Determination of detector efficiencies for gamma ray energies up to 12 MeV II. Monte Carlo calculation

Use of a Monte-Carlo Code to Determine in High Z Semi-Conductor CdTe and CZT, Both Carriers Lifetimes and Mobilities

This paper deals with a comparison between experimental gamma-ray spectra recorded with CdTe and CdZnTe detectors and a Monte Carlo code simulating the spectrum, in order to extract realistic values of the transport properties of both electrons and holes in these materials. In a second section, these values are compared to that obtained by others using other methods, in order to evaluate the accuracy of the various experimental procedures.

Patient risk from interproximal radiography

Computer simulation methods for determining patient dose from dental radiography have demonstrated that patient risk from a two-film interproximal examination ranges from 1.1 X 10(-8) to 3.4 X 10(-7) using 90-kVp beams, depending on film speed, projection technique, and age and sex of the patient. Further, changing from a short-cone round-beam to a long-cone technique with rectangular collimation reduces risk by a factor of 2.9, independent of other factors.

Backscatter factors for x-rays generated at voltages between 10 and 100 kV

Using the Monte Carlo method, backscatter factors were calculated for cylindrical phantoms (diameter, 33 cm; thickness along the beam direction, 20 cm) of various composition (water, graphite, acrylic glass, and M3) for x-ray beams of a mean energy between 7.5 and 52.0 keV, corresponding to first half-value layers in aluminium between 0.036 and 4.3 mm, generated by voltages between 10 and 100 kV. In contrast with the current literature, the backscatter factor in this work is defined as the ratio of the kerma rate with respect to a specified reference material at the intersection of the beam axis with the phantom surface to the kerma rate at the same point in space in the absence of the phantom. The calculations were performed for a source-surface distance of 100 cm and three field diameters at the phantom surface, namely 2 cm, 4 cm and 11.2 cm, where the latter corresponds to a square field of 10 cm X 10 cm.

Stripping of X-ray bremsstrahlung spectra up to 300 kVp on a desk type computer

The direct result of a spectrometric measurement is a pulse height distribution. In the energy region up to 300 keV three corrections in particular need to be applied to get the photon spectrum: corrections for K-escape, Compton scattering and inefficient photon absorption. A simple 'stripping' procedure is described which may be implemented on a desk type computer. All data necessary are either available in the literature or may be derived from the measurement of very heavily filtered X-ray spectra. The accuracy of the procedure is better than +/- 5% of the peak value. Results are compared with a more detailed stripping procedure, based on Monte Carlo calculated data.