Abstract
PURPOSE
To accurately quantify local seed displacement from Day 0 to Day 30 for our brachytherapy
procedure. To quantify seed loss/migration and to identify the locations from where
seeds are missing.
METHODS AND MATERIALS
Seed displacements were analyzed in 62 consecutive patients, who received brachytherapy
with stranded I-125 seeds. At the start of the procedure, four fiducial gold markers
were implanted. At the end of the implantation procedure an in-room 3D CBCT scan (Day
0) was acquired for accurate seed localization. At Day 30 a regular CT scan was acquired.
This CT scan was rigidly registered to the CBCT scan using the fiducials. Subsequently,
the Hungarian method was used to find pairs of corresponding seeds. Displacements
were calculated and missing seeds were identified.
RESULTS
Local seed displacements are smaller than 5 mm for 76.3% of the seeds; 2.3% show displacements
larger than 10 mm. The largest seed displacements are seen along the inferior-superior
axis: on average 1.0 ± 3.2 mm in superior direction with respect to the intraprostatic
fiducials. Largest displacements are seen at the inferior-lateral sides of the prostate.
On average, the inferior seeds move 1.0 ± 2.8 mm in anterior and 1.8 ± 3.3 mm in superior
direction. The percentage of missing seeds is 0.2% (8 out of 3893 seeds for 5 patients).
Most of the missing seeds were also originally implanted at the inferior-lateral sides
of the prostate.
CONCLUSIONS
Local seed displacements and number of missing seeds are small, and predominantly
occur around the apex.
Keywords
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Article info
Publication history
Published online: January 25, 2022
Accepted:
December 9,
2021
Received in revised form:
November 4,
2021
Received:
July 26,
2021
Footnotes
Disclosures: This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors. The authors report no proprietary or commercial interest in any product mentioned or concept discussed in this article.
Identification
Copyright
© 2021 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.
