Successful delivery of conformal fields requires stringent immobilization and treatment verification, as well as knowledge of the setup reproducibility. [1] Before coming OBI, electronic portal imaging detector was used to detect the setup errors. EPID images are not clear vision to identify correctly and immediately because they were produced by megavoltage X-ray during treatment setup. In OBI...

Introduction: Tumor control and treatment quality depend on accuracy of delivered dose. Various methods have been studied for treatment dosimetry verification. Among these methods, the use of electronic portal imaging device (EPID) is highly considered. Many efforts are underway to improve the results of this context.   Materials and Methods: In this study, ...

The purpose of this study was to evaluate electronic portal imaging (EPI) as a means of identifying and correcting field displacement in patients with problematic external beam radiotherapy setups. Fourteen patients with problematic setups were identified for pretreatment daily EPI beam monitoring as part of a physician-directed therapist intervention protocol. Pretreatment EPIs were used to re...

Introduction: Electronic portal imaging devices (EPIDs) could potentially be useful for intensity-modulated radiation therapy (IMRT) and VMAT QA. The data density, high resolution, large active area, and efficiency of the MV EPID make it an attractive option. However, EPIDs were designed as imaging devices, not dosimeters, and as a result they do not inherently measure dose in ...

Electronic Portal Imaging Devices (EPID) are used for the assessment of the geometric accuracy 2 during the radiation therapy process. EPID is also used like a major detector to test performances of the linear accelerator used for the treatment. Therefore, the quality control of portal images 4, 5, 6, 7 is essential for this task. Software tools that are capable to perform an automatic quality ...

The Electronic Portal Imaging Device has become an important tool for the clinician to verify the shape and the location of the therapy beam with respect to the patient’s anatomy [13]. Electronic Portal Imaging Devices use the high-energy treatment beam to project the body interior of the patient onto a fluorescent screen that is scanned by a camera. After on-line digitization, the images are a...

Many studies have reported dosimetric characteristics of amorphous silicon electronic portal imaging devices (EPIDs). Some studies ascribed a non-linear signal to gain ghosting and image lag. Other reports, however, state the effect is negligible. This study compares the signal-to-monitor unit (MU) ratio for three different brands of EPID systems. The signal was measured for a wide range of mon...