Abstract
Accurate determination of dosimetric parameters is vital in radiotherapy to avoid normal-tissue damage. For accurate delivery of dose to the target volume, uniform dose distribution is achieved by the use of wedge filters. It is important to measure all parameters of photon beam profile before calibrating linear accelerator (LINAC). Quality assurance of radiotherapy treatment planning procedure depends largely on symmetry parameter, which determines quality of radiation beam produced by LINAC. To make analysis of beam profile parameter, symmetry, for 6 MV and 15 MV beam energies is attained by varying different factors such as depth, field size and wedge angle. We measured photon beam profile for dual photon energies using DHX Clinic and PTW array detector. Data management, analysis and processing of isodose curves were carried out by PTW MP3-M water tank and PTW MEPHYSTO version 7.3 software. By the use of this software, dosimteric parameters for wedged beam profiles were calculated at different depths and field sizes for 6 MV and 15 MV energy for quality assurance and commissioning. Variation in symmetry was analyzed with parameters, such as field size, depth, wedge angle and beam energy, to match acceptance criteria as recommended by American Association of Physicists in Medicine (AAPM) protocols. This article describes symmetry parameter test of wedge-shaped beam profile. For treatment planning purpose this parameter can be treated as being independent of depth and field size for wedged shape beam profile. Values of symmetry were in good agreement with AAPM protocol and symmetrical radiation beam is useful in treating tumors.
