Quality of permanent prostate implants using automated delivery with seedSelectron versus manual insertion of RAPID Strands.

BACKGROUND AND PURPOSE

To compare the quality of manually inserted RAPID Strand implants with automatically inserted selectSeed implants using volumetric and dosimetric parameters.

PATIENTS AND METHODS

Patients with T1 to T2 prostate carcinoma were treated with brachytherapy. The (125)I seeds were implanted in the prostate in three different ways: manual insertion of RAPID Strands (R); insertion of selectSeeds using the seedSelectron (S); a combination of both techniques: manual insertion of RAPID Strands in the left half of the prostate and insertion of selectSeeds with the seedSelectron in the right half of the prostate (RS). The comparison is based on implant and target specific parameters. The implant specific parameters, V(100), homogeneity index (HI), and natural dose ratio (NDR), were determined at the time of implantation and four weeks later. MR images taken four weeks after the implantation were used for the calculation of the target specific parameters: D(90), HI, external index (EI), and conformation number (CN).

RESULTS

We found no significant difference between the groups of implants (R, S, RS) for the implant specific parameters V(100), HI, and NDR at t(0) and neither at t(4w). For each group, the V(100) values decreased significantly with time between t(0) and t(4w). The target specific parameters D(90), HI, EI and CN were not significantly different between the groups. For the group of patients with both RAPID Strands and selectSeeds, we found a significant difference in D(90) between both halves of the prostate.

CONCLUSIONS

The dosimetry parameters of a newly introduced implant technique using an automatic seed afterloader were not significantly different from the parameters of a manual insertion technique using RAPID Strands. Since either technique has its advantages and disadvantages regarding seed migration, physics quality assurance, efficiency, logistics, and ease of use, it was decided to use both techniques and to continue evaluations.