Evaluating the doismetric characteristics of some beta- emitter radionuclides for skin lesions irradiation

Abstract

Introduction: The dosimetric characteristics of patch sources including 32P, 90Y, 188Re and 166Ho, which are employed for radionuclide skin therapy, have been evaluated in current study Materials and Methods: The patch sources understudy were modeled by MCNPX Monte Carlo code and corresponding depth dose distribution, transverse dose profile and isodose curves were calculated in a realistic model of skin phantom. Results Calculated depth dose distributions had a good accordance with those reported by other measurement studies. Comparison of the calculated depth dose distributions for radionuclides understudy showed that the 166Ho and 32P have steeper dose gradient within the depth which can improve the sparing effect for underlying healthy tissues. Symmetric variations of calculated transverse dose profiles respect to the source central axis give a desirable dose uniformity within the target area for all studied patch sources. Obtained isodose curves showed that a circular area with the diameter of around 8 mm can cover the 90% isodose for all studied beta sources. Conclusion: Based on the obtained results, it can be concluded that the 166Ho and 32P have more desirable dosimetric characteristics for irradiating the superficial skin lesions. On the other hand, irradiation of deep skin tumors through 90Y and 188Re sources will improve the treatment quality viewpoint to the better coverage of target area. Size of employed patch source should be should be selected in such a way that the delivered dose to the adjacent tissues would be minimized.