組織内照射における金属マーカーの有用性　　ＣＴＶ‐ｂａｓｅｄ　Ｄｏｓｅ　Ｐｒｅｓｃｒｉｐｔｉｏｎへの応用

DOI 参考文献20件

書誌事項

タイトル別名
  • The usefulness of metal markers for CTV-based dose prescription in high-dose-rate interstitial brachytherapy.
  • HIGH-DOSE-RATE INTERSTITIAL BRACHYTHERAPY
  • CTV-based Dose Prescriptionへの応用

この論文をさがす

抄録

Purpose: We employ a clinical target volume (CTV)-based dose prescription for high-dose-rate (HDR) interstitial brachytherapy. However, it is not easy to define CTV and organs at risk (OAR) from X-ray film or CT scanning. To solve this problem, we have utilized metal markers since October 1999. Moreover, metal markers can help modify dose prescription. By regulating the doses to the metal markers, refining the dose prescription can easily be achieved. In this research, we investigated the usefulness of the metal markers. Methods and Materials: Between October 1999 and May 2001, 51 patients were implanted with metal markers at Osaka Medical Center for Cancer and Cardiovascular Diseases (OMCC), Osaka National Hospital (ONH) and Sanda City Hospital (SCH). Forty-nine patients (head and neck: 32; pelvis: 11; soft tissue: 3; breast: 3) using metal markers were analyzed. During operation, we implanted 179 metal markers (49 patients) to CTV and 151 markers (26 patients) to OAR. At treatment planning, CTV was reconstructed judging from the metal markers, applicator position and operation records. Generally, we prescribed the tumoricidal dose to an isodose surface that covers CTV. We also planned to limit the doses to OAR lower than certain levels. The maximum normal tissue doses were decided 80%, 150%, 100%, 50% and 200% of the prescribed doses for the rectum, the urethra, the mandible, the skin and the large vessel, respectively. The doses to the metal markers using CTV-based dose prescription were generated. These were compared with the doses theoretically calculated with the Paris system. Treatment results were also investigated.<BR>Results: The doses to the 158 metal markers (42 patients) for CTV were higher than “tumoricidal dose”. In 7 patients, as a result of compromised dose prescription, 9 markers were lower than the tumoricidal dose. The other 12 markers (7%) were excluded from dose evaluation because they were judged as miss-implanted. The doses to the 142 metal markers (24 patients) for OAR were lower than the maximum normal tissue doses. The doses of 2 markers (1 patient) for OAR (the urethra) were higher than the maximum normal tissue dose. Seven markers for OAR (the mandible) were not visualized because of metal crowns. If the Paris system (reference dose is prescribed to an isodose surface of 85% of the basal dose) had been used, 16 patients had been “underdosed” and 4 patients (the rectum+the urethra: 2; the urethra: 1; the large vessel: I)“overdosed”. Dose non-uniformity ratio (DNR) and maximum diameter of hyperdose sleeve were 0.31±0.08 and 4-49 mm (median: 7 mm) in CTV-based dose prescription. A statistically significant difference was seen between CTV-based dose prescription and Paris system 0.28±0.08 and 3-99 mm (median: 6 mm)(p<0.002, 0.0002). Two of 42 patients treated with higher than the tumoricidal dose had local recurrence, while 4 of 7 underdosed patients had local recurrence. A significant difference was found between them (p<0.0001).<BR>Conclusions: Metal markers were useful to prescribe the tumoricidal dose to CTV and to regulate the doses for OAR. Local control rate of the patients treated with higher than the tumoricidal dose was significantly better. Miss-implantation of metal markers was a problem that should be resolved.

収録刊行物

参考文献 (20)*注記

もっと見る

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ