HomeMy WebLinkAboutUntitled 4•IND /C&S Associates, Inc. -•1926 Elm Tree Drive �,�
Nashville, Tennessee 37210-3718 C`"a
•
800-522-2325 Fax 615-871-0856 ACCREDlTIEb
CALIIiRATiON CERT ft1864.01
CALIBRATION REPORT Report Number 140701
Fluke Biomedical 10500AMT Triad System Calibration Page 1 of 3
Submitted by California Medical Physics, Inc. Test Number: D140728
Medical Physics
16590 Sutties Drive Calibration Date: 03/18/2014
Next Due Date:
Riverside,CA 92504
instrument: Manufacturer Model Serial Temperature: 21
Fluke Biomedical 35050AT 0000000483 Pressure: 748
Fluke Biomedical 35080E 0000108306 Relative Humidity: 42
Fluke Biomedical 96035B 0000108009
K+S certifies that the above instrument was calibrated using instruments calibrated by,or traceable to,the National Institute of Standards
and Technology or other national standards laboratory. K+S further certifies that the calibration laboratory policies and procedures meet
or exceed the requirements of ANSI/iSO/IEC 17025:2005. The combined expanded uncertainty with a coverage factor of 2(95%
confidence)including the NIST uncertainty of the calibrations are as follows: kVp calibrations: 1.5%;exposure calibrations:3%;time
calibrations:0.6-1.3%;voltage calibrations:0.06%;charge calibrations:0.13%.
Caution:If a calibration due date is shown,it is shown for the convenience of the user only. The interval is not a recommendation by K+S
but is based on either the customers requirements or the manufacturer's recommendations. Any number of factors,such as time,
environment and handling may cause the instrument to drift out of calibration prior to the indicated date.
This laboratory is accredited by the American Association for Laboratory Accreditation(A2LA)and the results shown in this report have been
determined in accordance with the laboratory's terms of accreditation unless stated otherwise in this report
Calibration Unit Manufacturer: Electromed International Model: 5501.60-691 Beam: W/AI
Waveform: Constant Potential HVL: 3.4mm AI er 80 kVp(2.7 for Mobile pack)
kVp Standard Mfgr: Machlett/Fluke Model: Dynalyzer III High Voltage Unit/Model 87
Exposure Standard Mfgr: Exradin Model: A3#223
Switch Settings: RUN on the 35080;Chamber and filter pack selected on 35050A;Unit select:R;
kV Condition: Received in Tolerance,Returned as received
Exposure Condition: Received in Tolerance, Returned as received
Mfrs.kV Specification: ±2% Exposure Units: R Mfrs.Exposure Specification: t 5%
Measurements: kVp Measurements Dose Measurements
Filter Range Set Ref.kVp Rdg Error %Error RefDose Rdg CF
37617#107447 60 60.2 60.5 0.3 0.5 0.231 0.224 1.03
37617#107447 100 100.2 100.3 0.1 0.1 0.711 0.712 1.00
37617#107447 140 140.2 140.4 0.2 0.1 1.385 1.413 0.98
37946C#108260 60 60.2 61.1 0.9 1.5 0.231 0.224 1.03
37946C#108260 80 80.2 81.0 0.8 1.0 0.450 0.442 1.02
37946C#108260 120 120.2 119.9 -0.3 -0.2 1.027 1.036 0.99
Form:TRIAD+C This report shall not be reproduced except in full without the written approval of K+S.
CALIBRATION REPORT Report Number: 140701
Fluke Biomedical 10500AMT Triad System Calibration Page 2 of 3
Condition: Received in Tolerance,Returned as received
Time Settings: ON;Used TEST PACK
Timer Data: MfgrTimeSpec: ±1%or±0.2 mS
Time Set True Time Time Rdg %Error
250 246.7 246.4 -0.1
100 99.2 99.1 -0.1
50 50.0 49.9 -0.2
500 490.7 490.3 -0.1
1000 977.9 977.0 -0.1
Calibration Unit 2Manufacturer: Bennett Model: HF 150 Beam: Moly/Moly
Waveform: High Frequency HVL: 0.328 mm Al @ 28 kVp
kVp Standard Mfgr: Machlett/Fluke Model: Dynalyzer Ill High Voltage Unit/Model 87
Exposure Standard Mfgr: PRM Model: LE-.8 Be window
Switch Settings: ON;RUN;
kV Condition: Received in Tolerance,Returned as received
Measurements: Mfrs.kV Specification: ±2%
kVp Measurements
Detector Set Ref.kVp Rdg Error %Error
37355C#108114 28 28.14 28.1 0.0 -0.1
37355C#108114 28.5 28.62 28.6 0.0 -0.1
37355C#108114 29 29.05 29.1 0.1 0.2
37351#108099 25 25.12 25.1 0.0 -0.1
37351#108099 30 30.05 30.2 0.1 0.5
37351#108099 35 35.11 35.2 0.1 0.3
Comment: Battery checked prior to calibration.BAT CHK=9.3 vdc. Used K&S filter pack 32863C#80464
to check manufacturer's spec.Filter pack 37355C#108114 was done at 38 cm from source.
Filter pack 37351#108099 was done at 25 cm from source.Procedure:kVptime7
kVp Log References Log: F-36 Page: 45 Log: Page:
Form:TRIAD+C This report shall not be reproduced except in full without the written approval of K+S.
CALIBRATION REPORT Report Number: 140701
Fluke Biomedical 10500AMT Triad System Calibration Page 3 of 3
Accredited
Dosimetry Accredited Dosimetry Calibration
er;eatibration Electrometer Mfgr: Fluke Biomedical
Laboratory
Model: 35050AT Serial: 0000000483 CALL BRATION CHtT MUM
Manufacturer:Fluke Biomedical Calibration Unit Electromed CP60 at 100cm(3.4mmAl)
Model:960358 Orientation: Diagnostic focus toward source
Serial:0000108009 Bias: 309 V Leakage: Negligible
Conditions: ON;Battery level 9.5 volts OK;TEST FUNCTION:ion chamber bias 309 volts ok;I.C.Cal
Factor in use 1.897e+08 R/C;AIR DENSITY:Temp-20.9°C,Press 747 mmHg;UNIT SELECT:
R;DETECTOR SELECT:"15cc 108009 DIA ADC",35080 not used;RESET/MEASURE
0.000 mR; Field:20 x 20 cm.
Beam HVL HC kVp SCD Rate Calibration Factor Uncert. Log Page
W/AI 4.28 Al 0.67 100 100 0.71 R/s 1.00 mRP'mR"rdg 5% X-20 57
Notes: Batteries replaced prior to calibration,Procedure:AAPM39
Chamber is open to atmosphere. RATE C.F.=1.00(mR/min)/"mR/min"rdg
Corrections to 22 C and 760 mmHg have been made where needed.
AS FOUND condition equals the AS LEFT condition.
Manufacturer:Victoreen Calibration Unit Electromed CP60 at 100cm(3.4mmAl)
Model:500-200 Orientation: Centered in beam
Serial:101549 Bias: 309 V Leakage: Negligible
Conditions: ON;Battery level 9.5 volts OK;TEST FUNCTION:ion chamber bias 309 volts ok;I.C.Cal
Factor in use 3.107e+08 R/C*;AIR DENSITY:Temp-20.9°C,Press 747 mmHg;UNIT SELECT:
R;DETECTOR SELECT:"10cc 101549 M100ADC",35080 not used;RESET/MEASURE
0.000 mR; Field:20 x 20 cm.
Beam HVL HC kVp SCD Rate Calibration Factor Uncert. Log Page
W/AI 7.65 Al 0.83 120 100 0.61 R/s 1.00 mRP'mR"rdg 5% X-20 59
Notes: Batteries replaced prior to calibration.Procedure:AAPM39
Chamber is open to atmosphere.
Corrections to 22 C and 760 mmHg have been made where needed.
"changed CAL FACTOR from 3.156e+8 R/C
Manufacturer:Fluke Biomedical Calibration Unit: Bennett Constant Potential,60cm
Model:96035B Orientation: Mammography focus toward source
Serial:0000108009 Bias: 309 V Leakage: Negligible
Conditions: ON;Battery level 9.5 volts OK;TEST FUNCTION: ion chamber bias 309 volts ok; I.C.Cal
Factor in use 2.204e+08 R/C";AIR DENSITY:Temp-20.9"C,Press 747 mmHg;UNIT SELECT:
R;DETECTOR SELECT:"15cc 108009 MA■ ADC",35080 not used; RESET/MEASURE
0.000 mR; Field:10 x 10 cm.Distance to surface of chamber
Beam HVL HC kVp SCD Rate Calibration Factor Uncert. Log Page
Mo/Mo 0.328 Al 0.78 28 60 1.75 R/s 1.00 R./"R"rdg 3% R-8 251
Notes: Batteries replaced prior to calibration.Procedure:AAPM39
Chamber is open to atmosphere.
Corrections to 22 C and 760 mmHg have been made where needed.
changed CAL FACTOR from 2.154e+8 R/C
0—
° Horn
- �Calibrated By Brad
Calibration Technician Reviewed By aUi PP
eld
Title 'Title Associate
Director
Form:TRIAD+C This report shall not be reproduced except in full without the written approval of K+S.
J_�,HT«(,,,�T K&S Associates, Inc. Date: 3/18/2014 -
., i 1926 Elm Tree Drive '�Due Date:= s A Nashville, Tennessee 37210-3718 Report#: 140700 �d '
615-883-9760 Fax 615-871-0 � �
t .; ��a 856 Test#: M140728 ACCREDITED
CERTIFICATE OF CALIBRATION CALIBRATION CERT11881.U1
This is to certify that the instrument described below was calibrated by measurement in a radiation beam having a calibration which is traceable to
the National Institute of Standards and Technology. This calibration has been performed with a Quality Assurance Program which complies with
10 CFR 50,Appendix B and ISO/IEC 17025:2005. Unless stated otherwise,the Calibration Values represent an average of at least two points on
each scale. The combined expanded uncertainty for the calibration with a coverage factor of 2(95%confidence)is 11%for exposure rates below
0.5 mR/h and 8%for exposure rates above 0.5 mR/h. Procedure HPS 24 is used for HPS accredited calibrations.
Caution:If a calibration due date is shown,it is shown for the convenience of the user only. The interval is not a recommendation by K+ S but is
based on either the customers requirements or the manufacturer's recommendations. Any number of factors,such as time,environment and
handling may cause the instrument to drift out of calibration prior to the indicated date.
This laboratory is accredited by the American Association for Laboratory Accreditation(A2LA)and the results shown in this report have been
determined in accordance with the laboratory's terms of accreditation unless stated otherwise in this report.
MULTIPLYjthe reading of the instrument by the listed Calibration Value to obtain an exposure or exposure rate value.
Customer#: 2915 I
Name CALIFORNIA MEDICAL PHYSICS,INC Source 1 Cs-137
Address 16590 SUTTLES DRIVE Source 2
—
Address RIVERSIDE,CA 92504 Source 3
Address Probe Type: ION CHAMBER
Type •DIGITAL Probe Mfgr:
Mfgr FLUKE Probe Model:
Model 451P-RYR Probe Serial:
Serial 0000001754 Probe Window:
Probe Orientation: BOTTOM TOWARD SOURCE
_ TempI Pressure I RH% { Check Source Conditions Reading LBattery Chk:,IOK
21 deg C 748 mmHg ' 42 I( NO t
Status HPS Beam Scale Ref.Rate Reading Ref.Rate Reading Calibration Value
A2LA mR/h mR/h mR/h mR/h mR/h
F Y 500 uR/h 0.25 236 uR/h --- _-
L Y 500 uR/h 0.25 251 uR/h 0.100* 99 uR/h —
L Y 500 uR/h 0.40 392 uR/h — — 1.01
F Y 5 1.00 0.99 4.0 3.91 1.02
F Y 50 25 23.6 — — —
L Y 50 25 25.0 10.0 10.2 —
L Y 50 40 40.0 -- — 0.99
F Y 500 250 239 — — —
L Y 500 250 251 100 100 —
L Y 500 400 395 — — 1.00
F Y 5 R/h 1000 0.90 R/h — -_ —
L Y 5 R/h _ 1000 1.00 R/h — — 1.00
STATUS: F=AS FOUND;L=AS LEFT. HPS:Accredited Procedure="Y"for yes,"N"for no. Label: Cal by:REH i
CAUTION: 1. Application of the factors to an individual measurement is the responsibility of the user.
2. The factors shown are not necessarily valid over the entire scale.
3. Exercise caution in the interpolation or extrapolation of the factors.
NOTE:Please report any problems with the service provided by this HPS accredited laboratory to the HPS Secretariat.
Comments *With"true"background exposure rate of 7.0 uR/h,instrument reading was 4 uR/h.
Replaced 2(9V)batteries.
6.---
Calibrated by: r�.�i ,- -� Reviewed by a Log: M-42 Page 291
Title: -!chard ardison Title: Paul appenfield Log: Page
Calibration Technician Associate Director Log: Page
This report may not be reproduced except in full without written authorization. Page 1 of 1
,.
avDcocsriemdeitted® K&SAssociates' Inc. F
ry 1926 Elm Tree Drive ,r
�ErCalibration Nashvile, Tennessee 37210-3718 ♦aL
Laboratory Phone 80 0-522-2325 Feet 615-871-0858 ACCREW ED
CALIBRATION CERT 11866.01
ACCREDITED DOSIMETRY CALIBRATION LABORATORY
CALIBRATION REPORT
SUBMITTED BY: California Medical Physics, Inc.
Medical Physics
16590 Suttles Drive
Riverside, CA 92504
INSTRUMENT: PTW TN23342,#1699
REPORT NUMBER: 140745
TEST NUMBER(S): T140728
REPORT DATE: March 19,2014
The CALIBRATION COEFFICIENTS contained in this report were obtained by intercomparison
with instruments calibrated by, or directly traceable to, the National Institute of Standards and
Technology(NIST). K• S Associates, Inc. is licensed by the State of Tennessee to perform
calibrations, and is recognized by the American Association of Physicists in Medicine(AAPM) as an
ACCREDITED DOSIMETRY CALIBRATION LABORATORY with special accreditation for
the calibration of brachytherapy sources and well chambers. As part of the accreditation K • S
participates in a measurement assurance program conducted by the AAPM and NIST. K• S also
certifies that the calibration was performed using quality policies,methods and procedures that meet or
exceed the requirements of ANSI/ISO/IEC 17025:2005.
This laboratory is accredited by the American Association for Laboratory Accreditation(A2LA) and
the results shown in this report have been determined in accordance with the laboratory's terms of
accreditation unless stated otherwise in this report
The CALIBRATION COEFFICIENTS stated herein are valid under the conditions specified. It
is the instrument user's responsibility to perform the appropriate constancy tests prior to shipment
and after return from calibration. It is also the responsibility of the user to assure that the
interpretation of the information in this report is consistent with that intended by K• S Associates, Inc.
This report may not be reproduced except in full without the written permission of K•S Associates,
Page I of 2
Accredited e
Laboratory Ionization Chamber Calibration
Calibration
Laboratory ACCREDITED
CAUBRATION CERT 11e65.O1
March 19, 2014 Test Number T140728
CHAMBER: SUBMITTED BY:
Mfgr: PTW California Medical Physics,Inc.
Model: TN23342
Serial: 1699 Riverside, CA
ORIENTATION/CONDITIONS: ATMOSPHERIC COMMUNICATION: OPEN
window towards the source
distance to surface of window
ION COLLECTION EFFICIENCY: 0.996 Aio„ RATE: 24.0 Rlmin
ne ative charge 15
POLARIZING POTENTIAL - 300 V
( g arge collected) LEAKAGE: - 2 xl 0 A
BEAM QUALITY SCD EXPOSURE CALIBRATION
BEAM kVp HVL(mm) H.C. (cm) RATE COEFFICIENT UNCERT. LOG
W/A1 19 .076A1 0.8 33 24.0 R/min NX 1.448 x10 11 R/C 1.5% D15 83
Nk= 1.269 x10 9 Gy/C
Comments Refer to Appendix A of this report for details on ionization chamber calibrations.
Procedure: AAPM39. Temp.:21 C;Press.: 748 mmHg;47%RH.
Note:The Calibration Coefficient has been corrected to 22 degrees C and 760 mm Hg.
,T Calibrated B /
Y NA BoriR Reviewed By: a.
Pau appenfisld
Title: Staff Physicist Title: Associate Director
Checked By: (1/_"-- Prepared By: Form Cl
ACCREDITED DOSIMETRY CALIBRATION LABORATORY 2915 Page 2 of 2
grzed ited e
l ibration
boratory
ACCREb ED
CALBRATIDN CERT 01866.01
Appendix A
Ionization chambers
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t11 sDosimetry V -Calibration Laboratory i -`
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CALIBRATION COEFFICIENTS:
EXPOSURE CALIBRATION COEFFICIENTS (Nx)
R/RDG: Roentgen/reading calibration coefficients apply to the chamber-electrometer-readout system as
a unit, with scales, switch settings and output mode specified. To obtain the exposure in Roentgens at
the reference point*, in the absence of the chamber, the calibration coefficient is applied directly to the
instrument reading corrected for temperature and pressure:
• Exposure =RDG 'R/RDG' 1/At®„• TPC
where TPC=temperature pressure correction
R/C: Roentgen/Coulomb calibration coefficients apply to the ion chamber alone. To obtain the exposure
in Roentgens at the reference point*, in the absence of the chamber, an appropriately calibrated
(Coulomb/reading) electrometer must be used.
Exposure =RDG' R/C C/RDG'1/A,on • TPC
where C/RDG = calibration coefficient of electrometer
TPC= temperature pressure correction
AIR KERMA CALIBRATION COEFFICIENTS (Nk)
NOTE: Caution should be exercised in the use of the air kerma
calibration coefficient(NA) when determining N as for the TG-21 protocol.
This coefficient is NOT defined in the TG-21 protocol.
Gy/RDG: Gray/reading calibration coefficients apply to the chamber-electrometer-readout system as a
unit, with scales, switch settings and output mode specified. To obtain the air kerma in Grays at the
reference point*, in the absence of the chamber, the calibration coefficient is applied directly to the
instrument reading corrected for temperature and pressure:
Air Kerma =RDG' Gy/RDG'1/A10„ • TPC
where TPC= temperature pressure correction
Gy/C: Gray/Coulomb calibration coefficients apply to the ion chamber alone. To obtain the air kerma at
the point of measurement, in the absence of the chamber, an appropriately calibrated
(Coulomb/reading) electrometer must be used.
Air Kerma =RDG• Gy/C• C/RDG•1/Ak,„ • TPC
where C/RDG=calibration coefficient of electrometer
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CALIBRATION CERT#1B66A4
TPC= temperature pressure correction
RELATION BETWEEN AIR KERMA AND EXPOSURE:
The air kerma calibration coefficient is related to exposure calibration coefficient as follows:
-4
Nk =Nx' 2.58' 10 • (W/E)/(1-G)
where N is the exposure calibration coefficient
x
Nk is the air kerma calibration coefficient
W/E is the mean energy per unit charge expended by electrons in
thy air in Joules per Coulomb(J/C).
G is the fraction of the initial kinetic energy of secondmy
electrons dissipated in air as brernstrahlung.
The following values were provided by NIST:
W/E = 33.97 J/C
G = 0.0032 for Cobalt 60
G = 0.0016 for Cesium 137
G =0.0000 for x-rays < 300 keV.
N CALCULATION:
In order to assist in the determination of Ngas,pre-calculated ratios of N /(N 'A. )by Gastorf
gas x ion
y 2 et al,TG-39 or Reft, et al are provided when available. N may be calculated as follows:
gas
N =(N 'A. i'Ratio
gas x ,a
where N = the cavity-gas calibration coefficient(Gy/C or Gy/reading)as
gas
defined in TG-21 protocol
N =the exposure calibration coefficient(R/C or R/reading)as provided on the
x
calibration report(Cobalt 60)
A.4a,1 = the ion collection efficiency as provided on the calibration report
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ACCREDI ED
CAUBRAUON CERT#1886 Dl
Ratio = gas/(N,-At0)from the reference
1. Gastorf,R., Humphries, L.J. , Rozenfeld, M.: Medical Physics 13: 751, 1986
2. TG-39 The Calibration and use of Plane-Parallel Ionization Chambers for Dosimetry of
Electron Beams: An Extension of the 1983 AAPM Protocol: Medical Physics 21(8): 1251,1994
3. Reft, Kuchnir, DeWerd, Micka, Attix: Medical Physics 21:1953, 1994 and 22 (4), 481, 1995
TEMPERATURE-PRESSURE CORRECTION COEFFICIENT:
For chambers open to the atmosphere, the instrument readings were normalized to 760
millimeters of mercury and 22 degrees Celsius. Use of the chamber at other pressures and temperatures
requires correction by the following multiplicative coefficient:
(7'+ 273.15)/ 295.15 - (760/P)
where T is the temperature in degrees Celsius, and P is the chamber pressure in millimeters of
mercury.
No corrections were made for air humidity.
CALIBRATION CONDITIONS:
Unless otherwise indicated, the calibration field size is 10 cm x 10 cm for Co-60 and Cs-137 and 10 cm
diameter circle for x-rays. Stem effect is not investigated; the calibration coefficient applies only to the
field size defined at the stated source-chamber distance(SCD). Field size is the distance between the 50
percent intensity lines of the exposure in air at the central axis.
During calibration the chamber was centered in the beam with the stem perpendicular to the beam
direction, except for end-window chambers which are calibrated with the stem parallel to the beam
direction.
For cylindrical ion chambers the point of measurement is on the central axis of the cavity at the center of
the active volume of the cavity and for plane-parallel chambers the point of measurement is at the front
(upstream side)of the air cavity at the center of the collecting region.
The air kerma rate, or dose rate to water, at the calibration position was measured with a transfer-quality
ionization chamber which was calibrated by the National Institute of Standards and Technology
(formerly NBS).
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ACCRED'i-TED
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BEAM QUALITY:
X-ray beam quality is described in terms of the first half-value thickness in millimeters of aluminum or
copper. The ratio of the first to the second half-value thickness (homogeneity coefficient -H.C.) and the
kilovoltage are also given.
The half-value thicknesses were determined under "good geometry" narrow beam conditions with high
purity certified aluminum or copper attenuators. The focus-attenuator distance was approximately 50
cm, and the focus-chamber distance was approximately 100 cm.
ATMOSPHERIC COMMUNICATION:
All chambers are tested for communication to the atmosphere prior to calibration.
POLARIZING POTENTIAL:
Polarizing potential was measured using a calibrated digital voltmeter and is reported as the potential of
the thimble (outer electrode) with respect to the circuit low or guard. In this convention, the reported
polarity sign equals the sign of the charge collected in the volume.
AIR KERMA CALIBRATION UNCERTAINTY:
The uncertainties assigned by K&S are based on the stated NIST uncertainty of the calibration standard
used and the uncertainties associated with the measurement precision of the laboratory.
The stated uncertainties are the combined expanded uncertainties with a coverage coefficient of k=2
(95%confidence level)and include the NIST uncertainty of the standard used.
ELECTROMETER CALIBRATION UNCERTAINTY:
The combined expanded uncertainty including the NIST uncertainties of the standards used(K=2)are:
Electrometers, Charge (0.01 to 0.1)nC 0.32 %
(0.1 to 700)nC 0.13 %
(10 to 20 000)nC 0.24 %
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41111.0
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{ jx
ACCREDItED
CALIBRATION CERT 01666.01
Electrometers, Current 10 pA to 1000 nA 0.28
(2 to 10)pA 0.46 %
(1 to 2)pA 0.83%
DUE DATES:
Caution: If a due date is shown,it is at the request of the user only. The interval is not a
recommendation of K& S, but is based on the customer's requirements.Any number of
coefficients, such as time, environment and handling may cause the instrument to drift out of
calibration prior to the indicated date.
ABSORBED DOSE TO WATER CALIBRATION COEFFICIENT (ND,„,)
The absorbed dose to water calibration coefficient is defined in the AAPM TG-51 Protocol 8 as follows:
Np WCo-60 = DW Co-60 / M
where,
D„ is the absorbed dose to water in the K&S 60Cobalt beam at the specified source to chamber
(SCD)distance with a depth of 5 g/cm2 in a water phantom and having a nominal field size at the
position of the chamber of 10cm x 10 cm.
M fully corrected ion chamber reading: corrected to the standard environmental conditions of
temperature and pressure for which the ion chamber calibration coefficient applies; corrected for
ion recombination loss and electrometer accuracy. Unit: C or rdg.
If the user's chamber required water proofing which was supplied by K& S, the wall of the sleeve was
1 mm PMMA sealed to either a PMMA tube or latex tube for communication with the atmosphere.
Although the CALIBRATION COEFFICIENT has been corrected for the air density at the time of
calibration, water-proof chambers may have a coefficient of thermal expansion of the thimble material
which might increase/decrease the volume with temperature since these chambers are in intimate contact
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with the
water. For this reason,the average temperature of the water during calibration is reported on the
calibration page.
ABSORBED DOSE TO WATER CALIBRATION CONDITIONS:
Prior to measurements in water the user's chamber is tested for communication and calibrated in air as
described above in order to establish the constancy of its response.
A 37 x.37 x 37 cm water phantom is positioned such that the chamber position is at the reported source-
to-chamber distance(SCD) from the Cobalt source using a laser positioning system. The depth of the
chamber in water is 5 cm. The field size at the chamber position is a nominal 10cm x 10cm. If the
user's chamber is a Farmer style chamber which is not waterproof, an acrylic tube sealed to a lmm
PMMA sleeve is extended into the water phantom from a port on the side of the tank. The temperature
of the water is monitored during the calibration and reported on the calibration page.
ABSORBED DOSE TO WATER UNCERTAINTY:
The combined expanded uncertainty of the calibration is 1.3%with a coverage coefficient k=2 (95%
confidence level) and includes the uncertainty stated by NIST for the calibration standard used.
The calibration information stated in this report were derived from measurements with either of an
Exradin Al2 or an NEL 2571 standard ionization chamber calibrated by NIST and reported under test
numbers DG 10281/98 and DG 10280
ION COLLECTION EFFICIENCY:
The ion collection efficiency (Aion) stated in this report is based on measurements of the currents (or
charges)produced at the highest rate indicated on the calibration page(unless otherwise stated). A. has
on
5 6
been calculated using the two-voltage method of Boag -Greening for continuous radiation.
2
A ion. = ((V1/V 2) -Ratio)l((V�/V2)2- 1)
where V,=full polarizing potential
where V2=reduced polarizing potential
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laboratory ANA • 4't___;
ACCREDITED
CALIBRATION CERT 01866.01
Ratio = the current(or charge)at V
divided by the current (or charge)at V2
5. Boag, J. W., Radiation Dosimetry,2nd ed., edited by F.
Affix and W. Roesch(Academic,New York, 1966), Vol. II.
6. Greening,J. R., Phys. Med. Biol.,Vol. 9,p. 143 (1964).
NOTICE OF CHANGE IN AIR KERMA CALIBRATIONS
BASED ON CHANGES MADE BY NIST
On July 1 2003, NIST enacted adjustments to many of the air kerma standards including Co-60,
Cs-137, Ir-192 and W/AI x-ray beams. The dose to water (N0,w) standard has not changed. As of
October 1 2003, K&S is incorporating the NIST changes in subsequent calibrations, thus the
reported calibration coefficients in this report reflect that.
CO-60 AIR KERMA:
Changes in calculated corrections to the NIST primary standard graphite chambers result in a
new-to-old ratio of 1.0105. In addition, changes were made in the NIST calibration setup which
will effect therapy class calibrations. K&S Associates has adopted two new ion chambers with
current NIST calibrations for Co-60 air kerma. The observed ratio between those and the old
standard adhered to by K&S since 1982 is 1.015. For a given chamber, an Ni and Nk value
A Revision 5/7/2012 Page 8 of 9
Test#T140728 Report# 140745