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Dosimetric Advantages of Midventilation Compared With Internal Target Volume for Radiation Therapy of Pancreatic Cancer

2015; Elsevier BV; Volume: 92; Issue: 3 Linguagem: Inglês

10.1016/j.ijrobp.2015.02.015

1879-355X

E. Lens, Astrid van der Horst, Eva Versteijne, Geertjan van Tienhoven, Arjan Bel,

Hepatocellular Carcinoma Treatment and Prognosis

The midventilation (midV) approach can be used to take respiratory-induced pancreatic tumor motion into account during radiation therapy. In this study, the dosimetric consequences for organs at risk and tumor coverage of using a midV approach compared with using an internal target volume (ITV) were investigated.For each of the 18 patients, 2 treatment plans (25 × 2.0 Gy) were created, 1 using an ITV and 1 using a midV approach. The midV dose distribution was blurred using the respiratory-induced motion from 4-dimensional computed tomography. The resulting planning target volume (PTV) coverage for this blurred dose distribution was analyzed; PTV coverage was required to be at least V95% >98%. In addition, the change in PTV size and the changes in V10Gy, V20Gy, V30Gy, V40Gy, Dmean and D2cc for the stomach and for the duodenum were analyzed; differences were tested for significance using the Wilcoxon signed-rank test.Using a midV approach resulted in sufficient target coverage. A highly significant PTV size reduction of 13.9% (P<.001) was observed. Also, all dose parameters for the stomach and duodenum, except the D2cc of the duodenum, improved significantly (P≤.002).By using the midV approach to account for respiratory-induced tumor motion, a significant PTV reduction and significant dose reductions to the stomach and to the duodenum can be achieved when irradiating pancreatic tumors.