Journal of Research in Applied and Basic Medical Sciences (Dec 2021)
Analytical Formula for the total scatter factor of the Small Radiation Field Size
Abstract
Background & Aims: We present an analytical formula (AF) to calculate the total scatter factor of the MLC-shaped small radiation beams. Materials & Methods: Pinpoint, Semiflex, and Farmer ion chambers were used for MLC/Jaw-shaped fields extending from (10x10 cm2) down to (1x1 cm2). The total scatters factor, beam profiles, and penumbra was investigated for MLC/Jaw-shaped beams. Results: We found that the total scatters factor and the penumbra was clearly higher for MLC-shaped beams due to the MLC leakage, which becomes more and more significant for the small fields. The Analytical Formula was introduced as a least-square fit equation and verified against to measure data. The maximum deviation at small field size ( 4 cm2), and had small deviation with MLC-shaped small field size, emphasizing that our analytical formula is valid and reasonably good for the total scatters factor calculation of the MLC-shaped beams, especially the ultra-small field size.
