Arc therapy for total body irradiation--a robust novel treatment technique for standard treatment rooms.

BACKGROUND AND PURPOSE

We developed a simple and robust total body irradiation (TBI) method for standard treatment rooms that obviates the need for patient translation devices.

METHODS AND MATERIALS

Two generic arcs with rectangular segments for a patient thickness of 16 and 20 cm (arc16/arc20) were generated. An analytical fit was performed to determine the weights of the arc segments depending on patient thickness and gantry angle. Stability and absolute dose for both arcs were measured using EBT3 films in a range of solid water slab phantom thicknesses. Additionally ionization chamber measurements were performed every 10 cm at a source surface distance (SSD) of ∼ 200 cm.

RESULTS

The measured standard deviation for arc16 is ± 3% with a flatness ⩽ 9.0%. Arc20 had a standard deviation of ± 3% with a flatness ⩽ 7.3% for all measured thicknesses. The theoretical curves proved to be accurate for the prediction of the segment weightings for the two arcs. In vivo measurements for the first 22 clinical patients showed a dose deviation of less than 3%.

CONCLUSIONS

Arc therapy is a convenient and stable method for TBI. This cost-effective approach has been introduced clinically, obviating the need for field patches and to physically move the patient.