@misc{oai:repo.qst.go.jp:00061338,
 author = {Urakabe, Eriko and Minohara, Shinichi and 新谷 恵理子 and 蓑原 伸一},
 month = {Mar},
 note = {Objective:
Heavy ion radiotherapy is characterized its excellent physical dose localization and the biological 
effectiveness because of its high linear energy transfer (LET). The scanning irradiation of heavy 
ion, which is the highly conformal techniques, is more sensitive to motion effects. The 
consequence can be under-dosage of the target volume or over-dosage of critical structures. The 
effectiveness of scanning irradiation with the respiratory-gated techniques for the moving target is 
evaluated in this study.
Material and Methods:
The scanning irradiation using carbon ions is planed to the target contours on a set of 3D CT 
images. They are converted to the water equivalent depth coordinate and the prescribed dose is set 
in and around the target region. The Bragg peaks of beams are arranged in the water equivalent 
space, and the weight of each beam spot is optimized to meet the condition of the prescribed dose. 
From the optimized beam arrangement and the weight, the planned dose distribution is calculated 
and displayed on the axial, sagittal, or coronal multiplanar reconstruction CT image. The motion 
models are constructed based on a set of sequential 3D CT volume (4D CT) data of various 
clinical cases, such as lung and liver tumor. And the dose distribution simulated for the moving 
target is evaluated with this model. 
Results:
The scanning-irradiated dose distribution is simulated for the clinical targets based on the motion 
analysis of tumor. The motion of tumor is analyzed by the direction, distance, speed and variation 
of density. Especially for the heavy-ion radiotherapy, the density through beam path is crucial 
because it affects strongly on the dose coverage around the distal end of the tumor. For some 
clinical moving models, the dose uniformities in planning target volume and the outer dosage on 
normal tissue are estimated with the timing for respiration. The quantitative analysis with the 
scanning parameters such as beam size, arrangement and scanning speed, is on going.
Conclusion:
This simulation of scanning irradiation enables the clinical evaluation of the dose distribution for 
the moving target. The effect on dose uniformity is estimated and the engineering requirements for 
the scanning devices can be examined to the tumor on moving target., Third International Conference on Translational Research and Pre-Clinical Stratgies in Radiation Oncology},
 title = {Dose Distribution of Heavy-ion Scanning Irradiationfor Simulated for Moving Target},
 year = {2006}
}