Journal of Contemporary Brachytherapy最新文献

Purpose: This consensus statement of Indian Brachytherapy Society (IBS) aims to generate practical and reproducible guidelines allowing for direct implementation in the Indian scenario.

Material and methods: IBS board of directors appointed a panel of physicians with expertise in breast cancer and, in particular, breast brachytherapy, to develop a consensus statement. First, a literature review on breast brachytherapy was conducted, focusing on randomized trials, prospective studies, and multi-institutional series. Then, guidelines were drafted based on authors' consensus according to Indian scenario.

Results: IBS advocate accelerated partial breast irradiation (APBI) with brachytherapy following breast conservation surgery (BCS) for suitable groups of patients. Also, IBS recommends brachytherapy as the preferred technique for patients requiring tumor bed boost. Multi-catheter interstitial brachytherapy (MIB) is suitable in most situations, except for a large tumor to breast ratio, and type 2 oncoplasty or higher performed. For best cosmesis, IBS recommends a minimum 3-week gap between chemotherapy and APBI.

Conclusions: Brachytherapy continues to be an established technique for APBI as well as boost in appropriately selected patients with early breast cancer (EBC). As breast brachytherapy is an underutilized therapy in the Indian context, this article will hopefully encourage the readers to use its clinical potential in the suitable groups of patients.

Historically, several classification systems have been used for brachytherapy, and they were based on the type of clinical purpose, type of implant and timing of the implant, dose-rate, and type of loading for treatment delivery. However, over the last decades, there have been some major technological advancements, including the introduction of image-guidance and possibility to modulate the dose delivered, which have led several authors (in order to highlight the differences between old technique and new approach) to label it in a different way by replacing "brachytherapy" with "interventional radiotherapy". Modern interventional procedures involve several key aspects, which contribute to the complexity of implant phase, such as implant type, imaging used during the procedure, and role of multi-disciplinary team in operating room. By assigning scores to these procedural elements, it is possible to classify the procedure's complexity using a COMIRI classification (COMplexity Index of interventional Radiotherapy Implants). The aim of the COMIRI classification system is to appropriately highlight the need for suitable resources based on the complexity level of different procedures in terms of personnel expertise, equipment availability, and multi-disciplinary teamwork.

Purpose: Electromagnetic tracking (EMT) has great potential as a quality assurance tool in interstitial brachytherapy. Since its clinical application in most cases comprises a comparison with brachytherapy plan data, EMT registration and plan data are crucial. Registration uncertainties influence EMT outcomes and further decision-making processes. The impact of registration using four algorithms on the resulting data was investigated.

Material and methods: Registration abilities of four sub-algorithms, which share the same principle of an iterative closest point approach were considered. Sub-algorithms differ regarding underlying mathematical norms, and also include a non-geometric implementation focusing on stochastic optimization. This study focused on the registration of point clouds originating from data obtained during treatment with interstitial brachytherapy in breast cancer patients. Data were acquired from a hybrid device prototype, capable of EMT measurements and data extracted from treatment plan. Main criteria for good registration performance were good geometric agreement, including low Euclidean distances between registered data sets as well as short registration time. In addition, previously published patient data with different than employed in the original publication algorithm were re-analyzed to further investigate the impact of registration method on clinically influential results.

Results: The stochastic algorithm presented much higher registration times, and earliest implementation of geometric approaches occasionally misaligned patient data. The remaining two algorithms performed almost identically resulted in sufficiently accurate registration performance. The re-analysis of previously published data demonstrated minor inconsistencies between former registration method and different algorithm; however, the overall trends with almost identical mean Euclidean distance of 2.22 mm (2.19 mm in the original work) could be reproduced.

Conclusions: The choice of registration algorithm can influence the quality of registration. Therefore, it is advised to regularly examine the registration performance, especially in in-house programs.

A case report of non-classical treatment choice for mycosis fungoides (MF) presented on the left upper eyelid and forehead. Superficial brachytherapy using 3D technique was prescribed to preserve the lens's functionality, and successfully eliminate malignant lesion. Treatment was conducted with high-dose-rate (HDR) brachytherapy using iridium-192 (¹⁹²Ir) source as a base and Flexitron device as an afterloader. Applicators were immobilized and located near the lesion by manually shaped molds. Doses were calculated using Oncentra treatment planning system (ELEKTA^®) with 3D models based on CT scans. A 12-month follow-up showed sustained remission without any late toxicity or recurrence of MF skin lesions on the face. The proposed approach utilizing superficial, mold-based HDR brachytherapy to navigate anatomical challenges is demonstrated to be a clinically effective treatment option for MF of the lower eyelid or other dose-limiting locations.

Purpose: While the benefit of short-term androgen deprivation therapy (ADT) has been established for patients with intermediate-risk (IR) prostate cancer (PCa) receiving dose-escalated external beam radiation therapy (EBRT), the role of ADT for patients treated with brachytherapy (BT) with or without supplemental EBRT (sEBRT) is less clear.

Material and methods: We conducted a single-institution retrospective analysis of men with National Comprehensive Cancer Network (NCCN) unfavorable IR (UIR) PCa. All patients received BT with or without sEBRT, and were stratified by the receipt of 4-6 months of ADT. Kaplan-Meier method was used to measure biochemical progression- free survival (bPFS) between men who did vs. did not receive ADT. Multivariable Cox proportional hazards with backward selection was utilized to determine association of concomitant ADT with bPFS accounting for confounding variables.

Results: We identified 201 eligible patients treated between 2002 and 2019, 78 (38.8%) of whom received ADT. Median follow-up was 15 years. On univariable analysis, there was no significant association of ADT use with bPFS (HR = 0.95, 95% CI: 0.34-2.63, p = 0.92). Only PSA ≥ 10 was significant for association with worse bPFS (HR = 3.51, 95% CI: 1.29-9.52, p = 0.014). On multivariable analysis, there was no association of ADT use with bPFS (HR = 0.97, 95% CI: 0.34-2.78, p = 0.96).

Conclusions: Short-course ADT was not associated with improved bPFS in our study among men with UIR PCa treated with BT with or without sEBRT. These findings suggest that dose intensification achieved with BT may alone be sufficient in treating selected patients with UIR disease, but prospective studies are warranted.

Purpose: The present study evaluated the dosimetric impact and compared the dose variations between the advanced collapsed cone engine (Task Group 186) and Task Group 43 plans for cervical cancer using tandem and ovoid applicators.

Material and methods: Thirty cervical cancer patients underwent iridium-192 (¹⁹²Ir) high-dose-rate (HDR) intra-cavitary brachytherapy using tandem and ovoid applicator. Original treatment plans for all patients were created using TG-43 dose calculation formalism. Subsequently, these plans were re-calculated using ACE (TG-186) algorithm and were not re-optimized, so that dwell time and dwell positions were identical in both plans. High-risk clinical target volume and organs at risk were contoured in each dataset. Significant air gaps within region of interest and use of high density applicator materials were also considered. The assessment encompassed a point-based evaluation, extraction of dosimetric parameters from dose-volume histogram (DVH), and plan evaluation indices for each algorithm.

Results: Compared with ACE (TG-186) plans, TG-43 plans predicted higher doses for point A, point B, D₉₀, D₁₀₀, V₁₀₀, V₁₅₀, V₂₀₀, and V₃₀₀ for HR-CTV (p < 0.05). Similarly, TG-43 plans indicated higher doses for bladder point, rectum point, D_0.1cm ³, D_10cm ³, and D_2cm ³ for bladder, rectum, and sigmoid (p < 0.05). Additionally, overall plan quality score (PQS) was significantly greater in plans calculated with ACE (TG-186) formalism than in TG-43 plans (p < 0.05). In TG-186 (ACE) plans, gradient index (GI) was found to be lower than that in TG-43 plans (p < 0.05).

Conclusions: TG-43 tends to overestimate doses compared with ACE (TG-186); nonetheless, both methods meet clinical standards. Material differences in the applicator are notable, and dose overestimations by TG-43 are within 5%.

Purpose: The aim of this study was a retrospective dosimetric comparison of iridium-192 (¹⁹²Ir) high-dose-rate (HDR) interstitial brachytherapy plans using model-based dose calculation algorithm (MBDCA) following TG-186 recommendations and TG-43 dosimetry protocol for breast, head-and-neck, and lung patient cohorts, with various treatment concepts and prescriptions.

Material and methods: In this study, 59 interstitial ¹⁹²Ir HDR brachytherapy cases treated in our center (22 breast, 22 head and neck, and 15 lung) were retrospectively selected and re-calculated with TG-43 dosimetry protocol as well as with Acuros^TM BV dose calculation algorithm, with dose to medium option based on computed tomography images. Treatment planning dose volume parameter differences were determined and their significance was assessed.

Results: For the breast planning target volume (PTV), TG-43 formalism calculated higher D_90%, V_95%, V_100%, and V_150% values than Acuros^TM BV, ranging from 2.2% to 5.4% (mean differences), as it did for the head and neck cases, ranging from 2.5% to 4.7% and for the interstitial lung cases, ranging from 2.2% to 4.4%, showing statistical significance (p < 0.001). For the skin D_0.1cm3, D_0.2cm3, and D_1cm3, the values were overestimated by TG-43, with a mean absolute differences of 1.4, 1.8, and 2.0 Gy, respectively for the breast, and 1.0 Gy for all DVH statistics for the head and neck cases compared with Acuros^TM BV (p < 0.001). Ipsilateral lung V_5Gy was also higher in TG-43-calculated plans, with a mean difference of 1.0% and 1.1% in the breast and lung implants, respectively. For the chest wall TG-43, the respective overestimation in D_0.1cm3 and D_1cm3 was 0.8 and 0.8 Gy for the breast, and 0.4 and 0.3 Gy for the interstitial lung cases, respectively.

Conclusions: The TG-43 algorithm significantly overestimates the dose to PTVs and surrounding organs at risk (OARs) for breast, head and neck, and lung interstitial implants. TG-43 overestimation is in accordance with previous findings for breast and head and neck. To our knowledge, this is also exhibited for Acuros^TM BV for the first time in interstitial lung HDR brachytherapy.

Purpose: This retrospective study aimed to investigate the influence of bladder filling type (BFT) on the relationship between bladder volume (BV) and maximum absorbed dose (D_2cc) in intra-cavitary brachytherapy (ICBT) for cervical cancer.

Material and methods: The study enrolled 269 patients who underwent 3D-optimized ICBT guided by MRI scans between 2016 and 2022. Bladder shape (categorized as tilted, curved, or E) was determined based on specific applicators used. D_2cc values were recorded for critical organs, such as bladder, rectum, sigmoid colon, and small bowel.

Results: The tilted group exhibited lower D_2cc values for the small bowel when BV was less than 400 cc, while still ensuring minimal doses to the rectum and sigmoid colon. In the curved group (BV ≤ 100 cc), significant variations in D_2cc for organs at risk were observed. However, in the E group, no substantial correlation between BV and D_2cc was identified (p = -0.035). Additionally, the mean mid-sagittal line differences in the tilted group were 8.47 mm (pre-ICBT) and 7.11 mm (during ICBT simulation), surpassing measurements in the other two groups.

Conclusions: This study underscores the substantial impact of bladder shape on both the optimal bladder filling volume and maximum absorbed dose in cervical cancer ICBT. The implementation of BFT based on pre-ICBT MRI scans is both practical and beneficial. It accentuates the necessity of accounting for bladder shape when determining appropriate bladder filling volume, thus facilitating effective management of bladder and small bowel doses. Further prospective studies are warranted to assess the effect of BFT on the incidence of cystitis and proctitis following ICBT, all while maintaining consistent bladder distension.

Purpose: The aim of this study was to investigate the predictive value of radiomic features of pre-treatment T2-weighted magnetic resonance images (MRI) for clinical outcomes of radiotherapy in cervical cancer patients.

Material and methods: Ninety cervical cancer patients with stage IB-IVA were retrospectively analyzed. All patients received definitive radiotherapy with or without concurrent chemotherapy. Radiomic features were extracted from gross tumor volume (GTV) on pre-treatment T2-weighted MRI. The association between radiomic features and loco-regional recurrence (LRR) was analyzed with Student's t test, and false discovery rate was controlled using Storey method. Multivariate analysis with significant radiomic features with p-value < 0.01 and known clinical prognostic factors was performed using Cox proportional hazard model.

Results: The majority of patients were stage IIIB (47.8%) and stage IIB (36.7%), and the most common histology was squamous cell carcinoma (74.5%). The median GTV volume was 37.5 ml (IQR, 16.3-93.1). The median dose of D₉₀ received by high-risk clinical target volume (HR-CTV) was 86.2 Gy (IQR, 67.2-94.2). In a median follow-up time of 29.2 months, 12 of the 90 patients (13.3%) developed LRR. Eighty radiomic features were collected. There were four radiomic features, which showed significant correlation with LRR: Maximum intensity (p = 0.0002), Correlation135 GLCM (p = 0.0014), Correlation90 (p = 0.0015), and Correlation45 (p = 0.0034). Cox regression analysis yielded a significant hazard ratio for the maximum intensity (p = 0.038) and Correlation135 GLCM (p = 0.013) features. There was no statistically significant association for overall survival with any radiomic features.

Conclusions: The maximum intensity and Correlation135 GLCM radiomic features of the pre-treatment T2-weighted MR images are predictive of loco-regional recurrence in cervical cancer patients after definitive radiotherapy with 3D-IGABT.

Purpose: External beam radiotherapy with concurrent chemotherapy combined with brachytherapy has been described as the first treatment choice for locally advanced cervical cancer. This study aimed to systematically review the dose-effect relationship (DER) of target volumes and organs at risk (OARs) in external beam radiotherapy combined with brachytherapy for cervical cancer.

Material and methods: Studies reporting DER in radical radiotherapy for cervical cancer were determined by searching PubMed, Web of Science, and Cochrane Library databases till Jan 20, 2023. Dose parameters of DER, end-point of tumor control or type and grade of side effects of OARs as well as prediction results were analyzed from included studies. Coordinates of DER curves from the included studies were extracted and DER curves were reconstructed in the same coordinate system for comparison.

Results: Thirty studies, including eleven dose-response relationships for clinical end-points, and nineteen dose-toxicity relationships for OARs were evaluated in systematic review. The most common dose-response relationship between the same dose parameter and the same clinical end-point was HR-CTV D₉₀ vs. local tumor control, while it was D_2cc of rectum versus rectal grade 2-4 side effects for dose-toxicity relationship.

Conclusions: In the radical radiotherapy of cervical cancer, there were significant DERs for target volumes and OARs. Considering the interference of these factors, DERs in sub-group patients would provide precise and individualized dose constraints of radiotherapy for cervical cancer in the future.