Low-energy 103Pd gamma (X-ray) source for vascular brachytherapy.
OBJECTIVE
This article describes the merits of 103Pd, a low energy x-ray emitter, as a new and potentially superior candidate for intraluminal brachytherapy. 103Pd can be ion implanted into different materials, designs, and devices for vascular brachytherapy.


METHODS
The mass-analyzed ion implantation process has been used to embed the desired activity of 103Pd into the surface of 316L stainless steel stents. The low-energy, 21-keV x-ray from 103Pd delivers reasonably homogeneous radiation to the vessel wall and loses intensity rapidly beyond the immediate vicinity of the source. Shielding for 103Pd x-rays is trivial and the issues regarding safety, health hazards, storage, and handling are easily manageable.


RESULTS
Experimental data on 103Pd ion-implanted stents show a clean gamma-ray spectrum devoid of any radioimpurity. Activity measurements within a batch demonstrate little stent-to-stent variation (approximately 2%), excellent axial and radial uniformity (<10%), and minimal dissolution in a saline environment (approximately 0.02%). The dosimetry shows the focused radiation field for 103Pd stents and rapid fall-off beyond a few millimeters of the stent. Furthermore, the 103Pd dosimetry indicates that a 350 muCi stent will deliver approximately 14 Gy at 1-mm distance, over its lifetime.


CONCLUSIONS
103Pd is an appropriate source for vascular brachytherapy. It has an appropriate combination of half-life (16.93 days) and energy (21 keV). The half-life of 103Pd delivers the dose with an acceptable dose rate for stent applications while, at the same time, allowing for manageable shipping, storage, and/or disposal.
RadioMed Corporation, Billerica, Massachusetts 01821, USA. psio@radiomed.com
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Sioshansi
R J
RJ
Bricault
D000818:Animals; D001610:Beta Particles / Q000627:therapeutic use; D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods*; D005720:Gamma Rays / Q000627:therapeutic use; D006801:Humans; D010165:Palladium / Q000302:isolation & purification / Q000627:therapeutic use*; D011868:Radioisotopes / Q000302:isolation & purification / Q000627:therapeutic use*; D011879:Radiotherapy Dosage; D015607:Stents; D013679:Technology, Radiologic
D011868:Radioisotopes; D010165:Palladium