Live implant dosimetry may be an effective replacement for postimplant computed tomography in localized prostate cancer patients receiving low dose rate brachytherapy

Davood Roshan; Kieran Joyce; Peter Woulfe; Pradeep Reddy Gorakati; Richard Stock; Francis J Sullivan

doi:10.1016/j.brachy.2021.02.008

Live implant dosimetry may be an effective replacement for postimplant computed tomography in localized prostate cancer patients receiving low dose rate brachytherapy

Brachytherapy. 2021 Jul-Aug;20(4):873-882. doi: 10.1016/j.brachy.2021.02.008. Epub 2021 Apr 8.

Authors

Davood Roshan¹, Kieran Joyce², Peter Woulfe³, Pradeep Reddy Gorakati⁴, Richard Stock⁵, Francis J Sullivan⁶

Affiliations

¹ School of Mathematics, Statistics and Applied Mathematics, National University of Ireland, Galway, Ireland.
² School of Medicine, National University of Ireland, Galway, Ireland; CÚRAM, SFI Research Centre for Medical Devices, Biomedical Sciences Building, National University of Ireland, Galway, Ireland.
³ Department of Radiation Oncology, Galway Clinic, Ireland.
⁴ School of Medicine & M.Sc Clinical Research, National University of Ireland, Galway, Ireland.
⁵ School of Medicine, Mount Sinai, New York, NY.
⁶ School of Medicine, National University of Ireland, Galway, Ireland; Department of Radiation Oncology, Galway Clinic, Ireland; Prostate Cancer Institute, National University of Ireland, Galway, Ireland. Electronic address: frank.sullivan@galwayclinic.com.

PMID: 33840634
DOI: 10.1016/j.brachy.2021.02.008

Abstract

Purpose: To determine if Live Implant Dosimetry (LIDO) utilizing intraoperative transrectal ultrasound (TRUS) is equivalent to postimplant CT dosimetry (either day 0 or day 30) in patients with localized prostate cancer (PC) treated with low dose rate (LDR) prostate seed brachytherapy.

Methods and materials: The treated population consisted of 628 men with localized (T1-T2) PC. All d'Amico risk categories (low, intermediate, and high) were included, and 437 patients were treated with monotherapy (160 Gy) [low and low tier intermediate], and the remainder (191) [high tier intermediate and high risk] with an implant boost (106 Gy) post external beam radiation, to a volume including the prostate and seminal vesicles (46 Gy). LIDO with intraoperative TRUS, postimplant CT (day 0 and day 30) were performed in all cases. Prostate volumes (V), V₁₀₀ (prostate) and dose (D) D₉₀ (prostate), D₃₀ (urethra), and Rectum D_2cc, were recorded. No urinary catheter was used on Day 30 CT.

Results: More than 91.33% of monotherapy patients reached the target D₉₀ according to LIDO while only 82.99% of Day 0 CT and 92.82% of Day 30 CT achieved target D₉₀. When considering V₁₀₀, monotherapy patients recorded target dosimetry in 90.93%, 82.31%, and 92.02% of cases assessed by LIDO, Day 0 CT and Day 30 CT, respectively. Strong correlations are observed in D₉₀, Rectum D_2cc and Urethra D₃₀ across imaging modalities but V₁₀₀ and V₁₅₀ were poorly correlated due to the relative quantification of this parameter and high degree of error in measurement. Of all monotherapy patients with satisfactory dosimetry on LIDO, 94.82% reached target D₉₀ at day 30 CT and 94.19% reached target V₁₀₀.

Conclusions: LIDO and CT are both effective tools for assessing postimplant dosimetry. Patients with satisfactory LIDO dosimetry are highly likely to have equivalent dosimetry on CT at follow-up, indicating that postimplant CT may be eliminated in PC a patients implanted with this technique.

Keywords: D2cc(rectum); D30(urethra); D90; LDR brachytherapy; Live implant dosimetry; Postimplant dosimetry; Prostate cancer; V100.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Brachytherapy* / methods
Humans
Iodine Radioisotopes
Male
Prostatic Neoplasms* / diagnostic imaging
Prostatic Neoplasms* / radiotherapy
Radiotherapy Dosage
Tomography, X-Ray Computed

Substances

Iodine Radioisotopes