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

Int J Radiat Oncol Biol Phys. 2015 Jul 1;92(3):675-82. doi: 10.1016/j.ijrobp.2015.02.015. Epub 2015 Apr 16.


Purpose: 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.

Methods and materials: 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.

Results: 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).

Conclusions: 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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Duodenum / diagnostic imaging
  • Duodenum / radiation effects
  • Female
  • Fiducial Markers
  • Four-Dimensional Computed Tomography*
  • Humans
  • Male
  • Middle Aged
  • Movement*
  • Organs at Risk / diagnostic imaging*
  • Organs at Risk / radiation effects
  • Pancreatic Neoplasms / diagnostic imaging*
  • Pancreatic Neoplasms / radiotherapy*
  • Radiation Injuries / prevention & control
  • Radiotherapy Dosage
  • Radiotherapy Planning, Computer-Assisted*
  • Respiration*
  • Stomach / diagnostic imaging
  • Stomach / radiation effects