@article{oai:repo.qst.go.jp:00048089,
 author = {森, 慎一郎 and 古川, 卓司 and 森 慎一郎 and 古川 卓司},
 issue = {10},
 journal = {Physics in medicine and biology},
 month = {Apr},
 note = {To shorten treatment time in pencil beam scanning irradiation, we developed rapid phase-controlled rescanning (rPCR), which irradiates two or more isoenergy layers in a single gating window. Here, we evaluated carbon-ion beam dose distribution with rapid and conventional PCR (cPCR).
4 dimensional computed tomography (4DCT) imaging was performed on 12 subjects with lung or liver tumors. To compensate for intrafractional range variation, the  eld-speci c target volume (FTV) was calculated using 4DCT within the gating window (T20–T80). We applied an amplitude-based gating strategy, in which the beam is on when the tumor is within the gating window de ned by treatment planning. Dose distributions were calculated for layered phase-controlled rescanning under an irregular respiratory pattern, although a single 4DCT data set was used. The number of rescannings was eight times. The prescribed doses were 48 Gy(RBE)/1 fr (where RBE is relative biological effectiveness) delivered via four beam ports to the FTV for the lung cases and 45 Gy(RBE)/2 fr delivered via two beam ports to the FTV for the liver cases.
In the liver cases, the accumulated dose distributions showed an increased magnitude of hot/cold spots with rPCR compared with cPCR. The results of the dose assessment metrics for the cPCR and rPCR were very similar. The D95, Dmax, and Dmin values (cPCR/rPCR) averaged over all the patients were 96.3 ± 0.9%/96.0 ± 1.2%, 107.3 ± 3.6%/107.1 ± 2.9%, and 88.8 ± 3.2%/88.1 ± 3.1%, respectively. The treatment times in cPCR and rPCR were 110.7 s and 53.5 s, respectively.
rPCR preserved dose conformation under irregular respiratory motion and reduced the total treatment time compared with cPCR.},
 pages = {3857--3866},
 title = {Rapid phase-correlated rescanning irradiation improves treatment time in carbon-ion scanning beam treatment under irregular breathing},
 volume = {61},
 year = {2016}
}