@article{oai:repo.qst.go.jp:00079967,
 author = {He, Pengbo and Mori, Shinichiro and He, Pengbo and Mori, Shinichiro},
 journal = {Physica Medica},
 month = {May},
 note = {Purpose: To evaluate the patients’ set-up error-induced perturbation effects on 4D dose distributions (4DDD) of range-adapted internal target volume-based (raITV) treatment plan using lung and liver 4DCT data sets. Methods: We enrolled 20 patients with lung and liver cancer treated with respiratory-gated carbon-ion beam scanning therapy. PTVs were generated by adding a 2 mm range-adapted set-up margin on the raITVs. Set-up errors were simulated by shifting the beam isocenter in three translational directions of±2 mm,±4 mm, and ± 6 mm. 4DDDs were calculated for both nominal and isocenter-shifted situations. Dose metrics of CTV dose coverage (D95) and normal tissue sparing were evaluated. Statistical significance with p < 0.01 was considered by Wilcoxon signed rank test.
Results: The CTV dose coverage was more sensitive to set-up errors for lung cases than for liver cases, and more serious in superior-inferior direction. The sufficient CTV-D95 > 98% could be achieved with set-up errors less than ± 2 mm in all shift directions both for lung and liver cases. With the increase of set-up error, the CTV dose coverage decreased gradually. The clinical criterial of CTV-D95 > 95% could not be fulfilled with set-up error reached to ± 4 mm for lung cases, and ± 6 mm for liver cases. OAR doses did not have a significant difference with each set-up error for both lung and liver cases.
Conclusions: The range-adapted set-up margin successfully prevented dose degradation of 4DDDs in the presence of the same magnitude of set-up error for raITV-based carbon-ion beam scanning therapy.},
 pages = {74--82},
 title = {Perturbation analysis of 4D dose distribution for scanned carbon-ion beam radiotherapy},
 volume = {74},
 year = {2020}
}