eISSN: 2081-2841
ISSN: 1689-832X
Journal of Contemporary Brachytherapy
Current Issue Archive Supplements Articles in Press Journal Information Aims and Scope Editorial Office Editorial Board Register as Author Register as Reviewer Instructions for Authors Abstracting and indexing Subscription Advertising Information Links
Editorial System
Submit your Manuscript
SCImago Journal & Country Rank

2/2014
vol. 6
 
Share:
Share:
abstract:

Original paper
Pre-plan parameters predict post-implant D90 ≥ 140 Gy for 125I permanent prostate implants

Jes Alexander
,
Vivian Weinberg
,
Alexander R. Gottschalk
,
I-Chow Joe Hsu
,
Katsuto Shinohara
,
Mack Roach III

J Contemp Brachytherapy 2014; 6, 2: 143–153
Online publish date: 2014/06/03
View full text Get citation
 
Purpose: To find permanent prostate implant (PPI) pre-plan dosimetric parameters that predict post-implant D90 ≥ 140 Gy.

Material and methods: Pre-plans were evaluated for 504 patients undergoing PPI with 125I seeds for low or intermediate risk prostate cancer. Baseline patient and disease factors, numbers of seeds, ratios of number of seeds to available positions (occupancy proportion), and distances between the 100% isodose line and edge of the prostate (margin) planned for the whole prostate (WP), superior (S), inferior (I), anterior (A), and posterior (P) halves, SA, SP, IA, and IP quarters, and superior (ST), inferior (IT), and middle (MT) thirds, and anterior (AT) and posterior (PT) middle one-sixth segments were analyzed by post-implant D90 subset (≥ 140 Gy vs. < 140 Gy).

Results: 20% had post-implant D90 < 140 Gy (mean: 128.0 Gy, range: 97.5-139.2) vs. ≥ 140 Gy (mean: 154.4 Gy, range: 140.0-193.5). The D90 ≥ 140 Gy subset had larger AT and IA segment mean numbers of seeds (p = 0.01, 0.046), larger WP, S, A, SA, ST, AT, and MT segment mean margins (p = 0.01, 0.01, 0.001, 0.0001, 0.03, 0.005, 0.02), and lower PT segment occupancy proportion (p = 0.004). On multivariate analysis, independent predictors of post-implant D90 ≥ 140 Gy were increased SA mean margin, no pre-implant 5-α-reductase inhibitor, higher pre-plan D90, decreased P occupancy proportion, no pre-implant hormone therapy, and decreased SP mean margin.

Conclusions: Higher occupancy proportion and larger margins anteriorly and reduced occupancy proportion, and smaller margins posteriorly on PPI pre-plans predict post-implant D90 ≥ 140 Gy.
keywords:

LDR brachytherapy, prostate cancer, pre-plan dosimetry

 
Quick links
© 2024 Termedia Sp. z o.o.
Developed by Bentus.