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S G Chenery

Publications and source records attributed to S G Chenery.

6 recordsLinked to original sources
PubMed1988

Practical and technical considerations in establishing an intraoperative radiation therapy program in the community practice.

The Radiation Oncology Center in Sacramento, California, has developed a procedure for establishing an intraoperative radiation therapy facility in a community practice. The logistics pertaining to personnel, equipment, physical measurements, and quality assurance are presented. Particular emphasis is given to the most effective means of acquiring the large quantity of data needed to ensure a program of acceptable quality.

Facility Design and Construction↗
PubMed1986

Quantitative CT measurements: the effect of scatter acceptance and filter characteristics on the EMI 7070.

Non-linearities in projection values on computed tomography (CT) scanners cause corresponding errors in derived Hounsfield unit attenuation measurements. Existing commercial machines have been refined for clinical usefulness but not necessarily for quantitative accuracy. In this report the results of measurements on the EMI 7070 fourth-generation scanner are presented and compared with theory with particular attention being paid to the scatter artefact and fan-beam energy profile. It is concluded that, irrespective of any quality assurance protocol, interpatient and interslice errors can be expected to range from 3 to 10% for water-equivalent materials and the intraslice positional dependence of the CT number can vary up to 5% for dense bone-like materials in a uniform phantom. It seems as though the principal cause of this variation is an increase in the effective x-ray energy in the fan beam with increasing distance from the central ray.

Humans↗
PubMed1985

Physical characteristics of the Selectron high dose rate intracavitary afterloader.

The physics measurements on a Selectron high dose-rate afterloading cobalt-60 unit are reported. The installation was found to be acceptable from the standpoint of radiation safety and cost effectiveness; hospital bed space was saved as treatment could be on an outpatient basis. A source calibration 4% higher than the value stated by the manufacturer was obtained. Measurement of the ratio of exposure rate in water to that in air confirmed the calibration and the applicability of correction factors for routine clinical dosimetry recommended in the literature.

Brachytherapy↗
PubMed1983

Total body irradiation with a sweeping beam.

A technique for total body irradiation, in which the patient lies in the prone or supine position in the beam of a conventional column mounted 4 MV linear accelerator, is described. A sufficiently large radiation field is obtained by rotating the beam in a vertical plane about the source (i.e., sweeping beam) at a source-to-skin distance of 190 cm on the vertical axis. The variation of the midplane dose is less than +/- 5% in parallel-opposed beams, when attenuators are placed over the region containing the lungs and bolus is employed around the head and legs. The percentage depth dose for the sweeping beam is identical to that of a stationary beam for the same collimator setting and source-to-skin distance. A method for monitoring the dose to the patient by means of a thimble ionization chamber located on the vertical beam axis is outlined. The average dose rates used are between 5 and 10 cGy/min. The design and placement of lung attenuators is simple. The treatment technique with the sweeping beam requires minimal modification of a treatment unit and can be applied on any unit which has a head swivel option.

Humans↗
PubMed1983

Dosimetry of radioactive gold grains for the treatment of choroidal melanoma.

The dosimetry of small permanent gold grain implants for treating choroidal melanoma has been studied. A means of planning the source configuration required to deliver a desired minimum dose to a tumour has been developed. The interaction of the variable parameters, source activity, number of sources used, geometrical arrangement, and implant diameter, within the physical limitations imposed by the eye and the practical limitations occurring in clinical practice, are discussed.

Brachytherapy↗