ABSTRACT
A monitor unit (MU) is a measure of machine output of a proton accelerator. The Monte Carlo (MC) simulation would provide more accurate dose calculation. Factor-based methods determine absorbed dose per MU by using the product of standardized dose ratio measurements. Successive dose ratio factors are multiplied for a chain of geometries, and thus the dose ratio factors, are varied one by one until the geometry of interest is linked back to the reference geometry through an identity equation. The absorbed dose resulting from proton irradiation is equal to the product of the particle fluence incident onto the patient and linear energy transfer (LET), for a monochromic proton beam. MC simulations have been used to calculate the absorbed dose per MU. Uniform scanning delivers uniform intensity proton beams layer by layer along the beam axis by adjusting the proton energy and sweep the beam laterally using scanning magnet system.
