Dosimetric Comparison of Rapid arc, Intensity Modulated Radiotherapy and 3D Conformal Radiotherapy Plans in Periampullary and Pancreatic Head Carcinomas

Background and purpose This study was done to compare dosimetric characteristics between Rapid Arc, Intensity Modulated Radiotherapy and 3D-Conformal Radiotherapy plans in periampullary and pancreatic head carcinomas. Materials and methods For a total of 15 patients requiring adjuvant or radical radiotherapy; rapid arc, intensity modulated radiotherapy and 3D-Conformal radiotherapy plans were evaluated. The clinical target volume included the postoperative tumour bed or the gross tumour with a 3 cm margin within the body of the pancreas and the draining lymph nodal areas. The dose prescribed was 50.4 Gy in 28 fractions over 5 weeks. Homogeneity and Conformity indices, Organs at risk and planning target volume doses; MUs delivered and treatment times were compared. Results The conformity indices was better in rapid arc, intensity modulated radiotherapy had better homogeneity indices; conformity indices and homogeneity indices were significantly inferior in 3D-Conformal radiotherapy. Right kidney mean dose could be reduced in rapid arc; left kidney mean doses were comparable in all three techniques. Mean doses of stomach, gut and liver were minimised in rapid arc. MUs delivered and treatment times were lessened in rapid arc compared to intensity modulated radiotherapy. Conclusion Rapid Arc plans could provide slight improvements in organs at risk sparing, lower MUs and decreased treatment times with a slightly better target coverage compared to intensity modulated radiotherapy and significantly better to 3D-Conformal radiotherapy.