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Simple Summary: Locoregional hyperthermia has been widely used in combination with radiation therapy in several cancer types, including radiorecurrent tumors. Radiorecurrent prostate cancer is a challenging clinical situation, with few treatments available. Reirradiation combined with hyperthermia represents an appealing treatment strategy, although few studies have been reported to date. We aimed to design a specific transperineal focused ultrasound transducer for prostate cancer regional deep hyperthermia treatment, apt to ensure optimal target coverage and patient comfort. The existing prostate transducers (endorectal or transurethral) are not designed for treatments longer than 1h and are able to act upon limited volumes only. Design, embodiment, and experimental study of a novel concept of extracorporeal phased array ultrasound transducer for prostate cancer regional deep hyperthermia treatments using a transperineal acoustic window is presented. An optimized design of hyperthermia applicator was derived from a modelling software where acoustic and thermal fields were computed based on anatomical data. Performance tests have been experimentally conducted on gel phantoms and tissues, under 3T MRI guidance using PRFS thermometry. Feedback controlled hyperthermia (ΔT = 5 °C during 20min) was performed on two ex vivo lamb carcasses with prostate mimicking pelvic tissue, to demonstrate capability of spatio-temporal temperature control and to assess potential risks and side effects. Our optimization approach yielded a therapeutic ultrasound transducer consisting of 192 elements of variable shape and surface, pseudo randomly distributed on 6 columns, using a frequency of 700 kHz. Radius of curvature was 140 mm and active water circulation was included for cooling. The measured focusing capabilities covered a volume of 24 × 50 × 60 mm3. Acoustic coupling of excellent quality was achieved. No interference was detected between sonication and MR acquisitions. On ex vivo experiments the target temperature elevation of 5 °C was reached after 5 min and maintained during another 15 min with the predictive temperature controller showing 0.2 °C accuracy. No significant temperature rise was observed on skin and bonny structures. Reported results represent a promising step toward the implementation of transperineal ultrasound hyperthermia in a pilot study of reirradiation in prostate cancer patients. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the study was to evaluate the dosimetric impact of sexual-sparing radiotherapy for prostate cancer, with magnetic resonance-only treatment planning., Material and Methods: Fifteen consecutive patients receiving prostate cancer radiotherapy were selected. A synthetic CT was generated with a deep learning method from each T2-weighted MRI performed at the time of treatment planning. For each patient, two plans were performed: standard treatment planning and sexual-structures sparing treatment planning. The treatment plan was designed to deliver a dose of 78Gy to the prostate and 50Gy to the seminal vesicles in 2Gy daily fractions, using volumetric arc therapy. Dose-volume histograms were computed to compare treatment plans., Results: All plans fulfilled dosimetric objectives and were equivalent regarding planning target volume coverage. The doses delivered to both rectum, bladder, and femoral heads were similar between plans (P=0.20). Sexual-sparing plans enabled to decrease all dosimetric parameters on sexual organs-at-risk. The mean penile bulb dose in sexual-sparing plans was significantly reduced (21.1Gy±20.7 versus 13.4Gy±14.0, P<0.01), however with large variability observed between individuals. The mean dose delivered to the corpora cavernosa was also significantly reduced within sexual-sparing plans (13.1Gy±16.7 versus 8.6Gy±10.4, P<0.01). A significant reduction was also observed in the highest doses delivered to internal pudendal arteries (D10%: 48.4Gy±8.3 versus 33.1Gy±4.6, P<0.05; D5%: 52.0Gy±8.7 versus 36.8Gy±5.5, P<0.05)., Conclusion: Sparing of sexual structures appears feasible, without compromising neither planning target volume coverage nor doses delivered to non-sexual organs at risk. The clinical significance of this dose-reduction requires prospective evaluation., (Copyright © 2024 Société française de radiothérapie oncologique (SFRO). Published by Elsevier Masson SAS. All rights reserved.)

Minimal invasive surgery and reconstructive surgery tend to become the standard in France in the management of head and neck tumors. The use of endoscopic approaches (through endoscopic endonasal/transoral approaches±robot-assisted) instead of open surgery and the use of reconstructive surgery using autologous (flaps) or heterologous materials aim to reduce surgical morbidity by making-up for the loss of substance to restore the function. The impact of these substantial changes in surgical techniques has not been assessed with respect to postoperative radiotherapy practice. Endoscopic endonasal approaches result, however, in piecemeal resection, which, along the analysis of resection margins (a key prognostic factor), make the interpretation of the quality of resection more complex for radiation oncologists. The definition of tumour sub-volumes to be irradiated and doses to these sub-volumes then requires accurate histosurgical mapping and close multidisciplinary consultation between surgeons, pathologists, radiologists and radiation oncologists. Similarly, the increasing use of various types of flaps (of soft tissue or bone flaps), adapted to the patient and tumor anatomy, is associated with substantial modifications to the operating bed. The delineation of tumour volumes in postoperative radiotherapy is made more complex. Tremendous multidisciplinary efforts should now be initiated to fully take advantage of surgical advances and to further optimize the therapeutic index by making radiotherapy also less toxic, i.e. "mini-morbid"., (Copyright © 2020 Société Française du Cancer. Published by Elsevier Masson SAS. All rights reserved.)