start-ver=1.4 cd-journal=joma no-vol=14 cd-vols= no-issue=1 article-no= start-page=209 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=20191121 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Dose distribution of intensity-modulated proton therapy with and without a multi-leaf collimator for the treatment of maxillary sinus cancer: a comparative effectiveness study. en-subtitle= kn-subtitle= en-abstract= kn-abstract=BACKGROUND: Severe complications, such as eye damage and dysfunciton of salivary glands, have been reported after radiotherapy among patients with head and neck cancer. Complications such as visual impairment have also been reported after proton therapy with pencil beam scanning (PBS). In the case of PBS, collimation can sharpen the penumbra towards surrounding normal tissue in the low energy region of the proton beam. In the current study, we examined how much the dose to the normal tissue was reduced by when intensity-modulated proton therapy (IMPT) was performed using a multi-leaf collimator (MLC) for patients with maxillary sinus cancer.
METHODS:
Computed tomography findings of 26 consecutive patients who received photon therapy at Okayama University Hospital were used in this study. We compared D2% of the region of interest (ROI; ROI-D2%) and the mean dose of ROI (ROI-mean) with and without the use of an MLC. The organs at risk (OARs) were the posterior retina, lacrimal gland, eyeball, and parotid gland. IMPT was performed for all patients. The spot size was approximately 5-6?mm at the isocenter. The collimator margin was calculated by enlarging the maximum outline of the target from the beam's eye view and setting the margin to 6?mm. All plans were optimized with the same parameters.
RESULTS:
The mean of ROI-D2% for the ipsilateral optic nerve was significantly reduced by 0.48?Gy, and the mean of ROI-mean for the ipsilateral optic nerve was significantly reduced by 1.04?Gy. The mean of ROI-mean to the optic chiasm was significantly reduced by 0.70?Gy. The dose to most OARs and the planning at risk volumes were also reduced.
CONCLUSIONS:
Compared with the plan involving IMPT without an MLC, in the dose plan involving IMPT using an MLC for maxillary sinus cancer, the dose to the optic nerve and optic chiasm were significantly reduced, as measured by the ROI-D2% and the ROI-mean. These findings demonstrate that the use of an MLC during IMPT for maxillary sinus cancer may be useful for preserving vision and preventing complications. en-copyright= kn-copyright= en-aut-name=SugiyamaSoichi en-aut-sei=Sugiyama en-aut-mei=Soichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=KatsuiKuniaki en-aut-sei=Katsui en-aut-mei=Kuniaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TominagaYuki en-aut-sei=Tominaga en-aut-mei=Yuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=WakiTakahiro en-aut-sei=Waki en-aut-mei=Takahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=KatayamaNorihisa en-aut-sei=Katayama en-aut-mei=Norihisa kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=MatsuzakiHidenobu en-aut-sei=Matsuzaki en-aut-mei=Hidenobu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=KariyaShin en-aut-sei=Kariya en-aut-mei=Shin kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=KurodaMasahiro en-aut-sei=Kuroda en-aut-mei=Masahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=NishizakiKazunori en-aut-sei=Nishizaki en-aut-mei=Kazunori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=KanazawaSusumu en-aut-sei=Kanazawa en-aut-mei=Susumu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= affil-num=1 en-affil=Departments of Radiology, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine kn-affil= affil-num=2 en-affil=Departments of Proton Beam Therapy, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine kn-affil= affil-num=3 en-affil=Department of Radiation Technology, Tsuyama Chuo Hospital kn-affil= affil-num=4 en-affil=Department of Radiology, Tsuyama Chuo Hospital, Tusyama kn-affil= affil-num=5 en-affil=Departments of Radiology, Okayama University Hospital kn-affil= affil-num=6 en-affil=Departments of Oral Diagnosis and Dentomaxillofacial Radiology, Okayama University Hospital kn-affil= affil-num=7 en-affil=Departments of Otolaryngology-Head and Neck Surgery, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine kn-affil= affil-num=8 en-affil=Department of Radiological Technology, Graduate School of Health Sciences, Okayama University kn-affil= affil-num=9 en-affil=Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=10 en-affil=Departments of Radiology, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine kn-affil= en-keyword=Chemoradiotherapy kn-keyword=Chemoradiotherapy en-keyword=Intensity-modulated proton therapy kn-keyword=Intensity-modulated proton therapy en-keyword=Maxillary sinus cancer kn-keyword=Maxillary sinus cancer en-keyword=Multi-leaf collimator kn-keyword=Multi-leaf collimator en-keyword=Pencil beam scanning kn-keyword=Pencil beam scanning END