-1.

Figure 1-1. Model 35360A TRACKER Display and Model 35300A Detector

The 35360A TRACKER Display contains a five-channel electrometer capable of producing measurements of both dose and dose rate. A microcontroller performs air density corrections and displays the measurement results on the 4 line by 20 character vacuum fluorescent display (VFD) directly in the user's choice of radiological units. An integrated rechargeable battery and a 300 V electronic bias supply greatly simplify maintenance of the system. Another important feature built into the 35360A TRACKER Display includes the capability for fully remote and automated operation via an RS-232 computer interface (software is not included).

machines. While its ease of operation makes it ideal for

The 35300A Detector contains an array of four orthogonally placed ion chambers on 10 cm radii from a fifth isocentrally located ion chamber. The five ion chambers are of a vented, circular, parallel-plate configuration and are fully guarded for low leakage. An overlay label on the outside of the 35300A Detector marks the ion chamber locations for alignment with a therapy source light field system. The 35300A Detector connects to the 35360A TRACKER Display through a lightweight interface cable. This

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Model 90100

Operators Manual

cable is of a design that provides a high degree of flexibility and allows it to flatten to fit under a treatment room entrance door.

Included with each 90100 TRACKER System is an MS-DOS based Customization program that provides a means of performing field customization and calibrations. Some of the items that may be field customized include the measurement display units, temperature and pressure units, the ion chamber calibration factors, and the number of minutes to power down. This program may also be used to generate a printed report containing all of the customization and calibration settings.

A number of optional accessories including a carrying case for storage and transport, build-up plates of various thickness/materials, and a build-up retaining hardware kit are available also.

1.2 Features

• Measurement values from peripheral ion chambers may be displayed in either absolute dose

measurement units or as a percentage of the center ion chamber's measurement value.

• A wide AC Line Input Range of 100 to 240 VAC and the use of an IEC 320/C13 style receptacle

provide worldwide operation by use of the proper line cord.

• The levels of the internal 300 V electronic bias supply and the rechargeable battery supply are

continuously monitored. Annunciators appear on the display if an abnormal bias voltage or low battery voltage level is detected.

• All front panel settings are automatically stored at power down and restored at power up eliminating

the need to reconfigure the front panel settings upon each use.

• Dose measurement values may be displayed in units of roentgens, rads, sieverts, grays, or monitor

units. Dose rate measurement values may be displayed in units of roentgens/min, rads/min, sieverts/min, grays/min, or monitor units/min.

• Front panel gain settings allow the user to easily match displayed measurement values to the linear

accelerator's monitor readout or to a precision calibration.

• Precision five-channel electrometer provides ± 0.003% linearity and a long-term stability of better

than 0.25% of reading per year.

• The system may be operated from either AC line power source or from its internal battery. The

batteries will be charged during use from AC line power.

• A high performance rechargeable battery system provides 8 hours of continuous operation from a

3-hour charge. A low battery annunciator indicates when 30 minutes or less of operation remains.

1-2

General Information

Before You Start- Safety Precautions

1.3 Before You Start - Safety Precautions

This product is designed for quality assurance testing of therapeutic radiation treatment machines. It is not for machine calibration nor is it intended as a substitute for a precision dosimeter system (Farmer-type Probe and Electrometer with official calibration). Its use should be restricted to the monitoring of constancy of output, flatness, and symmetry. It is the responsibility of the user to establish the correct procedure of uses including the initial configuration of the device, (via the Customization program included). Quality assurance testing should be done by qualified personnel under the supervision of a trained medical physicist. The Model 90100 TRACKER System should be used only by people who are:

• aware of and understand the limitations of the device as they relate to the measurement of radiation

output;

• knowledgeable about safety procedures observed when working with radiation sources, such as

therapy radiation machines;

• aware of safety precautions required to avoid possible injury when using electrical/electronic

equipment.

Please take the time to read this manual carefully before operating this instrument.

1.4 Safety Terms

The following terms are used in this manual.

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.

WARNING

CAUTION

1.5 Manual Addenda

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

1.6 Specifications

1.6.1 Model 35300A Detector

Source Modes and Energies

Photons: 300 keV to 25 MeV, with suitable build-up material

Electrons: 2 MeV to 25 MeV, with suitable build-up material

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Recommended Operation Conditions

Source Distance: 100 cm Collimated Field Size: 25 × 25 cm

Source Dose Rate Range: 50 to 500 rads/min

Nominal Ion Chamber Characteristics

Wall and Window Material: Continental Polymers ACRYCAL-CP or equivalent

Window Area Density: 600 mg/sq cm (0.51 cm acrylic plastic)

Window Transmission: 95% for 662 keV photons; for electrons, transmission through window occurs above 1.5 MeV.

Sensitivity: 3.52 R/nC at 22°C and 760 mm Hg Active Volume: 0.93 cc ±5%

Active Diameter: 1.162 cm

Active Cross-Sectional Area: 1.06 sq cm

Collector-to-Bias Separation: 0.44 cm

Ion Transit Time: 0.418 ms @ bias voltage of 300V

Collection Efficiency: >99% at 500 rads/min pulsed; >99.9% at 500 rads/min continuous

Leakage: Less than 0.5 pA over the full operating temperature range

Ion Chamber Factory Calibration

Method: Each of the 5 ion chambers within the detector array is calibrated by comparison with a reference standard ion chamber in a Co60 beam. The comparison is performed in free air and results

in an R/nC Calibration Factor for each of the five ion chambers.

Comparison Standard: 0.6 cc NE Farmer Probe with 3 MeV buildup cap.

Uncertainty: 2.5% using IEC/NIST guidelines.

Mechanical Specifications

Detector Configuration: The detector array consists of four orthogonally placed ion chambers on 10 cm radii from a fifth centrally located ion chamber.

Dimensions: 33.7 cm wide x 43.8 cm deep x 2.2 cm high (13.25 in. x 17.25 in. x 0.875 in.). Depth dimension assumes handle is fully extended; height dimension assumes no accessory pegs or build-up added.

Weight: 4 kg (8.8 lbs)

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General Information

Specifications

1.6.2 Model 35360A TRACKER Display

Measurements Mode

The measurement mode is user-selected from the front panel prior to the start of the exposure.

Dose (rad): Electrometer is operated in integrating mode with capacitive feedback.

Dose Rate (rad/min): Electrometer is operated in non-integrating mode with resistive feedback.

Display Mode

The display mode is user-selected from the front panel and may be selected before, during, or following the exposure.

Absolute: All five ion chamber measurement values are displayed in absolute dose measurement units (typically rads or rad/min) as defined by the dose measurement unit's description.

Percent-of-Center: Only the center ion chamber measurement value is displayed in absolute dose measurement units (typically rad or rad/min) as defined by the dose measurement unit's description.

Four peripheral ion chamber measurement values (top, bottom, left, and right) are displayed as a percentage of the center ion chamber measurement value.

Electrometer / A-D Converter

Nominal Full Scale Output: 3 volts.

A/D Converter Resolution: 16 bits unipolar.

Nominal Full Scale and Sensitivity in Electrical Units:

A-D Dose

Full Scale

1000.0 nC ± 2% 0.015 nC/count 1000.0 nC/min ± 2% 0.015 (nC/min)/count

An overrange indication will be displayed when the input current or charge have exceeded the full-scale values. The full-scale value of any unit is guaranteed not to differ from nominal values by more than ± 2%.

Long Term Stability: Expected to be less than 0.25% of reading per year. Non-linearity: Less than ± 0.4% of range.

Display Resolution: 0.003% of range (4-3/4 digits) for both dose and dose rate. Display resolution is limited by the following relationship for all display units;

1 A-D Count ≤ 1 Display Count < 10 A-D Counts.

This relationship insures that the resolution of the measurement display values is as high as possible without exceeding the inherent resolving capability of the

A-D converter.

Gain Temperature Stability: Less than ± 0.4% of reading over operating range of 10°C to 35°C.

Measurement Noise: Charge and Current measurement noise are less than ± 1 count at the display exclusive of source noise effects. Typical effects from a Co60 source are on the order of ± 0.2 rad/min

at 100 rad/min. Source noise effects during dose rate measurements on a linear accelerator may be excessive.

Measurement Accuracy: Fluke Biomedical factory calibration will provide a basic Charge (Current) measurement accuracy of ±1% of reading ± 0.3 nC (± 0.3 nC /min) exclusive of long-term drift and temperature effects. Similar results may be obtained in the field using a suitable calibration source such as the Keithley Instruments, Inc. Model 263 Calibrator/Source and the included Customization software.

Current Leakage: Less than 1 pA (typically 1 rad in 5 minutes)

Zero Offset Voltage: Factory trimmed to 0 counts at the display.

A-D Dose

Sensitivity

A-D Rate

Full Scale

A-D Rate

Sensitivity

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Offset Temperature Drift: The zero offset voltage will drift less than ± 1 count at the display over the operating range of 10°C to 35°C.

High Performance Battery Charger

Battery Type and Capacity: 6V (3 cell) Lead Acid (5 AH) provide 8 hours of continuous operation.

Recharge Time: Fast recharge time on the order of 2 - 3 hours even during operation.

Battery Life Span: On the order of 8-10 years due to multiple level charging circuit (2000 charge/discharge cycles typically).

Low Battery Annunciator: Displayed when 30 minutes or less of operation remains.

Environment

Operating: 0°C to 35°C, up to 70% relative humidity.

Storage: -25°C to +65°C.

Mechanical

Dimensions: 21.6 cm wide x 8.9 cm high x 26 cm deep (10 in. x 9.4 in. x 4 in.)

Weight: 5 kg (11 lbs.)

1.6.3 Interface Cable - Detector to Display

Part Number: 37783-X where X denotes cable length in meters.

Standard Length: 15 m and 30 m.

Maximum Total Length: 60 m ( 197 ft.).

Ion Chamber Signal Cable Type: Five channels of RG-174 low noise coaxial.

Leakage: Less than 0.5 pA over the full operating temperature range.

Connector Type: Display interface end has five AMP male coaxial connectors and three AMP male single conductor connectors housed in a single DB-37 type housing. Detector interface end has a five AMP female coaxial connectors and three AMP female single conductor connectors housed in a single DB-37 type housing. Multiple cables may be interconnected to form other lengths.

Minimum Conduit Diameter: 7.6 cm (3 in.) without disassembly. Cable may be run through smaller opening by using special tool for disassembly. Consult factory for further details.

Weight: 2.25 kg (5 lbs.) at 15 m (weight is approximately proportional to cable length for other lengths).

* Specifications subject to change without notice.

1.7 Unpacking and Inspection

The 90100 TRACKER System was carefully inspected before shipment. Upon receiving the 90100 TRACKER System, 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 items in Figure 1-3 are included with every 90100 TRACKER System.

1-6

General Information

Unpacking and Inspection

Standard System Contents

• Model 35360A TRACKER Display

• Model 35300A Detector

• 15 m Detector to Display Interface Cable (37783-15)

• AC Line Cord

• Customization Software Kit (37827): Contains disk, cable, and adapters.

Optional Equipment

• System Carrying Case (37780): Dimensions are 41.9 cm wide x 45.2 cm long x 22.2 cm deep

(16.50 in. x 17.75 in. x 8.75 in.). Empty weight is 0.9 kg (2 lbs.).

• Cable (37783-30): 30 m Detector to Display Interface Cable

• Build-Up Kit (37825): Contains 10 pieces of 0.44 cm acrylic part number 37051-1. Kits containing

other quantities of plates, plate materials, and plate thicknesses are available.

• Pegs and Retainer Kit (37825): Contains eight each, pegs and retainers for attach build-up plates

to detector.

Figure 1-3. Model 90100 TRACKER System Parts and Accessories

OPTIONAL:

Build-Up Kit (37825)

15m Detector to Display Interface Cable (37783-15)

OPTIONAL:

Pegs and Retainer Kit (37825)

Model 35360A TRACKER Display

Model 90100 TRAKCER System Instruction Manual (37826)

Customization Software Kit (37827)

OPTIONAL:

System Carrying Case (37780)

Model 35300A Detector

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Operators Manual

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Operation

Introduction

Section 2

Operation

2.1 Introduction

This section contains set-up and connection procedures for the Model 90100 TRACKER System in order to measure therapy beam characteristics.

If you want to use build-up to simulate tissue, you can put plates of either "solid water" or acrylic (optional accessories) securely on one or both sides of the Model 35300A Detector. Build-up pegs and retainer rings for securing the plates to the 35300A Detector are optional with the 90100 TRACKER System. See Appendix A for additional information.

It is recommended that the user customize his Model 35360A TRACKER Display prior to its first use as a quality assurance tool. This customization may involve selecting the desired display units, display units conversion factor, temperature units, and pressure units. Procedures for carrying out the customization is covered in Section 5.

2.2 Rear Panel Familiarization

COMPUTER INTERFACE

RS-232

100-240V 50/60 Hz 50VA

DETECTOR INPUT

Figure 2-1. Model 35360A TRACKER Display Rear Panel

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Operators Manual

2.2.1 Powering the System

The Model 35360A TRACKER Display may be operated from either line or battery power. The line receptacle at the rear panel of the Model 35360A TRACKER Display mates with a 3-wire line cord to provide a connection to line voltage (high, neutral and earth ground).

When powering the 35360A TRACKER Display from an AC line, always use a 3-wire grounding type line cord such as the one supplied with the 90100 TRACKER System. In addition, only connect the 35360A TRACKER Display to an AC power outlet employing a third wire safety ground. Failure to ground the Model 35360A TRACKER Display may result in personal injury or death in the event of a short circuit or malfunction.

The 35360A TRACKER Display operates on battery power for eight hours after a full charge. The 35360A TRACKER Display can be recharged quickly, usually in two to three hours, even during instrument operation. A low battery annunciator is displayed when 30 minutes or less of operation remains. When the battery pack is fully discharged, the instrument automatically shuts off and will not operate until AC line power is connected.

WARNING

The Model 35360A TRACKER Display operates from line voltage ranging from 100 to 240 VAC without operator switching. An IEC 320/C13 style receptacle provides worldwide operation by simply changing line cords.

2.2.2 Detector Input

The Model 35360A TRACKER Display connects to the Model 35300A Detector through an interface cable. The cable connects to an 8-pin D connector on the back of the 35360A TRACKER Display housing (see Figure 2-1).

Before you attach the 35300A Detector to the 35360A TRACKER Display, you must perform the following procedure (refer to Figure 2-2 and Figure 2-3).

1. Turn the 35360A TRACKER Display OFF.

Always turn the Model 35360A TRACKER Display's power off prior to connecting or disconnecting the interface cable. Failure to do so may result in an electrical shock.

2. Firmly press the 8-pin D connectors at either end of the interface cable into the 35360A TRACKER Display and the 35300A Detector, see Figure 2-2 and Figure 2-3.

This interface cable has different mating pins for both the 35300A Detector and 35360A TRACKER

WARNIN

2-2

Operation

Real Panel Familiarization

Display. Be sure to use the correct end of the cable.

3. Secure the cable at each end by twisting the thumbscrews in a clockwise direction until tight.

Model 35300A Detector

To Model 35360A TRAK C ER D isplay

Figure 2-2. Connecting the Interface Cable to the Model 35360A TRACKER Display

Rear panel of the Model 35360A TRACKE R D isplay

100-240V 50/60 Hz 50VA

COMPUTER INTERFACE

RS-232

DETECTOR INPUT

To Model 35300A Detector

Figure 2-3. Connecting the Interface Cable to the Model 35300A Detector

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Operators Manual

4. Power can now be applied to the system. Wait for the Test/Detector screen shown below before pressing any keys.

Reverse the above procedure to disconnect the interface cable from the 35300A Detector.

WARNIN

Always turn the Model 35360A TRACKER Display's power off prior to connecting or disconnecting the interface cable. Failure to do so may result in an electrical shock.

2.2.3 RS-232 Computer Interface (RJ-45 Style)

The RS-232 Computer Interface provides a means for computer controlled factory test and calibration. It is also used in conjunction with the Customization program during the user customization process.

2.3 Positioning the Model 35300A Detector in the Beam

Proper and consistent positioning of the 35300A Detector is necessary for reliable measurement results. The 35300A Detector has a printed overlay on both of its flat surfaces to indicate the location of the five detectors inside the assembly. The overlays also include a black cross-hair to aid in centering the device in the treatment beam.

The 35300A Detector should be placed so that the center detector will be in the center of the treatment beam. For a gantry angle of 0 degrees, place the 35300A Detector on the treatment table with the axis label face up, and the connector facing away from the gantry. The "TOP" chamber should be the one nearest the gantry. This placement is shown in Figure 2-4.

2-4

Positioning the Model 353300A Detector in the Beam

Gantry arm

Treatment head

Gantry

Model 35300A Detector

Treatment table

To Model 35360A TRACKER Display

Treatment table

Gantry

Cable

To Model 35360A

TRACKER Display

Figure 2-4. Setup for 0-Degree Gantry Angle (NOTE: Build-up not shown for clarity)

Operation

For those who have purchased the optional Build-Up Peg and Retainer Kit, gantry angles other than 0 degrees may be used. For gantry angles of 90 or 270 degrees, place the 35300A Detector on its side so the label faces the head. Orient the connector away from the gantry. This placement is shown in Figure 2-5.

WARNING

Operating the 35300A Detector on edge without build-up pegs constitutes a tip-over hazard and could result in personal injury.

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Gantry

Gantry arm

Model 35300A Detector

Treatment head

Cable to 35360A TRACKER Display

Treatment table

90 degrees

Gantry

Cable

270 degrees

Treatment table

TRACKER Display

To 35360A

Figure 2-5. Setup for 90- and 270-Degree Angles (NOTE: Build-up not shown for clarity)

2.4 Operation Instructions

This section contains detailed instructions on the front panel operation of the Model 35360A TRACKER Display. The 35360A TRACKER Display front panel keys and display are explained. Please note that the display examples shown here correspond to a particular customization set-up. Other customization set-ups will produce different results.

2.4.1 Front Panel Controls

Figure 2-6 shows the front panel of the 35360A TRACKER Display. The front panel consists of control buttons and a display. The following paragraphs describe the operation of each control button and the corresponding display screens.

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