The use of activated aluminium foils for determination of fast neutron contaminations in photon beams.
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Aluminum↗
Biomedical subjects
A G Bukovitz
Publications and source records attributed to A G Bukovitz.
Orthogonal fields: variations in dose vs. gap size for treatment of the central nervous system.
Variations in dose at the junction at the lower end of two lateral skull portals and the upper end of a posterior spinal portal used for irradiation of the central nervous system (CNS) were studied using 60Co and 6 MV linear accelerator radiation. The relationship between dose and gap size was measured via film dosimetry. Small variations in gap size resulted in large variations in dose (+/- 40%) at the junction. These variations in dose were more pronounced for the 6 MV accelerator than for the 60Co, but the volume of high and low dose tended to be smaller with the 6 MV linear accelerator.
Central Nervous System Diseases↗
Computer program for central axis dose calculations for high energy photons.
A computer program is described for central axis dose calculations for 60Co and 6 MV photons. Fixed distance or isocentric calculations for regular or irregular fields can be performed. Corrections are made for wedges and blocking trays. Tissue-air ratios and percentage depth doses are calculated from scatter-air ratios eliminating the need for empirical formulas. Calculated tissue-air ratios and percentage depth doses for elongated fields agree to within 2 per cent with measured data, eliminating the need for tables of equivalent squares. Calculated values for irregular fields also agree to within 2 per cent with measured data.
Computers↗
A treatment accessory for CNS irradiation in children.
A treatment accessory for use in CNS radiotherapy of small children enables the head and spinal fields to be treated while the child lies supine. Children are not moved during therapy which minimizes the problem of gaps between the head and spinal fields.
Central Nervous System Diseases↗
Three-dimensional dose distributions for external beam radiotherapy.
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Computers↗
Fast and slow neutrons in an 18-MV photon beam from a Philips SL/75-20 linear accelerator.
Fast- and slow-neutron contamination in an 18-MV photon beam from a Philips SL/75-20 linear accelerator has been measured. Aluminum and indium foils were activated to determine fast- and slow-neutron fluence, which were largely independent of field sizes. Measured fast-neutron fluences were typically 13.9 X 10(4) and 4.4 X 10(4) neutrons/cm2/rad of x ray inside and 5 cm outside the field, respectively. Slow-neutron fluences, 1.3 X 10(4) neutrons/cm2/rad of x ray, remained relatively constant inside and outside the field. The reported results are about three times higher than neutron fluences recently reported with a betatron operated at the same energy.
Elementary Particles↗
Photon contamination in 8-20-MeV electron beams from a linear accelerator.
The amount of x-ray contamination near the surface of a phantom irradiated with electron beams was measured directly. Measurements were done to ascertain if photon contamination in the beam contributes a higher dose to the more superficial layers of an irradiated medium than indicated by conventional methods. A 1.4-kG magnetic field was used to deflect the electron beams generated by a Philips SL/75-20 linear accelerator. The electron energies studied were 8, 10, 12, 14, 17, and 20 Mev. After sweeping the electron beam, a significant amount of photon contamination was measured in all cases. The characteristic qualities of the photon contamination were measured directly in a water tank. They were found to agree with those of bremsstrahlung spectra generated in a thin target with a virtual source at the location of the scattering foil.
Electrons↗