A convolution-based calibration procedure has been developed to use an amorphous silicon flat-panel electronic portal imaging device (EPID) for accurate dosimetric verification of intensity-modulated radiotherapy (IMRT) treatments. Raw EPID images were deconvolved to accurate, high-resolution 2-D distributions of primary fluence using a scatter kernel composed of two elements: a Monte Carlo gen...

PURPOSE With the advent of state-of-the-art treatment technologies, the use of small fields has increased, and dosimetry in small fields is highly challenging. In this study, the potential use of Varian electronic portal imaging device (EPID) for small field measurements was explored for 6 and 15 MV photon beams. MATERIALS AND METHODS The output factors and profiles were measured for a range ...

AIMS This study investigates the impact of cine acquisition mode on the dosimetric characteristics of a Varian aS500 amorphous silicon electronic portal imaging device (a-Si EPID). MATERIALS AND METHODS The performance of an a-Si EPID operated in cine mode was assessed and compared to its performance when operated in an integrated mode and dose measurements using an ionization chamber. This s...

PURPOSE The aim of this study is to evaluate the ability of transit dosimetry using commercial treatment planning system (TPS) and an electronic portal imaging device (EPID) with simple calibration method to verify the beam delivery based on detection of large errors in treatment room. METHODS AND MATERIALS Twenty four fields of intensity modulated radiotherapy (IMRT) plans were selected from...

BACKGROUND Health information exchange is a national priority, but there is limited evidence of its effectiveness. OBJECTIVE We sought to determine the effect of health information exchange on ambulatory quality. METHODS We conducted a retrospective cohort study over two years of 138 primary care physicians in small group practices in the Hudson Valley region of New York State. All physicia...

In this study, we present an algorithm for three-dimensional (3-D) dose reconstruction using portal images obtained with an electronic portal imaging device (EPID). For this purpose an algorithm for 2-D dose reconstruction, which was previously developed in our institution, was adapted. The external contour of the patient was used to correct for absorption of primary photons, but the presence o...

Purpose To evaluate the Edose system, a novel three-dimensional (3D) in vivo dose monitoring system based on electronic portal imaging device (EPID), prior to clinical application, we analyzed the preliminary clinical data using Edose system in patients receiving intensity-modulated radiation therapy (IMRT). Materials and methods After the physical modeling, the measured results from the Edos...

INTRODUCTION Motion of the prostate is problematic in the accurate delivery of external beam radiation therapy (EBRT) for prostate cancer. This study investigated the relationship between body mass index (BMI), an easily measured indicator of obesity, and prostate motion. METHODS Prostate motion during EBRT was assessed by measuring the displacement of fiducial markers implanted within the pr...

The megavoltage electronic portal imaging is a very important task for cancer treatment in the radiation therapy. The megavoltage images (MVIs) , however, are very poor in quality because of imaging physics. For a reliable patient set-up verification we need better in-treatment images to track relevant features. In recent years, some researchers have applied the concept of fuzzy set theory to d...