Endovascular brachytherapy — Treatment planning and radiation protection

Abstract

The risk of restenosis, main late effect limiting the success of percutaneous transluminal coronary artery angioplasty, can be reduced significantly by vascular radiotherapy, subsequent to PTCA. This discovery lead to the development of new irradiation techniques. Endovascular brachytherapy is the choice in treatment of coronary artery stenosis. Successful irradiation, however, requires precise treatment planning. This review addresses the physical possibilities and problems of intravascular brachytherapy planning, and the radiobiologically based definition of the target volume and of structures at risk. Recommendations for dose specification, recording and reporting are given. The criteria for selecting a vascular radiotherapy technique are discussed as well as the possibilities of dosimetric treatment planning and quality assurance based on precise plastic scintillator dosimetry and intravascular ultrasound. Radiation protection and safety must be reconsidered prior to the usage of therapeutic radiation sources in the catheter laboratory and for the decision about emergency plans. Finally, the design of clinical trials, the role of medical physicists, and the future of irradiation treatment of stenosis is discussed.

Review of plastic and liquid scintillation dosimetry for photon, electron, and proton therapy

“…One of the first scintillator dosimeter used in brachytherapy was the OPTIDOS system by PTW (Freiburg, Germany) and employ for calibration and dosimetry of beta emitters used for intravascular brachytherapy (Rosenthal et al 2003, Hakanen et al 2004. In fact, an early design of PSD for this type of application (Quast et al 1998, Bambynek et al 2000 was directly based on the two-fiber subtraction method presented in section 3. However, like the intravascular brachytherapy procedure, this particular scintillation dosimeter is not available anymore.…”

Optimale intravaskuläre Brachytherapie

“…Neben Zuverlässigkeit und Präzision der intravaskulären Brachytherapie sind Sicherheit und Strahlenschutz [4,7,17,24,36,46] von Strahlern, Geräten und Verfahren Grundvoraussetzung für die Einführung der Methode [13,23,38,42,54]. Bisher gibt es noch keine nationalen Normen (DIN) oder internationalen Standards (IEC) zur Sicherheit der intravaskulären Brachytherapie.…”

“…Die organspezifische Anwendung umschlossener Strahler in der intravaskulären Brachytherapie erfordert nach dem jetzigen Entwurf der Richtlinie Strahlenschutz in der Medizin [53] für die Ärzte einen mindestens 18-monatigen Zeitraum zum Erwerb der Sachkunde, die erfolgreiche Teilnahme an einem Grundkurs und die Absolvierung eines 24-stündigen Spezialkurses im Strahlenschutz [41]. Bei der Anwendung offener radioaktiver Stoffe sind mindestens 36 Insgesamt sind die Veränderungen, die die neue Strahlenschutzverordnung für die intravaskuläre Brachytherapie bringt, gemessen an den Konsequenzen für andere medizinische Fachgebiete, relativ klein, und deshalb dürften keine Schwierigkeiten oder nicht lösba-ren Probleme auftreten.…”

A high‐precision, high‐resolution and fast dosimetry system for beta sources applied in cardiovascular brachytherapy

“…The introduction of cardiovascular brachytherapy into clinical routine requires an understanding of the clinical results and their correlation with treatment parameters. 17,18 The American Association of Physicists in Medicine ͑AAPM͒ Task Group 60 has given recommendations for source calibration and dose specification. 19 Thus for example, the radial dose function, geometry function, and anisotropy function should be determined for each specific source design of a commercial catheter-based system.…”