RESUMEN
Three-dimensional conformal radiation treatments are highly complex and may comprise a large number of coplanar and noncoplanar beams, virtually all of which are shaped and may also employ arbitrary intensity modulation. The delivery of such treatments with conventional means is highly labor intensive and limited to a relatively small number of fields. A generalized model for a system that can deliver 3-D conformal treatments rapidly and safely using a computer-controlled treatment machine equipped with a multileaf collimator is presented. The model emphasizes the separation of tasks between an external computer programmed by the user institution and a control computer proprietary to the treatment machine manufacturer. The treatment scheme that is employed consists of a sequence of fixed fields, called segments, which are delivered in succession without human intervention. Settings for all segments, derived from a 3-D conformal treatment planning system, are downloaded by the external computer into the control computer of the treatment machine. During patient setup, the control computer enables the operator to step through computer-controlled setup of the segments without radiation to ensure the absence of collisions, and to allow the adjustment of setup parameters if necessary. The external computer verifies the treatment setup and permits the control computer to carry out the treatment segment by segment. Safety aspects of the model and anomalous situations which may arise are discussed.
Asunto(s)
Simulación por Computador , Planificación de la Radioterapia Asistida por Computador/métodos , Radioterapia de Alta Energía/métodos , Humanos , Modelos Teóricos , Dosificación RadioterapéuticaRESUMEN
To improve the quality of patient care by detecting and preventing many types of treatment mistakes, we have implemented a computerized system for recording and verifying external beam radiation treatments on our therapy machines. It inhibits the radiation beam if treatment machine settings do not agree with prescribed values to within maximum permissible deviations (tolerances). The tolerances are determined from experience and adjusted when necessary to make the system more effective and less susceptible to "false alarms." The system uses a common data base for all treatment machines. As a result, it permits statistical analysis and generation of reports based on data encompassing the entire patient population as well as verification of treatments of patients transferred from one machine to another. Reports of verification failures reveal patterns of mistakes. Knowing these, attempts can be made to reduce the frequency of verification failures. "Significant" mistakes that were prevented are extracted by treatment planning personnel from these reports. Analysis of data indicates a rate of approximately 150 "significant" mistakes detected and prevented per machine per year, representing 1.0% of all fields treated. We present and discuss our experiences with the system and with the frequency, patterns, and significance of verification failures. We selected a few of the patients for whose treatments significant set-up mistakes were made, and were detected and prevented by the Record and Verify System. We include discussions of the overall effect these mistakes would have had on dose distribution had they not been prevented.
Asunto(s)
Computadores , Neoplasias/radioterapia , Radioterapia/instrumentación , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
We have developed a general purpose, comprehensive, and highly reliable computerized Record and Verify System to detect and prevent mistakes in the delivery of external beam radiation therapy. This system helps prevent accidental delivery of dangerous dose, improves quality control, and provides invaluable record keeping and report generating capabilities. Currently, treatment machine and couch parameter settings of four different machines are monitored by the system and compared with prescribed values. The system inhibits a machine from being turned on if the settings do not agree with the prescribed values to within specified maximum permissible deviations. The system is user-friendly and provides useful, complete, and easily accessible data. We describe many aspects of the system including hardware, software, data, and operation, and we conclude with a brief discussion of clinical experience and preliminary data.