{"created":"2023-05-15T14:58:40.650982+00:00","id":79606,"links":{},"metadata":{"_buckets":{"deposit":"498422bd-1a79-47f3-aef5-615395a53b8f"},"_deposit":{"created_by":1,"id":"79606","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"79606"},"status":"published"},"_oai":{"id":"oai:repo.qst.go.jp:00079606","sets":["10:28"]},"author_link":["857384","857379","857381","857388","857383","857386","857387","857389","857382","857385","857380"],"item_10005_date_7":{"attribute_name":"発表年月日","attribute_value_mlt":[{"subitem_date_issued_datetime":"2019-09-19","subitem_date_issued_type":"Issued"}]},"item_10005_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"HighlightsOptical evaluation method of polymer gel dosimeter irradiated to 400 MeV/n carbon-ion beam was researched. Regarding absorbed carbon dose to optical response, increasing the absorbed dose to irradiated gels, optical signal intensities were increased. When the prepared gels were irradiated to form carbon Bragg curve, the result of the scanned original optical computed tomography system was indicated dose concentration region.\n\nKey wordsoptical evaluation, polymer gel dosimetry, carbon therapy, HIMAC\n\nBackground and ObjectivesGel dosimeters as polymer gels and radiochromic gels, chemical dosimeters, are three-dimensional dosimeters that can spatially hold chemical reactions caused by radiation and are expected to be applied in radiation therapy that irradiates from various directions and irradiates them according to the shape of the tumor in clinical radiotherapy. In the future of this dosimeter, it will be used as a clinical QA tool.\nProton and carbon therapy, called particle therapy are spread in world. It is possible to set only to irradiate target volume including tumors in the deep of the body using Bragg peaks which are these features.\nIt has been reported that the gel dosimeter located in high LET region such as Bragg peak shows sensitivity loss because of radical recombination. However, detailed examinations are needed that there were few reports that is still because there are few carbon line facilities.\nPolymer gel dosimeter was irradiated with carbon beams in HIMAC (Heavy Ion Medical Accelerator in Chiba). The irradiated gels were evaluated to degree and distribution of polymerization related to radiation dose using original optical computed tomography (OCT) system. In the present study, we attempted to describe an availability of three-dimensional dose measurement using the optical tomographic apparatus in gel dosimetry.\n\nMaterials and Methods　1. Dose response of PAGAT gel dosimeter in carbon beams: PAGAT polymer gels sealed 20 ml cylindrical PET container were irradiated with 2, 4, 6 Gy in 400 MeV / u carbon beams, respectively. The irradiated gels were scanned with the constructed OCT (Fig. 1). The wavelength of the scanned laser was 632.8 nm, and a PIN photodiode was used as a detector. A mechanism for translation and rotation the irradiated gel dosimeter with the step motor and the chuck at the upper part was constructed, and the lateral movement and the rotation operation were operated by the stage controller. The gel dosimeter was placed in a water bath, the light intensity of transmitted the gels container was measured while moving the gel dosimeter with pass and rotational motion, and the result was reconstructed as images using Filtered-Backprojection (FBP) from 360° data. The region of interest (ROI) was set in the image, and the signal value was measured. \n2. Dose distribution images of Bragg peak: The prepared PAGAT gel dosimeter was placed in a 300 ml cylindrical container and the sample was irradiated with 400 MeV / u carbon beams so that the Bragg peak was at about half of the container. Dose evaluation using OCT after irradiation was performed in the same procedure as in 1.\n\nResults and DiscussionThe results of the measurement 1 are shown in Fig. 2. The optical response to irradiated gels were increased with respect to the absorbed dose. Clear linearity could not be confirmed.\n The obtained results of the measurement 2 are shown in Fig. 3. It was shown that it is possible to show the Bragg peak position from the resulting image.\n\nConclusion Carbon beam irradiation was performed on polymer gel dosimeter, and dose response characteristics and Bragg peak appearance were attempted by OCT instead of conventional MRI, R2 method. Even in optical CT, the measured value increased with increasing of the absorbed dose, and a tomographic image consistent with the Bragg peak was obtained.\n","subitem_description_type":"Abstract"}]},"item_10005_description_6":{"attribute_name":"会議概要（会議名, 開催地, 会期, 主催者等）","attribute_value_mlt":[{"subitem_description":"19th international conference on solid state dosimetry","subitem_description_type":"Other"}]},"item_access_right":{"attribute_name":"アクセス権","attribute_value_mlt":[{"subitem_access_right":"metadata only access","subitem_access_right_uri":"http://purl.org/coar/access_right/c_14cb"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Kawamura, Hiraku"}],"nameIdentifiers":[{"nameIdentifier":"857379","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Takanashi, Takaoki"}],"nameIdentifiers":[{"nameIdentifier":"857380","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Yoshii, Hiroshi"}],"nameIdentifiers":[{"nameIdentifier":"857381","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Matsuyama, Tsugufumi"}],"nameIdentifiers":[{"nameIdentifier":"857382","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Izumoto, Yukie"}],"nameIdentifiers":[{"nameIdentifier":"857383","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Satoh, Hitoshi"}],"nameIdentifiers":[{"nameIdentifier":"857384","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Kawamura, Hiraku","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"857385","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Yoshii, Hiroshi","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"857386","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Matsuyama, Tsugufumi","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"857387","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Izumoto, Yukie","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"857388","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Satoh, Hitoshi","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"857389","nameIdentifierScheme":"WEKO"}]}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"conference object","resourceuri":"http://purl.org/coar/resource_type/c_c94f"}]},"item_title":"Optical evaluation about polymer gel dosimeter in carbon ion beams","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Optical evaluation about polymer gel dosimeter in carbon ion beams"}]},"item_type_id":"10005","owner":"1","path":["28"],"pubdate":{"attribute_name":"公開日","attribute_value":"2020-03-23"},"publish_date":"2020-03-23","publish_status":"0","recid":"79606","relation_version_is_last":true,"title":["Optical evaluation about polymer gel dosimeter in carbon ion beams"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2023-05-15T22:16:42.407907+00:00"}