Objective: Small field dosimetry has gained importance with the development of new treatment techniques (Sterotactic Radiosurgery and Sterotactic Radiotherapy) in radiotherapy. One of the detector types frequently used in small area dosimetry are diode detectors. The aim of this study is to examine the response of the SNC diode type edge detector and pinpoint ion chamber detector, which is suitable for use in small area dosimetry, to dosimetric variables in 2x2, 3x3, 4x4 cm² area sizes.

Materials and Methods: In this study, edge detector and pinpoint ion chamber were used for small area dosimetry. In Varian brand Clinac IX model linear accelerator device, 6 MV photon beam, Sun Nuclear brand water phantom 2x2, 3x3, 4x4 cm² field sizes 1.5 cm deep facial dose (PDD) and 5 cm depth cross-plane and in-plane profile measurements were taken in the same field dimensions. In these measurements made by using edge detector and pinpoint detector, PDD, dosimetric field size and 20%-80% and 10%-90% penumbra widths were examined.

Results: The dosimetric performances of both detectors in small areas gave similar responses. It has been observed that the dosimetric field size response of the edge detector measured in 2x2 cm² area is closer to the real field size value and has a narrower penumbra in all areas.

Conclusion: It has been observed that both detectors may be suitable for use in small area dosimetry, but due to the small sensitive volume of the edge detector, it has a better response to steep dose gradients in small areas, especially in the penumbra region.