Journal of Contemporary Brachytherapy最新文献

Purpose: To evaluate the safety and efficacy of computed tomography (CT)-guided iridium-192 (¹⁹²Ir) high-dose-rate (HDR) interstitial brachytherapy (ISBT) for pleural and chest wall malignant tumours.

Material and methods: This single-centre retrospective cohort study involved 21 patients with pleural/chest wall malignant tumours treated between January 2024 and January 2025. All patients underwent HDR ISBT (30 Gy in a single fraction). Treatment included CT-guided needle implantation, three-dimensional dose optimisation (Oncentra system), and adherence to Radiation Therapy Oncology Group dose constraints for organs at risk (OARs). Efficacy endpoints included objective response (Response Evaluation Criteria in Solid Tumours v1.1), pain relief (Numerical Rating Scale), and dosimetric comparison with virtual stereotactic body radiotherapy. Safety was assessed using the Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer toxicity criteria.

Results: The median follow-up duration was 7.48 months. The objective response rate (complete response + partial response) was 76.19%, with 28.57% achieving a complete response and 47.62% achieving a partial response. Pain relief was achieved in 87.5% of patients with pretreatment pain, with numerical rating scale scores decreasing from moderate to severe (median, 6) to mild (median, 3) at 1 month. No ≥ grade II complications (e.g. bronchopleural fistula, pneumothorax) occurred; only four patients experienced minor subcutaneous haemorrhage/emphysema. Dosimetric analysis showed a significantly higher target mean dose with ISBT than with stereotactic body radiotherapy (p < 0.001), while OARs doses (e.g. lungs, heart, spinal cord) remained within Radiation Therapy Oncology Group limits. Rib and chest wall dose exceedances were rare and clinically insignificant.

Conclusions: Computed tomography-guided ¹⁹²Ir HDR ISBT offers safe, effective local control and rapid pain relief for pleural/chest wall tumours, demonstrating superior dosimetric conformity and lower toxicity to OARs. This minimally invasive approach is a viable option for patients unsuitable for surgery or external beam radiotherapy.

Purpose: Brachytherapy is a well-established modality in oncology, particularly for prostate and cervical cancers, offering precise radiation delivery while sparing healthy tissues. Despite its clinical benefits, the research trajectory of brachytherapy in clinical trials remains underexplored. This bibliometric analysis aimed to assess publication trends, research focus areas, and citation impact of prospective clinical trials on brachytherapy.

Material and methods: A bibliometric analysis was conducted using Web of Science database. Clinical trials were identified with key words "brachytherapy" and "prospective", without time restrictions. Bibliometric parameters analyzed included year of publication, journal distribution, authorship, institutional and geographical contributions, citation metrics, and disease focus.

Results: A total of 84 clinical trials published between 1982 and 2024 were analyzed. The United States was the leading contributor (44.0%). Prostate cancer was the most frequently studied malignancy (35.7%), followed by breast (15.5%) and gynecologic cancers (13.1%). The "International Journal of Radiation Oncology, Biology, Physics" published the most trials. Citation analysis showed significant differences among cancer types, with soft tissue sarcoma studies having the highest median citation count (p < 0.05).

Conclusions: While clinical trial research in brachytherapy has expanded over time, notable disparities in research intensity and citation impact exist among disease sites. Greater attention to underrepresented malignancies, along with sustained investment, interdisciplinary collaboration, and enhanced training, is needed to advance the role of brachytherapy in cancer care.

Purpose: For locally advanced cervical cancer (LACC), the addition of brachytherapy (BT) improves overall survival (OS), and interstitial BT has been prospectively shown to improve target and organ at risk dose. Brachytherapy is less common in patients without insurance, underrepresented minorities, and in low-volume cancer centers, which may in turn widen cancer disparities. In this study, we utilized the National Cancer Database (NCDB) to examine the patterns and predictors of interstitial brachytherapy in patients with LACC, and its impact on OS.

Material and methods: Patients with LACC (stage IIB-IVA) diagnosed between 2004-2018 and treated with radiation were included. A logistic regression model was fit with the predictors, such as race, nodes, T-stage, facility type, age, and Charlson-Deyo score, to estimate the probability of receiving interstitial brachytherapy treatment and to calculate propensity scores. Cox regression model was defined using the calculated propensity scores as a covariate to examine the effect of brachytherapy group on OS.

Results: In the study, 9,829 patients were included, and 15% of them received interstitial BT. On multivariable analysis, a higher stage and treatment at an academic center were associated with increased interstitial BT. African American patients and those with positive nodes were less likely to receive interstitial BT. After propensity score matching, there was no OS difference between patient treated with interstitial vs. intracavitary BT (HR: 0.985, p = 0.734).

Conclusions: Our work supports the growing body of literature on BT utilization impacted by patient race and treatment facility. Patients with a higher stage of cervical cancer and those treated at a high volume or academic center were more likely to receive interstitial BT, reflecting appropriate intensification of therapy for larger tumors. Interstitial BT did not indicate an OS benefit. Further study could lead to improved understanding of barriers to accessing interstitial brachytherapy.

Purpose: Total dose assessment for cervical cancer necessitates converting external beam radiotherapy (EBRT) and brachytherapy (BT) doses to equivalent doses in 2 Gy fractions (EQD₂), and compare them with dose constraints. However, this feature is absent in current treatment planning systems. To address this, we developed a system fulfilling this need, and evaluated its dosimetric impact.

Material and methods: The system can assess total dose by considering EQD₂ for targets and organs at risk (OARs), and provide ideal fractionated dose that satisfies dose constraints in each process. The current retrospective study included 82 cervical cancer patients treated with EBRT and four BT fractions. Forty-one patients were assigned to either of two groups (with or without system). These groups were compared with typical dosimetry parameters (DPs) for high-risk clinical target volume (HR-CTV), rectum, bladder, and percentage of dose constraint achievement of DPs to reveal dosimetric impact of the system. Sub-group analysis included 61 patients with HR-CTV doses of < 85 Gy to examine whether treatment planning was adequate with or without the system.

Results: The DP for HR-CTV was similar across BTs, but for OARs, it was statistically significantly lower in the group with system (p < 0.001) than in the other group. Also, the group with system had a higher percentage of cases meeting HR-CTV dose constraints (p = 0.02), with no variation in OARs. Sub-group analysis revealed better adherence to dose constraints in the group with system for each BT compared with the other group.

Conclusions: System usage would facilitate a balanced plan, increasing clinical target volume coverage as much as possible, while considering dose constraints of OARs.

Purpose: Timely and accurate delineation of the clinical target volume (CTV) in brachytherapy after parotid cancer surgery plays a crucial role in tailored delivery of radiation doses. This study aimed to develop and evaluate a deep learning-based model for auto-segmentation of the CTVs in postoperative adjuvant brachytherapy for patients with parotid gland cancer, addressing the challenge of achieving consistent, high-quality CTV delineations efficiently.

Material and methods: Using clinical imaging data from 326 patients with parotid gland carcinoma treated at Peking University School and Hospital of Stomatology between 2017 and 2023, we established a training dataset of 213 cases, a validation set of 53 cases, and a test set of 60 cases. The CTVs on the images were segmented using 3D Res-UNet, a deep learning model, and compared against manual delineations performed by experienced radiation oncologists. The performance of 3D Res-UNet was optimized through a comprehensive preprocessing and training process tailored to the dataset's characteristics.

Results: The deep learning model yielded a significant improvement in segmentation efficiency. The deep learning model generated initial CTV contours in 9.4 seconds of computational time. Subsequent expert review and minor adjustments required an average of 11.9 minutes, substantially shorter than the 46.7 minutes needed for fully manual delineation. Quantitative analysis showed that the Dice similarity coefficient (DSC) of automatic segmentation by 3D Res-UNet was 0.709, which improved to 0.924 after expert review. Qualitative evaluation by senior oncologists further affirmed the clinical acceptability of the automatically segmented CTVs.

Conclusions: Automatic contouring with physician review enabled high-accuracy and rapid CTV generation, reducing the overall delineation workload by more than 30 minutes. Consequently, the proposed deep-learning model functions as a useful support tool that streamlines postoperative adjuvant brachytherapy planning for parotid gland cancer and lessens the burden on radiation oncologists, thereby contributing to improved patient care.

Purpose: The aim of this paper was to present the measured photon fluence spectra emitted by the electronic brachytherapy (eBT) unit Papillon 50.

Material and methods: Spectra were collected with a compact CdTe spectrometer in air at a distance of 52 cm from the unit output window, for three different applicators attached to the unit and at several angles with respect to the beam axis.

Results: The fluence spectra recorded for this device showed lower energy of the photon spectrum end-point than anticipated. The end-point energy was found to be (47.6 ±0.2) keV for the nominal high voltage bias of 50 kV set by the operator. Full-energy peaks in the spectra identified characteristic photons emitted by the rhenium anode, and by molybdenum and silver supposedly present in the inner coating of the applicators. An asymmetry in the half-value layer values of measured spectra was observed.

Conclusions: The presented work provides a comprehensive dataset of photon fluence spectra for traceable dosimetry using the Papillon 50 eBT device, which is required, for example, for correcting the energy dependence of detectors or as an input for Monte Carlo calculations. Spectrometry and dose characterization studies are needed for eBT systems.

Purpose: This study aimed to evaluate applicator displacement due to patient transfer using traditional fixation (TRD) with and without patient transfer system (TS), and to assess its dosimetric impact on organs at risk (OARs).

Material and methods: Computed tomography (CT) images, including high-risk clinical target volume (HR-CTV) and OARs structures, were analyzed from 46 treatment plans involving 32 patients undergoing intracavitary brachytherapy with tandem-ovoid applicator, using either traditional fixation (TRD) alone or in combination with patient transfer system (TRD + TS). Applicator displacement was assessed by measuring the distance between applicator base in two sets of CT images: one acquired during treatment planning (pre-plan), and second at dose delivery (pre-load). Dosimetric impact was evaluated for each simulated applicator shift.

Results: The use of TRD + TS resulted in reduced applicator displacement compared with TRD alone. The mean magnitude of displacement decreased from 2.94 mm to 1.43 mm laterally, from 3.17 mm to 1.83 mm in the anterior-posterior direction, and from 3.45 mm to 2.00 mm longitudinally. Regarding dose variations to D_2cc for the bladder, rectum, sigmoid, and bowel, the average dose increases were 0.54%, 8.39%, 3.78%, and 0.58% for TRD, and 3.19%, 1.66%, 2.83%, and 1.19% for TRD + TS, respectively. No statistically significant difference was observed in either applicator displacement or radiation dose to OAR between the two systems.

Conclusions: The combination of traditional fixation and patient transfer system have the potential to reduce applicator displacement, thereby enhancing treatment accuracy. However, in this study, no statistically significant difference was observed when compared with our traditional fixation method.

Purpose: A keloid is a benign fibro-dermal tumor that produces an excess deposit of extra-cellular matrix. It usually occurs after a skin lesion, and it spreads beyond the wound. It is characterized by high recurrence rate after excision and lack of tendency of spontaneous involution. Multiple treatments have been described, with recurrence rates of up to 100%. One of the treatments considered most effective is combined therapy, i.e., surgery and subsequent radiotherapy using interstitial irradiation with iridium-192 (brachytherapy), with a clear reduction in recurrence rate.

Material and methods: In our center, the technique was introduced in 2012, and the current retrospective observational study was conducted among 27 patients treated till December 2020.

Results: The recurrence rate in the study was 25%, of which 83% recurred partially.

Conclusions: The most frequent complications observed were dehiscence and infection of the surgical wound, therefore this therapeutic approach can be considered both safe and effective.

Purpose: To compare the economic and dosimetric aspects of electronic brachytherapy (eBT) and high-dose-rate (HDR) iridium-192 (¹⁹²Ir) brachytherapy for exclusive vaginal cuff treatment in post-operative endometrial cancer patients.

Material and methods: This retrospective observational study was conducted among 115 patients treated with eBT and 70 patients treated with HDR ¹⁹²Ir between 2019 and 2023 at two institutions. All patients underwent 3 fractions of 7 Gy prescribed to a uniform target volume. Dosimetric parameters, including D₉₀, V₁₅₀, and V₂₀₀ for high-risk clinical target volume (HR-CTV) as well as D_2cc, D_1cc, and D_0.1cc for organs at risk (OARs), such as bladder, rectum, and sigmoid colon, were compared. Economic analysis focused solely on cost differences related to source replacement and maintenance, as all other procedural factors (i.e., personnel, clinical workflow, and logistics) were identical for both modalities. The cost of bunker was not considered in the analysis.

Results: Dosimetric analysis revealed comparable target volume coverage between eBT and HDR ¹⁹²Ir. The economic evaluation was focused on cost differences and their relative contributions. The relative average cost per patient under these assumptions was 18.4% lower for eBT (€273.9) than for HDR ¹⁹²Ir, based on Spanish pricing, largely due to differences in source-related expenditures.

Conclusions: While ¹⁹²Ir HDR remains the standard in brachytherapy due to its versatility, eBT presents a cost-benefit alternative for exclusive vaginal cuff treatments, particularly in settings where infrastructure limitations restrict isotope-based brachytherapy. These findings support the complementary role of eBT in clinical practice, optimizing resource allocation without compromising dosimetric quality.