Document Type : Original Article


1 Department of Physics, Faculty of Shahid Chamran of Kerman, Technical and Vocational University, Kerman, Iran

2 Department of Nuclear Medicine, Kerman Medical science University, Kerman, Iran


I131 is a famous radio-iodine isotope in use for diagnosis and treatment of hyper functioning and cancerous thyroid gland. It is a nuclear reactor product; however nuclear reactor may be unavailable in some areas. Replacement by I-124 may be possible, another iodine isotope producible by cyclotron; a system more available than reactor. Here absorbed fraction of Gamma and Beta rays of I-124 throughout thyroid and neck soft tissues are measured and compared with I-131. Employing I-124 as substitute for I-131 is also discussed. First of all, the input file for MCNPX code has been prepared to calculate F6 and F8 tallies. Then the code has been run for F6 and F8 tallies for variation of lobe volume from 1 to 25 milliliters. From the output file of tally F6, the gamma absorbed fraction in thyroid and neck tissue for the volume lobe variation from 1 ml to 25 ml have been derived. As well as, form the output of F8 tally the absorbed energy of beta in thyroid and soft tissue of neck is obtained and then absorbed fraction of beta has been calculated. Finding indicated that for constant activity in thyroid and soft tissue the gamma absorbed fraction for I-124 is less than I-131. For the same situation, the beta absorbed fraction of I-124 in thyroid is less than I-131 and in soft tissue is more than I-131. If I-131 is non-available it may be replaced by I-124for treatment of cancerous or hyper functional gland


Allah Abadia A, Daykin J, Sheppard MC, Gough CSCL, Franklyn JA.2001. Radiological treatment of hyperthyroidism-progonostic factors for outcome. The Journal of Clinical Endocrinology & Metabolism, 86(3): 3611-3617.
Cooper DS, Doherty GM, Haugen BR, Kloos RT.2006. Management guidelines for patients with thyroid nodules and differentiated thyroid cancer. THYROID, 16(2): 109-141.
Cember H, Johnson TE.2009. Introduction to health physics, 4th Edition, McGraw-Hill, New York.
Firestone RB, Ekström LP.1999. LBNL Isotopes Project - LUNDS Universitet WWW Table of Radioactive Isotopes. Version 2.1,. The website:
Snyder W, Ford M, Warner G.1969. Estimates of absorbed fractions for monoenergetic photon source uniformly distributed in various organs of a heterogeneous phantom: MIRD pamphlet no. 5. J Nucl Med 10 (suppl 3):5–52.
Traino AC, di Martino F, Lazzeri M,. Stabin MG.2000. Influence of thyroid volume reduction on calculated dose in radioiodine therapy of Graves’ hyperthyroidism. Phys Med Biol 45: 121–129.
Vini L, Harmer C.2000. Radioiodine treatment for differentiated thyroid cancer. Clin Oncl (Rcoll Radiol), 12(6): 365-72.
Waters L S.2002. “MCNPX User’s Manual, version 2.3.0”, LA-UR-02-2607, Los Alamos, NM, USA