Page 35 - 89Zr-Immuno-PET:Towards a Clinical Tool to Guide Antibody-based Therapy in Cancer

Dosimetry of immuno-PET with 89Zr-cmAb U36
Red marrow doses
The doses absorbed in the red marrow were estimated in 19 patients, as presented in Table 3. The mean red marrow dose was 0.07 ± 0.02 mSv/MBq in males and 0.09 ± 0.01 mSv/MBq in women.
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Table 3. Absorbed doses in red marrow
Patient no.
Males 2
5
7
8 11 12 14 15 17 19 20
Females 1
3
4
6 9 10 13 16
Mean ± SD * Conversion factor = 0.3
Red marrow dose* (mSv/MBq)
0.07 0.07 0.06 0.06 0.08 0.07 0.09 0.11 0.09 0.07 0.05
0.09 0.10 0.11 0.09 0.11 0.09 0.07 0.09
Mean ± SD
0.07 ± 0.02
0.09 ± 0.01
Absorbed doses in source organs and whole body
Residence times of the source organs were entered into the OLINDA/EXM 1.0 program. The results of the OLINDA/EXM 1.0 analysis are listed in Table 4. The effective dose for each patient was calculated using the available organ dosimetry data of the source organs. Excretion of 89Zr via the urinary pathway was 2.59 ± 1.89 %ID during the first 72 h after injection. As there is also very little activity seen in the intestines, most loss of radioactivity is due to physical decay. The mean effective dose for the whole body was 0.53 ± 0.03 mSv/MBq in males and 0.66 ± 0.03 mSv/ MBq in females. As an alternative, the effective dose was also calculated by considering the body to be a homogenous mass, i.e. ignoring organ doses and
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