Status of head and neck brachytherapy in Spain in 2022

Purpose Brachytherapy (BT) has been used for many years for disease control in tumours of the head and neck area (H&N). It is currently performed with high dose rate (HDR) or pulsed dose rate (PDR), but its use has been reduced due to the implementation of new non-invasive external beam radiotherapy techniques such as intensity modulation (IMRT) and volumetric modulated arc therapy (VMAT) and the improvement of surgical techniques. Methods The Spanish Brachytherapy Group (GEB) has carried out a survey to find out the number of centres in Spain that continue to use BT in H&N and its indications and expectations for the future. Results The results were presented at the XX GEB Consensus Meeting held on October 21, 2022, in Valencia (Spain) and it was confirmed that, although there are fewer and fewer centres that use BT in H&N, there are still units with extensive experience in this technique that should be positioned as referral centres. Conclusion It is necessary to carry out continuous work with other specialities involved, such as H&N surgeons, and other radiation oncologists, to improve the training of residents, both oncologists and medical physicists (AU)

Status of head and neck brachytherapy in Spain in 2022.

PURPOSE: Brachytherapy (BT) has been used for many years for disease control in tumours of the head and neck area (H&N). It is currently performed with high dose rate (HDR) or pulsed dose rate (PDR), but its use has been reduced due to the implementation of new non-invasive external beam radiotherapy techniques such as intensity modulation (IMRT) and volumetric modulated arc therapy (VMAT) and the improvement of surgical techniques. METHODS: The Spanish Brachytherapy Group (GEB) has carried out a survey to find out the number of centres in Spain that continue to use BT in H&N and its indications and expectations for the future. RESULTS: The results were presented at the XX GEB Consensus Meeting held on October 21, 2022, in Valencia (Spain) and it was confirmed that, although there are fewer and fewer centres that use BT in H&N, there are still units with extensive experience in this technique that should be positioned as referral centres. CONCLUSION: It is necessary to carry out continuous work with other specialities involved, such as H&N surgeons, and other radiation oncologists, to improve the training of residents, both oncologists and medical physicists.

End-To-End Procedure For IORT in Brain Metastases and Film Dosimetry.

Purpose: The study is intended to perform an end-to-end test of the entire intraoperative process using cadaver heads. A simulation of tumor removal was performed, followed by irradiation of the bed and measurement of absorbed doses with radiochromic films. Materials and Methods: Low-energy X-ray intraoperative radiotherapy (IORT) was used for irradiation. A computed tomography study was performed at each site and the absorbed doses calculated by the treatment planning system, as well as absorbed doses with radiochromic films, were studied. Results: The absorbed doses in the organs at risk (OAR) were evaluated in each case, obtaining maximum doses within the tolerance limits. The absorbed doses in the target were verified and the deviations were <1%. Conclusions: These tests demonstrated that this comprehensive procedure is a reproducible quality assurance tool which allows continuous assessment of the dosimetric and geometric accuracy of clinical brain IORT treatments. Furthermore, the absorbed doses measured in both target and OAR are optimal for these treatments.

An open-source development based on photogrammetry for a real-time IORT treatment planning system.

PURPOSE: This study presents a treatment planning system for intraoperative low-energy photon radiotherapy based on photogrammetry from real images of the surgical site taken in the operating room. MATERIAL AND METHODS: The study population comprised 15 patients with soft-tissue sarcoma. The system obtains the images of the area to be irradiated with a smartphone or tablet, so that the absorbed doses in the tissue can be calculated from the reconstruction without the need for computed tomography. The system was commissioned using 3D printing of the reconstructions of the tumor beds. The absorbed doses at various points were verified using radiochromic films that were suitably calibrated for the corresponding energy and beam quality. RESULTS: The average reconstruction time of the 3D model from the video sequence in the 15 patients was 229,6±7,0 s. The entire procedure, including video capture, reconstruction, planning, and dose calculation was 520,6±39,9 s. Absorbed doses were measured on the 3D printed model with radiochromic film, the differences between these measurements and those calculated by the treatment planning system were 1.4% at the applicator surface, 2.6% at 1 cm, 3.9% at 2 cm and 6.2% at 3 cm. CONCLUSIONS: The study shows a photogrammetry-based low-energy photon IORT planning system, capable of obtaining real-time images inside the operating room, immediately after removal of the tumor and immediately before irradiation. The system was commissioned with radiochromic films measurements in 3D-printed model.

Long-term results with custom-linked iodine-125 seeds and real-time brachytherapy in low- and intermediate-risk prostate cancer.

Purpose: Brachytherapy (BT) with iodine-125 (125I) seeds is effective in low- and intermediate-risk prostate carcinoma, with fewer side effects compared to other techniques, but relapses increase in long-term. In the present paper, 10-year biochemical relapse-free survival (BRFS) results are presented. Material and methods: Between 2007 and 2016, 706 patients were treated with real-time technique using Bard-ProLink™ system. 145 Gy was administered to the prostate with exclusive BT and 108 Gy after 46 Gy of external radiotherapy (EBRT). Androgen deprivation therapy was applied in 19.3% of patients. Results: Median follow-up was 96 months (range, 24-163 months). BRFS at 5 and 10 years was 95% and 91.1%, respectively. For 480 low-risk cases, BRFS at 5 and 10 years was 95.7% and 92.7%, and for 226 intermediate-risk cases, it was 92.7% and 88%, respectively (p < 0.05). With combined treatment of EBRT + BT, 133 cases (59%) of intermediate-risk were treated without differences with exclusive BT. Gleason score 4 + 3 cases dropped to 72.8% at 10 years (p < 0.001), with androgen deprivation therapy (ADT) to 90.9% and without ADT to 66.8%; it was worse if patients had exclusive BT. 10-year BRFS for T1c was 95% compared to 84% for T2 (p < 0.001). Initial prostate specific antigen (PSA) > or < 10 showed no differences. With > 50% biopsy cores positive, it fell to 80% at 10 years (p < 0.001). In 154 patients up to 60 years of age, 10-year BRFS was 97.6%. Urinary complications appeared in 16.9% of cases in exclusive BT vs. 26.1% in EBRT + BT. Grade 2+ urinary late complications were observed in 19.1% and grade 3+ in 5.8% of patients. Rectal toxicity was 4% (2.5% in BT alone and 10.1% in RT + BT), while G3+ was seen in 0.1%. Conclusions: Real-time BT with custom-linked 125I seeds is a very effective long-term treatment in low- and intermediate-risk prostate carcinoma. With Gleason score 4 + 3 or > 50% biopsy cores positive, we recommend combined treatment with additional ADT for 6 months.

H&N and Skin (HNS) GEC-ESTRO Working Group critical review of recommendations regarding prescription depth, bolus thickness and maximum dose in skin superficial brachytherapy with flaps and customized moulds.

The aim of this publication is the assessment of the existing guidelines for non-melanoma skin cancer (NMSC) superficial brachytherapy (BT) and make a critical review based on the existing literature about the maximum dose prescription depth, bolus thickness and maximum skin surface dose (Dmax) of the published clinical practice. A systematic review of NMSC superficial BT published articles was carried out by the GEC-ESTRO Head & Neck and Skin (HNS) Working Group (WG). 10 members and 2 external reviewers compared the published clinical procedures with the recommendations in the current guidelines and examined the grade of evidence. Our review verified that there is a large variation among centres with regards to clinical practice in superficial BT and identified studies where published parameters such as maximum dose prescription depth, bolus thickness and Dmax exceed the constraints recommended in the guidelines, while showing excellent results in terms of local control, toxicity and cosmesis. This review confirmed that current recommendations on skin superficial BT do not include published experience on tumours treated with superficial BT that require dose prescription depth beyond the recommended 5 mm under the skin surface and that the existing literature does not provide sufficient evidence to relate dosimetry of superficial BT to patient reported outcome measures. The GEC-ESTRO HNS WG considers acceptable to prescribe superficial BT dose at a depth above 5 mm beyond the skin surface, and modify the bolus thickness to optimize the treatment plan and adjust the acceptable maximum dose on the skin surface, all pending clinical situation.

Feasibility of electronic brachytherapy in cervix cancer-A dosimetric comparison of different brachytherapy techniques.

INTRODUCTION: This study analyzes cases in which electronic brachytherapy (eBT) led to acceptable treatment plans in cervical cancer. Findings were compared with dosimetry values obtained in 192Ir-based treatments according to the high-risk clinical target volume (HR-CTV) and the disease stage. MATERIAL AND METHODS: We retrospectively analyzed 48 patients with cervical cancer from two centers. The patients were treated with 192Ir based on MRI. It was possible to use interstitial needles via an Utrecht-type applicator. Dosimetry was simulated using eBT and the parameters D90 and D98 (HR-CTV) and D2cc, D1cc, and D0.1cc (bladder, rectum, and sigmoid colon) were evaluated. The Mann-Whitney U test was used for comparison. The overall cohort of patients was analyzed, as were the sub-cohorts based on stage (FIGO stages I+IIA, IIB and III-IV). Finally, the dosimetry of the eBT plans was evaluated, and the plans obtained were classified as "good", "acceptable", or "poor". RESULTS: Statistically significant differences were found between the eBT and 192Ir plans for D98 (HR-CTV), D1cc and D0.1cc (bladder), and D1cc and D0.1cc (sigmoid colon). A total of 31 cases (64.6%) were considered good, seven (14.6%) were considered acceptable, and 10 (20.8%) were considered poor. For volumes <30 cc, all the plans were good or acceptable; for volumes >30 cc, 54.3% were good, and 71.4% were good or acceptable. By stage, eBT plans for patients with stage IB-IIA disease were good in 100%, whereas those for patients with stage IIB were good in 70.6% and III-IV disease were good in 50%. CONCLUSIONS: eBT provides appropriate dosimetry for treatment of cervical cancer in selected cases.

Deep learning for fully automatic detection, segmentation, and Gleason grade estimation of prostate cancer in multiparametric magnetic resonance images.

Although the emergence of multi-parametric magnetic resonance imaging (mpMRI) has had a profound impact on the diagnosis of prostate cancers (PCa), analyzing these images remains still complex even for experts. This paper proposes a fully automatic system based on Deep Learning that performs localization, segmentation and Gleason grade group (GGG) estimation of PCa lesions from prostate mpMRIs. It uses 490 mpMRIs for training/validation and 75 for testing from two different datasets: ProstateX and Valencian Oncology Institute Foundation. In the test set, it achieves an excellent lesion-level AUC/sensitivity/specificity for the GGG[Formula: see text]2 significance criterion of 0.96/1.00/0.79 for the ProstateX dataset, and 0.95/1.00/0.80 for the IVO dataset. At a patient level, the results are 0.87/1.00/0.375 in ProstateX, and 0.91/1.00/0.762 in IVO. Furthermore, on the online ProstateX grand challenge, the model obtained an AUC of 0.85 (0.87 when trained only on the ProstateX data, tying up with the original winner of the challenge). For expert comparison, IVO radiologist's PI-RADS 4 sensitivity/specificity were 0.88/0.56 at a lesion level, and 0.85/0.58 at a patient level. The full code for the ProstateX-trained model is openly available at https://github.com/OscarPellicer/prostate_lesion_detection . We hope that this will represent a landmark for future research to use, compare and improve upon.

Very accelerated partial breast irradiation Phase I-II multicenter trial (VAPBI): Feasibility and early results.

PURPOSE: This is a multicenter Phase I-II trial endorsed by the GEC-ESTRO Breast Working Group, to analyze if very accelerated partial breast irradiation (VAPBI) with multicatheter interstitial brachytherapy is feasible and safe compared with the standard APBI treatment in 4-5 days for early stage breast carcinomas. METHODS AND MATERIALS: We have included 81 patients with pT1-2 pN0 invasive carcinomas after breast-conserving surgery. Between August 2017 and July 2019, 33 women received high-dose-rate brachytherapy, four fractions of 6.25 Gy in 2-3 days, and 48 patients received three fractions of 7.45 Gy in 2 days. Thirty-six patients were implanted perioperatively and 45 postoperatively. Mean age was 68 (51-90). Free surgical margins were of 2 mm or greater. RESULTS: Acute effects were 11% dermatitis, 18.5% hematoma, 3.7% infection, and 14.8% pain. At a median followup of 20 months (range 8-35), no relapse has occurred. Pigmentation changes in the entrance and exit of tubes were visible in 16%, but 1 year later, few cases remained. Patients developed G1-2 induration or fibrosis in 18.5% and 2.5%, respectively. No patient developed telangiectasia. The cosmetic outcome was good/excellent in 97.5% and fair in 2.5%. CONCLUSIONS: VAPBI with multicatheter interstitial brachytherapy using four fractions of 6.25 Gy or three fractions of 7.45 Gy in two or 3 days is feasible. No excess has been observed in acute effects. At a mean followup of 20 months, late side effects seem to be similar to standard fractionation. VAPBI in two to 3 days is beneficial for the patients and reduces the workload of the brachytherapy units.

Consensus statement from the Spanish Brachytherapy Group (GEB) on accelerated partial breast irradiation using multicatheter interstitial brachytherapy.

AIM: To establish consensus guidelines for a safe clinical practice of accelerated partial breast irradiation (APBI) interstitial multicatheter brachytherapy (BT). BACKGROUND: APBI with interstitial multicatheter BT has proved to be effective in the treatment of early stage breast cancer. This paradigm shift in the approach to early breast cancer conservative treatment, along with the existing controversies on the clinical practice of APBI, prompted the Spanish Brachytherapy Group (GEB) of the Spanish Societies of Radiation Oncology (SEOR) and Medical Physics (SEFM) to address BT APBI in a consensus meeting. MATERIALS AND METHODS: Prior to the meeting, a survey with 27 questions on indication, inclusion criteria, BT modality, implant technique, image guidance and simulation, CTV and OAR definition, dose prescription and fractionation, dose calculation, implant quality metrics and OAR dose constrains was distributed. Items not reaching a level of agreement of 70% were discussed and voted during the meeting. RESULTS: 26 Institutions completed the survey, 60% of them perform APBI procedures. The analysis of the survey showed consensus reached on approximately half the questions. An expert panel discussed the remaining items; thereafter, a voting established the definite consensus. CONCLUSIONS: This document summarizes the consensus guidelines agreed during the meeting of the Spanish Brachytherapy Group SEOR-SEFM. Institutions with BT facilities available should offer interstitial BT APBI as a treatment option to patients fulfilling the inclusion criteria. Institutions willing to implement interstitial BT APBI are encouraged to follow the consensus guidelines established herein.

Treatment of cervical cancer with electronic brachytherapy.

PURPOSE: We report the first cervical cancer cases treated with interstitial electronic brachytherapy (eBT) at our hospital and compare them with plans made with high-dose-rate interstitial brachytherapy based on Ir192 (HDR-BT). MATERIALS AND METHODS: Eight patients with cervical cancer were treated with the Axxent eBT device (Xoft, Inc.). Planning was with magnetic resonance imaging and computed tomography following the recommendations of the EMBRACE protocol. The dosimetry parameters of organs at risk (OAR) were evaluated for the bladder, rectum, and sigmoid colon (D2cc, D1cc, and D0.1cc). In addition, the V150 and V200 of irradiated tissue were compared for both eBT and HDR-BT. All patients received intensity-modulated external beam radiation therapy with a regimen of 23 sessions of 2 Gy followed by four sessions of 7 Gy of eBT performed over 2 weeks (two sessions followed by another two sessions a week later) following the EMBRACE recommendations. Each of the eight patients was followed to assess acute toxicity associated with treatment. RESULTS: The doses reaching OAR for eBT plans were lower than for HDR-BT plans. As for acute toxicity associated with eBT, very few cases of mucositis were detected. No cases of rectal toxicity and one case with grade 1 urinary toxicity were detected. The results at 1 month are equally good, and no relapses have occurred to date. CONCLUSIONS: The first results of treatment with the Axxent eBT device are promising, as no recurrences have been observed and toxicity is very low. eBT is a good alternative for treating cervical cancer in centers without access to conventional HDR.

Open Source 3D Printed Lung Tumor Movement Simulator for Radiotherapy Quality Assurance.

In OECD (Organization for Economic Co-operation and Development) countries, cancer is one of the main causes of death, lung cancer being one of the most aggressive. There are several techniques for the treatment of lung cancer, among which radiotherapy is one of the most effective and least invasive for the patient. However, it has associated difficulties due to the moving target tumor. It is possible to reduce the side effects of radiotherapy by effectively tracking a tumor and reducing target irradiation margins. This paper presents a custom electromechanical system that follows the movement of a lung tumor. For this purpose, a hysteresis loop of human lung movement during breathing was studied to obtain its characteristic movement equation. The system is controlled by an Arduino, steppers motors and a customized 3D printed mechanism to follow the characteristic human breathing, obtaining an accurate trajectory. The developed device helps the verification of individualized radiation treatment plans and permits the improvement of radiotherapy quality assurance procedures.

GEC-ESTRO ACROP recommendations in skin brachytherapy.

PURPOSE: The aim of this publication is to compile available literature data and expert experience regarding skin brachytherapy (BT) in order to produce general recommendations on behalf of the GEC-ESTRO Group. METHODS: We have done an exhaustive review of published articles to look for general recommendations. RESULTS: Randomized controlled trials, systemic reviews and meta-analysis are lacking in literature and there is wide variety of prescription techniques successfully used across the radiotherapy centers. BT can be delivered as superficial application (also called contact BT or plesiotherapy) or as interstitial for tumours thicker than 5 mm within any surface, including very irregular. In selected cases, particularly in tumours located within curved surfaces, BT can be advantageous modality from dosimetric and planning point of view when compared to external beam radiotherapy. The general rule in skin BT is that the smaller the target volume, the highest dose per fraction and the shortest overall length of treatment can be used. CONCLUSION: Skin cancer incidence is rising worldwide. BT offers an effective non-invasive or minimally invasive and relative short treatment that particularly appeals to elder and frail population.

Differentiation of benign and malignant lung lesions: Dual-Energy Computed Tomography findings.

PURPOSE: To determine whether parameters generated by Dual-Energy Computed Tomography (DECT) can distinguish malignant from benign lung lesions. METHODS: A prospective review of 125 patients with 126 lung lesions (23 benign and 103 malignant) who underwent lung DECT during arterial phase. All lesions were confirmed by tissue sampling. A radiologist semi-automatically contoured lesions and placed regions of interest (ROIs) in paravertebral muscle (PVM) for normalization. Variables related to absorption in Hounsfield units (HU), effective atomic number (Zeff), iodine concentration (ρI) and spectral CT curves were assessed. Receiver operating characteristic (ROC) curves were generated to calculate sensitivity and specificity as predictors of malignancy. Multivariate logistic regression analysis was performed. RESULTS: Reproducibility of measures normalized with PVM was poor. Bivariate analysis showed minimum Zeff and normalized mean Zeff to be statistically significant (p=0.001), with area under the curve (AUC) values: 0.66 (CI 95% 0.54-0.80) and 0.72 (CI 95%, 0.60-0.84), respectively. Logistic regression models showed no differences between raw and normalized measurements. In both models, minimum HU (OR: 0.9) and size (OR: 0.1) were predictive of benign lesions. CONCLUSIONS: A quantitative approach to DECT using raw measurements is simpler than logistic regression models. Normalization to PVM was not clinically reliable due to its poor reproducibility. Further studies are needed to confirm our findings.