Targeting the adventitia with intracoronary beta-radiation: comparison of two dose prescriptions and the role of centering coronary arteries.
OBJECTIVE
To compare by intravascular ultrasound (IVUS) the efficacy of delivering the prescribed dose to the adventitia between two commonly used dose prescriptions for intracoronary radiotherapy.


METHODS
In 59 human postangioplasty coronary vessels, one IVUS cross-section (1 mm thick) with the highest plaque burden was used for creating dose-volume histograms with different hypothetical positions of the source.


RESULTS
On average, prescription to 1 mm beyond lumen surface resulted in delivery of the prescribed dose (20 Gy +/- 20%) to a higher fraction of adventitial volume than with the prescription to 2 mm from the source, with source placed in vessel center, lumen center, or in the IVUS catheter position. Source placement in the lumen center resulted in a low dose heterogeneity to the adventitia and the least dose heterogeneity to the intima.


CONCLUSIONS
Prescription to 1 mm beyond lumen surface appeared more effective in delivering the prescribed dose to the adventitia than the American Association of Physicists in Medicine (AAPM) recommended prescription to 2 mm from the source center. Moreover, centering the source in the lumen provides the better balance of effective adventitial targeting and intimal dose homogeneity. Modification of the current AAPM recommendation for dose prescription for intracoronary radiotherapy should be considered.
Kałuza
Grzegorz L
GL
Methodist DeBakey Heart Center and Baylor College of Medicine, Houston, TX 77030, USA.
Jenkins
Todd P
TP
Mourtada
Firas A
FA
Ali
Nadir M
NM
Lee
David P
DP
Okura
Hiroyuki
H
Fitzgerald
Peter J
PJ
Raizner
Albert E
AE
D000704:Analysis of Variance; D015906:Angioplasty, Balloon, Coronary; D023903:Coronary Restenosis / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000528:radiation effects*; D019160:Endosonography; D004730:Endothelium, Vascular / Q000528:radiation effects; D005260:Female; D006801:Humans; D008297:Male; D011879:Radiotherapy Dosage; D017539:Tunica Intima / Q000528:radiation effects