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Biomedical subjects

M Tatcher

Publications and source records attributed to M Tatcher.

33 records · Page 2Linked to original sources
PubMed1978

Computer-assisted method for intracavitary radiotherapy of cancer of the uterine cervix.

This paper describes a simple computer system for calculating the radiation dose rate to selected points in the pelvis of a patient treated by gynaecological insertion of applicators loaded with radioactive sources. The calculations are performed on the basis of radiographs made before the sources are placed in the applicators. The system consists of a minicomputer, a teletype and a digitizer. The method allows an optimum loading distribution to be determined within a few minutes once the radiographic images are available.

Computers↗
PubMed1978

Time-dose effects in the matching of adjacent radiotherapy fields.

When adjacent radiotherapy fields are treated in different times, the dose fraction at the junction of the fields is different from that within the portals. When the width of the gab between the fields is adjusted to produce equality of dose at the junction, it will not give equality with respect to radiobiological effect. The authors have used Ellis's NSD equation to take into account time-dose relationships in the matching of adjacent fields. Distribution of physical dose and biologically effective dose in the region near the junction of opposed pairs of parallel 60Co fields are given.

Radiotherapy↗
PubMedDate not supplied

Equation for scatter-air ratios for megavoltage radiotherapy calculations.

Scatter-air ratios are tabulated quantities which are based on measurement and which are used to calculate the dose to points in the body of a patient exposed to radiation fields of arbitrary shape. For computing purposes it is convenient to represent these quantities by an equation. We have found a nine-parameter empirical function which expresses scatter-air ratio data for 60Co gamma rays and for 4- and 6-MV x rays. To test the equation it was used to calculate tissue-air ratios for a range of rectangular fields. The results are in good agreement with published values.

Cobalt Radioisotopes↗
PubMedDate not supplied

Head-scatter factors and effective x-ray source positions in a 25-MV linear accelerator.

The behavior of the effective source position and the correction factor associated with the collimator opening (head-scatter factor) were investigated for the 6- and 25-MV x-ray beams of a linear accelerator. The primary photon fluence was measured in air for square field sizes from 5 x 5 cm to 40 x 40 cm at distances from the nominal source of 80 to 140 cm, for open and wedged fields (wedge angle 60 deg). An inverse-square analysis shows that, for open fields, the effective source position of the accelerator is about the same (approximately 1 cm downstream) at 6 and 25 MV, for all field sizes. For the wedged fields, the effective source position depends on field size and ranges from about 2 to 4 cm. The head-scatter correction factors for given collimator settings were found to be essentially independent of distance at both energies.

Mathematics↗