Optimisation of the Radiation Shielding of Medical Cyclotrons using a Genetic Algorithm

Effective radiation shielding is imperative to safe operation of modern Medical Cyclotrons producing large activities of short-lived radioisotopes on a commercial basis. Like the containment shielding of Medical Linear Accelerators (1), the optimal shielding design of Medical Cyclotrons demands a careful balance between the radiological, economical and often the sociopolitical factors. One is required to optimize the cost of radiation protection and the cost of radiological health detriment (2). The cost of radiation protection depends explicitly on the nature of the ionising radiation field produced by the cyclotron, its operational condition, the cost of shielding material, the level of dose reduction, the projected net revenue from the from the sale of the radioisotopes, and the depreciation rate of the cyclotron facility. The mathematical methods of accelerator shielding optimisation (3, 4) within the guideline of ALARA (5) have been reported by various investigators.