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A T Redpath

Publications and source records attributed to A T Redpath.

33 records · Page 2Linked to original sources
PubMed1977

A comprehensive radiotherapy planning system implemented in Fortran on a small interactive computer.

A suite of Fortran programs for carrying out the various dose computational aspects of radiotherapy has been developed on an enhanced RAD8 computing system. The hardward configuration of the computer is described and the main features of the programs in the suite are discussed. The include: (a) beam data input systems for use with linear accelerators and cobalt units; (b) static and rotational teletherapy planning, with computer optimization in the static planning; (c) irregular field calculations with isodose visualization; (d) interstitial calculations including routines which will reconstruct a radium needle implant in three dimensions in addition to presenting the isodose distribution in any desired plane. The problems of implementing the programs on another computer system are discussed.

Computers↗
PubMed1977

The reconstruction and dose-rate calculation of radium needle implants.

A comprehensive computer program has been developed for carrying out the various tasks associated with radium needle implants. Data input for the program are obtained by digitizing an orthogonal pair of radiographs with an analogue tracing system. Corresponding needles in the two radiographs are automatically located, and the implant may be rotated to any desired position in three dimensional space, at the same time presenting a view of the rotation on a storage oscilloscope. Automatic determination of the mean plane of a planar implant is possible, and the dose-rate distribution may be calculated in any specified plane. A Paterson--Parker exposure rate calculation may be performed with a biological dose and treatment time correction incorporated. The program is written in Fortran and runs on a small interactive computer system.

Computers↗
PubMed1976

A new technique for radiotherapy planning using quadratic programming.

Previous attempts at optimization of radiotherapy planning are described and criticized, and consideration of these attempts has resulted in the development of a new technique using quadratic programming. Uniformity of tumour dose is selected as the most important feature of any plan, and this is achieved by minimizing the variance of the dose to preselected points within the tumour. The dose to vulnerable regions can be constrained not to exceed a given percentage of the mean tumour dose. Optimization of field weight and field type is possible. The operation of the system is described and some typical results are given.

Humans↗
PubMed1975

A set of fortran subroutines for optimizing radiotherapy plans.

Quadratic Programming techniques have been applied to the optimization of radiation field weighting in Radiotherapy planning. Wedge selection has also been included by means of an exhaustive search. The radiation dose at any point in the patient may be constrained to be less than a stated percentage of the tumour dose. The routines have been successfully interfaced into a small computer interactive planning system, but they could represent an even more powerful tool in batch and time sharing systems. Minimum operator intervention is required in their use.

Computers↗
PubMed1975

Rapid depth dose determination by a computer-controlled dosimetry system.

A comprehensive depth dose measuring system controlled by a small computer has been designed to enable full depth dose information for a linear accelerator to be obtained within one day. An ionization microchamber is moved rapidly under computer control in a horizontal plane to preselected points within a water phantom by two stepping motors to a spatial resolution of 0-025 mm. The ionization current pulses are converted to DC voltages by an interface providing complete charge integration and yet having a rapid response to drastic changes in dose level. These are fed to the computer for analysis and subsequent conversion to depth dose data. The chamber path follows a preselected fan-shaped grid after automatic determination of the X-ray beam central axis. The combination of rapid chamber motion with halts for charge integration and computer sampling has resulted in fast data acquisition independent of measurement response times. This information, which is stored on disc, can be directly read by a treatment planning program. The overall accuracy of measurement lies within 0-5% of the true depth dose at any point. Central axis and transverse profiles can be assessed at the time of measurement through visualization on the computer storage oscilloscope.

Computers↗
PubMed1970

Serum fibrin-fibrinogen degradation products associated with postoperative pulmonary embolus and venous thrombosis.

A total of 76 "high-risk" surgical patients were studied for evidence of venous thromboembolic disease. Episodes of deep vein thrombosis and of pulmonary embolism were related to changes in blood levels of fibrin degradation products (F.D.P.). When diagnosed either by ordinary clinical means or by venography and isotope scanning significantly raised F.D.P. levels were found in all cases. Serum F.D.P. estimations are unlikely to help in detecting deep vein thrombosis, but may prove valuable in diagnosing pulmonary embolism.

Adult↗