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

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.

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.

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.

Razor, with extremely small active volume, was very much suited for small field dosimetry, except for PDDs.