European Journal of Biomedical and Pharmaceutical Sciences

ASSESSMENT OF ABSORBED DOSE BY TARGET ORGANS USING MIRD FORMALISM DURING CERTAIN NUCLEAR MEDICINE PROCEDURES

Yassine Chahboub, Abdelmadjid Choukri, Oum Keltoum Hakam, Khalid Talsmat, Mohamed Benouhoud, Slimane Semghouli*

ABSTRACT

Objective: The purpose of this study was to evaluate the absorbed dose by organs during several nuclear medicine procedures at Clinic Anoual of Casablanca. Materials and Methods: Various radiological examinations in nuclear medicine with the use of different radiopharmaceuticals (Iodine-131, the FDG-18 and Tc-99m) were used to assess the absorbed doses by target organ and nearby organs using the Medical Internal Radiation Dose (MIRD) formalism. Such doses are then compared with those established by the International Commission of Radiological Protection (ICRP). Result: The percentage difference (PD) between the absorbed dose calculated by MIRD formalism and corresponding International Commission of Radiological Protection (ICRP) data for ten various examinations were evaluated. It varies between -1666 % to + 26 %. In case of thyroid sinticraphy, the PD is the 11, 13 and 26% for tyroid, liver and kidney respectively. For kidney sintigraphy, the PD varies between -31 and -43%. For bone sintigraphy, it is of - 22% for bone and - 25% for kidney. It is of 4% for thyroid during whole body Scintigraphy. For cancer diagnosic, it is of -1377% for liver and -1666% for lung. Conclusion: The MIRD formalism can be used to evaluate the absorbed dose by the thyroid and liver during thyroid scintigraphy and whole body scintigraphy, For kidney organ, the use of MIRD formalism require to take into account other factors such as the sensitivity of the kidneys, age, weight of the patient, in addition to the kidney function... For bone and kindey during bone scintigraphy scan, the use of MIRD formalism must take into account the morphology of the patient and the distribution of the delivered dose between the surrounding organs. For cancer diagnostic, MIRD formalism cannot be used owing the presence of tumor masse, bone metastases and the residence time of the radiopharmaceutical.

Keywords: MIRD formalism, Absorbed dose, Medical examination, Target Organs, Radiopharmaceuticals.