Comparing of dosimetric measurements of small field treatment plans

This study including some measurements which are necessary for treatment planning system. These measurements are output, percentage depth dose and profiles. Measurements are taken by ion chambers have different volumes and different types of diode detectors in 6MV photon energies in different open areas. In output measurements, differences in ion chamber readings and diode detectors readings are discussed. Especially in small field areas, the readings of ion chamber deterctors, theese have large effectif measurement volume, are effeceting negatively in recording the radiation. As a results of output measurements, the diode detectors are gives more sensitive readings of radiation. Measurements of percentage depth dose are discussed numerically and graphically in two parts as large and small fields. As a result in large fields there is no differences between the detectors. But in small fields detected a difference of 5.3% between ion detectors and diyode detectors. The most important reasons of this result are volume effect and the normalisation value of the graphs. In small fields, if the normalisation value assigned as 100%, the graph will belie us. The profiles measured for 5 different depths as 15mm, 50mm, 100mm, 200mm and 300mm, in gun to target direction with 6 different detectors. The used datas in depth of 50mm and measurements are compared as ion chamber vs. diyot detector and diode detector vs. Gaussian (Normal) distribution. As a result, the diode detectors are not effected as much as ion chabers from volume effect and normalisation tocentral axis (100%). The diode detectors are more sensitive and usable than ion chambers in small fields profile measurements. As a result of the study, in small field measuremets, diode detectors gives closer results to Gaussian distribution graphs. This means that, diode detectors gives more normal distribution than ion chambers. Because of that, small field`s dose datas installing to treatment planning systems, must be measured by diode detectors. If there is no chance to use diode detectors, we assumed a new formalism that can convert the datas measured by ion chambers to model of diode or Gaussian distribution datas.