Beam focal spot position: The forgotten linac QA parameter. An EPID-based phantomless method for routine Stereotactic linac QA.

In this study a novel, phantomless method has been developed using the EPID (Electronic Portal Imaging Device) that utilizes the different heights of the MLC and jaws. The method has been performed on four linear accelerators and benchmarked against an alternate ion chamber-based method. The method has been found to be reproducible to within ±0.012 mm (1 SD) and in agreement with the ion chamber-based method to within 0.001 ± 0.015 mm (1 SD). The method could easily be incorporated into a departmental routine linac QA (Quality Assurance) program.
PMID: 28786168 [PubMed - as supplied by publisher]

Source: Journal of Applied Clinical Medical Physics - August 8, 2017 Category: Physics Authors: Chojnowski JM, Barnes MP, Sykes JR, Thwaites DI Tags: J Appl Clin Med Phys Source Type: research