Comparison of computer codes' applicability in shielding design for hadron therapy facilities

摘要

Various computer codes have already been developed and applied forcomputation of the dose produced in the clinical environments due to proton and carbonion therapy procedures. Computer codes BULK-I, BULK-II, PHITS, SHIELD-HIT,MARS15, FLUKA and GEANT4 have been utilized to obtain the secondary radiationdose or the required thickness of the shield around such facilities. Differences in theangular distribution of secondary neutrons and transmitted dose from the shield areobserved among above mentioned codes. In the present work, a practical approach isundertaken to compute the shield thickness with the use of semi-empirical formulaealong with the results of computer codes. The results are compared and the differencesare explained. For this purpose, the spectra of secondary neutrons that have beensimulated by various codes are studied. The discrepancies in outcomes are attributed tothe nuclear models and approximations employed in each code. Then the shieldthickness is evaluated from engineering point of view. One goal of this study is todevelop engineering expertise for shielding design of newly established hadron therapycenters. Another goal is to compare these codes and choose the most proper one oncost-benefit basis. Finally, the proposed analytical calculations will be comparedagainst the results of above codes.