The Properties of Beam Intensity Scanner (BInS) in IMRT

The BInS equipped with custom made software is like an EPID type radiation detector. In order to examine the properties of the BInS, such as accuracy, reproducibility, efficiency and cost effectiveness, we investigate IMRT for head/neck case. In three steps, the applicability of the BInS to the case of head/neck treatment is tested. First, we make and study an inhomogeneous phantom with parts made of Aluminum rod and air cavity as bone and lung equivalent materials. It is found that the BInS is a very accurate and efficient dosimeter that can detect beam modulation depending on the type and position of inhomogeneity of Aluminum and air cavity. Second, a real nine segments head/neck treatment planning is studied using the versatile digital image processing capability of the BInS. It turns out that dose profiles by the Bins are much more accurate and efficient compared with those by film. Third, the photon beam profile is measured before and after radiation on the head/neck part of anthropomorphic phantom. The measured beam profile is accurate enough to show clearly the existence of bony structure such as chin, neck, spinal cord and thorax.