Brachytherapy最新文献

Background: Cervical cancer is the second most common cancer among women in Nigeria where, the gap between need for, and access to, radiation therapy including brachytherapy is significant. This report documents the implementation of the first three-dimensional high-dose-rate (3D-HDR) brachytherapy service for cervical cancer in Nigeria.

Purpose: This report details the steps taken to implement the 3D-HDR brachytherapy program, the challenges faced, and the adaptive strategies employed to overcome them. Our objective is to provide a guide for teams and centers in similar resource-restricted settings to implement 3D-HDR brachytherapy services, by leveraging our shared experience and lessons learned.

Method and meterials: The implementation process required investment in infrastructure: creating a dedicated brachytherapy suite equipped with modern technology; and human capital: conducting both virtual and hands-on training for staff; and involving international experts during the initial treatment phases. Quality assurance protocols were established to ensure the accuracy and safety of treatments. Key adaptations included extensive remote training, international experts flying in for the initiation phase, and preemptively re-ordering the radioisotope to prevent delays.

Results: The 3D-HDR brachytherapy program was successfully implemented, with five cases treated in the first 2 months despite challenges such as high equipment costs, expertise and proficiency needs, and source replacement delays. Continuous training and quality assurance measures ensured the program's sustainability and effectiveness.

Conclusions: Implementing a 3D-HDR brachytherapy program in a system with restricted resources is possible with thorough planning, flexible strategies, and adaptive measures. We document our experience to provide insights for other institutions aiming to establish similar programs. Collaboration and innovative financial strategies are essential for ensuring sustainable access to cancer treatment in the region. Strategies such as remote training and proactive resource management, are critical for overcoming implementation barriers.

Background and purpose: Cervical cancer is the most prevalent type of cancer among women in numerous low and middle-income countries. Tandem-based applicator is a widely used technique in High Dose Rate Intercavitary Brachytherapy (HDR-ICBT) for treating cervical cancer. For cases where central tandem insertion is not feasible due to patient-specific conditions, a ring-only applicator is used as an alternative. This paper presents an assessment of the impacts of dose distribution on cervical cancer treatment using HDR-ICBT without a central tandem applicator.

Materials and method: Total 30 patients with cervical cancer (stage IB to IVA) who received brachytherapy with a ring applicator alone were singled out and used in the study. Orthogonal radiographs were used during dose treatment planning.

Results: Results indicate that the dose normalized to the Equivalent dose in 2 Gy fractions (EQD2) at Manchester Dosimetry System (MDS) point A was 60.60 ± 1.08 Gy, which is significantly below the recommended curative dose of 80 Gy. This suggests that relying solely on a ring applicator may not provide enough radiation doses to the tumor. The results also show that the International Commission on Radiation Units (ICRU) dose point underestimated the radiation doses to the bladder and rectum, with the ratios of maximum dose (D_Max) to D_ICRU for both organs being 1.15.

Conclusion: The study underscores the importance of not exclusively depending on a ring applicator alone in HDR-ICBT treatment for cervical cancer, as it may lead to suboptimal tumor doses. The ICRU point's results show an underestimation of the rectum and bladder dose during HDR-ICBT.

Purpose: To evaluate treatment outcomes and toxicity in patients with stage T1-3N0M0 oral cancer treated with surgery followed by high-dose-rate brachytherapy (HDR-BT).

Methods and materials: Retrospective study of 50 patients with stage T1-T3N0 tongue and floor-of-mouth cancer who underwent tumour excision (+ elective neck dissection) followed by postoperative HDR-BT due to the presence of negative prognostic factors (close or positive resection margins, lymphovascular and/or perineural invasion, deep invasion). The plastic tube technique (dose: 18 x 3 Gy b.i.d.) was used. Survival outcomes, toxicity, and prognostic factors were evaluated.

Results: At a median follow-up of 81 months (range, 4-121), actuarial 5-year local control (LC), nodal control (NC) and progression-free survival (PFS) rates were 79%, 69%, and 64%. After salvage treatment (surgery + external beam radiotherapy), LC, NC, and PFS increased to 87%, 77%, and 72.3%, respectively. Five-year overall survival and cancer-specific survival (CSS) rates were 73% and 77%. Treatmentrelated toxicity included two cases of mandibular osteoradionecrosis and five cases of small soft tissue necrosis. T stage was significantly correlated with nodal control (p=0.02) and CSS (p=0.04). Tumour grade correlated with DFS (p=0.01).

Conclusion: Postoperative HDR-BT 18 x 3 Gy b.i.d. seems to be an effective method in patients with T1-3N0M0 oral cancer with negative prognostic factors after tumour resection.

Aim: To demonstrate how workshop and mentoring across a network of radiotherapy centers helped in transitioning from point A to volume-based image guided brachytherapy in carcinoma cervix.

Materials and methods: Based on discussion with different centers across the network, the lapses in cervical cancer treatment were identified and a workshop was designed to change the practice pattern. The main focus of the workshop was to streamline EBRT dose prescription protocols and implement volume based image guided brachytherapy through mentoring and hands on training. Patient data was analyzed 1 year post workshop to assess the impact in changing practice pattern.

Results: A total of 246 cervical cancer patients treated with radical chemo radiotherapy and image guided brachytherapy were analyzed. 207 patients received CT based intracavitary brachytherapy whereas 39 patients received MR based hybrid brachytherapy. In patients who received EBRT and brachytherapy at the same center, the EBRT prescription dose was 45Gy in 25 fractions in 95% patients. The mean dose received by 90% of the HRCTV was 80.8Gy EQD2 in CT based intracavitary brachytherapy and 89.48Gy EQD2 in MR based hybrid brachytherapy. The mean bladder, rectum, sigmoid and small bowel D2cc doses were 63.87Gy, 62.18Gy, 61.2Gy and 55.1Gy EQD2 respectively.

Conclusion: This report demonstrates successful implementation and change of carcinoma cervix treatment practice pattern through workshop and mentoring across a network of radiotherapy centers in India.

Purpose: The purpose of this study was to compare the effect of catheter shift errors and determine patient specific error thresholds (PSETs) for different high dose rate prostate brachytherapy (HDRPBT) plans generated by different forms of inverse optimization.

Methods: Three plans were generated for 50 HDRPBT patients and PSETs were determined for each of the 3 plans. Plan 1 was the original Oncentra Prostate (v4.2.2.4, Elekta Brachytherapy, Veenendaal, The Netherlands) plan, the second plan used the graphical processor unit multi-criteria optimization (gMCO) algorithm, and plan 3 used gMCO but had a robustness parameter as an additional optimization criterion (gMCOr). gMCO and gMCOr plans were selected from a pool of 2000 pareto optimal plans. gMCO plan selection involved increasing prostate V100% and reducing rectum Dmax/urethra D01.cc progressively until only 1 plan remained. The gMCOr plan was the most robust plan (using robustness parameter) that met the clinical DVH criteria (V100% ≥ 95%, rectum Dmax ≤ 80%, urethra D0.1cc ≤ 118%). PSETs were determined using catheter shift software.

Results: The initial dose volume histogram (DVH) characteristics showed all 50 patient plans met a prostate V100% > 95% and resulted in significant reduction in rectum Dmax and urethra D0.1cc for gMCO and gMCOr plans. No single plan showed benefits in PSETs for all shift directions compared to the other plans, however gMCO and gMCOr plans exhibit the best initial DVH characteristics assuming no errors occur. The robustness parameter showed no significant impact when considered in plan optimization.

Conclusions: PSETs were found to be equivalent regardless of optimization method. Indicating, no single optimization method can significantly increase the patient specific thresholds.

Purpose: To present long-term toxicity and effectiveness outcomes of three prostate high-dose-rate (HDR) brachytherapy schedules: 38 Gy in 4 fractions, 24 Gy in 2 fractions, and 27 Gy in 2 fractions for men with low- or intermediate-risk prostate cancer.

Methods and materials: Patients treated with HDR brachytherapy monotherapy for prostate cancer were identified in a prospectively maintained, single institution database. Patients with AJCC T-stage ≤ T2b, Gleason score ≤ 7, prostate-specific antigen level ≤ 20 ng/mL, and ≥2 years of follow-up were included.

Results: 671 patients were evaluated. 310 patients received 38 Gy in 4 fractions, 129 received 24 Gy in 2 fractions, and 232 received 27 Gy in 2 fractions. Median follow-up was 12.8 years, 10.6 years, and 8.1 years (p < 0.001), respectively. 231 (74.5%), 92 (71.3%), and 81 (34.9%) patients (p < 0.001) had low-risk disease. Rates of acute grade ≥2 GU toxicity were 11.1%, 12.3%, and 25.0% (p = 0.004), while chronic grade ≥2 GU toxicity were 17.0%, 22.6%, and 26.5% (p = 0.06). For low-risk patients, 10-year overall survival (OS), freedom from biochemical failure (ffBF), local control (LC), and freedom from distant metastasis (ffDM) were 86.6%, 93.3%, 97.9%, and 99.3%. For intermediate-risk patients, 10-year OS, ffBF, LC, and ffDM were 89.5%, 82.6%, 90.5%, and 97.4%. Higher PSA, higher Gleason score, perineural invasion, and 24 Gy or 27 Gy treatment schedules were predictors of biochemical failure.

Conclusions: HDR brachytherapy monotherapy with 38 Gy in 4 fractions was associated with improved long-term ffBF compared with 24 Gy/27 Gy in 2 fractions, without any associated increase in GI or GU toxicity rates.

Purpose: This study aims to evaluate the outcomes of patients treated for low-risk (LR) and favorable intermediate risk (FIR) prostate cancer with brachytherapy (BT) in monotherapy with LDR or HDR and its relationship with nadir PSA (nPSA).

Materials and methods: We retrospectively analyzed 139 patients (2005-2019) with exclusive LDR (46%. 145/160 Gy) /HDR (54%. 2 implants of 13.5 Gy each separated 10 days). 69% LR and 31% FIR. PSA nadir was grouped into two categories: ≤ 0.2 ng/mL and > 0.2 ng/mL.

Results: Median patient age was 69 years (46-84). Seventy-six patients (55%) received androgen deprivation therapy, and 37% received neoadjuvant therapy. Median follow-up period was 90 months. Actuarial biochemical failure-free survival (BFFS), local control (LC), overall survival (OS), and cause-specific survival (CSS) rates for the total cohort were 78%, 87%, 68%, and 98% at 10 years, respectively. BFFS, LC, OS and CSS in nPSA ≤ 0,2 ng/ml was 90%, 96%, 67%, 100% at 10 years respectively, whereas, those with a nPSA > 0.2 ng/ml had a BFFS, LC, OS and CSS of was 37%, 51%, 72%, 90% at 10 years respectively Statistical significance between both groups was reached in BFFS (p=0,000), LC (p=0,000) and CSS (p=0,007)). In the univariate analysis, there was no difference between risk stratification, BT technique, ADT, or the development of bouncing.

Conclusions: Prostate brachytherapy as monotherapy (LDR and HDR) is an effective treatment option for patients with LR and FIR prostate cancer. nPSA ≤0,2 ng/ml is a representative value that provides prognostic information for favorable outcomes in this group of patients.

Background: Poor needle placement in prostate high-dose-rate brachytherapy (HDR-BT) results in sub-optimal dosimetry and mentally predicting these effects during HDR-BT is difficult, creating a barrier to widespread availability of high-quality prostate HDR-BT.

Purpose: To provide earlier feedback on needle implantation quality, we trained machine learning models to predict 2D dosimetry for prostate HDR-BT on axial TRUS images.

Methods and materials: Clinical treatment plans from 248 prostate HDR-BT patients were retrospectively collected and randomly split 80/20 for training/testing. Fifteen U-Net models were implemented to predict the 90%, 100%, 120%, 150%, and 200% isodose levels in the prostate base, midgland, and apex. Predicted isodose lines were compared to delivered dose using Dice similarity coefficient (DSC), precision, recall, average symmetric surface distance, area percent difference, and 95th percentile Hausdorff distance. To benchmark performance, 10 cases were retrospectively replanned and compared against the clinical plans using the same metrics.

Results: Models predicting 90% and 100% isodose lines at midgland performed best, with median DSC of 0.97 and 0.96, respectively. Performance declined as isodose level increased, with median DSC of 0.90, 0.79, and 0.65 in the 120%, 150%, and 200% models. In the base, median DSC was 0.94 for 90% and decreased to 0.64 for 200%. In the apex, median DSC was 0.93 for 90% and decreased to 0.63 for 200%. Median prediction time was 25 ms.

Conclusion: U-Net models accurately predicted HDR-BT isodose lines on 2D TRUS images sufficiently quickly for real-time use. Incorporating auto-segmentation algorithms will allow intra-operative feedback on needle implantation quality.