M. Jabari: Radioprotection 2025, 60( 3), 277 – 284 279
Table 1. Summery of the decay transition of the radionuclides investigated in this study. The third column to fifth column shows respectively the number of emitted rays, sum of the yield of each ray( P P
Yi: Ei
Yi) and sum of the product of yield and energy divided by total yield P
Yi named mean energy.
Radionuclide |
Radiation |
Number |
Total yield per disintegration |
Mean energy( MeV) |
Lutetium 177 |
Gamma |
6 |
1.803E – 01 |
1.750E – 01 |
|
X-ray |
60 |
1.374Eþ00 |
2.576E – 03 |
|
Beta |
4 |
1.000Eþ00 |
1.333E – 01 |
|
Int. Conv. |
36 |
1.548E _ 01 |
8.737E – 02 |
|
Auger |
15 |
1.117Eþ00 |
1.014E – 03 |
Yttrium 90 |
Gamma |
1 |
1.400E – 08 |
2.186Eþ00 |
|
x-ray |
40 |
1.466E – 03 |
8.193E – 04 |
|
Int. Conv. |
10 |
1.150E – 04 |
1.745Eþ00 |
|
Beta |
3 |
1.000Eþ00 |
9.329E – 01 |
|
Auger |
11 |
1.273E – 03 |
5.144E – 04 |
Table 2. S-values( mGy / MBq. s) for 177 Lu-DOTATATE & 90 Y-DOTATATE for BMI 23.0 of male ICRP phantom Source organs
Target organs
|
|
Kidney |
Spleen |
Liver |
Bladder |
Prostate |
Bladder |
90 Y-DOTATATE |
1.010e-05 ± 1.23e-06 |
1.715e-06 ± 1.32e-07 |
1.342e-05 ± 0.65e-06 |
2.451e-03 ± 1.12e-04 |
1.761e-05 ± 1.02e-06 |
|
177 Lu-DOTATATE |
3.410e-08 ± 2.28e-9 |
5.904e-08 ± 2.21e-08 |
7.698e-08 ± 5.31e-09 |
7.381e-04 ± 3.21e-09 |
1.165e-07 ± 1.12e-09 |
|
Kidney
90
|
Y-DOTATATE |
2.312e-03 ± 1.13e-05 |
2.341e-04 ± 1.32e-05 |
2.654e-05 ± 2.11e-06 |
9.923e-06 ± 2,43e-09 |
3.123e-04 ± 1.21e-05 |
|
177 Lu-DOTATATE |
3.260e-04 ± 1.67e-05 |
3.165e06 ± 2.21e-07 |
1.132e-07 ± 1.01e-08 |
4.114e-08 ± 1.87e-08 |
4.673e-06 ± 1.21e-06 |
|
Spleen
90
|
Y-DOTATATE |
3.204e-05 |
2.204e-05 |
1.745e-05 |
1.637e-06 |
2.523e-05 |
|
177 Lu-DOTATATE |
2.829e-07 ± 1.31e-08 |
1.013e-07 ± 1.07e-08 |
2.282e-07 ± 1.21e-08 |
2.345e-09 ± 1.45e-09 |
9.113e-08 ± 2.21e-08 |
Liver |
90 Y-DOTATATE |
1.331e-04 ± 1.10e-05 |
8.421e-05 ± 2.21e-05 |
9.543e-05 ± 3.21e-05 |
1.056e-04 ± 2.21e-05 |
1.321e-04 ± 2.30e-05 |
|
177 Lu-DOTATATE |
2.012e-06 ± 4.21e-07 |
1.111e-06 ± 3.02e-07 |
1.110e-03 ± 2.94e-04 |
1.845e-06 ± 1.1e-06 |
1.532e-06 ± 2.11e-07 |
multiregional target; and S( rT ∈ mreg) is the S-value for a subregion.
In this study, paired t-test and linear regression were used to evaluate the correlation of the interested organ absorbed dose per unit cumulated activity as S-values and BMI. All statistical tests and comparisons were done using SPSS version 18 and SYSTAT 13 software.
3 Results
Results are presented in Tables 2 – 7. The S values in both self-absorptions and target organs were lower for 177 Lu-DOTATATE as compared to 90 Y-DOTATATE. Differences of S- values were not significant( P < 0.005). The highest difference between the absorption is in kidneys( P = 0.0032) when source is in kidney. When the source organ is the kidneys, the greatest S value is 0.0025 from 90 Y-DOTATATE and 3.55e-04 from 177 Lu-DOTATATE in
BMI of 28.3. The highest S-value in BMI of 34.5 in bladder from bladder is 0.01 from 90 Y-DOTATATE, whereas it is 0.0049 from 177 Lu-DOTATAE. The most self-absorption( when source and target are the same) in spine is in BMI of 28.3 and is 7.04e-04 from 90 Y-DOTATATE and 1.12e-04 from 177 Lu-DOTATAE. For the spleen as source organs’ selfabsorption have the S-value( in mGy / MBq. s) of 0.0035 from the source of 90Y-DOTATATE and about 7.5e-04 from 177Lu-DOTATAE in all BMI. Moreover, when liver is considered as the source organ( source is distributed in liver), the absorption in kidneys and bladder is approximately 100 times lower in 177 Lu-DOTATAE.. In the case of organs such as liver and pancreas, all the trend lines varied inversely with S-values and they demonstrated a strong or weak tendency to decrease with BMI. Also, plots in Figure 2 illustrate that for 177 Lu-DOTATAE, the self-absorption is dramatically lower than that of 90 Y-DOTATATE. The dependence of the dose to the morphology of the patient is