AbstractID: 6911 Title: Stepping the ⁹⁰Sr/⁹⁰Y Source Train
for Intravascular Brachytherapy Treatment: A Monte Carlo Dosimetric Study
A Monte Carlo (MC) dosimetric study, which examines the stepping of the Novoste Beta-Cath
system source train for in-stent restenosis treatments, is performed. Twelve cylindrical sealed
90
Sr/90Y Beta radiation sources are simulated using the EGS4 code system with dimensions of
2.5 mm long [ 0.64 mm diameter each contained within ceramic and encapsulated in 0.04 cm
thick stainless steel. Two 2.5 mm gold markers, each placed at the end of the source train, are
also simulated. The 3 cm long 90Sr/90Y source train is simulated to treat lesions with the length
of 2.5, 2.9, 3.5, 3.9 and 4.5 cm by stepping the source train a distance ranging from 0.4 cm to
2.0 cm. The total dose deposited along the source train axis at 2 mm in water is calculated.
The EGS4 MC dose distributions show a maximum increase in dose by 100% (hot spot) over
90% of the treatment area when irradiating a 2.9 cm long lesion, compared to the 2.5 cm lesion.
The results also show a maximum increase in dose by 100% over 10% of the treatment area
when irradiating a 4.5 cm lesion. The increase in dose must be considered when treating
lesions longer than 2.5 cm. Methods to reduce the hot spots and increase the dose uniformity
over the treated area are suggested.