A comparison of treatment planning techniques for low-dose-rate (LDR) prostate brachytherapy

David Connolly,Gordon Sands,Helen Winter,Mark J Foley,Christoph Kleefeld

doi:10.1016/j.brachy.2020.10.006

David Connolly, Gordon Sands + Show 3 more

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https://doi.org/10.1016/j.brachy.2020.10.006

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Abstract

PurposeThe purpose of this study was to compare low-dose-rate prostate brachytherapy treatment plans created using three retrospectively applied planning techniques with plans delivered to patients. Methods and MaterialsTreatment plans were created retrospectively on transrectal ultrasound (TRUS) scans for 26 patients. The technique dubbed 4D Brachytherapy was applied, using TRUS and MRI to obtain prostatic measurements required for the associated webBXT online nomogram. Using a patient's MRI scan to create a treatment plan involving loose seeds was also explored. Plans delivered to patients were made using an intraoperative loose seed TRUS-based planning technique. Prostate V100 (%), prostate V150 (%), prostate D90 (Gy), rectum D0.1cc (Gy), rectum D2cc (Gy), urethra D10 (%), urethra D30 (%), and prostate volumes were measured for each patient. Statistical analysis was used to assess and compare plans. ResultsProstate volumes measured by TRUS and MRI were significantly different. Prostate volumes calculated by the webBXT online nomogram using TRUS- and MRI-based measurements were not significantly different. Compared with delivered plans, TRUS-based 4D Brachytherapy plans showed significantly lower rectum D0.1cc (Gy) values, MRI-based 4D Brachytherapy plans showed significantly higher prostate V100 (%) values and significantly lower rectum D0.1cc (Gy), urethra D10 (%), and urethra D30 (%) values, and loose seed MRI-based plans showed significantly lower prostate V100 (%), prostate D90 (Gy), rectum D0.1cc (Gy), rectum D2cc (Gy), urethra D10 (%), and urethra D30 (%) values. ConclusionsTRUS-based 4D Brachytherapy plans showed similar dosimetry to delivered plans; rectal dosimetry was superior. MRI can be integrated into the 4D Brachytherapy workflow. The webBXT online nomogram overestimates the required number of seeds.

Highlights

Low-dose-rate prostate brachytherapy (LDRPB) involves the permanent implantation of small radioactive sources called ‘seeds’ into the prostate of a patient with localized prostate cancer for curative treatment purposesReceived 14 January 2020; received in revised form 30 September 2020; accepted 16 October 2020
Three treatment planning techniques were retrospectively applied to create monotherapy LDRPB treatment plans for 26 patients, who were treated between January and July 2019, on transrectal ultrasound (TRUS) scans saved from procedures on which prostates, rectums, urethras, and planning target volume (PTV) were contoured by radiation oncologists in the operating room (OR)
Prostate volumes calculated by the webBXT online nomogram (WON) displayed a wider range of values than their TRUS- and MRIbased counterparts

Summary

Objectives

The purpose of this study was to compare low-dose-rate prostate brachytherapy treatment plans created using three retrospectively applied planning techniques with plans delivered to patients. The purpose of this study was to compare the dosimetry of plans created using three retrospectively applied planning techniques with the dosimetry of delivered plans and assess whether the retrospectively applied techniques could produce superior plans to delivered plans if applied prospectively

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Conclusion