Room: AAPM ePoster Library
Purpose: Total body irradiation (TBI) has long been used as a form of systematic therapy for various malignant diseases. To the best of our knowledge there is no commercial treatment planning system (TPS) for TBI. Thus we developed an in-house TPS and implemented a method to insure efficient use of compensators in the planning process.
Methods: In our institution the TBI bilateral technique is used with patient seated on a couch in a semifetal position. To achieve dose uniformity within ±10%, patient-specific brass compensators are designed and fabricated. We also use tissue equivalent materials between the patient’s legs to assure equivalent thickness with the level of the umbilicus. In our method, we were able to define a set of uniform body compensator shapes that can be used for most patients. A library of these shapes is available to our in-house TPS during the planning process. A graphical user interface for our in-house TPS was developed using MATLAB connected with the library of stored compensators.
Results: We analyzed TBI treatment plans for 100 patients. All achieved our dose uniformity acceptance criterion of ±10%. In all cases, in-vivo measurements insured accurate delivery of the prescribed dose. In 15 patients, a head compensator was enough and there was no need for other body compensators. In 60 patients, an additional body compensator was needed, all sharing the same geometric shape but with different thicknesses. In 7 cases, a simple shaped plate was used to cover the ankle. Our results indicated that a small set of compensators shapes can be stored and reused for TBI treatment planning for more than 80% of patients.
Conclusion: clinical results show that our in-house TPS is an efficient planning tool for TBI with clinically acceptable accuracy based on in-vivo measurement validation.