Bouquet brachytherapy: feasibility and optimization of conically spaced implants.
OBJECTIVE
To examine the dosimetric feasibility of a conical implantation approach to robotic-assisted prostate brachytherapy.


METHODS
An in-house inverse planning software based on the genetic algorithm (GA) was used to optimize the needle angulations and the seed positions along needles that form one or two bouquets. Volume data from 20 prostate seed implant patients (six 125I and 14 103Pd) previously treated using the conventional rectilinear template approach were used. The dosimetry outcomes of the optimized treatment plan in the conical approach were compared with those from the original treatment plans based on the conventional rectilinear template approach.


RESULTS
When seed spacing is restricted to nominal 1 cm center-to-center spacing, dosimetry results in the conical approach suffer from a higher urethra dose and higher dose heterogeneity compared with the original rectilinear template plans. When the seed loading patterns are optimized as part of inverse planning, the resulting dosimetry plans exhibit adequate dose coverage and uniformity through the target volume, as well as satisfactory sparing of the urethra and rectum.


CONCLUSIONS
Conically spaced implantation for prostate brachytherapy with 125I and 103Pd seeds is feasible in terms of dosimetry outcomes. Techniques for optimized inverse planning for this approach have been developed.
Fu
Lei
L
Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY 14642-8647, USA.
Ng
Wan Sing
WS
Liu
Haisong
H
O'Dell
Walter
W
Rubens
Deborah
D
Strang
John
J
Schell
Michael C
MC
Brasacchio
Ralph
R
Liao
Lydia
L
Messing
Edward
E
Yu
Yan
Y
D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods* / Q000592:standards; D005240:Feasibility Studies; D012371:Robotics