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

Abstract

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 (FC65-G, CC13, CC01) and diode (razor) chambers. Material and Methods: Applying TRS-398 in Varian Clinac™ IX-5982 for 6 MV photon beams, the conditions (pressure, temperature, direction, polarity) were kept the same for a set of field sizes (1 × 1, 2 × 2, 3 × 3, 4 × 4, 5 × 5, 7 × 7, and 10 × 10 cm2), 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 CC13. Taking CC01 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