Suitability of Chambers in Relative Dose Measurement of Small Fields for Accelerated Photon Delivered by a Medical Linear Accelerator

Introduction: Using the small field in modern radiotherapy, the present study aimed at measuring the relative dosimetry (scattering factor, percentage depth dose (PDD), and profile of penumbra) with ionization (FC۶۵-G, CC۱۳, CC۰۱) and diode (razor) chambers.  Material and Methods: Applying TRS-۳۹۸ in Varian Clinac™ IX-۵۹۸۲ for ۶ MV photon beams, the conditions (pressure, temperature, direction, polarity) were kept the same for a set of field sizes (۱ × ۱, ۲ × ۲, ۳ × ۳, ۴ × ۴, ۵ × ۵, ۷ × ۷, and ۱۰ × ۱۰ cm۲), and relative dosimetry was performed at the North-East Cancer Hospital, Sylhet, Bangladesh. Results: During the output factor measurement in small fields, the razor showed better results than CC۱۳. Taking CC۰۱ as a standard in small fields, the data obtained from the study showed a good agreement with those of the previously published works. Conclusion: Razor, with extremely small active volume, was very much suited for small field dosimetry, except for PDDs.

Keywords:

Clinical Protocols , Scattering Factors , Radiation Dosimetry , Linac