Gafchromic MD-55-2 fi1mのLaser Densitometer Model 1710における線量計測体系上の適合性

医療の高度化に伴い,放射線治療分野においても急速な技術革新が行われている｡QOL(Quality of Life)を考慮に入れた治療が求められる多くの場合,放射線治療が大きな選択肢の一つであることは言うまでもない｡このような状況下の中で,正常組織に影響を与えず病巣に限局した放射線を照射する技術が開発され,外照射においては,欧米に習い我が国でも研究段階から臨床へ移り変わろうとしている｡その際に,投与線量評価を欠かすことができないが,従来から使用されているいずれの線量計も新しい治療法に対応しきれていない｡そこで,フィルムタイプ線量計, Gafchromic MD-55-2 film の開発により,いくつかの問題が解決されてきている｡しかし,この線量計を精度良く測定する濃度測定器が必要になるが,現段階において規格化されたガイドラインが存在しないのが現状である｡そこで本研究では,当施設で保有しているⅩ線フィルム線量測定用 Laser Densitometer Model 1710 を用いて Gafchromic MD-55-2 fllm による線量測定を行い,問題点の抽出を行うとともに線量測定精度の考察を行った｡

For the medical advancement, the speedy technical innovation is performed also in the radiotherapy. When patients can search for QOL (Quality of Life), the radiation therapy is one of the choices. The radiation therapy system for limited irradiation to lesion without affecting normal tissue has been developed over several years. On the technology of external irradiation in our country, the level is improving to clinical stage from study grade. In such things, a new requirement will come out also as for the measuring method of the medication dose. However, conventional various radiometers have many problems to the dosimetry of the new radiotherapy method. Gafchromic MD-55-2 film, which has new form of radiochromic film based on poly-diacetylene and has been introduced for medical applications recently, is expected to solve some problems. Now, in clinical usage of this film, there is no comprehensive guideline for densitometry system and it's calibration yet. So, in this paper, the densitometry of Gafchromic MD-55-2 film was performed with Laser Densitometer Model 1710 for general-purpose film dosimetry system. And then, problems in the densitometry were extracted and the accuracy of dosimetry was investigated.