A prerequisite for accurate dose delivery of IMRT profiles produced with dynamic multileaf collimation (DMLC) is highly accurate leaf positioning. In our institution, leaf verification for DMLC was initially done with film and ionization chamber. To overcome the limitations of these methods, a fast, accurate and two-dimensional method for daily leaf verification, using our CCD-camera based elec...

PURPOSE We recently developed a novel, open-source in vivo dosimetry that uses the electronic portal imaging device to detect dose delivery discrepancies. We applied our method on patients with rectal cancer treated on a belly board device. METHODS In vivo dosimetry was performed on 10 patients with rectal cancer treated prone on the belly board with a 4-field box arrangement. Portal images w...

We investigated an electronic portal image device (EPID)-based method to see whether it provides effective and accurate relative dose measurement at abutment leaves in terms of positional errors of the multi-leaf collimator (MLC) leaf position. A Siemens ONCOR machine was used. For the garden fence test, a rectangular field (0.2 20 cm) was sequentially irradiated 11 times at 2-cm intervals. Dev...

Portal vein aneurysm is a relatively uncommon entity. It is often an incidental, asymptomatic nding. With the increasing availability of advanced imaging modalities like Doppler ultrasound, computed tomography and magnetic resonance imaging, portal venous system aneurysms are being increasingly reported. We report two cases of intra hepatic portal vein aneurysm diagnosed incidentally on ultra-...

PURPOSE With the development of patient portals, the opportunity exists to identify gaps in practice by analyzing priorities patients place on the receipt and comprehension of radiology reports. Our purpose was to describe the nature of radiology-specific patient information requests by analysis of patient-initiated messages submitted through a web-based electronic patient portal. METHODS Ins...

PURPOSE To investigate the feasibility of fully automated detection of fiducial markers implanted into the prostate using portal images acquired with an electronic portal imaging device. METHODS AND MATERIALS We have made a direct comparison of 4 different methods (2 template matching-based methods, a method incorporating attenuation and constellation analyses and a cross correlation method) ...

The relationship between the pixel value and exit dose was investigated for a new commercially available amorphous silicon electronic portal imaging device. The pixel to dose mapping function was established to be linear for detector distances between 116.5 cm to 150 cm from the source, radiation field sizes from 5 x 5 cm2 to 20 x 20 cm2 and beam energies of 6 to 18 MV. Coefficients in the mapp...

Treatment verification has been a weak link in external beam radiation therapy. As new and more complicated treatment techniques, such as intensity-modulated radiation therapy (IMRT), are implemented into clinical practice, verifying the accuracy of treatment delivery becomes increasingly important. Existing methods for treatment verification are highly labor intensive. We have developed a meth...

Megavoltage, cone-beam computed tomography (MV CBCT) employing an electronic portal imaging device (EPID) is a highly promising technique for providing soft-tissue visualization in image-guided radiotherapy. However, current EPIDs based on active matrix flat-panel imagers (AMFPIs), which are regarded as the gold standard for portal imaging and referred to as conventional MV AMFPIs, require high...