First report on the use of a thinner 125I radioactive seed within 20-gauge needles for permanent radioactive seed prostate brachytherapy: Evaluation of postimplant dosimetry and acute toxicity

Urethral toxicity after LDR brachytherapy: Experience in Japan

“…Sylvester et al (16) reported on the use of thinner 125 I radioactive seeds inside 20-gauge needles for the first time. The use of thinner 125 I radioactive seeds inside 20-gauge needles resulted in significantly less acute perineal pain and bruising.…”

103Pd strings: Monte Carlo assessment of a new approach to brachytherapy source design

“…This approach of having sources of standard and thinner diameters is similar to that for the models 6711 and 9011 125 I seeds, respectively. 22 For a deeper understanding of the dosimetric characteristics for these 12 sources, an additional source (referred to as Ti05) was modeled to emulate a representative 103 Pd seed such as the model 200 (Theragenics Corp., Buford, GA). The theoretical Ti05 source had only two 103 Pd middle wells (one on either side of the Au marker), with a physical extent of radioactivity spanning 5 mm, and included a Ti capsule (0.75 and 0.85 mm inner and outer diameters, respectively).…”

Should the dimensions of brachytherapy seeds be altered?

“…I am pleased that Sylvester et al (1) have reported their early experience implanting 0.5-mm diameter 125 I seeds (ThinSeed Model 9011; Oncura, Plymouth Meeting, PA), and have compared the dosimetry and acute toxicity of ThinSeed implants with a historical control of implants using standard 0.8-mm seeds. It would be appropriate to explore the rationale for current seed dimensions before adopting a new standard (2).…”

“…Although there is no clinical rationale to maintain current seed dimensions, Sylvester et al (1) have not provided a compelling reason to change them. Perhaps the larger, randomized trial that they are pursuing will demonstrate a significant benefit for using a thinner seed.…”

“…But should their dimensions be changed? Sylvester et al (1) have acknowledged that it would be difficult improve on the clinical efficacy demonstrated by standard seeds, and have focused their comparison on ''technical, dosimetric, (and) initial toxicity outcomes.'' Presumably, the thinner (20G) needle used to implant the new seeds would inflict less trauma than the standard 18G needle, but the advantage may be offset if its increased flexibility necessitates repeat punctures to achieve accurate placement.…”