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J A Brace

Publications and source records attributed to J A Brace.

5 recordsLinked to original sources
PubMed1986

Conformation therapy: a method of improving the tumour treatment volume ratio.

Restriction of the volume irradiated is a fundamental tenet of radiotherapy. Conventional two-dimensional treatment results in geometrically shaped high-dose regions, the sizes of which are defined by the greatest dimensions of a tumour mass. Conformation therapy permits a tumour to be considered for treatment as multiple short segments, and the radiation field to be tailored to fit each segment accurately. This paper demonstrates that this results in a reduction of the treatment volume of between 10% and 80%, depending on the shape of the tumour. Also, it is shown that a greater proportion of the high-dose region is occupied by tumour, thus reducing the volume of normal tissue treated to a high dose. Smaller treatment volumes allow the prescription of tumoricidal doses and improve the tolerance of radiation by patients.

Aorta↗
PubMed1985

Treatment of medulloblastoma using a computer-controlled tracking cobalt unit.

Radiation therapy of the length of the spinal column presents various clinical and physical problems. The completed plan may be complicated to set up, be time-consuming and require daily variation to achieve reasonable dose homogeneity. A case of medulloblastoma is used to illustrate the steps in producing a plan for dynamic treatment using a computer-controlled tracking cobalt unit. After definition by computed tomography, the target is considered in segments in order to develop a plan which keeps the spinal cord constantly positioned at the beam isocentre. The main computer is used to develop the patient treatment file and information is transferred to a second computer which controls and monitors the safe functioning of the cobalt unit. The cranial fields are treated separately in a conventional way. Good and consistent control of the dose distribution is achieved along the entire target volume. This technique is a marked improvement over all existing methods of treating the spinal axis.

Cerebellar Neoplasms↗
PubMed1982

A computer controlled tele-cobalt unit.

A computer controlled cobalt treatment unit was commissioned for treating patients in January 1980. Initially the controlling computer was a minicomputer, but now the control of the therapy unit is by a microcomputer. The treatment files, which specify the movement and configurations necessary to deliver the prescribed dose, are produced on the minicomputer and then transferred to the microcomputer using minitape cartridges. The actual treatment unit is based on a standard cobalt unit with a few additional features e.g. the drive motors can be controlled either by the computer or manually. Since the treatment unit is used for both manual and automatic treatments, the operational procedure under computer control is made to closely follow the manual procedure for a single field treatment. The necessary safety features which protect against human, hardware and software errors as well as the advantages and disadvantages of computer controlled radiotherapy are discussed.

Cobalt Radioisotopes↗
PubMed1981

Conformation therapy at the Royal Free Hospital. A progress report on the tracking cobalt project.

A computer-controlled tracking cobalt unit (CCTCU) was commissioned for treating patients in January 1980. The system has proved to be reliable and acceptable in routine use for conventional and conformation therapy. The system comprises a modified TEM MS90 Mobaltron, a Hewlett-Packard System 1000 Model 30 mini-computer and user programmes. Tracking techniques are suitable for the treatment of tumours of the oesophagus, thyroid, bronchus, chains of lymph nodes or medulloblastoma. Tumours 85 cm long can be treated at the isocentre. The high dose volume may be considerably reduced when tracking techniques are used instead of conventional techniques. The major obstacle to the routine use of conformation therapy is treatment planning. Work in progress is designed to produce a computerized planning system linking a CT scanner and the CCTCU. It is expected that the system will produce both a plan optimized in 3-D and the necessary control data in machine readable form within an hour of a patient being scanned. The present planning system is based on a Rad-8 planning system and an Alderson phantom to verify the dose distribution in 3-D. An outline of the tracking technique is given. The computer control system is described briefly, with its methods of use for treating patients. Brief reverence is made to work at other centres using conformation therapy.

Cobalt Radioisotopes↗