Pseudorabies virus infections among animals, especially swine, have become prevalent in the United States in the past few years. The disease in swine is now economically important. Test systems and antigens are being developed for use in control and disease suppression efforts. Pseudorabies virus was inactivated by three methods: chemically, with bromo-ethylene-imine; physically, with 60Co irra...

An experimental determination of the energy correction factor for alanine/paraffin pellets in the 192Ir spectrum at varying distances from the source is presented. Alanine dosimeters were irradiated in water under full scatter conditions with a high dose rate (HDR) 192Ir source (Flexisource), using a dedicated holder. Up to six line sources (catheters) fit in a regular pattern at fixed radial d...

In the algorithm of Leksell GAMMAPLAN (the treatment planning software of Leksell Gamma Knife), scattered photons from the collimator system are presumed to have negligible effects on the Gamma Knife dosimetry. In this study, we used the EGS4 Monte Carlo (MC) technique to study the scattered photons coming out of the single beam channel of Leksell Gamma Knife. The PRESTA (Parameter Reduced Elec...

The relative biological effectiveness (RBE) of various energy neutrons produced from a Schenkel-type accelerator at the Research Institute for Radiation Biology and Medicine, Hiroshima University (HIRRAC), compared with 60Co gamma-ray radiation was determined. The neutron radiations and gamma-ray radiation produced good linear changes in the frequency of micronuclei induced in the root-tip cell...

BACKGROUND Radiation-therapy is a complex process with multiple steps, each of which has an impact on the quality of treatment. Accurate dosimetry is a critical step during the radiotherapy of cancer patients.The aim of the present study was to measure and evaluate the doses of two cobalt- 60 (60Co) teletherapy units GWXJ80 of NPIC China and Theratron 780 of AECL Canada at various points within...

Several groups are developing ultra-miniature x-ray machines for clinical use in radiation therapy. Current systems are for interstitial radiosurgery and for intravascular insertion for irradiation to prevent re-stenosis. Typical generating voltages are low, in the 20 to 40 kV range. It is well established that the biological effectiveness of such low-energy photons is large compared with highe...

Reported doses of external beam radiotherapy and radioimmunotherapy (RIT) to produce equivalent therapeutic effects are inconsistent, with many proposed causes. Calculations of effective dose were performed for the case of LS174T human colon cancer xenografts, where a 60Co single fraction exposure (6 Gy) was matched with 131I-labeled 17-1A monoclonal antibody therapy (300 microCi injection, 19 ...

From 1995 to 1996 about 15 people suspected of being overexposed to ionizing radiation were referred to the Institute for Nuclear Safety and Protection in Fontenay-aux-Roses, France, for investigation by chromosome aberration analysis. Biological estimates of accidental overexposure were first obtained by scoring radio-induced unstable structural chromosome aberrations (dicentrics, centric ring...

When discussing local treatment modalities, physicians often quip that there can be no blind surgeons, suggesting that an inherent advantage to surgery is the ability to precisely visualize the target. Advances in radiation therapy (RT) technology over the years have significantly improved the radiation oncologists’ abilities to precisely sculpt high-dose radiation to a variety of targets, simu...

Current dosimetry protocols (AAPM, IAEA, DIN) recommend the use of parallel-plate ionization chambers for the measurement of absorbed dose-to-water in clinical electron beams. For well-guarded plane-parallel chambers, it is assumed that the perturbation correction pQ is unity for all electron energies. In this study, we present detailed Monte Carlo simulations with the EGSnrc code for the widel...