Ivan A. Brezovich

Learn More
The capability of a commercial respiratory gating system based on video tracking of reflective markers to reduce motion-induced CT planning and treatment errors was evaluated. Spherical plastic shells (2.8-82 cm3), simulating the gross target volume (GTV), were placed in a water-filled body phantom that was moved sinusoidally along the longitudinal axis of(More)
BACKGROUND There is clinical evidence that very low and safe levels of amplitude-modulated electromagnetic fields administered via an intrabuccal spoon-shaped probe may elicit therapeutic responses in patients with cancer. However, there is no known mechanism explaining the anti-proliferative effect of very low intensity electromagnetic fields. METHODS To(More)
BACKGROUND Therapeutic options for patients with advanced hepatocellular carcinoma (HCC) are limited. There is emerging evidence that the growth of cancer cells may be altered by very low levels of electromagnetic fields modulated at specific frequencies. METHODS A single-group, open-label, phase I/II study was performed to assess the safety and(More)
In the past century, there have been many attempts to treat cancer with low levels of electric and magnetic fields. We have developed noninvasive biofeedback examination devices and techniques and discovered that patients with the same tumor type exhibit biofeedback responses to the same, precise frequencies. Intrabuccal administration of 27.12 MHz(More)
Radiotherapy for brain cancer inevitably results in irradiation of uninvolved brain. While it has been demonstrated that irradiation of the brain can result in cognitive deficits, dose-volume relationships are not well established. There is little work correlating a particular cognitive deficit with dose received by the region of the brain responsible for(More)
Fast contouring is important in image-guided radiation therapy (IGRT) and adaptive radiation therapy (ART) where large computed tomography (CT) volumes have to be segmented. In this study, a modified active contour (also called snake) segmentation method based on a faster gradient-vector-flow (GVF) calculation algorithm is proposed. The accelerated method(More)
The heating of deep visceral tumors with implanted electrodes and with self-regulating ferromagnetic thermoseeds was inves tigated. Clinical trials on six patients heated with implanted electrodes indicate that good local tumor control can be obtained by application of hyperthermia during a normal course of radio therapy. The heating method was found(More)
Thermocouple thermometry errors in radiofrequency (typically 13, 56 MHZ) electromagnetic fields such as are encountered in hyperthermia are described. RF currents capacitatively or inductively coupled into the thermocouple-detector circuit produce errors which are a combination of interference, i.e., 'pick-up' error, and genuine rf induced temperature(More)
Some modern treatment-planning systems (TPSs) provide for input of wedge factor (WF) tables covering the entire range of square and elongated fields available on the LINAC. Depending on the field size increment chosen and the number of available wedge orientations, one may have to take more than 100 measurements per wedge and photon energy to commission the(More)
PURPOSE Spatial accuracy is most crucial when small targets like the trigeminal nerve are treated. Although current quality assurance procedures typically verify that individual apparatus, like the MRI scanner, CT scanner, Gamma Knife, etc., are meeting specifications, the cumulative error of all equipment and procedures combined may exceed safe margins.(More)