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Purpose To update outcome and toxicity results of a prospective trial of 19-Gy single-fraction high-dose-rate (HDR) brachytherapy for men with low- and intermediate-risk prostate cancer. Methods and Materials Patients were treated on a prospective study of single-fraction HDR brachytherapy. All patients had low- or intermediate-risk prostate cancer. Patients with prostate volumes >50 cm3, taking alpha-blockers for urinary symptoms, or with baseline American Urologic Association symptom scores >12 were ineligible. Patients underwent transrectal ultrasound–guided interstitial implant of the prostate followed by single-fraction HDR brachytherapy to a prescription dose of 19 Gy. Results Sixty-eight patients were enrolled with a median follow-up of 3.9 years. Median age was 62 years. Median gland volume at the time of treatment was 35 cm3, 92.6% of patients had T1 disease, 63.2% had a Gleason score of 6, and median pretreatment prostate-specific antigen was 5.0 ng/mL. Chronic grade 2 genitourinary toxicity was 14.7%. No grade 3 urinary toxicity occurred. A single patient experienced grade 2+ rectal toxicity (grade 3 diarrhea) that was transient and resolved with medical management. The 5-year estimated disease-free survival was 77.2% with no significant difference between low- and intermediate-risk patients. A single patient developed distant metastases during the follow-up period. Biopsy-proven local failure at 5 years was 18.8%, occurring at a median interval of 4.0 years posttreatment. No deaths occurred during follow-up. Conclusions With extended follow-up, toxicity rates after single-fraction 19-Gy HDR brachytherapy remain low. Higher-than-expected rates of biochemical and local failure, however, raise concerns regarding the adequacy of this dose. Additional investigation to define the optimal single-fraction HDR brachytherapy dose is warranted, and single-fraction treatment currently should not be offered outside the context of a clinical trial.

BACKGROUND Using a prospectively collected institutional database, we compared rectal toxicity following high dose rate (HDR) brachytherapy as monotherapy relative to dose-escalated external beam radiotherapy (EBRT) for patients with localized prostate cancer. METHODS 2683 patients treated with HDR or EBRT between 1994 and 2017 were included. HDR fractionation was 38 Gy/4 fractions (n = 321), 24 Gy/2 (n = 96), or 27 Gy/2 (n = 128). EBRT patients received a median dose of 75.6 Gy in 1.8 Gy fractions [range 70.2-82.8 Gy], using either 3D conformal or intensity modulated radiotherapy (IMRT). EBRT patients underwent 3D image guidance via an off-line adaptive process. RESULTS Median follow-up was 7.5 years (7.4 years for EBRT and 7.9 years for HDR). 545 patients (20.3%) received HDR brachytherapy and 2138 (79.7%) EBRT. 69.1% of EBRT patients received IMRT. Compared to EBRT, HDR was associated with decreased rates of acute grade ≥2 diarrhea (0.7% vs. 4.5%, p

Purpose: To investigate dosimetry improvement in prostate brachytherapy by conforming needles to urethral and prostate shape using an electromagnetictracking device.Methods: We have reported a needle tracking system using an electromagneticsensor embedded inside the tip of the needle to improve needle reconstruction accuracy and efficiency in conventional prostate HDR brachytherapy. Utilizing the same system, we propose to guide needle insertion following pre‐optimized tracks based onthe target shape. In this study, we investigate possible dosimetry improvement and needle number reduction by comparing plans using the conventional implant method and the proposed method. Twelve prostate brachytherapy patients were selected and studied retrospectively. New virtual plans were created using the proposed method and conforming needle tracks to the urethral and prostate shapes. Same optimization constraints were applied to both the conventional and the new plans. DVH parameters and total needles used have been analyzed to quantify dosimetry improvement and potential toxicity sparing due to reduction in implant needles. Results: Prostate volumes are 41.16±13.27 cc. Number of needles used for the conventional plan is 16.6±1.2, vs. 13 for all the new plans. The prostate volume receiving 100% (V100), 125% (V125), and 150% (V150) of the prescription dose in conventional plans vs. those in the new plans are 99.48%±0.21% vs. 99.53%±0.20%, 53.90%±5.61% vs. 50.30%±5.23%, and 25.37%±4.91% vs. 20.96%±3.41%, respectively. The corresponding urethra V100 and V110 are 90.96%±3.10% vs. 85.78%±7.76% and 2.06%±1.23 vs. 0.46%±0.28%. Conclusions: The needle numbers and the urethral V110 in the new plans are significantly lower than those in conventional plans(p

Purpose To report the toxicity and preliminary clinical outcomes of a prospective trial evaluating 19-Gy, single-fraction high-dose-rate (HDR) brachytherapy for men with low- and intermediate-risk prostate cancer. Methods and Materials A total of 63 patients were treated according to an institutional review board-approved prospective study of single-fraction HDR brachytherapy. Eligible patients had tumor stage ≤T2a, prostate-specific antigen level ≤15 ng/mL, and Gleason score ≤7. Patients with a prostate gland volume >50 cm 3 and baseline American Urologic Association symptom score >12 were ineligible. Patients underwent transrectal ultrasound-guided transperineal implantation of the prostate, followed by single-fraction HDR brachytherapy. Treatment was delivered using 192 Ir to a dose of 19 Gy prescribed to the prostate, with no additional margin applied. Results Of the 63 patients, 58 had data available for analysis. Five patients had withdrawn consent during the follow-up period. The median follow-up period was 2.9 years (range 0.3-5.2). The median age was 61.4 years. The median gland volume at treatment was 34.8 cm 3 . Of the 58 patients, 91% had T1 disease, 71% had Gleason score ≤6 (29% with Gleason score 7), and the median pretreatment prostate-specific antigen level was 5.1 ng/mL. The acute and chronic grade 2 genitourinary toxicity incidence was 12.1% and 10.3%, respectively. No grade 3 urinary toxicity occurred. No patients experienced acute rectal toxicity grade ≥2, and 2 experienced grade ≥2 chronic gastrointestinal toxicity. Three patients experienced biochemical failure, yielding a 3-year cumulative incidence estimate of 6.8%. Conclusions Single-fraction HDR brachytherapy is well-tolerated, with favorable preliminary biochemical and clinical disease control rates.

5 Background: We present a large retrospective analysis comparing rectal toxicity following high dose rate (HDR) brachytherapy as monotherapy relative to dose-escalated external beam radiotherapy (EBRT) for patients with localized prostate cancer. Methods: 2683 patients treated with HDR or EBRT between 1994 and 2017 were included. 545 (20.3%) received HDR and 2138 (79.7%) EBRT. HDR fractionation was 38 Gy/4 fractions (n=321), 24 Gy/2 (n=96), or 27 Gy/2 (n=128). EBRT patients received a median dose of 75.6 Gy in 1.8 Gy fractions [range 70.2-82.8 Gy], using either 3D conformal or intensity modulated radiotherapy (IMRT). All EBRT patients underwent 3D image guidance via an off-line adaptive process. Treatment was directed to prostate only (n=780) or prostate and seminal vesicles (n=1351). No nodal therapy was given. Target volume for HDR patients included the prostate with no expansion. Acute and chronic gastrointestinal (GI) toxicity was defined as occurring ≤ 6 and > 6 months, respectively, after radiotherapy and was graded per CTCAE version 3.0. Toxicity variables were analyzed with χ2 test. Results: Median follow-up was 7.5 years (7.4 years for EBRT and 7.9 years for HDR). 69.1% of EBRT patients received IMRT with the remainder treated using 3D conformal technique. Compared to EBRT, HDR was associated with decreased rates of acute grade ≥ 2 diarrhea (0.7% vs. 4.5%, p < 0.001), rectal pain/tenesmus (0.6% vs. 7.9%, p < 0.001), and rectal bleeding (0% vs. 1.6%, p=0.001). Rates of chronic grade ≥ 2 rectal bleeding (1.3% vs. 8.7%, p < 0.001) and radiation proctitis (0.9% vs. 3.3%, p=0.001) favored HDR over EBRT. Rates of any chronic rectal toxicity grade ≥ 2 were 2.4% vs. 10.5% (p < 0.001) for HDR vs. EBRT, respectively. For the 1478 EBRT patients treated with IMRT, acute and chronic rates of any grade ≥ 2GI toxicity were 4.2% and 5.6%, respectively, compared to 1.5% (p=0.002) and 2.4% (p=0.002), respectively, for HDR patients. Conclusions: In appropriately selected patients with localized prostate cancer undergoing definitive radiation therapy, HDR brachytherapy as monotherapy is an effective strategy for reducing acute and chronic rectal toxicity.

The development of new catheter and applicator technologies in recent years has significantly improved treatment accuracy, efficiency, and outcomes in brachytherapy. In this paper, we review these advances, focusing on the performance of catheter imaging and reconstruction techniques in brachytherapy procedures using magnetic resonance images and electromagnetic tracking. The accuracy of catheter reconstruction, imaging artifacts, and other notable properties of plastic and titanium applicators in gynecologic treatments are reviewed. The accuracy, noise performance, and limitations of electromagnetic tracking for catheter reconstruction are discussed. Several newly developed applicators for accelerated partial breast irradiation and gynecologic treatments are also reviewed. New hypofractionated high dose rate treatment schemes in prostate cancer and accelerated partial breast irradiation are presented.