title: Intravascular ultrasound based dose assessment in endovascular brachytherapy.
abstract: BACKGROUND
  the role of endovascular brachytherapy in restenosis prevention is well documented. Dose is usually prescribed at a fixed distance from the source axis by angiographic quantification of vessel diameter. Recently, intravascular ultrasound (IVUS) was introduced in dose prescription, allowing a better evaluation of the vessel anatomy. This study retrospectively explores the difference between prescription following angiographic vessel sizing and delivered dose calculated with IVUS.
  
  
  RESULTS
  Seventeen lesions were studied with IVUS, identifying on irradiated segment, three sections on which measuring minimal and maximal distance from the centre of IVUS catheter to the adventitia; using dedicated software, corresponding doses were calculated. The dose ranged widely, with maximal and minimal values of 71.6 and 4.9 Gy; furthermore, heterogeneity in dose among different sections was observed. In the central section, the maximal dose was 206% of the one prescribed with the QCA model at 2 mm from the source axis, while the minimal dose was 96%. In proximal and distal sections, respective values were 182, 45, 243, and 122%.
  
  
  CONCLUSIONS
  Our analysis confirmed the dose inhomogeneity delivered with an angiographic fixed-dose prescription strategy. A dose variation was found along the irradiated segment due to the differences in vessel thickness. IVUS emerged as an important tool in endovascular brachytherapy, especially for irregular-shaped vessels.
authors.affiliation: Division of Radiotherapy, European Institute of Oncology, via Ripamonti 435, 20141 Milan, Italy.
authors.forename: Gianpiero
authors.initials: G
authors.lastname: Catalano
authors.forename: Vittorio
authors.initials: V
authors.lastname: Tamburini
authors.forename: Antonio
authors.initials: A
authors.lastname: Colombo
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nishida
authors.forename: Giovanni
authors.initials: G
authors.lastname: Parisi
authors.forename: Chiara
authors.initials: C
authors.lastname: Mazzetta
authors.forename: Roberto
authors.initials: R
authors.lastname: Orecchia
mesh_terms: D015906:Angioplasty, Balloon, Coronary; D001918:Brachytherapy / Q000379:methods; D023903:Coronary Restenosis / Q000517:prevention & control; D023921:Coronary Stenosis / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000628:therapy; D003331:Coronary Vessels / Q000000981:diagnostic imaging; D006801:Humans; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D015607:Stents; D018084:Ultrasonography, Interventional