Total scatter factor for small fields in radiotherapy: a dosimetric comparison

Abstract

AbstractPurposeSmall field dosimetry is complicated and accuracy in the measurement of total scatter factor (TSF) is crucial for dosimetric calculations, in making optimum intensity-modulated radiotherapy plans for treating small target volumes. In this study, we intended to determine the TSF measuring properties of CC01 and CC04 detectors for field sizes ranging from sub-centimetre to the centimetre fields.Material and methodsCC01 and CC04 chamber detectors were used to measure TSF for 6 and 18 MV photon beam delivered from the linear accelerator, through small fields in a water phantom. Small fields were created by collimator jaws and multi-leaf collimators separately, with field sizes ranging from 0·6 to 10 cm2and 0·5 to 20 cm2, respectively.ResultsCC01 measured TSF at all the given field sizes created by jaws and multi-leaf collimators for both 6 and 18 MV beams whereas CC04 could not measure TSF for field sizes <1 cm2due to volume averaging and perturbation effects.ConclusionCC01 was shown to be effective for measurement of TSF in sub-centimetre field sizes. CC01 can be employed to measure other dosimetric quantities in small fields using different energy beams.