The fixity of prostate seed implants: The impact of the strand surface on its ability to migrate inside oil and gel medium


Purpose: Radioactive seed implants are widely used to treat cancer patients, most commonly those with prostate cancer. However, the seeds have a tendency to migrate after placement in patients, a phenomenon that can result in unfavorable outcomes. The ability of the seed strand to migrate was investigated by examining the impact of the strand surface on the velocity of its movement inside oil and gel media.

Methods and materials: We investigated the motion of smooth surface strands and strands with different grooved helical profiles after they were placed in oil and gel media. Three patterns of grooved helices were studied (60, 140, and 300 rotations per meter). The movement of the strands through a tube filled with the medium was recorded by the motion sensor, and the drag forces on the individual strands were calculated and compared for the oil and gel media.

Results: The strands with 60, 140, and 300 rotations/meter grooved helical surfaces demonstrated less mobility in both oil and gel than the strands with a smooth surface. The strand with the highest number of helical grooves per meter recorded the largest drag force and moved more slowly in both media. Conclusions: The differential in the motion of the smooth strand and the strands with grooved surfaces can be attributed to the increased surface area of the grooved strands. This finding is significant since it will impact, theoretically, the design, and thus the migration of seed implants that are used to treat cancer patients, particularly those with prostate cancer.


Physics, Astronomy, and Materials Science

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Drag forces, Grooved helical surface, Migration, Radioactive seed, Strands

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