Brachytherapy最新文献

Background: An update of the 2007 and 2014 surveys of the American Brachytherapy Society (ABS) will elucidate current practice patterns of cervical cancer brachytherapy.

Methods: A 40-question survey was sent to all ABS members in June-July 2023 and February 2024; 167 responses were received, with 140 used for analysis. Results were compared to the 2014 survey using chi-squared testing. Multivariable logistic regression was used to calculate adjusted odds ratios (aOR) with 95% confidence intervals (CI) for outcomes of interest.

Results: Compared to 2014, MRI use for treatment planning of the first brachytherapy fraction increased from 34% to 63% (p < 0.001), prescription to the high-risk clinical target volume (HR-CTV) increased from 52% to 94% (p < 0.001), while Point A prescription decreased from 42% to 16% (p < 0.001). Additionally, procedural guidance with ultrasound significantly increased (79% vs. 32%, p < 0.001) along with the use of interstitial needles (always or nearly always, >80%) (29% vs. 4%, p < 0.001). MRI availability around the time of procedure was the largest challenge to incorporating MRI into brachytherapy treatment planning. Compared to those with MRI access reserved specifically for Radiation Oncology, respondents with shared-access or out-of-department MRI were less likely to obtain treatment planning MRIs for each brachytherapy fraction (22% vs. 75%; aOR 0.10 [95% CI, 0.03-0.30], p < 0.001).

Conclusion: For cervix cancer brachytherapy there has been significant increase in the use of MRI-based volumetric brachytherapy treatment planning, ultrasound guidance during procedures and the addition of interstitial needles. These advancements in practice patterns are congruent with published consensus guidelines and ongoing training initiatives. However, MRI access and lack of easy availability continue to be significant challenges for optimizing cervix brachytherapy.

Background: Radical urethectomy ± cystectomy has long represented the standard of care for rare primary urethral cancer (PUC). With our analysis, we want to demonstrate the efficacy and safety of brachytherapy (BT) of urethra for organ preservation.

Materials and methods: We analyzed treatment procedures and results of 3 patients with PUC, which have been treated in our department between 2011 and 2020 with brachytherapy. One male patient underwent brachytherapy with chemoradiotherapy after transurethral resection (TUR). Brachytherapy has been performed as high-dose-rate (HDR) boost with a cumulative dose of 8 Gy (9.3 Gy _{EQD2-α/β = 10 Gy}). The 2 further female patients have been treated with sole pulsed-dose-rate (PDR) brachytherapy with a total dose of 49.9 Gy (50.3 Gy _{EQD2-α/β = 10 Gy}) and 62.2 Gy (64.6 Gy _{EQD2-α/β = 10 Gy}).

Results: Median follow-up was 103 months (41-153). No local recurrence occurred and all patients are still alive. For the male patient we documented Grade 3 cystitis. As late side effects the pre-existing Grade 2 incontinence worsened to Grade 3. Among female patients one developed Grade 3 vaginal synechiae. There was no Grade ≥4 toxicity.

Conclusion: Brachytherapy in PUC is a feasible and promising option with high local control rate and tolerable toxicity. It provides a good alternative to surgery for organ preservation in selected patients.

Purpose: Brachytherapy (BT) is a time and resource intensive treatment modality. Constraints to efficiency and throughput include resource, staff and physician availability. Herein, we introduce a daily BT procedure scorecard, designed to ensure adequate resource allocation based on the type of procedure(s) being performed.

Methods: Data on BT procedures, number of fractions, number of patients, and the average daily caseload from 2021 to 2024 in our clinic were collected. Each BT procedure was assigned a score from 1 to 3 based on complexity and labor intensity, with 1 representing the least and 3 the most complex procedures. This data was then used to evaluate the efficiency of the BT scoring system.

Results: Implementing the BT scorecard improved scheduling efficiency without compromising patient throughput. Despite the growth in case complexity, we demonstrated that the scoring system effectively prevents understaffing in our clinics. The goal is to limit the daily BT score to 10 per day when creating the schedule, ensuring balanced resource allocation.

Conclusion: The strategies presented can enhance scheduling by ensuring an equitable workload distribution based on the BT schedule. These approaches should be considered in all high-volume BT clinics to optimize patient scheduling and throughput. Additionally, the scoring system allows clinics to develop full-time equivalent (FTE) staffing models that account for patient volume and case types, ensuring optimal resource utilization.

Purpose: Before this study, no institution in China had undertaken the calculation and official establishment of reference values for the reference air kerma rate associated with high-dose rate ¹⁹²Ir sources used in brachytherapy. This research, carried out at the National Institute of Metrology (NIM) in China, has successfully established an ¹⁹²Ir reference radiation facility. Consequently, it has achieved the absolute measurement of the reference air kerma rate for high-dose rate brachytherapy using ¹⁹²Ir sources.

Methods and materials: For this study, a medical afterloader machine was acquired. The radiation source employed was a high-dose rate ¹⁹²Ir source for brachytherapy, produced by HTA Co., Ltd. A reference graphite cavity ionization chamber with a volume of 100 cm³ was designed to serve as the ionization chamber for absolute measurements. The determination of various correction factors and physical constants was achieved through a method that combines Monte Carlo simulations with experimental techniques.

Results: The study successfully accomplished the absolute measurement of the reference air kerma rate for the high-dose rate brachytherapy ¹⁹²Ir radiation source. The expanded uncertainty of the measurement results was 0.72% (k = 2). The relative standard deviation for the RAKR of the same ¹⁹²Ir radiation source was 0.073%.

Conclusions: This study marks a significant advancement in the field of radiation therapy in China, particularly in the accurate dosimetry for brachytherapy using high-dose rate ¹⁹²Ir sources. The study will contribute to the BIPM.RI(I)-K8 international comparison, organized by the Bureau International des Poids et Mesures (BIPM), thus facilitating the international recognition of the measurement values.

Purpose: We investigated the feasibility of AI to provide an instant feedback of the potential plan quality based on live needle placement, and before planning is initiated.

Materials and methods: We utilized YOLOv8 to perform automatic organ segmentation and needle detection on 2D transrectal ultrasound images. The segmentation and detection results for each patient were then fed into a plan quality prediction model based on ResNet101. Its outputs are values of selected dose volume metrics. Imaging and plan data from 504 prostate HDR boost patients (456 for training, 24 for validation, and 24 for testing) treated in our clinic were included in this study. The segmentation, needle detection, and prediction results were compared to the clinical results (ground truth).

Results: For prediction model, the p-values of t-test between the predicted values and ground truth for either rectum D2cc or urethra D20% were larger than 0.8. The sensitivity of prediction model in finding implant geometries resulting in below-median rectum D2cc and urethra D20% were 83% and 87%.

Conclusion: The proposed method has great potential to facilitate the current prostate HDR brachytherapy workflows by providing valuable feedback during needle insertion, and facilitating decision making of where and if additional needles are required.

Introduction: There is some evidence of a dose-response relationship for intravascular brachytherapy (IVBT) of native vessel or first-time in-stent restenosis (ISR). It has also been shown that in-field failure predominates following intravascular brachytherapy-treated lesions. Accordingly, it may be advantageous to increase the radiation dose(s) currently used. Given the rationale for escalation from currently doses, a scrutiny of the potential complications that have been reported seems timely.

Methods: PubMed was searched from 1966 through November 21st, 2023, using the terms coronary and brachytherapy, yielding 1287 references. A 10/16/24 follow-up search of Embase, using the terms "coronary and brachytherapy and complications", yielding 511 articles. In total, 68 articles were identified as adverse event reports based on their title, or by scrutinizing articles that did not mention adverse events in their titles.

Results: The best documented adverse IVBT-related event is the occurrence of late (> 1 month) thrombosis. Following identification of the risk, longer DAPT regimens were adopted, bringing the incidence to non-IVBT levels. A variety of other adverse events have been reported, including aneurysms, dissections, arterial spasm, "black holes" and vasomotor response inhibition. However, none of which were associated with adverse clinical outcomes.

Conclusions: Nearly all reports regarding IVBT-related complications are retrospective analyses of a limited number of events, subject to reporting bias. Clinically important IVBT-related complications, at current doses, appear highly unlikely.

Purpose: The bladder and rectal toxicities in cervical cancer brachytherapy are positively correlated with the DVH parameter: D2cc. This study evaluates the feasibility of knowledge-based planning to predict the D2cc, identify suboptimal plans, and improve the plan quality with Direction Modulated Brachytherapy (DMBT) applicators using knowledge-based planning based on linear relationship between overlap distances and D2cc.

Methods: The overlap volume histogram (OVH) method was used to determine the distances for 2 cm³ of overlap between the Organs at Risks (OAR) and High-Risk Clinical Target Volume (CTV_HR). Linear plots were utilized to model the OAR D2cc and 2 cm³ overlap distances. Two datasets from 45 patients (125 plans) were used to create 2 independent models: Model 1 from 59 Intracavitary (IC) and Model 2 from 66 Intracavitary-Interstitial (ICIS) plans. Performances were compared using 5-fold cross-validation. The predicted D2cc values were used as the maximum constraints in the inverse planning optimization.

Results: The mean bladder D2cc decreased by 4.3% and 10.3% for conventional applicators, and 4.4% and 3.6% for DMBT applicators for Models 1 and 2, respectively. The rectum D2cc decreased by 3.4% and 10.7% for conventional and 3.0% and 5.0% for DMBT applicators, respectively. The sigmoid D2cc decreased by 3.1% and 6.9% for conventional and 3.2% and 5.9% for DMBT applicators, respectively. There were also significant reductions for the recto-vaginal (RV-RP) point and posterior-inferior border of symphysis (PIBS) reference points: PIBS+2cm, PIBS+1cm, PIBS-1cm, and PIBS-2cm, for both models as well.

Conclusions: A knowledge-based planning method successfully predicted D2cc and optimized brachytherapy plans for cervical cancer. The proposed model demonstrates the feasibility of predicting D2cc, detecting suboptimal plans, and improving the plan quality especially for DMBT where cumulative clinical experience is limited.

Purpose: To describe the clinical presentation and treatment outcomes of patients undergoing Ruthenium-106 (¹⁰⁶Ru) plaque brachytherapy as salvage treatment for retinoblastoma (RB) following intravenous chemotherapy (IVC).

Methods: Retrospective chart review of 44 eyes of 42 patients. The indications for plaque brachytherapy included solid tumor recurrence (n=20; 45%), solid tumor residual (n=16; 36%), new subretinal seeds (n=5; 12%), and new solid tumor (n=3; 7%).

Results: The median age at the presentation was 12 months (range, 3-72 months). Based on ICRB classification, 8 (18%), 8 (18%), 16 (36%), and 5 (12%) tumors belonged to Groups B, C, D, and E, respectively. A median interval of 5 months (range 3-21 months) was noted between the last IVC cycle and plaque brachytherapy. The mean tumor height was four mm (range, 1.5-6 mm). All patients were treated with ¹⁰⁶Ru plaque (round or notch) with a median total dose of 45 Gy (range, 40-55 Gy) delivered to the tumor apex. At a mean post plaque follow-up period of 28 months (median, 23 months; range, 3-132 months), tumor completely regressed in 25 eyes (56%). Tumor recurrence within the plaque site was noted in eight eyes (18%) associated with a type 2 regression pattern (75%). At the last follow-up, the globe salvage rate was 24 eyes (55%), while 2 patients (5%) died due to metastasis.

Conclusion: ¹⁰⁶RU plaque brachytherapy can be a useful salvage treatment for focal tumors (new or recurrent) following systemic IVC.

Purpose: Brachytherapy is associated with improved overall survival in cervical cancer patients, but the utilization seems hindered by high costs and relatively low reimbursement, particularly in the US. A one-room brachytherapy suite with CT (ORBT) could optimize the treatment workflow. By eliminating transport and waiting times, limiting applicator movement, and providing real-time applicator placement feedback, treatment time and costs could potentially be reduced. This study assesses the potential value of implementing ORBT in cervical cancer treatment.

Methods and materials: A variable cost model was developed to compare current (multi-room) brachytherapy workflows (MBRT) to ORBT, taking into account staff utilization, staff, equipment and consumables costs and room expenses. Two current care scenarios were simulated; applicator placement performed in the operating room (S1), and applicator placement performed in a brachytherapy suite (S2). For both scenarios literature reported fraction times of MBRT were compared to a range of ORBT times. Sensitivity analyses were performed to determine the influence of input parameters.

Results: In scenario one, the results showed yearly savings of $45,572 up to $339,439 (USD), assuming a 5% and 20% reduction in fraction duration, respectively, in ORBT compared to MRBT. In scenario two, ORBT does not result in costs savings at 5% to 15% improvement. Therefore, only when ORBT results in a >20% improvement of fraction time, cost will be saved.

Conclusions: The results indicate that reducing procedure time (using ORBT) can lead to cost savings, depending on the current workflow. Savings seem to depend mostly on applicator placement location, number of patients per year, and involved personnel.

Purpose: To investigate the occurrence of errors in transrectal ultrasound (TRUS)-based implant reconstructions for high-dose-rate brachytherapy (HDR-BT) in prostate cancer using an afterloader-integrated electromagnetic tracking (EMT) system.

Materials and methods: Fourteen patients were treated with one TRUS-based treatment fraction in an intraoperative setting while under general anesthesia, as part of their prostate HDR-BT (2×13.5 Gy) treatment. EMT measurements were performed before the start of the treatment in all implanted needles at dwell positions (DPs) with an interval of 5 mm. The Euclidean distances (EDs) between clinically reconstructed and EMT-measured DPs after registration were calculated. Errors were evaluated per needle (minimum ED of 2mm) and stratified into 4 severity levels (minor, moderate, major and severe). Error causes were investigated through retrospective inspection of TRUS imaging.

Results: The median (range) ED between EMT-measured and clinically reconstructed DPs was 1.0 (0.1-9.4) mm. Higher EDs were observed in the anterior and lateral regions of the prostate. From 265 evaluated needle reconstructions, 23% (61/265) had minor errors or higher, while 9% (24/265) had major or severe errors. Severe errors were mostly caused by incorrect needle or depth selection. Major, moderate and minor errors were mostly caused by artifact, shadowing, and user errors, respectively.

Conclusions: This study found that a quarter of needle reconstructions contained errors >2mm, and that high and severe errors were not uncommon. EMT can play an important role in detecting and preventing these reconstruction errors without disrupting the clinical workflow.