evaluating the performance of various detectors in the small field size by 6 mv linac

Introduction: we present a comprehensive evaluation of three different dosimeters in 6 mv flattening filter-free beam (fff) under charged particle dis-equilibrium conditions. material and methods: diamond detector, gafchromic film, and un-shielded diode detector were used in this study. the total scatters factor of jaw-shaped fields was measured starting from (10x10 cm²) down to (0.5x0.5 cm²) using true beam linear accelerator (varian) and solid water phantom. results: the diamond detector presented more accurate results at an ultra-small field size (0.5x0.5 cm²) with a 14.1% deviation of the diode results. on the other hand, all the measurements ranged within 5% for large field sizes “i.e. larger than 4.0x4.0 cm²”. the relative output factor (rof) was introduced as a total scatter factor measured by a given dosimeter (x) to total scatter factor measured by diamond detector (𝑂𝐹𝑥𝑂𝐹𝑑𝑖𝑎𝑚𝑜𝑛𝑑)⁄, the relative output factor values were 0.859 and 0.104 for both diode/diamond (𝑅𝑂𝐹𝐷𝑖𝑎𝑚𝑜𝑛𝑑𝑑𝑖𝑜𝑑𝑒) and film/diamond(𝑅𝑂𝐹𝐷𝑖𝑎𝑚𝑜𝑛𝑑𝑓𝑖𝑙𝑚), combinations, respectively. conclusion: we found that the diamond detector is the most appropriate detector for the small field dosimetry with high accuracy.