Assessment of self- and cross-absorbed SAF values for HDRK- man using GEANT4 code: internal photon and electron emitters Maroua Bhar 1,2 • Omrane Kadri 2 • Kais Manai 2 Received: 14 January 2019 / Revised: 9 April 2019 / Accepted: 19 May 2019 Ó China Science Publishing & Media Ltd. (Science Press), Shanghai Institute of Applied Physics, the Chinese Academy of Sciences, Chinese Nuclear Society and Springer Nature Singapore Pte Ltd. 2019 Abstract The ultimate need to account for the partial amount of energy deposited in target tissue/organ resulting from internal inhalation, ingestion, and injection intakes of radionuclides, defined by the Medical Internal Radiation Dosimetry committee as the specific absorbed fraction (SAF), has become obvious. In this study, we assessed the SAF values for self- and cross-absorption, which were calculated for a uniform distribution of monoenergetic photon and electron emitters with energies ranging from 15 keV to 3 MeV. The voxelized human phantom ‘‘High- Definition Reference Korean-man’’ (HDRK-man), which was implemented using the Monte Carlo simulation code GEANT4 (version 10.1), was used for several combinations of target–source organs. The results were compared to those of the International Commission on Radiological Protection Reference (ICRP133) and Zubal phantoms. It was found that the SAF values of the three models have a similar trend. However, the SAF values for the HDRK-man phantom were higher than those of the other two models, with a relatively good agreement with those for the ICRP133 phantom (differences of 13.9 ± 2.8 and 12.1 ± 3.2 for photon and electron emitters, respectively). To analyze the differences in SAF values, we calculated the chord length distributions (CLDs) for selected target– source combinations. The parameters of organ mass (or volume) and CLDs, in addition to the adopted computa- tional procedures, mainly cause such discrepancies. For realistic radionuclide emission spectra, an overall overes- timation was observed when computing the S values for three radiopharmaceuticals studied (I-131, In-111, and Lu- 177) and for liver–spleen intra- and inter-organ absorption when compared with published data. The new arrangement of S and SAF values is expected to add value for multi- disciplinary research and clinical communities. Keywords GEANT4  Monte Carlo simulation  Internal dosimetry  HDRK-man  S and SAF values 1 Introduction Nuclear medicine is based on the administration of radionuclides into the human body for diagnostic or ther- apeutic applications. According to the International Com- mission on Radiological Protection (ICRP) regulations, it is intended to limit the occupational and man-made radiation exposure. It is necessary to know the internal dose to better assess the risk of early and late effects in irradiated organs during treatment. Improved dosimetry tools have been used for this purpose. However, direct measurement of the absorbed dose to the human body is not possible. The Medical Internal Radiation Dosimetry (MIRD) committee has published a systematic formalism, the MIRD schema, for assessing internal doses to overcome this problem [1]. The specific absorbed fraction (SAF) and S values are useful parameters of internal dose assessment derived from this approach. Hence, many publications have been added Electronic supplementary material The online version of this article (https://doi.org/10.1007/s41365-019-0675-2) contains supple- mentary material, which is available to authorized users. & Maroua Bhar bhar.maroua@yahoo.com 1 Higher Institute of Medical Technologies of Tunis, Tunis El Manar University, Tunis, Tunisia 2 Nuclear Physics and High Energy Unit, Faculty of Sciences of Tunis, Tunis El Manar University, Tunis, Tunisia 123 NUCL SCI TECH (2019)30:149 https://doi.org/10.1007/s41365-019-0675-2