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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Accuracy in dosimetry of diagnostic agents: impact of the number of source tissues used in whole organ S value-based calculations

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Author(s):
Josefsson, Anders [1] ; Siritantikorn, Klaikangwol [1] ; Ranka, Sagar [1] ; de Carvalho, Jose Willegaignon de Amorim [2] ; Buchpiguel, Carlos Alberto [2] ; Sapienza, Marcelo Tatit [2] ; Bolch, Wesley E. [3] ; Sgouros, George [1]
Total Authors: 8
Affiliation:
[1] Johns Hopkins Univ, Sch Med, Russell H Morgan Dept Radiol & Radiol Sci, Baltimore, MD 21218 - USA
[2] Univ Sao Paulo, Sch Med, Inst Canc Estado Sao Paulo, Sao Paulo, SP - Brazil
[3] Univ Florida, Dept Biomed Engn, Gainesville, FL - USA
Total Affiliations: 3
Document type: Journal article
Source: EJNMMI RESEARCH; v. 10, n. 1 MAR 19 2020.
Web of Science Citations: 0
Abstract

Background Dosimetry for diagnostic agents is performed to assess the risk of radiation detriment (e.g., cancer) associated with the imaging agent and the risk is assessed by computing the effective dose coefficient, e. Stylized phantoms created by the MIRD Committee and updated by work performed by Cristy-Eckerman (CE) have been the standard in diagnostic dosimetry. Recently, the ICRP developed voxelized phantoms, which are described in ICRP Publication 110. These voxelized phantoms are more realistic and detailed in describing human anatomy compared with the CE stylized phantoms. Ideally, all tissues should be represented and their pharmacokinetics collected for an as accurate a dosimetric calculation as possible. As the number of source tissues included increases, the calculated e becomes more accurate. There is, however, a trade-off between the number of source tissues considered, and the time and effort required to measure the time-activity curve for each tissue needed for the calculations. In this study, we used a previously published Ga-68-DOTA-TATE data set to examine how the number of source tissues included for both the ICRP voxelized and CE stylized phantoms affected e. Results Depending upon the number of source tissues included e varied between 14.0-23.5 mu Sv/MBq for the ICRP voxelized and 12.4-27.7 mu Sv/MBq for the CE stylized phantoms. Furthermore, stability in e, defined as a < 10% difference between e obtained using all source tissues compared to one using fewer source tissues, was obtained after including 5 (36%) of the 14 source tissues for the ICRP voxelized, and after including 3 (25%) of the 12 source tissues for the CE stylized phantoms. In addition, a 2-fold increase in e was obtained when all source tissues where included in the calculation compared to when the TIAC distribution was lumped into a single reminder-of-body source term. Conclusions This study shows the importance of including the larger tissues like the muscles and remainder-of-body in the dosimetric calculations. The range of e based on the included tissues were less for the ICRP voxelized phantoms using tissue weighting factors from ICRP Publication 103 compared to CE stylized phantoms using tissue weighting factors from ICRP Publication 60. (AU)

FAPESP's process: 13/03876-4 - Evaluation of the use of 68Ga-peptide somatostatin analogue PET/CT as a diagnostic tool in neuroendocrine tumors and its correlation with molecular markers
Grantee:Ana Amélia Fialho de Oliveira Hoff
Support Opportunities: Regular Research Grants