Evaluation of absorbed and effective doses to patients from radiopharmaceuticals using the ICRP 110 reference computational phantoms and ICRP 103 formulation

Abstract

In diagnostic nuclear medicine, mean absorbed doses to patients' organs and effective doses are published for standard stylised anatomic models. To provide more realistic and detailed geometries of the human morphology, the International Commission on Radiological Protection (ICRP) has recently adopted male and female voxel phantoms to represent the reference adult. This work investigates the impact of the use of these new computational phantoms. The absorbed doses were calculated for 11 different radiopharmaceuticals currently used in diagnostic nuclear medicine. They were calculated for the ICRP 110 reference computational phantoms using the OEDIPE software and the MCNP extended Monte Carlo code. The biokinetic models were issued from ICRP Publications 53, 80 and 106. The results were then compared with published values given in these ICRP Publications. To discriminate the effect of anatomical differences on organ doses from the effect of the calculation method, the Monte Carlo calculations were repeated for the reference adult stylised phantom. The voxel effect, the influence of the use of different densities and nuclear decay data were also investigated. Effective doses were determined for the ICRP 110 adult reference computational phantom with the tissue weighting factor of ICRP Publication 60 and the tissue weighting factors of ICRP Publication 103. The calculation method and, in particular, the simulation of the electron transport have a significant influence on the calculated doses, especially, for small and walled organs. Overestimates of >200 % were observed for the urinary bladder wall of the stylised phantom compared with the computational phantoms. The unrealistic organ topology of the stylised phantom leads to important dose differences, sometimes by an order of magnitude. The effective doses calculated using the new computational phantoms and the new tissue weighting factors are globally lower than the published ones, except for some radiopharmaceuticals, where the differences can reach 60 % higher than the published values. This study analyses the first set of absorbed and effective doses with the new ICRP male and female reference computational phantoms for different radiopharmaceuticals. It highlights the importance of taking into account the electron transport and the realism of the shape and inter-organ distances of the anthropomorphic model used.

The contributions of source regions to organ doses from incorporated radioactive iodine

“…The absorbed doses for 123 I (25% thyroid uptake) and 131 I (55% thyroid uptake) are compared in Tables 1 and 2, respectively. The organ doses calculated in this study were in good agreement with the values reported by Smith et al (2000), Zankl et al (2010Zankl et al ( , 2011, and Hadid et al (2013) within 7% on average. Some values for wall organs, however, showed larger differences; for example, the urinary bladder wall doses for 25% uptake of 123 I were 7.06 × 10 −2 (obtained from Zankl et al, 2011) and 3.69 × 10 −2 (calculated in this study) mGy (MBq)…”

Effective dose to adult patients from 338 radiopharmaceuticals estimated using ICRP biokinetic data, ICRP/ICRU computational reference phantoms and ICRP 2007 tissue weighting factors

“…The previously used mathematically describable MIRD-phantoms were developed using highly simplified organ shapes, which sometimes resulted in less realistic distances within and between organs. For a limited number of radiopharmaceuticals, and for adults, it has been shown that there is a difference between earlier estimations of the effective dose and the results of the calculations using the new ICRP/ICRU reference phantoms and the new ICRP tissue weighting factors [ 10 – 12 ]. The aim of this work was to use published biokinetic data [ 13 – 15 ] as a base for a complete recalculation of the effective dose for all radiopharmaceuticals hitherto published by the ICRP, using the new adult reference phantoms [ 6 ] and the ICRP publication 103 tissue weighting factors [ 1 ].…”

Assessment of the Absorbed Dose in the Kidney of Nuclear Nephrology Paediatric Patients using ICRP Biokinetic Data and Monte Carlo Simulations with Mass-Scaled Paediatric Voxel Phantoms

“…Zankl et al 13 report that, when comparing calculations using voxel phantoms with calculations using stylized ("MIRD-type") phantoms, deviations between 50% and 100% can be obtained. And finally, Hadid et al 14,15 and Parach et al 16 reach similar conclusions, showing that when calculating dose coefficients with voxel phantoms and comparing them with a MIRD phantom, significant variations (up to few hundred percent) were obtained.…”