The Study of Daily Linear Accelerator Output Constancy Using PTW QUICKCHECKwebline and Elekta AQUA System at Mahavajiralongkorn Thanyaburi Hospital

Daily Linear Accelerator Output Constancy Using PTW QUICKCHECKwebline and Elekta AQUA System

Abstract

         Quality assurance (QA) of linear accelerators in radiation therapy is a critical process that must be performed daily to ensure accurate and consistent radiation output within acceptable limits, as recommended by the American Association of Physicists in Medicine (AAPM) Task Group (TG)-142. PTW QUICKCHECK^webline and Elekta AQUA systems are commonly used for daily QA. This Retrospective Study collected photon beam output data at 6 Megavolt (MV) and 10 MV over eight months. The results showed that the average output measurements from both devices differed by no more than ±1%, with no statistically significant difference (p > 0.05). The Spearman’s rank correlation coefficient (r_s) indicated a positive but weak correlation for both energies: r_s = 0.241 for 6 MV and r_s = 0.181 for 10 MV. The Bland–Altman analysis demonstrated good agreement between the two measurement systems, with a mean difference of −0.0006 and limits of agreement (LOA) from −0.008 to 0.006 for 6 MV, and a mean difference of −0.0002 with LOA from −0.008 to 0.008 for 10 MV. In conclusion, both devices provide reliable daily dose constancy checks and can be used interchangeably for daily linear accelerator quality assurance.