apmp supplementary comparison report of absorbed dose rate …i)-s2/... · 2017-03-07 · apmp...

Metrologia 54 (2017) Tech. Suppl. 06003

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APMP supplementary Comparison Report of absorbed dose rate

in tissue for beta radiation

(BIPM KCDB: APMP.RI(I)-S2)

M. Katoa, T. Kurosawa

a, N. Saito

a, T. B. Kadni

b, I.J. Kim

c, B.C. Kim

c, C.-Y. Yi

c,

V. Pungkund and C.-H. Chu

e

aNational Metrology Institute of Japan, AIST, 1-1-1 Umezono Tsukuba, 305-8568 Japan

bMalaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor Darul Ehsan, Malaysia

cKorea Research Institute of Standards and Science, 1 Doryong-Dong Yusong-Gu Deajeon

305-340, Korea

dOffice of Atoms for Peace, 16 Vibhavadi Rangsit Road, Laadyaw, Chatuchak, Bangkok 10900,

Thailand

eInstitute of Nuclear Energy Research, No 1000, Wuhua Rd., Jiaan Village, Longtan Township,

Taoyuan County, 32546, Taiwan

Abstract

The supplementary comparison of absorbed dose rate in tissue for beta radiation

(APMP.RI(I)-S2) was performed with five national metrology institutes in 2013 and

2014. Two commercial thin window ionization chambers were used as transfer

instruments and circulated among the participants. Two of the NMIs measured the

calibration coefficients of the chambers in reference fields produced from Pm-147,

Kr-85 and Sr-90/Y-90, while the other three measured those only in Sr-90/Y-90

beta-particle field. The degree of equivalence for the participants was determined and

this comparison verifies the calibration capabilities of the participating laboratories. In

addition, most of the results of this comparison are consistent with another

international comparison (EUROMET.RI(I)-S2) reported before this work.

1. Introduction

The personal dose equivalent and directional dose equivalent are used as the

operational quantities in the field of radiation protection. For weakly penetrating

radiation including beta-particle radiation, personal dose equivalent and directional


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dose equivalent are specified as dose equivalent in soft tissue at the depth of 0.07 mm

and that in ICRU sphere at the depth of 0.07 mm, respectively [1-3]. Since the dose

equivalent is defined to be a product of the absorbed dose and the radiation quality

factor, calibration laboratories disseminate the absorbed dose rate in tissue at the depth

of 0.07 mm for beta-particle fields, 𝐷𝑡,𝛽̇ (0.07). This supplementary comparison was

performed in order to establish the degree of equivalence of 𝐷𝑡,𝛽̇ (0.07) among the

participating National Metrology Institutes (NMIs) and support the calibration and

measurement capabilities for the quantity.

Until now, no comparisons for 𝐷𝑡,𝛽̇ (0.07) have been performed within the scope of

the APMA while a EUROMET comparison has taken place in 2004-2007 [4] and

several bilateral comparisons have performed between the LPRI (LNE-LNHB) and

PTB (1996), PTB and VNIM (1999/2001), NIST and PTB (2001) and LPRI

(LNE-LNHB) and VNIM (2001) [4].

Two thin-window chambers of different type were used as transfer standards for the

comparison. The calibration coefficients of the transfer instruments have been obtained

by each participant. Five laboratories have been taken part in the comparison: NMIJ

(Japan), INER (Taiwan), KRISS (Korea), Nuclear Malaysia (Malaysia) and OAP

(Thailand). The contact persons of the laboratories are listed in Table 1.

The comparison was arranged by the NMIJ as a pilot laboratory. In this comparison,

there was a star-shaped circulation of the transfer chambers among the participants.

The transfer chambers were sent back to the NMIJ for stability tests after each

measurement of the calibration coefficients in participating laboratory. Each

participant should provide the calibration coefficients of the transfer chambers in terms

of the absorbed dose rate in tissue for one or three of the beta-particle radiations:

Sr-90/Y-90, Kr-85 and Pm-147. The schedule of the comparison is shown in Table 2.

The comparison was scheduled to begin in January 2013 and completed in January

2014.

2. Procedure

2.1 Transfer chambers

The two thin-window chambers of different type were used as transfer standards for

the comparison, as listed in Table 3. The signal connections of the chambers are a

tri-axial BNT plug for the Magna chamber and a BNC with a 4-mm ‘banana’ plug for


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the CE-II chamber. The reference point of these chambers is the front surface of the

detector case. The chambers were tested in the NMIJ for 5 months before they were

delivered to the first participant to ensure stable performance of the chambers.

The chambers were circulated without an electrometer. A collecting voltage listed in

Table 3 was applied at each laboratory. Appling a negative voltage for the Magna

chamber or a positive voltage for the CE-II chamber results that the measured current is

positive. This voltage was applied at least 30 minutes before starting measurements. A

pre-irradiation of at least 30 minutes was also made before the measurements. The

leakage current was measured before and after each measurement. Photographs of each

chamber are presented in appendix B. Plastic cover of each chamber for protecting its

entrance window was removed during the measurements. The Magna chamber is

supported by its stem, 100 mm in length, 19 mm wide and 10 mm deep (in the beam

direction). The CE-II is likewise supported by its cylindrical stem, 300 mm long and

12 mm in diameter. All stated dimensions are indicated in the Appendix B. The

chambers were transported in an air tight box of around 500 mm height, 635 mm width,

305 mm depth, and weighing about 8 kg.

2.2 Reference conditions

The reference conditions for the chamber calibrations are as follows:

1. Field size at the reference point: larger than 15 cm in diameter.

2. The variation of the dose rate over the field size at the calibration distance

should be less than ± 5 % for 90

Sr + 90

Yand 85

Kr, and less than ± 10 % for 147

Pm.

3. Air temperature, pressure and relative humidity of T = 293.15 K, P =

1013.25 hPa and h = 65 %.

4. The calibration coefficients for the transfer chambers should be given in terms

of the absorbed dose rate in tissue per current, in units of mGy/(h A).

5. The values of the half-lives that have been presented in ISO 6980-1:2006 [1]:

(10523 35) days for Sr-90 / Y-90

(3915 3) days for Kr-85

(958.2 8) days for Pm-147

6. Calibration distances are 30 cm for Sr-90/Y-90 and Kr-85, and 20 cm for

Pm-147.

7. Beam flattening filters are set at 10 cm of the source-to-filter distance. The

material and dimensions of the filters followed the ISO6980-1:2006 [1].


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2.3 Beta-particle fields

Each participant calibrated the transfer chambers in one or three beta-particle

reference fields. The reference fields in which each participant calibrated the transfer

chambers are listed in Table 4. The standard instrument and/or the source of its

traceability of the participant laboratories are also listed in the table. Three participant

laboratories used the primary extrapolation chambers for realizing their reference

absorbed dose rate values. The others have the standard beta-particle radiation fields

which is traceable to the primary standard of PTB.

3 Analysis of the results

3.1 Quantity to be measured by the participants

The calibration coefficient for a transfer chamber measured by a laboratory i, xi, is

given by the following equation.

𝑥𝑖 =𝐷�̇�(0.07)

(|𝐼𝑐+|+|𝐼𝑐

−|)/2 (1)

where 𝐷�̇�(0.07) is the conventional true value of the absorbed dose rate in tissue at the

depth of 0.07 mm during the calibration measurement, Ic+

is the ionization current

measured in one of the ionization chambers corrected to the current at the reference

conditions with the positive applied voltage, and Ic- is that with the negative applied

voltage. The participant laboratories corrected the difference in ionization currents due

to the air density to obtain Ic+ and Ic

-.

3.2 Reference value and the degree of equivalence

The reference value CE of the comparison and the degree of equivalence were

determined by the method described as follows. The analysis method is based on the

references [4-9].

1) Using the generalized least-squares method [4,5], a candidate for CE, 𝐶�̃�, is given as

𝐶�̃� =(∑ 𝑥𝑖

𝑁𝑖=1 ∑ [𝑐𝑜𝑣−1]𝑖𝑗

𝑁𝑗=1 )

(∑ ∑ [𝑐𝑜𝑣−1]𝑖𝑗𝑁𝑗=1

𝑁𝑖=1 )

⁄ (2)

The [cov-1

] is the inverse matrix of the covariance matrix [cov]. The elements of [cov],

[cov]ij = rij ui,corr uj,corr for i=1, …, N and j=1, …, N where rij is the correlation

coefficient [6,7] between xi and xj, and ui,corr (uj,corr) are the corrected uncertainty of the


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calibration coefficient given by the equation(3) [4].

𝑢𝑖,corr = √𝑢𝑖2 + 𝑣rep2 (3)

where ui is the standard uncertainty of xi reported by the participants and vrep is the

standard deviation of the repeated measurements performed at the NMIJ (see detail in

session 4). The W value of air and mass electron stopping powers which are needed to

derive 𝐷�̇�(0.07) were considered as the factors of the correlation.

2) The candidate of the reference value, 𝐶�̃�, was examined by the chi-square testing

with the manner presented by Douglas and Steele [5]. If the set of the N calibration

results was not consistent, to find a consistent subset of N-1 results, one value of xi was

omitted and 𝐶�̃� were determined again. In this comparison, all the calibration results

for the magna chamber in Kr-85 and Pm-147 radiation fields and those for the CE-II

chamber in Sr-90/Y-90 and Kr-85 radiation fields were consistent. One of the

calibration coefficient of the magna chamber in Sr-90/Y-90 field was not statistically

consistent with the others. The calibration coefficients of the CE-II chamber in Pm-147

field in which only two participants have performed the measurements were not

statistically consistent so that the reference value of the calibration coefficient of the

CE-II chamber in Pm-147 field could not be determined.

3) The reference value, CE, and the uncertainty of the reference value, u(CE), were

determined by the equations with the number of the consistent results, Ncons [4,8].

𝐶𝐸 =(∑ 𝑥𝑖

𝑁𝑐𝑜𝑛𝑠𝑖=1 ∑ [𝑐𝑜𝑣−1]𝑖𝑗

𝑁𝑐𝑜𝑛𝑠𝑗=1 )

(∑ ∑ [𝑐𝑜𝑣−1]𝑖𝑗𝑁𝑐𝑜𝑛𝑠𝑗=1

𝑁𝑐𝑜𝑛𝑠𝑖=1 )

⁄ (4)

1

𝑢2(𝐶𝐸)=

1

(∑ ∑ [𝑐𝑜𝑣−1]𝑖𝑗𝑁𝑐𝑜𝑛𝑠𝑗=1

𝑁𝑐𝑜𝑛𝑠𝑖=1

) (5)

4) The degree of equivalence of each laboratory i relative to CE , Di, is given by

Di =xi - CE. The uncertainty of Di, u(Di), is given by 𝑢(𝐷𝑖) = √𝑢𝑛,corr2 − 𝑢(𝐶𝐸)2 in

the case xi was used to determine CE. If xi was not used to determine CE, 𝑢(𝐷𝑖) =

√𝑢𝑛,corr2 + 𝑢(𝐶𝐸)2 [9].


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3.3 Evaluation of the ratio between this comparison results and the EUROMET

comparison

The calibration results with BIPM has not been in available until now. The only

regional comparison result is that of EUROMET.R(I)-S2. To evaluate the ratio

between the results of the APMP participant laboratory and the EUROMET

comparison reference value, Ri, E, the APMP comparison results were analyzed by the

following method. This is a similar analysis that presented in ref [10], but partly

reformed for this study.

The NMIJ had made the comparisons in the EUROMET program therefore the ratios

of the calibration coefficient measured at the NMIJ in the EUROMET comparison to

the reference value, RNMIJ,E, was used for the evaluation. Ri, E is given by the following

equation.

Ri, E = Ri, NMIJ RNMIJ,E. (6)

In this equation, Ri, NMIJ is the ratio of the calibration coefficient between one of the

participants i and the NMIJ. RNMIJ,E is listed in Table 5. Ri,NMIJ is expressed by the

equation (7).

𝑅𝑖,𝑁𝑀𝐼𝐽 = (𝑥𝑖,𝑘1

𝑥NMIJ,𝑘1+

𝑥𝑖,𝑘2

𝑥NMIJ,𝑘2) ×

1

2 (7)

where, k1 and k2 refer the transfer chambers Magna and CE-II, respectively.

The uncertainty of Rn, E was estimated based on the following model equation derived

from the equation (6).

𝑅𝑖,E =1

2× (

𝑥𝑖,𝑘1×𝐼NMIJ,𝑘1

𝐷NMIJ,𝑘1+

𝑥𝑖,𝑘2×𝐼NMIJ,𝑘2

𝐷NMIJ,𝑘2) ×

𝐷NMIJ,E

𝐼NMIJ,E×

1

𝑥𝑅 (8)

In the equation (8), DNMIJ,k1 (DNMIJ,k2) and DNMIJ,E are 𝐷�̇�(0.07) at the NMIJ in the

APMP comparison and that in the EUROMET comparison, respectively. INMIJ,k1

(INMIJ,k2) and INMIJ,E are the ionization current from a transfer chamber measured at the

NMIJ in the APMP comparison and that in the EUROMET comparison, respectively.

xR is the reference value of the EUROMET comparison. Since DNMIJ,k1 and DNMIJ,k2 are

nearly equal to each other, the equation can be described as follows.

𝑅𝑖,𝐸 =1

2× (𝑥𝑛,𝑘1𝐼NMIJ,𝑘1 + 𝑥𝑛,𝑘2𝐼NMIJ,𝑘2) ×

1

𝐷NMIJ,𝑘

𝐷NMIJ,E

𝐼NMIJ,E×

1

𝑥𝑅 (9)

The correlations among the input quantities were taken into account in the uncertainty

estimation.


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4. Results

Tables 6 and 7 list the data of the calibration coefficients of the transfer chambers

measured at the NMIJ for the stability tests. The mean values of the calibration

coefficients and the standard deviation are given as the calibration coefficients of the

NMIJ. In figures 1, 2 and 3, the deviation of each calibration coefficient measured at

the NMIJ are plotted in relative scale for the reference field produced from Sr-90/Y-90,

Kr-85, and Pm-147, respectively. The calibration coefficients were well reproduced

within the uncertainties for any reference field.

The calibration coefficients for the transfer chambers, Magna and CE-II measured by

the participants are given in Tables 8, 9 and 10. The detailed uncertainty budgets for all

the participants are given in the Appendix A. For each chamber, the reference value

and its uncertainty were evaluated. Fig 4 shows the degree of equivalence for each

laboratory. The reference value of CE-II chamber in Pm-147 field is not shown

because the calibration coefficients from the participants were not statistically

consistent.

Table 11 and Fig. 5 show the ratio of the calibration coefficient between participants

and the reference value of the EUROMET comparison. The value of the NMIJ plotted

in Fig. 5 is the value listed in Table 5. The results of all the participants for Sr-90/Y-90

and Kr-85 agreed with the EUROMET reference value within the uncertainty. For

Pm-147, the value of one participant (Nuclear Malaysia) is significantly higher than

the EUROMET reference value. It could have been caused by that the dose rate in their

Pm-147 reference field was much lower than the other reference fields (See Tables 8, 9

and 10).

5. Conclusion

The supplementary comparison of absorbed dose to tissue standards has been carried

out among five laboratories. The two transfer chambers were circulated among them

and each laboratory was asked to provide the calibration coefficients and associated

uncertainties. The reproducibility of the measurements with the transfer chambers

were confirmed through repeated measurements made at the NMIJ. The results of the

most of the calibration coefficients were consistent within the uncertainties. Even if

one of the calibration coefficients of the two chambers reported by a participant was

statistically inconsistent, the other calibration coefficient was surely consistent.


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Besides, most of the APMP comparison results agreed with the EUROMET reference

value within the stated uncertainty. This comparison verified the calibration and

measurement capability of the participating laboratories.

References

[1] International Organization for Standardization. ISO 6980-1: 2006, Nuclear energy

-Reference beta-particle radiation – Part 1: Methods of production

[2] International Organization for Standardization. ISO 6980-2: 2004, Nuclear energy

-Reference beta-particle radiation – Part 2: Calibration fundamentals related to

basic quantities characterizing the field

[3] International Organization for Standardization. ISO 6980-3, 2006, Nuclear energy

-Reference beta-particle radiation – Part 3: Calibration of are and personal

dosemeters and determination of their response as a function of energy and angle

of incidence

[4] Behrens, K. et al, International comparison of extrapolation chamber

measurements of the absorbed dose rate in tissue for beta radiation, Metrologia 44,

06003 (2007)

[5] Douglas R.J. and Steele A.G. Pair-difference chi-squared statistics for Key

Comparisons, Metrologia 43, 89 (2006)

6 International Organization of Standards, Switzerland, Guide to the Expression of

Uncertainty in Measurement, (1995)

7 Joint Committee for Guides in Metrology, Evaluation of measurement data - Guide

to the Expression of Uncertainty in Measurement, JCGM100:2008 (2008)

[8] Elster C. and Link A., Analysis of key comparison data: assessment of current

methods for determining a reference value, Meas. Sci. Technol. 12, 1431-1438

(2001)

[9] Maurice G. Cox, The evaluation of key comparison data: determining the largest

consistent subset, Metrologia 44, 187-200 (2007)

[10] Burns D.T. and Allisy-Roberts P.J., The evaluation of degrees of equivalence in

regional dosimetry comparisons, CCRI(I)/07-04 (2007)


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Tables

Table 1. Participating laboratories and their contact persons for the APMP.RI(I)-S2

supplementary comparison

Participating Laboratory Acronym or Abbreviation,

Country

Contact Person

National Metrology Institute of Japan NMIJ, Japan Masahiro Kato

Norio Saito

Institute of Nuclear Energy Research INER, Taiwan Chien-Hau Chu

Korea Research Institute of Standards and

Science KRISS, Korea Chul-Young Yi

Malaysian Nuclear Agency Nuclear Malaysia, Malaysia Taiman Bin Kadni

Office for Atoms for peace OAP, Thailand Vithit Pungkun


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Table 2: Schedule of APMP.RI(I)-S2 comparison

Participant

Date of chambers

leaving NMIJ for

participant

Measurement duration at

the laboratory

Date of chambers leaving

NMIJ - Stability test

Nuclear Malaysia 7-Jan-2013 21-Jan-2013 to

25-Jan-2013 28-Jan-2013

NMIJ Stability test

KRISS 3-Jun-2013 17-Jul-2013 to

21-Jul-2013 24-Jun-2013

NMIJ Stability test

OAP 28-Oct-2013 11-Nov-2013 to

15-Nov-2013 18-Nov-2013

NMIJ Stability test

INER 15-Dec-2013 6-Jan 2014 to

10-Jan-2014 27-Jan-2014

NMIJ Stability test -


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Table 3. Main characteristics of the transfer chambers

Supplier EXRADIN OYOGIKEN

Model Magna CE-II

Serial number D070313 2803290

Outer diameter (mm) 53,4 130

Outer depth (mm) 20,8 39

Diameter of the

collecting electrode

(mm)

- 79

depth of the collecting

volume (mm)

8 9,5

window foil material Conductive Kapton

film

Al coated

polyethylene-tere

phthalate

windows thickness 0,001 inch,

3,86 mg/cm2

25 m,

3,54 mg/cm2

Volume (cm3) 3,0 60

Cable length (m) 1,2 -

Stem length (mm) 100 300

Stem size or diameter

(mm)

19 x 10 12 in diamter

Cable connection Tri-axial (BNT) Signal: BNC

HV: banana plug

Outer electrode Ground Ground

Middle electrode Negative -250 V/

Positive +250 V

NG

Inner electrode Current

measurement

(Negative -250 V/

Positive +250 V)

Current

measurement

(Ground)

banana plug NG Positive +400 V/

Negative -400 V

Measured current Positive/Negative Positive/Negative


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Table 4. Standard traceability and reference fields in which each participant calibrated

the transfer chambers.

Participant Standard traceability

Reference fields

90Sr/

90Y

85Kr

147Pm

NMIJ Primary extrapolation

chamber

yes yes yes

INER Primary extrapolation

chamber

yes no no

KRISS Primary extrapolation

chamber

yes no no

Nuclear Malaysia, Beta radiation field

traceable to PTB, Germany

yes yes yes

OAP Beta radiation field

traceable to PTB, Germany

yes no no


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Table 5. Ratios of the calibration coefficient measured by NMIJ to the reference value

reported in EUROMET.RI(I)-S2 [4].

Radionuclide RNMIJ,E Expanded uncertainty

(k=2)

90Sr/

90Y 1.004 0.017

85Kr 0.998 0.019

147Pm 1.005 0.046


14

Table 6. Stability of the transfer chamber, Magna, in the beta-particle reference fields.

Table 6a. Stability of the Magna chamber in the reference field from Sr-90/Y-90

Table 6b. Stability of the Magna chamber in the reference field from Kr-85

Date Radio-

nuclide

Calibration

distance

(m)

Dose rate

(mGy/h)

Chamber

current

(pA)

Calibration

coefficient

(1013

mGy/(hA))

2012-08 Kr-85 0.3 91.82 2.404 3.820 (0.053)

2012-12 Kr-85 0.3 89.72 2.318 3.871 (0.054)

2013-04 Kr-85 0.3 88.44 2.310 3.829 (0.054)

2013-05 Kr-85 0.3 86.95 2.261 3.846 (0.054)

2013-07 Kr-85 0.3 86.88 2.265 3.836 (0.054)

2013-10 Kr-85 0.3 84.89 2.234 3.800 (0.053)

2013-12 Kr-85 0.3 84.34 2.179 3.871 (0.054)

2014-01 Kr-85 0.3 83.25 2.172 3.834 (0.054)

Mean value and standard deviation 3.838 (0.024)

Date Radio-

nuclide

Calibration

distance

(m)

Dose rate

(mGy/h)

Chamber

current

(pA)

Calibration

coefficient

(1013

mGy/(hA))

2012-08 Sr-90/Y-90 0.3 35.06 1.012 3.463 (0.046)

2012-12 Sr-90/Y-90 0.3 34.85 1.018 3.424 (0.045)

2013-04 Sr-90/Y-90 0.3 34.54 1.000 3.455 (0.046)

2013-05 Sr-90/Y-90 0.3 34.50 1.000 3.451 (0.046)

2013-07 Sr-90/Y-90 0.3 34.34 0.999 3.437 (0.045)

2013-10 Sr-90/Y-90 0.3 34.13 0.990 3.447 (0.046)

2013-12 Sr-90/Y-90 0.3 34.05 0.983 3.465 (0.046)

2014-01 Sr-90/Y-90 0.3 33.91 0.980 3.460 (0.046)



15

Table 6c. Stability of the Magna chamber in the reference field from Pm-147

Date Radio-

nuclide

Calibration

distance

(m)

Dose rate

(mGy/h)

Chamber

current

(pA)

Calibration

coefficient

(1013

mGy/(hA))

2012-08 Pm-147 0.2 6.296 1.012 1.906 (0.043)

2012-12 Pm-147 0.2 5.562 1.018 1.896 (0.043)

2013-04 Pm-147 0.2 5.464 1.000 1.930 (0.044)

2013-05 Pm-147 0.2 4.795 1.000 1.904 (0.043)

2013-07 Pm-147 0.2 5.101 0.999 1.903 (0.043)

2013-10 Pm-147 0.2 4.348 0.990 1.898 (0.043)

2013-12 Pm-147 0.2 4.328 0.983 1.926 (0.044)

2014-01 Pm-147 0.2 4.268 0.980 1.961 (0.044)



16

Table 7 Stability of the transfer chamber, CE-II, in the beta-particle reference fields.

Table 7a. Stability of the CE-II chamber in the reference field from Sr-90/Y-90

Date Radio-

nuclide

Calibration

distance

(m)

Dose rate

(mGy/h)

Chamber

current

(pA)

Calibration

coefficient

(1011

mGy/(hA))

2012-08 Sr-90/Y-90 0.3 35.10 18.97 18.50 (0.24)

2012-12 Sr-90/Y-90 0.3 34.82 18.81 18.51 (0.24)

2013-04 Sr-90/Y-90 0.3 34.56 18.41 18.77 (0.25)

2013-05 Sr-90/Y-90 0.3 34.50 18.36 18.50 (0.25)

2013-07 Sr-90/Y-90 0.3 34.35 18.39 18.50 (0.25)

2013-10 Sr-90/Y-90 0.3 34.17 18.10 18.50 (0.25)

2013-12 Sr-90/Y-90 0.3 34.04 17.99 18.50 (0.25)

2014-01 Sr-90/Y-90 0.3 33.92 18.02 18.50 (0.25)


Table 7b. Stability of the CE-II chamber in the reference field from Kr-85

Date Radio-

nuclide

Calibration

distance

(m)

Dose rate

(mGy/h)

Chamber

current

(pA)

Calibration

coefficient

(1011

mGy/(hA))

2012-08 Kr-85 0.3 91.52 48.06 19.04 (0.26)

2012-12 Kr-85 0.3 90.23 46.89 19.25 (0.27)

2013-04 Kr-85 0.3 88.31 46.13 19.14 (0.27)

2013-05 Kr-85 0.3 86.93 45.25 19.21 (0.27)

2013-07 Kr-85 0.3 86.99 45.16 19.26 (0.27)

2013-10 Kr-85 0.3 85.10 44.83 18.98 (0.26)

2013-12 Kr-85 0.3 84.64 44.53 19.01 (0.26)

2014-01 Kr-85 0.3 83.46 43.65 19.12 (0.27)



17

Table 7c. Stability of the CE-II chamber in the reference field from Pm-147

Date Radio-

nuclide

Calibration

distance

(m)

Dose rate

(mGy/h)

Chamber

current

(pA)

Calibration

coefficient

(1011

mGy/(hA))

2012-08 Pm-147 0.2 6.162 6.827 9.03 (0.20)

2012-12 Pm-147 0.2 5.906 6.352 9.30 (0.21)

2013-04 Pm-147 0.2 5.364 5.765 9.31 (0.21)

2013-05 Pm-147 0.2 4.804 5.275 9.11 (0.20)

2013-07 Pm-147 0.2 5.119 5.515 9.28 (0.21)

2013-10 Pm-147 0.2 4.502 4.877 9.23 (0.21)

2013-12 Pm-147 0.2 4.467 4.791 9.33 (0.21)

2014-01 Pm-147 0.2 4.232 4.515 9.37 (0.21)



18

Table 8. The calibration coefficients (N) of the transfer chambers for 90

Sr+90

Y reference

field in the APMP RI(I)-S2 supplementary comparison.

Participant EXRADIN (S/N 3025) OYOGIKEN (S/N 2340)

Dese rate

(mGy/h) N (mGy/(h A))

Relative standard

uncertainty (%)

Dese rate


Relative standard

uncertainty (%)

NMIJ 34.42* 3.450 1013 1.29 34.56* 1.873 10

12 1.29

Nuclear Malaysia 32.44 3.551 1013 1.16 32.44 1.896 10

12 1.16

KRISS 95.995 3.504 1013 0.59 95.969 1.881 10

12 0.59

OAP 134.99 3.371 1013** 1.07 134.99 1.873 10

12 1.06

INER 59.61 3.515 1013 1.56 59.61 1.895 10

12 1.65

Reference value CE 3.505 1013

0.64 1.882 1012 0.78

* These are mean values. See detail in Tables 6 and 7.

** The value is not statically consistent with the others and is not used for estimating the CE.


Kr reference



Dese rate


Relative standard

uncertainty (%)

Dese rate


Relative standard

uncertainty (%)

NMIJ 87.04* 3.838 1013 1.35 87.15* 1.913 10

12 1.34


12 1.07


1.06 1.914 1012

1.03



Pm reference



Dese rate


Relative standard

uncertainty (%)

Dese rate


Relative standard

uncertainty (%)

NMIJ 5.02* 1.916 1013 2.30 5.07* 9.243 10

11 2.26


11 1.68


1.94 -



19

Table 11. Combined comparison ratios between participants and the EUROMET.RI(I)

supplementary comparison, Ri, E.

Radionuclide Participant Ri, E Expanded

uncertainty

(k=2)

90Sr+90Y Nuclear Malaysia 1.024 0.027

KRISS 1.014 0.021

OAP 0.992 0.024

INER 1.019 0.030

85Kr Nuclear Malaysia 1.009 0.025

147Pm Nuclear Malaysia 1.057 0.050


20

Figure 1. Stability of transfer chambers in the reference field produced from

Sr-90/Y-90. Relative deviation of each calibration coefficient from the mean value of

the calibration coefficients are plotted. All measurements were made at NMIJ. (a)

Magna(Exradin s/n D07313), (b) CE-II.(Ooyogiken s/n 2803290). The error bars refer

the expanded uncertainty (coverage factor k = 2) of each calibration coefficient.

-5

0

5

Aug-12 Dec-12 Apr-13 May-13 Jul-13 Oct-13 Dec-13 Jan-14

Re

lative

de

via

tio

n (

%)

-5

0

5


Re

lative

de

via

tio

n (

%)

(a)

-5

0

5


Re

lative

de

via

tio

n (

%)

(b)


21

Figure 2. Stability of transfer chambers in the reference field produced from Kr-85.

Relative deviation of each calibration coefficient from the mean value of the

calibration coefficients are plotted. All measurements were made at NMIJ. (a)



-5

0

5


Re

lative

de

via

tio

n (

%)

-5

0

5


Re

lative

de

via

tio

n (

%)

(a)

-5

0

5


Re

lative

de

via

tio

n (

%)

(b)

-5

0

5


Re

lative

de

via

tio

n (

%)


22

Figure 3. Stability of transfer chambers in the reference field produced from Pm-147.

Relative deviation of each calibration coefficient from the mean value of the

calibration coefficients are plotted. All measurements were made at NMIJ. (a)



-5

0

5


Re

lative

de

via

tio

n (

%)

-5

0

5


Re

lative

de

via

tio

n (

%)

(a)

(b)


23

Figure 4. Degree of equivalence Di of each laboratory relative to the reference value CE.

(a) Magna(Exradin s/n D07313), (b) CE-II.(Ooyogiken s/n 2803290). The error bars

refer the uncertainty of the degree of equivalence with the coverage factor k = 2. Square:

Sr-90/Y-90, Triangles: Kr-85, Circles: Pm-147. The reference value for CE-II chamber

in Pm-147 reference field could not be determined (See section 3.2).

*) This value was not used for determining the reference value.

-5

0

5

NM

IJ

Malay

sia

KRIS

S

OAP

INER

Di /

CE =

(x

i- C

E)

/ C

E

NM

IJ

NM

IJ

Malay

sia

Malay

sia

(%)

-8

-4

0

4

8

NM

IJ

Malay

sia

KRIS

S

OAP

INER

Di /

CE =

(x

i- C

E)

/ C

E

NM

IJ

Malay

sia

(%)

(a)

(b)

*)


24

Figure 5. Ratio of the calibration coefficient for each participating laboratory relative

to the reference value in the EUROMET.RI(I)-S2. The error bars refer the expanded

uncertainty of the ratio of the calibration coefficient with the coverage factor k = 2.

Open square: Sr-90/Y-90, Open triangles: Kr-85, Open circles: Pm-147.

0.9

1

1.1

NM

IJ

Malay

sia

KRIS

S

OAP

INER

Ra

tio

of th

e c

alib

ratio

n c

oe

ffic

ien

t

NM

IJ

Malay

sia

Malay

sia

NM

IJ


25

Appendix A

NMIJ Uncertainty budget

Uncertainty associated with the standard

Sr-90+Y-90 Kr-85 Pm-147

Component Relative standard uncertainty (%)

W-value 0.18 0.18 0.18

Ratio of the mass-electronic stopping

power in ICRU tissue to air 0.60 0.60 0.60

Air density at the reference conditions 0.04 0.04 0.04

Effective are of the collecting electrode 0.2 0.2 0.2

Effect of humidity 0.1 0.1 0.1

Effect of bremsstrahlung 0.2 0.2 0.2

Backscatter effect 0.3 0.3 0.3

Radial non-uniformity 0.25 0.4 0.8

Limiting value of the slope of the

corrected current versus chamber depth 0.75 0.76 1.79

Reference absorbed dose rate to tissue 1.09 1.13 2.11

Uncertainty associated with the calibration of the transfer chambers

Sr-90+Y-90 Kr-85 Pm-147


Reference absorbed dose rate to tissue 1.09 1.13 2.11

Attenuation and scattering of beta

particles in the air path 0.3 0.4 0.49

Radioactive decay 0.1 0.1 0.1

Corrected ionization current by the

transfer chamber Magna / CE-II 0.61 / 0.60 0.62 / 0.60 0.73 /0.61

Calibration coefficient of Magna /

CE-II 1.29 / 1.29 1.35 / 1.34 2.29 /2.25


26

Nuclear Malaysia Uncertainty budget


Sr-90+Y-90 Kr-85 Pm-147


absorbed dose rate to tissue 1.05 1 1.3

Radioactive decay 0.333 0.077 0.835

Corrected ionization current by the

transfer chamber Magna / CE-II 0.38 / 0.37 0.46 /0.36 2.03 /0.66

Calibration coefficient of Magna /

CE-II 1.16 / 1.16 1.10 / 1.07 2.56 / 1.68


27

KRISS Uncertainty budget


Sr-90+Y-90


W-value 0.15


power in ICRU tissue to air 0.25

Air density at the reference conditions 0.01

Effective are of the collecting electrode 0.01

Effect of humidity 0.08

Effect of bremsstrahlung 0.08

Backscatter effect 0.10

Radial non-uniformity 0.13

Limiting value of the slope of the corrected

current versus chamber depth 0.44

Reference absorbed dose rate to tissue 0.58


Sr-90+Y-90



Radioactive decay 0.00

Corrected ionization current by the transfer

chamber Magna / CE-II 0.06 / 0.06

Calibration coefficient of Magna / CE-II 0.59 / 0.59


28

OAP Uncertainty budget


Sr-90+Y-90




Transmission factor 0.51


chamber Magna / CE-II 0.08 / 0.07

Calibration coefficient of Magna / CE-II 1.07 / 1.06


29

INER Uncertainty budget


Sr-90+Y-90


W-value 0.09


power in ICRU tissue to air 0.68

Air density at the reference conditions 0.01

Effective are of the collecting electrode 0.01

Effect of humidity 0.06

Effect of bremsstrahlung 0.25

Backscatter effect 0.35

Radial non-uniformity 0.25

Limiting value of the slope of the corrected

current versus chamber depth 0.60



Sr-90+Y-90



Attenuation and scattering of beta particles

in the air path 0.45


Transmission factor 0.30


chamber Magna / CE-II 1.02 /1.15

Calibration coefficient of Magna / CE-II 1.56 /1.65


30

Appendix B Photographs of the chambers

EXRADIN Magna

Oyogiken CE-II

19 mm 100 mm

12 mm

300 mmCenter of the chamber

apmp supplementary comparison report of absorbed dose rate …i)-s2/... · 2017-03-07 · apmp...

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