Quality assurance of intensity modulated radiation therapy using an electronic portal imaging device

• Main Authors: Hsi-Chang Chang, 張席昌
• Other Authors: Ching-Tsorng Tsai
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/43109989319659697306

碩士 === 東海大學 === 資訊工程與科學系碩士在職專班 === 93 === Now with the technical development, we cannot desultory treat a patient before design a perfect radiation treatment plan. In department of radiation oncology, must install a Linac Accelerator with the function of DMLC (Dynamic MultiLeaf Collimator) and provide a patient more appropriate treatment plan. We know that radiation therapy will kill tumor cell and hurt normal tissue from the past experience. However, sometimes this is unable to avoid. But regarding other accident of radiation therapy, like as treatment dose error, treatment position error, operation mistake and so on. All is we needs to avoid as possible. In order to reduce the radiation complication proceeding from overdose, we need to execute pre-treatment QA (quality assurance) like as film dosimetry and position check. Now new methodology of pre-treatment QA is presented: Quality assurance of IMRT (intensity modulated radiation therapy) using an EPID (electronic portal-imaging device). It makes radiation treatment QA efficient. We present measurement of ISO center and leaf position verification of DMLC using IMRT technique via using boundary detection we define a threshold of pixel value. However, We never destroy original imaging signal and, ISO center and leaf position of MLC can be calculated within 1 mm of mechanical tolerance. This will ensure radiation treatment dose within tolerance. Before treat patient, we pre-simulate and calculate an electronic imaging signal of patient. We can correct ISO center and pre-find out wrong leaf position of MLC. The presented method makes radiation therapy safer for patient.