Brachytherapy最新文献

Purpose: Reirradiation for para-aortic lymph node (PALN) recurrence is technically challenging due to prior radiation exposure and the anatomical proximity of critical organs such as the small intestine and kidneys, making external beam radiation therapy (EBRT) difficult or unfeasible. High-dose-rate interstitial brachytherapy (HDR-IBT) offers a highly localized treatment alternative; however, it requires precise applicator placement to ensure safety and efficacy.

Methods and materials: We report a case of PALN recurrence located between the aorta and inferior vena cava (IVC) in a patient previously treated with multiple courses of EBRT. Due to the lesion's high-risk location and prior irradiation, further EBRT was not a viable option. In collaboration with interventional radiologists, a novel posterior paravertebral approach was adopted. Under fluoroscopic and computed tomography (CT) guidance, a 17 G percutaneous transhepatic cholangiography (PTC) needle was inserted from the patient's back. The guidewire was advanced through the psoas muscle and intentionally redirected caudally at an angle of nearly 90 degrees to avoid major vascular structures. Following tract dilation using a ureteral balloon and dilator system, a flexible brachytherapy applicator was inserted and fixed in place. The patient received six fractions of 5 Gy (total dose: 30 Gy), with the applicator maintained in situ throughout the treatment period.

Results: The treatment was completed without any adverse events. CT imaging at 4 months post-treatment showed tumor shrinkage and reduced contrast enhancement. No radiation-related toxicities were observed during or after treatment. Local control has been maintained for over 4 years.

Conclusions: This case demonstrates the feasibility and safety of fractionated HDR-IBT for reirradiation of deeply located PALN recurrence in a previously irradiated field. While single-fraction HDR-IBT can be performed via a direct posterior approach, fractionated treatment requires stable applicator placement over several days. To mitigate the risk of vascular injury due to applicator displacement, precise angulation of the insertion trajectory was critical. This report highlights how interdisciplinary collaboration enabled accurate, vessel-sparing needle placement, providing a minimally invasive and effective treatment option for patients with PALN recurrence who are not candidates for further EBRT.

Purpose: Patients are increasingly using artificial intelligence (AI) chatbots for health information. Evaluating their reliability for specialized topics, such as brachytherapy, is crucial for guiding their safe use. We assessed a readily accessible AI chatbot's suitability for answering frequently asked questions (FAQ) related to brachytherapy.

Methods: We compared responses from an AI chatbot (ChatGPT 4o-mini) against gold standard (GS) authoritative sources for 10 brachytherapy frequently asked questions. Four blinded board-certified brachytherapy experts evaluated 80 response pairs using metrics, including accuracy, clinical appropriateness, readability, and tone. Five simulated patient personas with varying literacy levels were used to assess helpfulness, readability, and emotional tone. The objective readability metrics were also calculated.

Results: Experts rated the AI chatbot higher for accuracy (75% highly/mostly accurate vs. 50% for GS) and appropriateness (77% vs 55%), although inaccuracies were noted in both sources in a blinded review. Simulated patients preferred GS responses (62% vs. 34%), particularly lower-literacy personas, citing better perceived readability (92% easy/very easy vs. 44% for AI) and a more reassuring tone (42% vs. 24% for AI). Objective analysis confirmed that both sources significantly exceeded the recommended reading levels (e.g., >12th grade Flesch-Kincaid), with AI responses being substantially longer. Performance varied considerably across individual questions for both AI and GS sources.

Conclusions: In this blinded cross-sectional evaluation, a publicly available AI chatbot provided accurate responses to brachytherapy-related FAQs. However, further development and validation focused on accessibility, trustworthiness, and user-centered design are required before these tools can be safely and effectively integrated into patient-care workflows.

Purpose: COMS established iodine-125 (¹²⁵I) brachytherapy as standard of care for medium-sized choroidal melanomas. However, there remains a gap in the literature regarding reduced dosing for medium-sized choroidal melanomas and standard dosing for small-sized choroidal melanomas. We explored the impact of reduced dose ¹²⁵I brachytherapy on local tumor control and ocular adverse events (AEs).

Methods: Patients diagnosed 2005-2019 with choroidal melanoma <5 mm thick and managed with ¹²⁵I brachytherapy dose of 65 Gy to depth of 5 mm were included. Dose metrics were calculated using Monte Carlo-based dosimetry. Kaplan-Meier method was used to estimate overall survival and radiation-related AEs. Distant metastasis and local recurrence were reported using cumulative incidence with death as a competing risk. Univariate and multivariate associations were analyzed using Cox proportional hazards regression.

Results: 143 patients met inclusion criteria with median follow-up of 7 years. Five-year Kaplan-Meier estimates of ocular AEs were 59.6% radiation maculopathy, 42.0% cystoid macular edema, 55.2% nonproliferative radiation retinopathy, 10.8% proliferative radiation retinopathy, and 35.6% radiation papillopathy. Five-year cumulative incidence of local recurrence was 0%, 5-year cumulative incidence of distant metastasis was 6.1%, and 5-year Kaplan-Meier estimate of overall survival was 96.5%.

Conclusion: Reduced dose ¹²⁵I brachytherapy is feasible with excellent local tumor control.

Purpose: Androgen deprivation therapy (ADT) for prostate cancer typically reduces prostate volume. This study investigated how the timing of ADT relative to low-dose-rate (LDR) brachytherapy influences the resulting dosimetric outcomes.

Methods: Using deformable image registration and principal component analysis on pre- and post-ADT magnetic resonance images of 34 patients, we developed a statistical model of ADT-induced prostate deformation. We applied this model to 30 low-dose-rate (LDR) brachytherapy plans (prescription dose: 145 Gy) to simulate seed displacement and dose distribution changes from prostate shrinkage. Prostate deformation over time post-ADT was categorized into early, linear, and late response phases. Dosimetric outcomes were analyzed across scenarios with varying prostate volume reduction magnitudes and different intervals between ADT initiation and brachytherapy.

Results: When ADT was initiated concurrently with brachytherapy, the model predicted substantial dose escalation if prostate shrinkage occurred early (prostate D90 ∼206 Gy; urethral V200 ∼47.7%) compared to late shrinkage response (D90 ∼183 Gy; V200 ∼7.1%). In contrast, separating the treatments in time greatly mitigated this effect. For example, assuming early response, performing brachytherapy 3 months before ADT yielded a prostate D90 of ∼183.0 Gy (urethral V200 ∼7.7%), while delaying brachytherapy to 3 months after ADT yielded a D90 of ∼177.8 Gy (V200 ∼1.2%).

Conclusions: Dosimetric analysis showed that greater prostate volume reduction, early ADT response, and concurrent ADT all corresponded to substantially increased doses to the prostate and urethra. Clinically, these findings underscore the importance of carefully planning the timing of ADT relative to brachytherapy to optimize target coverage and minimize unintended dose escalation to normal tissues.

Purpose: The purpose of this work, a first-in-human randomized clinical trial, was to compare gMCO, a GPU-based multi criteria optimization (MCO) algorithm, to reference plans in terms of planning time and plan quality for prostate HDR brachytherapy.

Methods and materials: The brachytherapy procedure was as follows: (1) Patient installation, (2) Catheter implantation under transrectal ultrasound (US) guidance, (3) 3D US scan, (4) Contouring/catheter reconstruction on Oncentra Prostate (Elekta, Veenendaal, Netherlands), (5) Planning, (6) Treatment. Planning (step 5) was performed, after randomization, using either IPSA (Oncentra Prostate, Veenendaal, Netherlands) or gMCO. The planning times on IPSA or gMCO were recorded. Patients previously had a planning MR in order to identify whether a gross tumor volume (GTV, PIRADS 3 and above) was visible and, if present, the GTV was boosted to a minimum of 19 Gy of the prescription dose. Fifty-five patients were accrued and distributed randomly between both treatment arms. Dosimetric indices (Prostate V100, V150, V200, GTV D90, Urethra D10, Rectum and Bladder V75 and D1cc) of gMCO and Inverse-Planning Simulated Annealing algorithm (IPSA) plans were compared to determine if plan quality and planning times were statistically different.

Results: Results show that the optimization time is reduced by half when using gMCO as compared to IPSA, going from 10-5.2 minutes. Although no statistically significant difference is present between gMCO and IPSA plans when comparing pairs of individual dosimetric indices, gMCO plans exhibit a higher pass rate (higher by a factor ranging from 1.3 to 1.6), as compared to IPSA, when considering a basket of dosimetric indices simultaneously.

Conclusion: The use of gMCO halves the planning time for prostate HDR brachytherapy as compared to IPSA, without decreasing plan quality. The overall gain in efficiency related to the planning process has led to the use of gMCO for all of our HDR prostate cases.

Purpose: The purpose of this study is to evaluate clinical outcomes for medically inoperable endometrial cancer (MIEC) patients treated with triple tandem brachytherapy (TTB) ± external beam radiation therapy (EBRT).

Methods: This single institution retrospective review analyses MIEC patients treated definitively with TTB ± EBRT from 2014 to 2021. FIGO stage I-II with Grade 1-2 histology were considered low-risk endometrial cancer (LREC) and FIGO stage III-IVB and/or any Grade 3 endometrioid carcinoma, clear cell, or serous carcinoma were considered high-risk endometrial cancer (HREC). Planning parameters for target volume(s) and OARs (organs at risk) were per ABS guidelines. Overall survival (OS) and local failure-free survival (LFFS) were estimated by Kaplan-Meier analysis. Local control (LC), acute and late toxicities were evaluated clinically.

Results: Of 26 patients, 92.3% (n = 24) received TTB + EBRT. The median age at diagnosis was 66.5 years (40.5-88.7 years). Median follow up was 41.1 months (1.7-109.9 months). Median prescribed doses to the uterus were 45 Gy (0-50.4 Gy) for EBRT and 22.25 Gy (18-49.1 Gy) for TTB. 53.8% (n = 14) had LREC and 46.2% (n = 12) had HREC. 88.5% had endometrioid histology. The median OS for the entire cohort was 43.5 months with no difference for the LREC and HREC (p = 0.563). LC was superior (p = 0.032) in LREC patients (100% 4-year LFFS) with all recurrences occurring in the HREC cohort (1-/4-year LFFS 90.9%/62.3%). Late toxicities > Grade 2 were: Grade 2 GU (n = 2) and Grade 2 GI (n = 1).

Conclusions: Definitive TTB ± EBRT for MIEC patients was associated with excellent LFFS and acceptable toxicity rates.

Purpose: Rectal spacing has been shown to reduce toxicity following external beam radiation therapy for prostate cancer. However, real-world evidence of effectiveness for rectal spacers with brachytherapy (BT) monotherapy remains limited. This study used U.S. claims datasets to assess the association between rectal spacer use and bowel, urinary, and sexual function following BT.

Materials and methods: A retrospective study was conducted among patients treated with BT monotherapy for prostate cancer between 2015 and 2021, using Medicare 5% and 100% Files, MarketScan, and Premier Databases. Polyethylene glycol rectal spacer use was identified. Post-BT treatment diagnoses of bowel, urinary, and sexual dysfunction were evaluated using Cox proportional hazards models, adjusting for age, comorbidity, region, baseline dysfunction, secondary cancers, and BT modality (low-dose rate [LDR] or high-dose rate).

Results: Among 13,858 BT monotherapy patients, 1198 (8.6%) received a spacer. Patients with spacer were younger and had fewer baseline dysfunctions. At 5-year median follow-up, spacer use was associated with significantly lower incidence of bowel (adjusted hazard ratio, aHR: 0.76, p = 0.027) and urinary (aHR: 0.84, p = 0.008) dysfunction. Sexual dysfunction trended lower (aHR: 0.79, p = 0.120), although not significant. In LDR patients, spacer use remained significantly associated with reduced bowel (aHR: 0.74, p = 0.021) and urinary (aHR: 0.83, p = 0.005) dysfunction. Significant associations were not found in high-dose rate patients.

Conclusions: In this large real-world study, rectal spacing as a standard-of-care intervention showed sustained significant benefit in reducing bowel and urinary dysfunction, which appeared to be greatest in those treated with LDR BT.

Purpose: Accelerated partial breast irradiation (APBI) has emerged as an alternative to whole-breast irradiation (WBI) for selected patients with low-risk early breast cancer (EBC). While external beam APBI techniques are widely available, multicatheter interstitial brachytherapy (MIB) offers superior conformity and reduced normal tissue exposure. We evaluated the feasibility, toxicity, and early outcomes of an ultra-hypo fractionated approach using a single-fraction MIB-APBI in older patients.

Methods and materials: We conducted a single-institution retrospective study of 20 women (range, 69-88 years) with low-risk EBC treated with a single-fraction APBI (uAPBI) 16 Gy using MIB, between January 2023 and October 2024. All patients had undergone lumpectomy with sentinel lymph node biopsy. Eligibility criteria included age ≥65 years, tumor size ≤3 cm, unifocal disease, sentinel node-negative status and microscopically clear resection margins. Acute and late toxicities, cosmetic outcomes, oncological endpoints and dosimetric parameters were evaluated.

Results: Acute toxicity was limited to Grade 1/2 dermatitis in 25% of patients while no severe late toxicity was observed. Cosmetic outcomes were excellent to good in 100% of patients. At median follow-up of 18 months (range, 10-26), all patients remained alive with no locoregional recurrence or distant metastasis. Dosimetric parameters demonstrated excellent target coverage (median V100%: 97%, range 90-98%).

Conclusions: Single-fraction MIB-based APBI delivering 16 Gy appears to be a feasible, well-tolerated, and effective treatment approach for carefully selected older patients with EBC. This ultra-hypo fractionated approach significantly reduces treatment burden while maintaining excellent local control and favorable toxicity profiles.

Background: ¹²⁵I seed migration is a persistent safety concern in hepatic brachytherapy. Inflammatory and metabolic biomarkers may influence both tissue vulnerability and implantation strategies, contributing to migration risk.

Methods: In this retrospective study of 625 patients undergoing ¹²⁵I seed implantation for primary or metastatic liver tumors, clinical, laboratory, and procedural data were analyzed. Migration was assessed via follow-up chest radiography or CT. Univariate and multivariate Cox regression identified predictors of migration. Kaplan-Meier analysis evaluated seed migration-free survival (SMFS). Causal mediation analysis examined whether procedural factors-total number of seeds implanted (NSI) and maximum number per session (MAX)-mediated the effects of lactate dehydrogenase (LDH), neutrophil ratio, and lymphocyte ratio on migration.

Results: Seed migration occurred in 134 patients (21.4%). Elevated LDH, neutrophil ratio, MAX, and NSI were significantly associated with migration (all p < 0.01), while higher lymphocyte ratio was protective. Cox regression identified LDH, MAX, lymphocyte ratio, platelet count, and NSI as independent predictors. Kaplan-Meier analysis showed shorter SMFS in patients with high LDH or neutrophils and low lymphocytes. Mediation analysis revealed that LDH and neutrophils increased migration risk both directly and indirectly through procedural intensity (MAX, NSI), whereas lymphocytes had protective effects via both pathways.

Conclusion: Systemic inflammation and metabolic status influence both physiologic susceptibility and procedural factors associated with ¹²⁵I seed migration. Causal mediation analysis highlights modifiable indirect mechanisms, supporting personalized implantation planning to reduce migration risk.