Abstract
Purpose
High-dose-rate (HDR) prostate brachytherapy treatment is usually delivered in one
or a few large dose fractions. Poor execution of a planned treatment could have significant
clinical impact, as high doses are delivered in seconds, and mistakes in an individual
fraction cannot be easily rectified. Given that most potential errors in HDR brachytherapy
ultimately lead to a geographical miss, a more direct approach to verification of
correct treatment delivery is to directly monitor the position of the source throughout
the treatment. In this work, we report on the clinical implementation of our treatment
verification system that uniquely combines the 2D source-tracking capability with
2D pretreatment imaging, using a single flat panel detector (FPD).
Methods and Materials
The clinical brachytherapy treatment couch was modified to allow integration of the
FPD into the couch. This enabled the patient to be set up in the brachytherapy bunker
in a position that closely matched that at treatment planning imaging. An anteroposterior
image was acquired of the patient immediately before treatment delivery and was assessed
by the Radiation Oncologist online, to reestablish the positions of the catheters
relative to the prostate. Assessment of catheter positions was performed in the left-right
and superior-inferior directions along the entire catheter length and throughout the
treatment volume. Source tracking was then performed during treatment delivery, and
the measured position of the source dwells were directly compared to the treatment
plan for verification.
Results
The treatment verification system was integrated into the clinical environment without
significant change to workflow. Two patient cases are presented in this work to provide
clinical examples of this system, which is now in routine use for all patient treatments
in our clinic. The catheter positions were visualized relative to the prostate, immediately
before treatment delivery. For one of the patient cases presented in this work, they
agreed with the treatment plan on average by 1.5 mm and were identifiable as a predominantly
inferior shift. The source tracking was performed during treatment delivery, and for
the same case, the mean deviation from the planned dwell positions was 1.9 mm (max = 4.9 mm)
for 280 positions across all catheters.
Conclusion
We have implemented our noninvasive treatment verification system based on an FPD
in the clinical environment. The device is integrated into a patient treatment couch,
and the process is now included in the routine clinical treatment procedure with minor
impact on workflow. The system which combines both 2D pretreatment imaging and HDR
2D source tracking provides a range of information that can be used for comprehensive
treatment verification. The system has the potential to meaningfully improve safety
standards by allowing widespread adoption of routine treatment verification in HDR
brachytherapy.
Keywords
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Article info
Publication history
Published online: September 22, 2017
Accepted:
August 9,
2017
Received in revised form:
July 29,
2017
Received:
February 11,
2017
Footnotes
Financial disclosure: This research received funding from the Radiation Oncology Section of the Australian Government Department of Health (formerly Department of Health and Aging) through Cancer Australia's Priority-driven Collaborative Cancer Research Scheme (Project ID: 616614).
Identification
Copyright
© 2017 Published by Elsevier Inc. on behalf of American Brachytherapy Society.
