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Biomedical subjects

W D Renner

Publications and source records attributed to W D Renner.

8 recordsLinked to original sources
PubMed1989

An algorithm for design of beam compensators.

Beam compensators are optimally designed to give a uniform dose to any plane or midsurface that intersects a single beam, or to give a uniform dose to the volume defined by the intersection of two or more beams. The primary and scatter components are taken into account separately, as well as the patient's shape and internal heterogeneities. The design of the beam compensators is formulated as a linear programming problem and solved with a variation of the Simplex Method. Beam weighting factors are also obtained as part of the solution.

Algorithms↗
PubMed1989

A dosimetric comparison of three compensator design methods for the mantle field.

The mid-plane dose was measured in an anthropomorphic phantom for parallel opposed mantle fields as typically used in the treatment of Hodgkin's Disease. Doses were measured for four cases: no compensator, a compensator designed by a three-dimensional CT based treatment planning algorithm, a compensator designed from a port film, and a compensator designed from surface topography. The results showed all three compensators gave a significant better dose distribution than using no compensator at all. Without a compensator, doses varied from 92 percent to 131 percent, with a standard deviation of 10.9 percent for 65 measured points. The treatment planning algorithm gave the best performance with a standard deviation of 3.2 percent with all points but three within 5 percent out of the 65 points measured, and no points outside of 10 percent. The port film compensator was next best with a standard deviation of 4.4 percent, with 19 points outside of 5 percent, and doses from 88 to 106 percent. The surface topography compensator had a standard deviation of 6.1 percent with 31 points outside of 5% and doses from 89 to 114 percent.

Hodgkin Disease↗
PubMed1987

An algorithm for planning stereotactic brain implants.

A computer software package was developed for the planning and execution of brain biopsy and radioactive implant procedures with the BRW Stereotaxic System. With the application of computer graphics and a zero-one integer variable programming algorithm, an implant plan with accompanying isodose distributions and stereotactic coordinates can be easily accomplished at the time of the operation when the computer imaging terminal and a printer/plotter is placed in the operating room.

Algorithms↗
PubMed1977

The use of photogrammetry in tissue compensator design. Part I: photogrammetric determination of patient topography.

The surface topography of a patient can be determined by photogrammetry before beginning radiotherapy. The source light of the therapy unit or simulator is used to project a grid pattern onto the patient, and this is then photographed together with control points consisting of miniature light bulbs mounted on a frame suspended from the wedge slot of the therapy machine. When the photograph is projected onto a graphics terminal for data entry into a computer, the three-dimensional topography of the patient's surface can be reconstructed as a two-dimensional matrix of discrete points. A computer algorithm can then design a tissue compensator to fit the individual patient.

Humans↗
PubMed1977

The use of photogrammetry in tissue compensator design. Part II: experimental verification of compensator design.

A computer algorithm for designing sheet lead tissue compensators is described. Corrections are made for scatter within the radiation field as well as the shape of the patient for the mantle fields used in treating Hodgkin's disease. The method was tested experimentally with a phantom and found to be clinically acceptable. The advantages of employing this technique with parallel opposed fields are emphasized.

Hodgkin Disease↗
PubMedDate not supplied

An algorithm for generation of implant plans for high-dose-rate irradiators.

An algorithm is described for generating a treatment plan with minimal input from the user for a remote high-dose-rate afterloading irradiator. The algorithm generates a plan after locating all catheters involved and an area of interest on each catheter, and two additional numbers are specified: a radial distance and a target dose. The treatment volume becomes the locus of all points that are within the specified radial distance from any point within the area of interest on any catheter (except for the end points). For a single catheter, the volume may be alternately outlined on an x-ray film of the implant. The routine uses a linear programming formulism to compute which dwell positions are to be used, as well as the dwell time at each position, to irradiate the treatment volume to the target dose while minimizing the total volume integrated dose to the patient.

Algorithms↗