A Comparative Analysis of the Photon Beam Percentage Depth Dose in an Elekta Linear Accelerator at a Comprehensive Cancer Center

Abstract

This study aims to verify the photon beam energy characteristics of an Elekta Synergy Platform LINAC at Kathmandu Cancer Center, Tathali Nala road by comparing measured PDD data with established British Journal of Radiology (BJR) Supplement 25 and other published literature. PDD measurements were performed for photon energies of 4 MV, 6 MV, and 15 MV using seven different field sizes. All measurements were taken under consistent environmental and setup conditions, including identical pressure, temperature, incremental depth steps, geometry, chamber voltage, and polarity. For the reference 10 × 10 cm² field size, the measured maximum depth doses (dₘₐₓ) were found to be 1.18 cm, 1.58 cm, and 2.68 cm for 4 MV, 6 MV, and 15 MV photon beams, respectively. The corresponding PDD values at 10 cm depth (d₁₀) were 62.2% for 4 MV, 66.1% for 6 MV, and 74.9% for 15 MV photon energies. The measured values for 4, 6, and 15 MV photon beams fell within acceptable tolerance limits. The resulting PDD curves demonstrated strong agreement with the reference data in BJR-25 and other published studies, thereby confirming the consistency of beam quality of the Elekta Synergy Platform LINAC.