A case of appendicitis which resulted in portal pyaemia, hepatic and splenic abscesses, presumed portal vein thrombosis and subsequent portal hypertension is described. It confirms the merit of ultrasonic imaging in monitoring abscess resolution but questions the ability of the technique to recognise acute suppurative portal endophlebitis.

Portal hypertension is a common clinical syndrome, defined by a pathologic increase in the portal venous pressure. Increased resistance to portal blood flow, the primary factor in the pathophysiology of portal hypertension, is in part due to morphological changes occurring in chronic liver diseases. This results in rerouting of blood flow away from the liver through collateral pathways to low-p...

This study evaluated the agreement of fiducial marker localization between two modalities--an electronic portal imaging device (EPID) and cone-beam computed tomography (CBCT)--using a low-dose, half-rotation scanning protocol. Twenty-five prostate cancer patients with implanted fiducial markers were enrolled. Before each daily treatment, EPID and half-rotation CBCT images were acquired. Transla...

This work validates the use of an amorphous-silicon, flat-panel electronic portal imaging device (a-Si EPID) for use as a gauge of patient or phantom radiological thickness, as an alternative to dosimetry. The response of the a-Si EPID is calibrated by adapting a technique previously applied to scanning liquid ion chamber EPIDs, and the stability, accuracy and reliability of this calibration ar...

A recent control system update for Elekta linear accelerators includes the ability to deliver volumetric-modulated arc therapy (VMAT) with continuously variable dose rate (CVDR), rather than a number of fixed binned dose rates (BDR). The capacity to select from a larger range of dose rates allows the linac to maintain higher gantry speeds, resulting in faster, smoother deliveries. The purpose o...

In-vivo dosimetry techniques are currently being applied only by a few Centers because they require time-consuming implementation measurements, and workload for detector positioning and data analysis. The transit in-vivo dosimetry performed by the electronic portal imaging device (EPID) avoids the problem of solid-state detector positioning on the patient. Moreover, the dosimetric characterizat...

PURPOSE To perform a quantitative study to verify that the mechanical field center coincides with the radiation field center when both are off from the isocenter during the single-isocenter technique in linear accelerator-based SRS/SBRT procedure to treat multiple lesions. METHODS We developed an innovative method to measure this accuracy, called the off-isocenter Winston-Lutz test, and here ...

PURPOSE To use a graphic processing unit (GPU) calculation engine to implement a fast 3D pre-treatment dosimetric verification procedure based on an electronic portal imaging device (EPID). METHODS The GPU algorithm includes the deconvolution and convolution method for the fluence-map calculations, the collapsed-cone convolution/superposition (CCCS) algorithm for the 3D dose calculations and ...