AbstractID: 7790 Title: Development of a Pratical IMRT QA System
A practical quality assurance (QA) system for intensity modulated radiation therapy (IMRT) to fulfil current clinical demands was
developed. The system is consisted of a water phantom system and an analyzing software. The phantom was designed to measure
point doses, axial isodose distributions with the film or the TLD in the water. A hexahedron part of the phantom acts roles as a
phantom stand, a chamber holder and a film insert holder. An ion chamber holder on the attachable/detachable axes with two digital
vernier calipers keeps the ion chamber position accurate. Dose measurements can be done in the cylindrical part of the phantom,
which mimics the patient’s torso. Film or TLD’s also can be inserted into the cylindrical part of the water phantom for the
measurement of the axial dose distributions from the phantom supporter. The software is able to read the dose distribution
information from the IMRT RTP system (Helax, MDS Nordion) and to extract the dose distribution curves from the exposed film.
The analyzing software enables the comparison of the measurement and the calculation. The software also has a function to
compare the beam intensity patterns between the RTP generated pattern and the dry run images from the film or the image based
dosimetry system (BIS 710, Welhoefer). The new IMRT QA system developed in this study, was found to be practical to use in the
clinical IMRT QA, since it is easy to use and gives accurate results.