Dose mapping of porcine coronary arteries using an optical fiber dosimeter.
BACKGROUND
This study is about the measurement of radiation dose contribution to the coronary arteries during intravascular brachytherapy with beta and gamma emitters utilizing in vivo optical fiber dosimeters.


METHODS
Domestic pigs were used. With each measurement, catheters were introduced into two different coronary arteries, including the left circumflex (LCX), the left anterior descending (LAD), the first diagonal, and/or the right coronary artery (RCA). A radioactive source (192Ir, 90Sr/Y, or 32P) and the dosimeter were loaded in each of these catheters. Data were collected as the dosimeter was being retracted at a constant rate via computer control.


RESULTS
The radiation dose was normalized to 100% at a 2-mm radial distance from the source. When radiating a branching artery, the dose to the bifurcation at 5 mm from the source was 35%, 10%, and 3% for the 192Ir (10 seeds), 90Sr/Y (40 mm), and 32P sources, respectively. When utilizing a 23-seed 192Ir source, the dose is 40% at a 5-mm distance. However, radiation of the RCA did not result in dosing to the LAD or LCX using any source.


CONCLUSIONS
The dose to adjacent artery segments is less with beta than with gamma emitters. Significant dose exposition is noted when using gamma emitters at a distance of 5 mm. The results can serve as a guideline for establishing prescription doses and safety margins for the treatment of bifurcation lesions and retreatment of the arteries.
Dilcher
Christian
C
Division of Cardiology, Washington Hospital Center, Washington, DC, USA.
Chan
Rosanna
R
Justus
Brian L
BL
Falkenstein
Paul
P
Huston
Alan L
AL
Waksman
Ron
R
D000818:Animals; D001918:Brachytherapy / Q000379:methods*; D017023:Coronary Angiography; D023903:Coronary Restenosis / Q000000981:diagnostic imaging / Q000532:radiotherapy; D003331:Coronary Vessels / Q000528:radiation effects*; D004867:Equipment Design; D005336:Fiber Optic Technology; D007496:Iridium Radioisotopes / Q000627:therapeutic use; D055100:Optical Fibers; D010761:Phosphorus Radioisotopes / Q000627:therapeutic use; D011874:Radiometry / Q000295:instrumentation; D013326:Strontium Radioisotopes / Q000627:therapeutic use; D013552:Swine; D015021:Yttrium Radioisotopes / Q000627:therapeutic use
D007496:Iridium Radioisotopes; D010761:Phosphorus Radioisotopes; D013326:Strontium Radioisotopes; D015021:Yttrium Radioisotopes