**4.2.1 Photon spectra and recalculated of for 182Ta radionuclide**

As can be seen from Table 2, the entire of photon ray spectrum of 182Ta is divided into five characteristic groups of photon lines. The air kerma rate constant was calculated for every

Air Kerma Rate Constants

radionuclide

for Nuclides Important to Gamma Ray Dosimetry and Practical Application 7

Bearing in mind that standard tantalum sources are usually packed into 0.1 mm of platinum, it was calculated the constant for this type of source also. For that goal, it was calculated the absorption of tantalum photons into 0.1 mm of platinum and obtained that in this way the air kerma rate constant is reduced by 4,46 %. After this correction, a value of (42.8 0.9) aGy m2 s-1 Bq-1 was obtained for air kerma rate constant for standard packaged

Fig. 1a. Low energy region (50-300 keV) of the photons spectrum emitted in decay of 182Ta

encapsulated tantalum source (Ninkovic & Raicevic, 1992).


Table 1. Air kerma rate constant for some radionuclide considering photon energy above 20 keV

discrete photon line with yield per decay event >0.01 % and starting with energy of 0.03174 MeV as the delta value. That means that four characteristic X-ray lines are included. The group and total air kerma rate constant are obtained then by addition of partiale or single photon lines constant. Finally, a value of ( 44.8 0.9 ) aGy m2 s-1 Bq-1 for an unshielded 182Ta source has been obtained. That value is in good agreement with a new recalculated value given in Table 1.

Table 1. Air kerma rate constant for some radionuclide considering photon energy above

discrete photon line with yield per decay event >0.01 % and starting with energy of 0.03174 MeV as the delta value. That means that four characteristic X-ray lines are included. The group and total air kerma rate constant are obtained then by addition of partiale or single photon lines constant. Finally, a value of ( 44.8 0.9 ) aGy m2 s-1 Bq-1 for an unshielded 182Ta source has been obtained. That value is in good agreement with a new recalculated value

20 keV

given in Table 1.

from to aGy m-2 Bq-1 s-1 Gy m-2 GBq-1 h-1

Radionuclide Half – life Energy interval (MeV) Air kerma rate constant

11C 20.38 min - 0.5110 38.7 139.3 13N 9.965 min - 0.5110 38.7 139.4 15O 2.037 min - 0.5110 38.7 139.5 18F 109.8 min 0.0005 0.5110 37.5 135.1 24Na 14.96 h 1.3690 3.8660 121.3 436.7 42K 12.36 h 0.3126 2.4240 9.10 32.8 43K 22.3 h 0.2206 1.3940 35.5 127.8 51Cr 27.70 h 0.0005 0.3201 1.17 4.22 52Fe 8.275 h 0.0006 1.0399 27.01 97.24 59Fe 44.50 d 0.0069 1.4817 40.54 145.9 57Co 271.74 d 0.0007 0.6924 3.92 14.11 58Co 70.86 d 0.0007 1.6747 35.84 129.0 60Co 5.271 a 1.1732 1.3325 85.82 309.0 67Ga 3.261 d 0.0010 0.8877 5.40 19.45 68Ga 1.127 h 0.0010 1.8830 35.84 129.0 75Se 119.79 d 0.0013 0.5722 13.40 48.25 99Mo 65.94 h 0.0024 0.9608 5.49 19.77 99mTc 6.01 h 0.0024 0.1426 3.92 14.10 111In 67.31 h 0.0031 0.2454 23.09 83.13 113mIn 99.49 min 0.0033 0.3917 12.22 44.00 123I 13.27 h 0.0038 0.7836 10.0 36.1 125I 59.4 d 0.0038 0.0355 10.48 37.73 131I 8.021 d 0.0041 0.7229 14.50 52.20 127Xe 36.4 d 0.0039 0.6184 14.19 51.09 133Xe 5.243 d 0.0043 0.1606 3.98 14.33 137Cs/137Ba 30.04 a 0.0045 0.6617 22.80 82.10 152Eu 13.537 a 0.0056 1.7691 41.36 148.9 154Eu 8.593 a 0.0061 1.5965 44.23 159.2 170Tm 128.6 d 0.0070 0.0843 0.154 0.554 182Ta 114.43 d 0.0084 1.4531 44.45 160.0 192Ir 73.827 d 0.0089 1.0615 30.30 109.1 197Hg 2.672 d 0.0097 0.2687 3.159 11.37 198Au 2.695 d 0.0100 1.0877 15.15 54.54 201Tl 3.038 d 0.0058 0.1674 2.84 10.22 241Am 432.2 a 0.0139 0.1030 1.102 3.97

Bearing in mind that standard tantalum sources are usually packed into 0.1 mm of platinum, it was calculated the constant for this type of source also. For that goal, it was calculated the absorption of tantalum photons into 0.1 mm of platinum and obtained that in this way the air kerma rate constant is reduced by 4,46 %. After this correction, a value of (42.8 0.9) aGy m2 s-1 Bq-1 was obtained for air kerma rate constant for standard packaged encapsulated tantalum source (Ninkovic & Raicevic, 1992).

Fig. 1a. Low energy region (50-300 keV) of the photons spectrum emitted in decay of 182Ta radionuclide

Air Kerma Rate Constants

Group of lines Energy

[MeV]

for Nuclides Important to Gamma Ray Dosimetry and Practical Application 9

Air mass energy transfer coeff. [10-3 m2 kg-1]

0.04272 0.24 0.02 5.650 0.01 0.001 0.02 0.05798(\*) 10.1 0.4 3.145 0.24 0.01 0.53 0.05932(\*) 17.6 0.6 3.045 0.41 0.02 0.91 0.06572 3.00 0.07 2.720 0.07 0.002 0.16 0.06695(\*) 2.1 0.1 2.760 0.05 0.002 0.11 0.0672(\*) 7.5 0.3 2.665 0.17 0.01 0.38 0.06775 41.0 1.0 1.645 0.94 0.02 2.10 1.91 0.1 4.26

0.10011 14.0 0.4 2.320 0.41 0.01 0.92 0.11367 1.90 0.04 2.345 0.06 0.01 0.13 0.11642 0.43 0.01 2.350 0.02 0.001 0.04 0.15243 6.9 0.1 2.500 0.34 0.01 0.76 0.15639 2.7 0.2 2.520 0.14 0.01 0.31 0.17639 3.1 0.2 2.595 0.18 0.01 0.40 0.19835 1.5 0.1 2.665 0.10 0.01 0.22 0.22211 7.4 0.2 2.735 0.57 0.12 1.27 0.22932 3.7 0.1 2.750 0.30 0.01 0.67 0.26408 3.6 0.1 2.830 0.34 0.01 0.76 2.53 0.08 5.64

0.95872 0.36 0.05 2.815 0.12 0.02 0.27 1.00170 2.1 0.1 2.810 0.75 0.04 1.67 1.04443 0.24 0.01 2.775 0.09 0.004 0.20 1.17 0.22 2.61

1.12130 35.0 0.7 2.750 13.76 0.27 30.71 1.1575 0.98 0.06 2.730 0.39 0.02 0.87 1.18905 16.3 0.3 2.710 6.70 0.12 14.96 1.22141 27.2 0.5 2.700 11.46 0.21 25.58 1.23102 11.6 0.4 2.750 4.92 0.17 10.98 1.25742 1.50 0.05 2.690 0.65 0.03 1.45 1.27373 0.65 0.01 2.670 0.28 0.01 0.63 1.28916 1.35 0.03 2.665 0.59 0.02 1.32 38.90 0.82 86.83

1.37384 0.22 0.01 2.635 0.10 0.01 0.22 1.38740 0.09 0.01 2.625 0.04 0.01 0.09 1.41010 0.05 0.01 2.618 0.02 0.01 0.04 1.45305 0.04 0.01 2.600 0.02 0.01 0.04 0.30 0.003 0.66

Air Kerma-rate const., [aGy m2 s-1 Bq-1] Yield to total [%]

Yield per decay [%]

1 2 3 4 5 6 I 0.03174 0.46 0.07 12.780 0.02 0.003 0.05

II 0.08468 2.6 0.3 2.352 0.07 0.01 0.16

III 0.92798 0.63 0.02 2.830 0.21 0.01 0.47

IV 1.11341 0.38 0.07 2.752 0.15 0.03 0.33

V 1.34273 0.27 0.01 2.645 0.12 0.01 0.27

Total air-kerma rate constant 44.8 0.9 100.0

Table 2. Data for calculation and calculated Partial, Groups and Total Air kerma rate

(\*)- Characteristic X-ray KKK� andK respectively

constant of 182Ta radionuclide (Ninkovic & Raicevic, 1992)

Fig. 1b. Middle energy region (250-1200 keV) of the photons spectrum emitted in decay of 182Ta radionuclide

Fig. 1c. High energy region (800-1500 keV) of the photons spectrum emitted in decay of 182Ta radionuclide

Fig. 1b. Middle energy region (250-1200 keV) of the photons spectrum emitted in decay

Fig. 1c. High energy region (800-1500 keV) of the photons spectrum emitted in decay of 182Ta

of 182Ta radionuclide

radionuclide


(\*)- Characteristic X-ray KKK� andK respectively

Table 2. Data for calculation and calculated Partial, Groups and Total Air kerma rate constant of 182Ta radionuclide (Ninkovic & Raicevic, 1992)

Air Kerma Rate Constants

interval from 550 to 900 keV

from the RaC, MsTh and 60Co

for Nuclides Important to Gamma Ray Dosimetry and Practical Application 11

Fig. 2c. Energy spectrum of the photons emitted in decay of 192Ir radionuclide in energy

Fig. 2d. Energy spectrum of the photons emitted in decay of 192Ir radionuclide in energy interval from 750 t0 1400 keV. This part of the spectrum contains many background lines

#### **4.2.2 Photon spectra and calculated of for 192Ir radionuclide**

Fig. 2b. Energy spectrum of the photons emitted in decay of 192Ir radionuclide in energy interval from 250 to 650 keV

Fig. 2a. Energy spectrum of the photons emitted in decay of 192Ir radionuclide in energy

Fig. 2b. Energy spectrum of the photons emitted in decay of 192Ir radionuclide in energy

interval from 50 to 350 keV

interval from 250 to 650 keV

**4.2.2 Photon spectra and calculated of for 192Ir radionuclide** 

Fig. 2c. Energy spectrum of the photons emitted in decay of 192Ir radionuclide in energy interval from 550 to 900 keV

Fig. 2d. Energy spectrum of the photons emitted in decay of 192Ir radionuclide in energy interval from 750 t0 1400 keV. This part of the spectrum contains many background lines from the RaC, MsTh and 60Co

Air Kerma Rate Constants

**radionuclide** 

Group of lines

source (Ninkovic & Raicevic, 1993).

Energy [MeV]

for Nuclides Important to Gamma Ray Dosimetry and Practical Application 13

aGy m2 s-1 Bq-1 was obtained for the air kerma rate constant for standard packaged iridium

Air mass energy transfer coeff. [10-3 m2 kg-1]

0.2419 8.56 0.42 2.78 0.737 0.033 1.25 0.2588 0.49 0.04 2.28 0.046 0.004 0.08 0.2748 0.38 0.15 2.84 0.038 0.013 0.06 0.2952 19.74 1.00 2.86 2.125 0.104 3.61 0.3520 38.27 2.00 2.92 5.015 0.262 8.51 0.3868 - - 2.94 - - - 0.3888 0.76 0.14 2.94 0.111 0.020 0.19 0.4550 0.28 0.07 2.98 0.048 0.013 0.08 0.4621 0.16 0.06 2.98 0.028 0.006 0.06 0.4805 - - 2.98 - - - 0.4872 0.38 0.05 2.98 0.080 0.007 0.12 0.6094 46.46 1.42 2.96 10.685 0.334 18.14 19.20 0.96 32.60

Air Kerma-rate const., [aGy m2 s-1 Bq-1] Yield to total [%]

**4.2.3 Results of calculation for 226Ra (in equilibrium with its decay product)** 

1 2 3 4 5 6 I 0.1857 4.83 0.26 2.63 0.301 0.020 0.51

II 0.6656 1.68 0.05 2.945 0.420 0.013 0.71

III 1.1338 0.28 0.04 2.745 0.111 0.013 0.19

1.1553 1.58 0.10 2.735 0.636 0.040 1.08 1.2078 0.42 0.05 2.715 0.176 0.020 0.30 1.2382 6.03 0.16 2.695 2.565 0.066 4.35 1.2811 1.52 0.05 2.675 0.664 0.020 1.13

0.7031 0.58 0.05 2.935 0.135 0.013 0.26 0.7199 0.40 0.05 2.925 0.107 0.013 0.18 0.7684 4.88 0.05 2.892 1.383 0.026 2.35 0.7860 1.10 0.05 2.89 0.319 0.013 0.54 0.8062 1.31 0.04 2.89 0.389 0.013 0.66 0.8212 0.10 0.04 2.88 0.030 0.012 0.05 0.8392 0.52 0.05 2.875 0.160 0.013 0.27 0.9340 3.20 0.15 2.83 1.078 0.033 1.83 0.9641 0.38 0,05 2.82 0.132 0.020 0.22 0.0520 0.35 0.04 2.78 0.130 0.013 0.22 0.1040 0.15 0.04 2.76 0.058 0.012 0.10 0.1204 16.70 0.42 2.75 6.560 0.231 11.14 10.92 0.40 18.54

Yield per decay

[%]


Table 3. Data for calculation and calculated Partial, Groups and Total Air kerma rate constant of 192I radionuclide (Ninkovic & Raicevic, 1993)

As can be seen from Table 3, the entire of photon ray spectrum of 192Ir is divided into five characteristic groups of photon lines. The air kerma rate constant was calculated for each discrete photon line with yield per decay event >0.05 % and starting with energy of 0.1363 MeV as the lowest energy. That means X-ray were not included. The air kerma rate constant for the groups and for the total were obtained by addition of partial or single photon lines constant. Finally, a value of ( 30.0 0.9 ) aGy m2 s-1 Bq-1 for an unshielded 192Ir source has been obtained. That value is in good agreement with a new recalculated value given in Table 1.

Keeping in mind that standard iridium sources are usually packed into 0.15 mm of platinum, the constant for that type of source was also calculated. For that goal, it was calculated the absorption of iridium photons into 0.15 mm of platinum and found that in the air kerma rate constant is reduced by 7.33 %. After this correction, a value of (27.8 0.9)

Air mass energy transfer

0.2013 0.47 0.04 2.67 0.03 0.003 0.1 0.2058 3.32 0.18 2.68 0.23 0.002 0.8 0.2832 0.27 0.02 2.85 0.03 0.003 0.1 0.30 0.03 <1.1

0.10011 29.65 0.45 2.88 3.35 0.12 11.2 0.11367 82.90 0.4 2.88 9.63 0.28 32.1 16.08 0.44 53.6

0.4165 0.64 0.04 2.95 0.10 0.01 0.3 0.4681 47.94 0.80 2.97 8.50 0.31 28.4 0.4846 3.18 0.15 2.98 0.58 0.04 1.9 0.4891 0.40 0.04 2.98 0.08 0.01 0.2 9.36 0.34 31.1

0.6044 8.25 0.45 2.96 1.88 0.14 6.3 0.6125 5.26 0.27 2.96 1.22 0.09 4.1 4.10 0.30 13.7

0.8845 0.29 0.05 2.88 0.09 0.02 0.3 1.062 0.06 0.01 2.76 0.02 0.004 0.1 0.12 0.03 0.5

As can be seen from Table 3, the entire of photon ray spectrum of 192Ir is divided into five characteristic groups of photon lines. The air kerma rate constant was calculated for each discrete photon line with yield per decay event >0.05 % and starting with energy of 0.1363 MeV as the lowest energy. That means X-ray were not included. The air kerma rate constant for the groups and for the total were obtained by addition of partial or single photon lines constant. Finally, a value of ( 30.0 0.9 ) aGy m2 s-1 Bq-1 for an unshielded 192Ir source has been obtained. That value is in good agreement with a new recalculated value given in

Keeping in mind that standard iridium sources are usually packed into 0.15 mm of platinum, the constant for that type of source was also calculated. For that goal, it was calculated the absorption of iridium photons into 0.15 mm of platinum and found that in the air kerma rate constant is reduced by 7.33 %. After this correction, a value of (27.8 0.9)

Air Kerma-rate const., [aGy m2 s-1 Bq-1] Yield to total

[%]

coeff. [10-3 m2 kg-1]

1 2 3 4 5 6 I 0.1363 0.17 0.02 2.47 0.01 0.001 <0.1

II 0.08468 28.67 0.50 2.86 3.10 0.12 10.3

III 0.3745 0.70 0.03 2.94 0.10 0.01 0.3

IV 0.5886 4.47 0.35 2.97 1.00 0.10 3.3

V 0.785 0.05 0.01 2.88 0.01 0.003 <0.1

 Total air-kerma rate constant: 30.0 0.9 100.0 Table 3. Data for calculation and calculated Partial, Groups and Total Air kerma rate

constant of 192I radionuclide (Ninkovic & Raicevic, 1993)

Group of lines

Table 1.

Energy [MeV]

Yield per decay [%]

aGy m2 s-1 Bq-1 was obtained for the air kerma rate constant for standard packaged iridium source (Ninkovic & Raicevic, 1993).

#### **4.2.3 Results of calculation for 226Ra (in equilibrium with its decay product) radionuclide**


Air Kerma Rate Constants

**5. Conclussion** 

obtained.

**6. References** 

Radiography, 50, 174-176

Wiley and Sons, Ink

Bq-1 for an unshielded 226Ra source has been obtained.

recommended by ICRU (ICRU, Handbook 86, 1963).

for Nuclides Important to Gamma Ray Dosimetry and Practical Application 15

As it can be seen from this table , the entire of photon ray spectrum of 226Ra (in equilibrium with its decay products) are divided into five characteristic groups of photon lines. The air kerma rate constant was calculated for each discrete photon line with yield per decay event >0.05 % and starting with energy of 0.1857 MeV as value. That means X-ray were not included. The air kerma rate constant for the groups and for the total were obtained by addition of partial or single photon lines constant. Finally, a value of ( 56.9 2.4 ) aGy m2 s-1

Having seen that standard radium sources are usually packed into 0.5 mm of platinum, the constant for that type of source was also calculated. For that goal it was used analyses of Shalek and Stoval (Shalek & Stovall, 1969), which is in good accordance with the earlier estimate of Aglincev et al. (Aglincev et al., 1960), that 0,5 mm of Pt by absorption of gamma radiation of radium and its decay products, reduce the air kerma rate constant with 9.25 %. After this correction, a value of ( 53.4 2.2 ) aGy m2 s-1 Bq-1 was obtained for the air kerma rate constant for standard packaged radium sources (Ninkovic, 1987). On the basis of this calculated value and experimentally measured value of Aglincev et al. (Aglincev et al., 1960) it was concluded (Ninkovic, 1987) that the real value of air kerma rate constant of 226 Ra in equilibrium with its decay product is smaller by about 1 to 2 %, than the value

Presented process of recalculation the values for air kerma rate constants, for 35 of the most often used radionuclide in practice, was based on the newest appropriate decay data for every radionuclide and latest numerical data for mass energy-transfer coefficient. That is the reason why, according to the authors opinion, obtained values for listed in the table 1,

It has to be pointed out that to calculate the absorbed dose to soft tissue the air kerma rate has to be multiplied by the ratio of the mass energy-absorption coefficient of soft tissue to that of air, which can be taken as 1,11 between 2 and 0,1 MeV and drops to 1,04 at 0,02 MeV. Also, since the radiation-waiting factor for gamma rays and X rays is 1, by multiplying air kerma rate constants by a factor 1,11, the soft tissue-equivalent dose constant can be

Aird, E.G.A, Williams, S. & Glover, C. (1984). *SI Units and radionuclides: Teaching problems,* 

Attix, F.H. (1986). *Introduction to radiological physics and radiation dosimetry,* New York: John

British Committee on Radiation Units and Measurements (1982). *Memorandum from British Committee on Radiation Units and Measurements,* Br. J. Radiol., 55, 375-377

Hubbell, J.H. (1969). *Photon Cross Sections, Attenuation Coefficients and Energy Absorption Coefficient from 10 keV to 100 GeV,* Washington DC: NBS Publication NSRDS-NBS 29

are the most accurate data that can be found in the literature available at present.

Aglincev, K.K, Ostromuhova, G.P. and Holnova, E.A (1960). Izm. Techn. 12, 40

Fireston,R.B. (1996). *Tables of Isotopes, eight edn,* New York: John Wiley and Sons


Table 4. Data for calculation and calculated partial, proup`s and total air kerma rate constant of 226Ra radionuclide in equilibrium with its decay products (Ninkovic, 1987)

As it can be seen from this table , the entire of photon ray spectrum of 226Ra (in equilibrium with its decay products) are divided into five characteristic groups of photon lines. The air kerma rate constant was calculated for each discrete photon line with yield per decay event >0.05 % and starting with energy of 0.1857 MeV as value. That means X-ray were not included. The air kerma rate constant for the groups and for the total were obtained by addition of partial or single photon lines constant. Finally, a value of ( 56.9 2.4 ) aGy m2 s-1 Bq-1 for an unshielded 226Ra source has been obtained.

Having seen that standard radium sources are usually packed into 0.5 mm of platinum, the constant for that type of source was also calculated. For that goal it was used analyses of Shalek and Stoval (Shalek & Stovall, 1969), which is in good accordance with the earlier estimate of Aglincev et al. (Aglincev et al., 1960), that 0,5 mm of Pt by absorption of gamma radiation of radium and its decay products, reduce the air kerma rate constant with 9.25 %. After this correction, a value of ( 53.4 2.2 ) aGy m2 s-1 Bq-1 was obtained for the air kerma rate constant for standard packaged radium sources (Ninkovic, 1987). On the basis of this calculated value and experimentally measured value of Aglincev et al. (Aglincev et al., 1960) it was concluded (Ninkovic, 1987) that the real value of air kerma rate constant of 226 Ra in equilibrium with its decay product is smaller by about 1 to 2 %, than the value recommended by ICRU (ICRU, Handbook 86, 1963).
