Radioprotection 60-3 | Page 80

280 M. Jabari: Radioprotection 2025, 60( 3), 277 – 284

Table 3. S-values( mGy / MBq. s) for 177 Lu-DOTATATE & 90 Y-DOTATATE for BMI 24.9 of male ICRP phantom Source organs

Bladder

Kidney

Spleen

Liver

Target organs

Table 4. S-values( mGy / MBq. s) for 177 Lu-DOTATATE & 90 Y-DOTATATE for BMI 27.1 of male ICRP phantom Source organs

Bladder

Kidney

Spleen

Liver

Target organs

shown in these figures for the percentile-specific phantoms.. More specifically, all the R2 values were greater than 0.7. For all these results, organ doses decreased with increasing BMI. The S values negatively correlates strongly with body mass index( Spearman r = 0.9505; P < 0.0001).

4 Discussion

The high interest for dosimetry of 90 Y-DOTATATE in clinical researches, necessitate a knowledge on the absorbed dose of organs( Cwikla et al., 2010; Kunikowska et al., 2011; Sowa-Staszczak et al., 2011). But, to the best of our knowledge, there are very few studies that compare the differences between the absorbed doses between 90 Y-DOTATATE and 177 Lu-DOTATAE. Capala et al. evaluated the dosimetry methods for radiopharmaceutical therapy and stated that the main different feature between 177 Lu-DOTATAE and 90 Y-DOTATATE is the particles and

energy emitted by each disintegration( Capala et al., 2021). Beside this factor, patient specifics such as height, weight, sex, and underlying physical factors( such as linear energy transfer, attenuation) affect S-values. Due to lower energy of beta particles emitted from 90 Y as compared to 177 Lu and consequently due to the lower range of these particles, the absorbed dose to the organs would be lower. Alnaaimi et al. calculated S-Values( in mGy / MBq s) in some of the critical