@article{oai:repo.qst.go.jp:00049271,
 author = {Mizuno, Hideyuki and Fukumura, Akifumi and Kanematsu, Nobuyuki and Yonai, Shunsuke and Shirai, Toshiyuki and Yusa, Ken and Yanou, Toshihiro and Suga, Masaki and Mizota, Manabu and Minohara, Shinichi and Kanai, Tatsuaki and Kamada, Tadashi and Mizuno, Hideyuki and Fukumura, Akifumi and Kanematsu, Nobuyuki and Yonai, Shunsuke and Shirai, Toshiyuki and Yusa, Ken and Yanou, Toshihiro and suga, masaki and Mizota, Manabu and Minohara, Shinichi and Kanai, Tatsuaki and Kamada, Tadashi},
 issue = {1},
 journal = {Journal of Applied Clinical Medical Physics},
 month = {Nov},
 note = {Purpose: The QA team of the Japan carbon‐ion radiation oncology study group
(J‐CROS) was organized in 2015 to enhance confidence in the accuracy of clinical
dosimetry and ensure that the facility QA procedures are adequate. The team conducted
onsite dosimetry audits in all the carbon‐ion radiation therapy centers in
Japan.
Materials and Methods: A special phantom was fabricated for the onsite dosimetry
audit. Target volumes such as the GTV, CTV, and PTV were contoured to the
obtained CT images, and two plans with different isocenter depths were created.
The dose at the isocenter was measured by an ionization chamber, in the onsite
audit and compared with the calculated dose.
Results: For all the centers, the average of the percentage ratio between the measured
and calculated doses (measured/calculated) was 0.5% (−2.7% to +2.6%) and
the standard deviation, 1.7%. In all the centers, the beams were within the set tolerance
level of 3%.
Conclusions: The audit demonstrated that the dose at a single point in the water
phantom was within tolerance, but it is a big step to say that all doses are correct.
In addition, this external dosimetry audit encouraged centers to improve the quality
of their dosimetry systems.},
 pages = {31--36},
 title = {External dosimetry audit for quality assurance of carbon‐ion radiation therapy clinical trials},
 volume = {20},
 year = {2018}
}