A simple calibration routine for small inorganic scintillation detectors for in vivo dosimetry during brachytherapy.

BACKGROUND: In vivo dosimetry (IVD) is rarely performed in brachytherapy (BT), allowing potential dose misadministration to go unnoticed. This study presents a clinical routine-calibration method of detectors for IVD in high (HDR) and pulsed dose rate (PDR) Ir-192 BT. PURPOSE: To evaluate the dosimetric precision and feasibility of an in-clinic calibration routine of detectors for IVD in afterloading BT. METHODS: Calibrations were performed in a PMMA phantom with two needles inserted 20 mm apart. The source was loaded in one of the needles at 15 dwells for 10 s. The detector was placed in the other needle, and its signal was recorded. The mean signal at each dwell position was fitted to the expected dose rate with the calibration factor and the detector's longitudinal position being free parameters. The method was tested with an inorganic scintillation detector using one Ir-192 FlexiSource HDR and two Ir-192 GammaMedPlus PDR sources and followed by validation measurements in water. RESULTS: The standard measurement uncertainty (k = 1) of the calibration factor in absolute terms (Gy/s) was 3.2/3.4% for the HDR/PDR source. The uncertainty was dominated by source strength uncertainty, and the precision of the method was <1%. The mean ± 1SD of the difference in measured and expected dose rate during validation was 1.5 ± 4.7% (HDR) and 0.0 ± 4.1% (PDR) with a positional uncertainty in the setup of 0.33/0.23 mm (HDR/PDR) (k = 1). CONCLUSION: A precise and feasible in-clinic calibration method for IVD and source strength consistency tests in BT was presented.

Co-occurrence of symptoms after radiochemotherapy in locally advanced cervix cancer patients: a cluster analysis.

BACKGROUND: State of the art combined radiochemotherapy and image-guided brachytherapy for locally advanced cervical cancer (LACC) has shown improved disease control and survival as well as a significant reduction of organ related morbidity. However, LACC cancer survivors are still experiencing a spectrum of symptoms. The aim of this study was to identify co-occurring symptoms in cervix cancer survivors by using patient-reported outcome and physician assessed morbidity. MATERIALS AND METHOD: EMBRACE I is a multicenter prospective observational study with 1416 LACC patients (2008-2015). Information on physician-assessed morbidity and patient-reported outcome was assessed at baseline and at regular follow-ups up with the CTCAE v.3 and EORTC-C30/CX24, respectively. Patients with at least 2 years of follow-up were included and data from 3 months to 2 years was used in the analysis. Factor analysis was used on both EORTC and CTCAE data with symptoms and follow-ups as observations. The extracted factors represent clusters of symptoms. Subsequently, regression models were built to investigate associations between the symptom clusters and QOL. RESULTS: The analysis included 742 patients. Despite the differences in the definition of physician-assessed and patient-reported symptoms, similar clusters are identified by the two assessment methods. Three main organ-related clusters are recognized for urinary, gastro-intestinal and vaginal morbidity. Furthermore, a general symptoms cluster where fatigue, pain, insomnia, neuropathy, and hot flashes have large weights is found. Lastly, a cluster with nausea, vomit and lack of appetite is also identified. The general, gastrointestinal and nausea clusters show significant associations with general QOL. CONCLUSIONS: This analysis on both PRO and physician-assessed morbidity found a cluster associated with general symptoms and organ-related symptom clusters (urinary, gastrointestinal, vaginal). This shows that LACC survivors experience a variety of co-occurring symptoms. Our analysis also shows that the cluster of general symptoms is associated with a decrease in QOL.

Stages I-III Inoperable Endometrial Carcinoma: A Retrospective Analysis by the Gynaecological Cancer GEC-ESTRO Working Group of Patients Treated with External Beam Irradiation and 3D-Image Guided Brachytherapy.

BACKGROUND/PURPOSE: Analyse the outcomes of stages I-III inoperable endometrial cancer (IEC) patients treated with external-beam-irradiation (EBRT) and 3D-image-guided-brachytherapy (IGBT). MATERIAL AND METHODS: Medical records of IEC patients receiving EBRT + IGBT in eight European and one Canadian centres (2004-2019) were examined, including: pelvic ± para-aortic EBRT and lymph node boost; anaesthetic procedure, applicators, BT-planning imaging, clinical target volume (CTV), brachytherapy schedule, and EQD2 to the CTV(α/ß=4.5Gy) and D2 cm3(α/ß=3Gy) for organs at risk. Complications are evaluated using CTCAEv4 scores. The 2- and 5-year survival probability according to stages was estimated (cancer-specific survival (CSS), disease-free survival (DFS), local relapse-free survival (LRFS), loco-regional relapse-free survival (LRRFS), and distant metastasis-free survival (DMFS)). STATISTICS: descriptive analysis and the Kaplan-Meier method. RESULTS: 103 patients (stages: I-44, II-14, III-44) were included. Median follow-up: 28 months (7-170). All patients received pelvic ± para-aortic EBRT. Median D90-EQD2(α/ß=4.5) to the CTV:73.3 Gy (44.6-132.7), 69.9 Gy (44.7-87.9 and 75.2 Gy (55.1-97) in stages I, II, and III, respectively. Thirty patients presented relapse (stages: 10-I, 3-II, 17-III): 24 uterine (stages: 7-I, 3-II, 14-III), 15 nodal (stages: 4-I, 1-II, 10-III), and 23 distant (stages: 6-I, 2-II, 15-III). Five year CSS was 71.2% (stages: 82%-I-II and 56%-III) and DFS, LRFS, LRRFS, and DMFS were 55.5%, 59%, 72%, and 67.2%, respectively. Late G3-G4 complications (crude): 1.3% small bowel, 2.5% rectum, and 5% bladder. CONCLUSION: In stages I-III of the IEC, EBRT + IGBT offer good 2- and 5-year CSS of 88.7% and 71.2%, respectively, with the best outcomes in stages I-II. Prospective studies are needed to determine how better outcomes can be achieved.

EviGUIDE - a tool for evidence-based decision making in image-guided adaptive brachytherapy for cervical cancer.

PURPOSE: To develop a novel decision-support system for radiation oncology that incorporates clinical, treatment and outcome data, as well as outcome models from a large clinical trial on magnetic resonance image-guided adaptive brachytherapy (MR-IGABT) for locally advanced cervical cancer (LACC). METHODS: A system, called EviGUIDE, was developed that combines dosimetric information from the treatment planning system, patient and treatment characteristics, and established tumor control probability (TCP), and normal tissue complication probability (NTCP) models, to predict clinical outcome of radiotherapy treatment of LACC. Six Cox Proportional Hazards models based on data from 1341 patients of the EMBRACE-I study have been integrated. One TCP model for local tumor control, and five NTCP models for OAR morbidities. RESULTS: EviGUIDE incorporates TCP-NTCP graphs to help users visualize the clinical impact of different treatment plans and provides feedback on achievable doses based on a large reference population. It enables holistic assessment of the interplay between multiple clinical endpoints and tumour and treatment variables. Retrospective analysis of 45 patients treated with MR-IGABT showed that there exists a sub-cohort of patients (20%) with increased risk factors, that could greatly benefit from the quantitative and visual feedback. CONCLUSION: A novel digital concept was developed that can enhance clinical decision- making and facilitate personalized treatment. It serves as a proof of concept for a new generation of decision support systems in radiation oncology, which incorporate outcome models and high-quality reference data, and aids the dissemination of evidence-based knowledge about optimal treatment and serve as a blueprint for other sites in radiation oncology.

ESGO/ESTRO quality indicators for radiation therapy of cervical cancer.

BACKGROUND: The European Society of Gynaecological Oncology (ESGO) has previously defined and established a list of quality indicators for the surgical treatment of cervical cancer. As a continuation of this effort to improve overall quality of care for cervical cancer patients across all aspects, ESGO and the European SocieTy for Radiotherapy and Oncology (ESTRO) initiated the development of quality indicators for radiation therapy of cervical cancer. OBJECTIVE: To develop a list of quality indicators for radiation therapy of cervical cancer that can be used to audit and improve clinical practice by giving to practitioners and administrators a quantitative basis to improve care and organizational processes, notably for recognition of the increased complexity of modern external radiotherapy and brachytherapy techniques. METHODS: Quality indicators were based on scientific evidence and/or expert consensus. The development process included a systematic literature search for identification of potential quality indicators and documentation of scientific evidence, consensus meetings of a group of international experts, an internal validation process, and external review by a large international panel of clinicians (n = 99). RESULTS: Using a structured format, each quality indicator has a description specifying what the indicator is measuring. Measurability specifications are detailed to define how the quality indicators will be measured in practice. Targets were also defined for specifying the level which each unit or center should be aiming to achieve. Nineteen structural, process, and outcome indicators were defined. Quality indicators 1-6 are general requirements related to pretreatment workup, time to treatment, upfront radiation therapy, and overall management, including active participation in clinical research and the decision making process within a structured multidisciplinary team. Quality indicators 7-17 are related to treatment indicators. Quality indicators 18 and 19 are related to patient outcomes. DISCUSSION: This set of quality indicators is a major instrument to standardize the quality of radiation therapy in cervical cancer. A scoring system combining surgical and radiotherapeutic quality indicators will be developed within an envisaged future ESGO accreditation process for the overall management of cervical cancer, in an effort to support institutional and governmental quality assurance programs.

ESGO/ESTRO quality indicators for radiation therapy of cervical cancer.

BACKGROUND: The European Society of Gynaecological Oncology (ESGO) has previously defined and established a list of quality indicators for the surgical treatment of cervical cancer. As a continuation of this effort to improve overall quality of care for cervical cancer patients across all aspects, ESGO and the European SocieTy for Radiotherapy and Oncology (ESTRO) initiated the development of quality indicators for radiation therapy of cervical cancer. OBJECTIVE: To develop a list of quality indicators for radiation therapy of cervical cancer that can be used to audit and improve clinical practice by giving to practitioners and administrators a quantitative basis to improve care and organizational processes, notably for recognition of the increased complexity of modern external radiotherapy and brachytherapy techniques. METHODS: Quality indicators were based on scientific evidence and/or expert consensus. The development process included a systematic literature search for identification of potential quality indicators and documentation of scientific evidence, consensus meetings of a group of international experts, an internal validation process, and external review by a large international panel of clinicians (n=99). RESULTS: Using a structured format, each quality indicator has a description specifying what the indicator is measuring. Measurability specifications are detailed to define how the quality indicators will be measured in practice. Targets were also defined for specifying the level which each unit or center should be aiming to achieve. Nineteen structural, process, and outcome indicators were defined. Quality indicators 1-6 are general requirements related to pretreatment workup, time to treatment, upfront radiation therapy, and overall management, including active participation in clinical research and the decision making process within a structured multidisciplinary team. Quality indicators 7-17 are related to treatment indicators. Quality indicators 18 and 19 are related to patient outcomes. DISCUSSION: This set of quality indicators is a major instrument to standardize the quality of radiation therapy in cervical cancer. A scoring system combining surgical and radiotherapeutic quality indicators will be developed within an envisaged future ESGO accreditation process for the overall management of cervical cancer, in an effort to support institutional and governmental quality assurance programs.

Tools for large-scale data analytics of an international multi-center study in radiation oncology for cervical cancer.

PURPOSE: To develop and implement a software that enables centers, treating patients with state-of-the-art radiation oncology, to compare their patient, treatment, and outcome data to a reference cohort, and to assess the quality of their treatment approach. MATERIALS AND METHODS: A comprehensive data dashboard was designed, which al- lowed holistic assessment of institutional treatment approaches. The software was tested in the ongoing EMBRACE-II study for locally advanced cervical cancer. The tool created individualized dashboards and automatic analysis scripts, verified pro- tocol compliance and checked data for inconsistencies. Identified quality assurance (QA) events were analysed. A survey among users was conducted to assess usability. RESULTS: The survey indicated favourable feedback to the prototype and highlighted its value for internal monitoring. Overall, 2302 QA events were identified (0.4% of all collected data). 54% were due to missing or incomplete data, and 46% originated from other causes. At least one QA event was found in 519/1001 (52%) of patients. QA events related to primary study endpoints were found in 16% of patients. Sta- tistical methods demonstrated good performance in detecting anomalies, with precisions ranging from 71% to 100%. Most frequent QA event categories were Treatment Technique (27%), Patient Characteristics (22%), Dose Reporting (17%), Outcome 156 (15%), Outliers (12%), and RT Structures (8%). CONCLUSION: A software tool was developed and tested within a clinical trial in radia- tion oncology. It enabled the quantitative and qualitative comparison of institutional patient and treatment parameters with a large multi-center reference cohort. We demonstrated the value of using statistical methods to automatically detect implau- sible data points and highlighted common pitfalls and uncertainties in radiotherapy for cervical cancer.

Overall Severe Morbidity After Chemo-Radiation Therapy and Magnetic Resonance Imaging-Guided Adaptive Brachytherapy in Locally Advanced Cervical Cancer: Results From the EMBRACE-I Study.

PURPOSE: To evaluate overall severe late morbidity (grade ≥3) in patients with locally advanced cervical cancer treated with chemo-radiation therapy and magnetic resonance image guided adaptive brachytherapy within the prospective EMBRACE-I study, and to compare the results with published literature after standard radiograph based brachytherapy (BT). METHODS AND MATERIALS: From 2008 to 2015 the EMBRACE-I study enrolled 1416 patients. Morbidity was assessed (Common Terminology Criteria for Adverse Events version 3.0) every 3 months the 1st year, every 6 months the second and third year, and yearly thereafter and 1251 patients had available follow-up on late morbidity. Morbidity events (grade 3-5) were summarized as the maximum grade during follow-up (crude incidence rates) and actuarial estimates at 3 and 5 years. To compare with the published literature on standard radiograph based BT, Common Terminology Criteria for Adverse Events scores from the EMBRACE-I study were retrospectively converted into a corresponding score in the Radiation Therapy Oncology Group and European Organization for Research and Treatment of Cancer system. RESULTS: In total, 534 severe events occurred in 270 patients; 429 events were grade 3 and 105 were grade 4 events. Actuarial estimates for grade ≥3 gastrointestinal (GI), genitourinary (GU), vaginal and fistula events at 5 years were 8.5% (95% confidence interval [CI], 6.9%-10.6%), 6.8% (95% CI, 5.4%-8.6%), 5.7% (95% CI, 4.3%-7.6%), and 3.2% (95% CI, 2.2%-4.5%), respectively. The 5-year actuarial estimate for organ-related events (GI, GU, vaginal, or fistula) was 18.4% (95% CI, 16.0%-21.2%). The 5-year actuarial estimate when aggregating all G≥3 endpoints (GI, GU, vaginal, fistulas, and non-GI/GU/vaginal) was 26.6% (95% CI, 23.8%-29.6%). Thirteen patients had a treatment-related death, 8 of which were associated with GI morbidity. CONCLUSIONS: This report assesses severe morbidity from the largest prospective study on chemo-radiation therapy and image guided adaptive brachytherapy for locally advanced cervical cancer to date. Severe late morbidity was limited per endpoint and organ category, but considerable when aggregated across organs and all endpoints. The late morbidity results in the EMBRACE-I study compare favorably with published literature on standard radiograph based BT for GI morbidity, vaginal morbidity, and fistulas.

Risk Factors for Local Failure Following Chemoradiation and Magnetic Resonance Image-Guided Brachytherapy in Locally Advanced Cervical Cancer: Results From the EMBRACE-I Study.

PURPOSE: To report clinical and treatment characteristics, remission and failure patterns, and risk factors for local failure (LF) from the EMBRACE-I study. MATERIALS AND METHODS: EMBRACE-I was a prospective, observational, multicenter cohort study on magnetic resonance imaging-based image-guided adaptive brachytherapy (MR-IGABT) in locally advanced cervical cancer. Treatment consisted of external beam radiotherapy, concurrent chemotherapy, and MR-IGABT. LF was defined as progressive or recurrent disease in the cervix, uterus, parametria, pelvic wall, or vagina. Competing risk analysis was used to estimate local tumor control (LC) and Cox proportional regression models for multivariable analysis and dose-response analysis. RESULTS: One thousand three hundred eighteen patients with a median follow-up of 52 months were available for this analysis. Eighty-one patients had persistent disease 3 months after end of treatment. Of those, 60 patients achieved LC at 6-9 months without further treatment, whereas 21 patients had progressive disease. In addition, 77 patients developed a local recurrence after complete remission comprising a total number of 98 LFs. LFs were located inside the MR-IGABT target volumes in 90% of patients with LF. In multivariable analysis, histology, minimal dose to 90% of high-risk clinical target volume (CTVHR), maximum tumor dimension, CTVHR > 45 cm3, overall treatment time, tumor necrosis on magnetic resonance imaging at diagnosis, uterine corpus infiltration at diagnosis and at MR-IGABT, and mesorectal infiltration at MR-IGABT had significant impact on LF. Dose-response analysis showed that a minimal dose to 90% of 85 Gy to the CTVHR led to 95% (95% CI, 94 to 97) LC 3 years postintervention for squamous cell in comparison to 86% (95% CI, 81 to 90) for adeno/adenosquamous carcinoma histology. CONCLUSION: The present study demonstrates the safety and validity of the GYN GEC-ESTRO/ICRU-89 target concept and provides large-scale evidence for dose prescription and new risk factors for LF in MR-IGABT in locally advanced cervical cancer.

Association of persistent morbidity after radiotherapy with quality of life in locally advanced cervical cancer survivors.

PURPOSE: To quantify the association of persistent morbidity with different aspects of quality of life (QOL) in locally advanced cervical cancer (LACC) survivors. MATERIAL AND METHODS: Longitudinal outcome from the EMBRACE-I study was evaluated. Patient-reported symptoms and QOL were prospectively scored (EORTC-C30/CX24) at baseline and regular follow-ups. Physician-assessed symptoms were also reported (CTCAEv.3). Persistent symptoms were defined if present in at least half of the follow-ups. QOL items were linearly transformed into a continuous scale. Linear mixed-effects models (LMM) were applied to evaluate and quantify the association of persistent symptoms with QOL. Overall QOL deterioration was evaluated by calculating the integral difference in QOL over time obtained with LMM for patients without and with persistent symptoms. RESULTS: Out of 1416 patients enrolled, 741 with baseline and ≥ 3 late follow-ups were analyzed (median 59 months). Proportions of persistent EORTC symptoms ranged from 21.8 % to 64.9 % (bowel control and tiredness). For CTCAE the range was 11.3-28.6 % (limb edema and fatigue). Presence of any persistent symptom was associated with QOL, although with varying magnitude. Role functioning and Global health/QOL were the most impaired aspects. Fatigue and pain showed large differences, with reductions of around 20 % for most of the QOL aspects. Among organ-related symptoms, abdominal cramps showed the largest effect. CONCLUSION: Persistent symptoms are associated with QOL reductions in LACC survivors. Organ-related symptoms showed smaller differences than general symptoms such as fatigue and pain. In addition to optimizing treatment to minimize organ-related morbidity, effort should be directed towards a more comprehensive and targeted morbidity management.

Brachytherapy training survey among radiation oncology residents in Europe.

We aim to investigate the current state of brachytherapy (BT) training among the radiation oncology trainees in Europe. MATERIAL AND METHODS: A 22-question online survey based on the one by the American Association of Radiation Oncology Residents (2017) with added queries pertinent to training in Europe was sent to 1450 residents in two iterations. These included site-specific training, volume of experience, barriers to training, institutional support, and preferences for further education. Responses to individual statements were given on a 1 to 5 Likert-type scale. The answers were reported by junior (≤3 years of training) and senior years of training (year of training 4/5/6 and junior staff). Descriptive statistics were used to describe frequencies. RESULTS: Residents from 21 European countries participated, 445 (31%) responded. 205 (47%) were senior residents. 60% residents consider that performing BT independently at the end of residency is very or somewhat important. Confidence in joining a brachytherapy practice at the end of residency was high or somewhat high in 34% of senior residents. They reported as barriers to achieving independence in BT to be lack of appropriate didactic/procedural training from supervisors (47%) and decreased case load (31%). 68% reported their program lacks a formal BT curriculum and standardized training assessment. CONCLUSIONS: Residents in Europe, feel independent BT practice is very or somewhat important, but do not feel confident they will achieve this goal. To address this gap, efforts are needed to develop and implement a formal and comprehensive BT curriculum with easy access to trained instructors.

Coverage probability planning for simultaneously integrated boosts of inguinal lymph nodes in vulvar cancer.

BACKGROUND AND PURPOSE: Strategies for minimizing irradiation of organs at risk (OARs) from pathological inguinal lymph node (PILN) boosting are needed to minimize the risk of morbidity. Coverage probability (CovP) is a conformal planning strategy for simultaneously integrated boost (SIB). Our aim was to investigate if SIB of PILN using CovP can be delivered safely in vulvar cancer. MATERIALS AND METHODS: Ten consecutive patients treated with definitive radiotherapy (RT) including SIB of PILN and with daily cone beam CT (CBCT) were included. Dose prescription was 51.2/32 fx to the elective target and 64 Gy/32 fx to the gross disease at the vulva and to positive lymph nodes (LN). PILN were contoured on both planning CT and MRI (GTV-N) and combined to form ITV-N. Each PILN GTV-N was contoured on every third CBCT, in total 11 CBCT for each patient. OARs were subcutaneous tissue (SC), inguinal vessels, skin rim, bowel, and body contour. Three plans were created for every patient: A) Standard CT-based planning; PTV-N based on GTV-NCT with a 10 mm isotropic margin. B) CT and MRI-based planning with smaller margins: PTV-N based on ITV-N with a 5 mm isotropic margin. C) CovP. The total delivered dose to GTV-Ns was estimated by accumulating dose across all fractions based on GTV-Ns contoured on CBCT. RESULTS: Thirty-five PILNs were boosted. There was no significant difference in accumulated GTV-N D98% between the three plans. CovP delivered a higher mean dose to the GTV-N D50% and D2% (p < 0.001). The planned mean doses to the OARs were reduced when applying CovP. CONCLUSIONS: SIB of PILN in vulvar cancer based on CovP and a 5 mm PTV margin does not compromise target coverage during RT and reduces the dose to normal tissues in the groin.

Dosimetric impact of target definition in brachytherapy for cervical cancer - Computed tomography and trans rectal ultrasound versus magnetic resonance imaging.

Background and Purpose: Magnetic Resonance Imaging (MRI) based target definition in cervix brachytherapy is limited by its availability, logistics and financial implications, therefore, use of computed tomography (CT) and Trans Rectal UltraSonography (TRUS) has been explored. The current study evaluated the dosimetric impact of CT + TRUS based target volumes as compared to gold standard MRI. Methods and Materials: Images of patients (n = 21) who underwent TRUS followed by MRI and CT, were delineated with High-Risk Clinical Target Volume in CT (CTVHR-CT) and in MRI (CTVHR-MR). CTVHR-CT was drawn on CT images with TRUS assistance. For each patient, two treatment plans were made, on MRI and CT, followed by fusion and transfer of CTVHR-MR to the CT images, referred as CTVHR-MRonCT. The agreement between CTVHR-MRonCT and CTVHR-CT was evaluated for dosimetric parameters (D90, D98 and D50; Dose received by 90%, 98% and 50% of the volumes) using Bland-Altman plots, linear regression, and Pearson correlation. Results: No statistically significant systematic difference was found between MRI and CT. Mean difference (±1.96 SD) of D90, D98 and D50 between CTVHR-MRonCT and CTVHR-CT was 2.0, 1.2 and 5.6 Gy respectively. The number of patients who have met the dose constraints of D90 > 85 Gy were 90% and 80% in MR and in CT respectively, others were in the borderline, with a minimum dose of 80 Gy. The mean ± SD dose-difference between MR and CT plans for bladder was significant (5 ± 13 Gy; p = 0.12) for D0.1cm3, while others were statistically insignificant. Conclusion: CT + TRUS based delineation of CTVHR appear promising, provide useful information to optimally utilize for brachytherapy planning, however, MRI remains the gold standard.

Point-A vs. volume-based brachytherapy for the treatment of cervix cancer: A meta-analysis.

BACKGROUND & PURPOSE: To report disease-free survival (DFS) for volume-based and point-A based brachytherapy (BT) in locally advanced cervical cancer. MATERIALS & METHODS: We conducted a meta-analysis of studies assessing the effects of point-A and volume-based brachytherapy on 3-year DFS. Studies including stage I-IVA cervical cancer patients were included if standard treatment of concomitant chemo-radiotherapy and high-dose- or pulsed dose rate BT was delivered. The primary outcome was 3-year DFS, and secondary outcomes were 3-year local control (LC), 3-year overall survival (OS) and late toxicity. A random-effects subgroup meta-analysis was done. RESULTS: In total, 5499 studies were screened, of which 24 studies with 5488 patients were eligible. There was significant heterogeneity among point-A studies (1538 patients) (I2 = 82%, p < 0.05) relative to volume-based studies (3950 patients) (I2 = 58, p = 0.01). The 3-year DFS for point-A and volume-based studies were 67% (95% CI 60%-73%) and 79% (95% CI 76%-82%) respectively (p = 0.001). Three-year LC for point-A and volume-based studies were 86% (95% CI 81%-90%) and 92% (91%-94%) respectively (p = 0.01). The difference in 3-year OS (72% vs. 79%, p = 0.12) was not statistically significant. The proportion of prospectively enrolled patients was 23% for point-A studies and 33% for volume-based studies. There was no difference in late grade 3 or higher gastrointestinal (3% vs. 4%, p = 0.76) genitourinary toxicities (3% vs. 3% p = 0.45) between the two groups. CONCLUSION: Volume-based BT results in superior 3-year DFS and 3-year LC. In the absence of randomized trials, this meta-analysis provides the best evidence regarding transition to 3D planning.

Role of Brachytherapy in the Postoperative Management of Endometrial Cancer: Decision-Making Analysis among Experienced European Radiation Oncologists.

BACKGROUND: There are various society-specific guidelines addressing adjuvant brachytherapy (BT) after surgery for endometrial cancer (EC). However, these recommendations are not uniform. Against this background, clinicians need to make decisions despite gaps between best scientific evidence and clinical practice. We explored factors influencing decision-making for adjuvant BT in clinical routine among experienced European radiation oncologists in the field of gynaecological radiotherapy (RT). We also investigated the dose and technique of BT. METHODS: Nineteen European experts for gynaecological BT selected by the Groupe Européen de Curiethérapie and the European Society for Radiotherapy & Oncology provided their decision criteria and technique for postoperative RT in EC. The decision criteria were captured and converted into decision trees, and consensus and dissent were evaluated based on the objective consensus methodology. RESULTS: The decision criteria used by the experts were tumour extension, grading, nodal status, lymphovascular invasion, and cervical stroma/vaginal invasion (yes/no). No expert recommended adjuvant BT for pT1a G1-2 EC without substantial LVSI. Eighty-four percent of experts recommended BT for pT1a G3 EC without substantial LVSI. Up to 74% of experts used adjuvant BT for pT1b LVSI-negative and pT2 G1-2 LVSI-negative disease. For 74-84% of experts, EBRT + BT was the treatment of choice for nodal-positive pT2 disease and for pT3 EC with cervical/vaginal invasion. For all other tumour stages, there was no clear consensus for adjuvant treatment. Four experts already used molecular markers for decision-making. Sixty-five percent of experts recommended fractionation regimens of 3 × 7 Gy or 4 × 5 Gy for BT as monotherapy and 2 × 5 Gy for combination with EBRT. The most commonly used applicator for BT was a vaginal cylinder; 82% recommended image-guided BT. CONCLUSIONS: There was a clear trend towards adjuvant BT for stage IA G3, stage IB, and stage II G1-2 LVSI-negative EC. Likewise, there was a non-uniform pattern for BT dose prescription but a clear trend towards 3D image-based BT. Finally, molecular characteristics were already used in daily decision-making by some experts under the pretext that upcoming trials will bring more clarity to this topic.

Toward 3D dose verification of an electronic brachytherapy source with a plastic scintillation detector.

BACKGROUND: Electronic brachytherapy (eBT) is considered a safe treatment with good outcomes. However, eBT lacks standardized and independent dose verification, which could impede future use. PURPOSE: To validate the 3D dose-to-water distribution of an electronic brachytherapy (eBT) source using a small-volume plastic scintillation detector (PSD). METHODS: The relative dose distribution of a Papillon 50 (P50) (Ariane Medical Systems, UK) eBT source was measured in water with a PSD consisting of a cylindrical scintillating BCF-12 fiber (length: 0.5 mm, Ø: 1 mm) coupled to a photodetector via an optical fiber. The measurements were performed with the PSD mounted on a motorized stage in a water phantom (MP3) (PTW, Germany). This allowed the sensitive volume of the PSD to be moved to predetermined positions relative to the P50 applicator, which pointed vertically downward while just breaching the water surface. The percentage depth-dose (PDD) was measured from 0 to 50 mm source-to-detector distance (SDD) in 1-3 mm steps. Dose profiles were measured along two perpendicular axes at five different SDDs with step sizes down to 0.5 mm. Characterization of the PSD consisted of determining the energy correction through Monte Carlo (MC) simulation and by measuring the stability and dose rate linearity using a well-type ionization chamber as a reference. The measured PDD and profiles were validated with corresponding MC simulations. RESULTS: The measured and simulated PDD curves agreed within 2% (except at 0 mm and 43 mm depth) after the PSD measurements were corrected for energy dependency. The absorbed dose decreased by a factor of 2 at 7 mm depth and by a factor of 10 at 26 mm depth. The measured dose profiles showed dose gradients at the profile edges of more than 50%/mm at 5 mm depth and 15%/mm at 50 mm depth. The measured profile widths increased 0.66 mm per 1 mm depth, while the simulated profile widths increased 0.74 mm per 1 mm depth. An azimuthal dependency of > 10% was observed in the dose at 10 mm distance from the beam center. The total uncertainty of the measured relative dose is < 2.5% with a positional uncertainty of 0.4 mm. The measurements for a full 3D dose characterization (PDD and profiles) can be carried out within 8 h, the limiting factor being cooling of the P50. CONCLUSION: The PSD and MP3 water phantoms provided a method to independently verify the relative 3D dose distribution in water of an eBT source.

Prognostic Implications of Uterine Cervical Cancer Regression During Chemoradiation Evaluated by the T-Score in the Multicenter EMBRACE I Study.

PURPOSE: A simple scoring system (T-score, TS) for integrating findings from clinical examination and magnetic resonance imaging (MRI) of the primary tumor at diagnosis has shown strong prognostic capability for predicting local control and survival in locally advanced cervical cancer treated with chemoradiation and MRI-guided brachytherapy (BT). The aim was to validate the performance of TS using the multicenter EMBRACE I study and to evaluate the prognostic implications of TS regression obtained during initial chemoradiation. METHODS AND MATERIALS: EMBRACE I recruited 1416 patients, of whom 1318 were available for TS. Patients were treated with chemoradiation followed by MRI-guided BT. A ranked ordinal scale of 0 to 3 points was used to assess 8 anatomic locations typical for local invasion of cervical cancer. TS was calculated separately at diagnosis (TSD) and at BT (TSBT) by the sum of points obtained from the 8 locations at the 2 occasions. RESULTS: Median TSD and TSBT was 5 and 4, respectively. TS regression was observed in 71% and was an explanatory variable for BT technique (intracavitary vs intracavitary/interstitial) and major dose-volume histogram parameters for BT, such as high-risk clinical target (CTVHR), CTVHR D90 (minimal dose to 90% of the target volume), D2cm3 bladder (minimal dose to the most exposed 2 cm3 of the bladder), and D2cm3 rectum. TS regression (TSBT≤5) was associated with improved local control and survival and with less morbidity compared with patients with TSBT remaining high (>5) despite initial chemoradiation. TS regression was significant in multivariate analysis for both local control and survival when analyzed in consort with already established prognostic parameters related to the patient, disease, and treatment. CONCLUSIONS: TS was validated in a multicenter setting and proven to be a strong multidisciplinary platform for integration of clinical findings and imaging with the ability to quantitate local tumor regression and its prognostic implications regarding BT technique, dose-volume histogram parameters, local control, survival, and morbidity.

Dose-effect relationship between vaginal dose points and vaginal stenosis in cervical cancer: An EMBRACE-I sub-study.

BACKGROUND AND PURPOSE: To evaluate dose-effect relationships between vaginal dose points and vaginal stenosis in patients treated for locally advanced cervical cancer with radio(chemo)therapy and image-guided adaptive brachytherapy. MATERIAL AND METHODS: Patients from six centres participating in the EMBRACE-I study were included. Information on doses to different vaginal dose points, including the Posterior-Inferior Border of Symphysis (PIBS) points and recto-vaginal reference (RV-RP) point, were retrieved from the treatment planning system. In addition, the vaginal reference length (VRL) was evaluated. Vaginal stenosis was prospectively assessed according to the CTCAEv3.0 system at baseline and follow-up. Primary endpoint was grade 2 or higher (G ≥ 2) vaginal stenosis. Impact of dose to the vaginal dose points, and impact of VRL, age, vaginal involvement and applicator on vaginal stenosis G ≥ 2 was evaluated with a Cox proportional-hazard regression model. RESULTS: 301 patients were included. Median follow-up was 49 months. During follow-up, the incidence of G0, G1, G2, and G3 vaginal stenosis was 25% (76), 52% (158), 20% (59) and 3% (8), respectively. Median total doses to PIBS+2 cm, PIBS, PIBS-2 cm and the RV-RP were 52.9 (IQR 49.3-64.7), 41.0 (IQR 15.4-49.0), 4.1 (IQR 2.9-7.0) and 64.6 (IQR 60.0-70.6) Gy EQD23, respectively. Higher doses to the PIBS, PIBS + 2 cm and RV-RP points were significantly associated with increased risk for vaginal stenosis G ≥ 2. Other risk factors for vaginal stenosis were: vaginal involvement at diagnosis, higher age, shorter VRL and use of a tandem-ovoid applicator. CONCLUSION: Higher doses to the PIBS+2 cm, PIBS and RV-RP dose points are associated with vaginal stenosis G ≥ 2.

3D dose reconstruction based on in vivo dosimetry for determining the dosimetric impact of geometric variations in high-dose-rate prostate brachytherapy.

INTRODUCTION: In vivo dosimetry (IVD) can be used for source tracking (ST), i.e., estimating source positions, during brachytherapy. The aim of this study was to exploit IVD-based ST to perform 3D dose reconstruction for high-dose-rate prostate brachytherapy and to evaluate the robustness of the treatments against observed geometric variations. MATERIALS AND METHODS: Twenty-three fractions of high-dose-rate prostate brachytherapy were analysed. The treatment planning was based on MRI. Time-resolved IVD was performed using a fibre-coupled scintillator. ST was retrospectively performed using the IVD measurements. The ST identified 2D positional shifts of each treatment catheter and thereby inferred updated source positions. For each fraction, the dose was recalculated based on the source-tracked catheter positions and compared with the original plan dose using differences in dose volume histogram indices. RESULTS: Of 352 treatment catheters, 344 had shifts of less than 5 mm. Shifts between 5 and 10 mm were observed for 3 catheters, and shifts greater than 10 mm for 2 catheters. The ST failed for 3 catheters. The maximum relative difference in clinical target volume (prostate + 3 mm isotropic margin) D90% was 5%. In one fraction, the bladder D2cm3 dose increased by 18% (1.4 Gy) due to a single source position being inside the bladder rather than nearby as planned. The max increase in urethra dose was 1.5 Gy (15%). CONCLUSION: IVD-based 3D dose reconstruction for high-dose-rate prostate brachytherapy is feasible. The dosimetric impact of the observed catheter shifts was limited. Dose reconstruction can therefore aid in determining the dosimetric impact of geometric variations and errors in brachytherapy.