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Title: SU-F-T-189: Dosimetric Comparison of Spot-Scanning Proton Therapy Techniques for Liver Tumors Close to the Skin Surface

Abstract

Purpose: Spot-scanning technique has been utilized to achieve conformal dose distribution to large and complicated tumors. This technique generally does not require patient-specific devices such as aperture and compensator. The commercially available spot-scanning proton therapy (SSPT) systems, however, cannot deliver proton beams to the region shallower than 4 g/cm2. Therefore some range compensation device is required to treat superficial tumors with SSPT. This study shows dosimetric comparison of the following treatment techniques: (i) with a tabletop bolus, (ii) with a nozzle-mounted applicator, and (iii) without any devices and using intensity-modulated proton therapy (IMPT) technique. Methods: The applicator composed of a combination of a mini-ridge filter and a range shifter has been manufactured by Hitachi, Ltd., and the tabletop bolus was made by .decimal, Inc. Both devices have been clinically implemented in our facility. Three patients with liver tumors close to the skin surface were examined in this study. Each treatment plan was optimized so that the prescription dose of 76 Gy(RBE) or 66 Gy(RBE) would be delivered to 99% of the clinical target volume in 20 fractions. Three beams were used for tabletop bolus plan and IMPT plan, whereas two beams were used in the applicator plan because the gantrymore » angle available was limited due to potential collision to patient and couch. The normal liver, colon, and skin were considered as organs at risk (OARs). Results: The target heterogeneity index (HI = D{sub 5}/D{sub 95}) was 1.03 on average in each planning technique. The mean dose to the normal liver was considerably less than 20 Gy(RBE) in all cases. The dose to the skin could be reduced by 20 Gy(RBE) on average in the IMPT plan compared to the applicator plan. Conclusion: It has been confirmed that all treatment techniques met the dosimetric criteria for the OARs and could be implemented clinically.« less

Authors:
;  [1]; ;  [2];  [3]; ;  [4];  [5]; ;  [6];  [7]
  1. Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Hokkaido (Japan)
  2. Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido (Japan)
  3. (GI-CoRE), Hokkaido University, Sapporo, Hokkaido (Japan)
  4. Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido (Japan)
  5. Department of Radiation Oncology, Hokkaido University Hospital, Sapporo, Hokkaido (Japan)
  6. Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido (Japan)
  7. (Japan)
Publication Date:
OSTI Identifier:
22648806
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; EQUIPMENT; LARGE INTESTINE; LIVER; NEOPLASMS; PLANNING; PROTON BEAMS; RADIATION DOSE DISTRIBUTIONS; RADIOTHERAPY; RBE; SKIN

Citation Formats

Takao, S, Matsuzaki, Y, Matsuura, T, Umegaki, K, Global Institution for Collaborative Research and Education, Fujii, Y, Fujii, T, Katoh, N, Shimizu, S, Shirato, H, and Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido. SU-F-T-189: Dosimetric Comparison of Spot-Scanning Proton Therapy Techniques for Liver Tumors Close to the Skin Surface. United States: N. p., 2016. Web. doi:10.1118/1.4956326.
Takao, S, Matsuzaki, Y, Matsuura, T, Umegaki, K, Global Institution for Collaborative Research and Education, Fujii, Y, Fujii, T, Katoh, N, Shimizu, S, Shirato, H, & Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido. SU-F-T-189: Dosimetric Comparison of Spot-Scanning Proton Therapy Techniques for Liver Tumors Close to the Skin Surface. United States. doi:10.1118/1.4956326.
Takao, S, Matsuzaki, Y, Matsuura, T, Umegaki, K, Global Institution for Collaborative Research and Education, Fujii, Y, Fujii, T, Katoh, N, Shimizu, S, Shirato, H, and Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido. Wed . "SU-F-T-189: Dosimetric Comparison of Spot-Scanning Proton Therapy Techniques for Liver Tumors Close to the Skin Surface". United States. doi:10.1118/1.4956326.
@article{osti_22648806,
title = {SU-F-T-189: Dosimetric Comparison of Spot-Scanning Proton Therapy Techniques for Liver Tumors Close to the Skin Surface},
author = {Takao, S and Matsuzaki, Y and Matsuura, T and Umegaki, K and Global Institution for Collaborative Research and Education and Fujii, Y and Fujii, T and Katoh, N and Shimizu, S and Shirato, H and Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido},
abstractNote = {Purpose: Spot-scanning technique has been utilized to achieve conformal dose distribution to large and complicated tumors. This technique generally does not require patient-specific devices such as aperture and compensator. The commercially available spot-scanning proton therapy (SSPT) systems, however, cannot deliver proton beams to the region shallower than 4 g/cm2. Therefore some range compensation device is required to treat superficial tumors with SSPT. This study shows dosimetric comparison of the following treatment techniques: (i) with a tabletop bolus, (ii) with a nozzle-mounted applicator, and (iii) without any devices and using intensity-modulated proton therapy (IMPT) technique. Methods: The applicator composed of a combination of a mini-ridge filter and a range shifter has been manufactured by Hitachi, Ltd., and the tabletop bolus was made by .decimal, Inc. Both devices have been clinically implemented in our facility. Three patients with liver tumors close to the skin surface were examined in this study. Each treatment plan was optimized so that the prescription dose of 76 Gy(RBE) or 66 Gy(RBE) would be delivered to 99% of the clinical target volume in 20 fractions. Three beams were used for tabletop bolus plan and IMPT plan, whereas two beams were used in the applicator plan because the gantry angle available was limited due to potential collision to patient and couch. The normal liver, colon, and skin were considered as organs at risk (OARs). Results: The target heterogeneity index (HI = D{sub 5}/D{sub 95}) was 1.03 on average in each planning technique. The mean dose to the normal liver was considerably less than 20 Gy(RBE) in all cases. The dose to the skin could be reduced by 20 Gy(RBE) on average in the IMPT plan compared to the applicator plan. Conclusion: It has been confirmed that all treatment techniques met the dosimetric criteria for the OARs and could be implemented clinically.},
doi = {10.1118/1.4956326},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}