Strahlentherapie und Onkologie最新文献

{"title":"Multicenter ProKnow-based plan evaluation of postprostatectomy salvage radiotherapy patients using SPPORT and RADICALS-HD trial-defined dose constraints.","authors":"Michael Keilholz, Erik F Moar, Frederike Brose, Sebastian H Maier, Claus Belka, Paul Rogowski, Matthias Zähringer, Jan C Peeken, Stephanie E Combs, Stephan Schönecker, Florian Putz, Christoph Süß, Marius Treutwein, Vasiliki Angnostatou, Nina Schmidt-Hegemann","doi":"10.1007/s00066-026-02584-3","DOIUrl":"https://doi.org/10.1007/s00066-026-02584-3","url":null,"abstract":"<p><strong>Purpose: </strong>Salvage radiotherapy (sRT) after radical prostatectomy is the only curative treatment for patients with biochemical recurrence. Sparing organs at risk (OAR) is essential to minimize long-term toxicity. This multicenter study analyzed radiotherapy plans from Bavarian university centers within the Bavarian Cancer Research Center (BZKF) using dose-volume constraints from the SPPORT and RADICALS-HD trials.</p><p><strong>Methods: </strong>In this retrospective multicenter analysis, 117 patients treated with prostate bed sRT were included. Radiotherapy plans were anonymized and evaluated using ProKnow (Elekta, Stockholm, Sweden). Scorecards based on SPPORT and RADICALS-HD dose-volume constraints were used to assess plan quality. Planning metrics, including planning target volume (PTV), D95, conformality index, and V66, were recorded, and their correlations with OAR dose were analyzed.</p><p><strong>Results: </strong>The median PTV was 213.9 cm³ (interquartile range [IQR] 154.4-267.8 cm³), with a median D95 of 64.5 Gy (IQR 63.7-67.1 Gy). The median volume receiving 66 Gy (V66) was 192.62 cm³ (IQR 146.59-244.49 cm³). Bladder dose constraints were met in 92-100% of plans according to RADICALS-HD and in 89-97% according to SPPORT. Rectal constraints were fulfilled in 98-100% and 95-100% of plans, respectively. All femoral head plans met the SPPORT V50 constraint. Correlation analyses showed weak associations with bladder dose and weak-to-moderate associations with rectal dose.</p><p><strong>Conclusion: </strong>This multicenter analysis demonstrates that dose-volume objectives in the postoperative salvage setting can be reliably assessed across centers and are met in the majority of cases. ProKnow enables structured and objective plan evaluation and serves as a useful tool for standardized quality assurance.</p>","PeriodicalId":21998,"journal":{"name":"Strahlentherapie und Onkologie","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148798109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing inter-fraction set-up accuracy and margin minimization (E-SAMM): a comparison of maskless surface-guided and mask-based laser alignment positioning in pelvic radiotherapy.","authors":"Pramod Kumar Gupta, Sharad Singh, Rumita Singh, Sumanta Manna, Ragul T, Ritika Ranjan, Himanshu Verma, Shweta Srivastava, M L B Bhatt","doi":"10.1007/s00066-026-02585-2","DOIUrl":"https://doi.org/10.1007/s00066-026-02585-2","url":null,"abstract":"<p><strong>Purpose: </strong>Surface-guided radiation therapy (SGRT) is a non-invasive, tattoo-less technique that enables real-time optical surface monitoring during radiotherapy. This prospective E‑SAMM study compared inter-fraction set-up accuracy, estimated PTV margin requirements derived from CBCT-based pre-correction setup deviations, and set-up time between maskless SGRT and mask-based setup in patients receiving pelvic radiotherapy.</p><p><strong>Methods: </strong>One hundred patients with pelvic malignancies (cervical, endometrial, rectal, and prostate cancers) undergoing radical or neoadjuvant radiotherapy (45-68 Gy delivered in 25-28 fractions, five fractions per week) were prospectively enrolled. A total of 2376 fractions were analysed. Patients were randomised to either maskless SGRT with AlignRT, knee support, and intrafraction monitoring (Group A, n = 50) or six-clamp mask-based laser alignment with image-guided radiotherapy (Group B, n = 50). All patients underwent online cone-beam computed tomography (CBCT) verification on a TrueBeam SVC linear accelerator with a six-degree-of-freedom couch. Inter-fraction translational (medio-lateral [ML], cranio-caudal [CC], antero-posterior [AP]) and rotational set-up errors were derived from CBCT corrections. PTV margin estimates were calculated using the van Herk formula from CBCT-recorded pre-correction setup deviations. Statistical comparisons were performed using analysis of variance and the Mann-Whitney U test.</p><p><strong>Results: </strong>SGRT demonstrated significantly improved translational accuracy in the ML (1.97 ± 1.54 mm vs 2.63 ± 2.06 mm, P = 0.03) and CC (3.13 ± 2.34 mm vs 4.03 ± 2.67 mm, P = 0.001) directions compared with mask-based alignment, whereas larger shifts were observed in the AP direction (P = 0.001). Rotational differences were not statistically significant (P = 0.14). The mean three-dimensional vector displacement was significantly lower with SGRT (1.91 ± 0.36 mm) than with mask-based positioning (2.26 ± 0.48 mm; P < 0.05). Estimated PTV margins were smaller with SGRT in all translational directions. Mean set-up time was significantly reduced with SGRT (2.51 ± 0.81 min vs 3.55 ± 0.99 min, P = 0.007).</p><p><strong>Conclusions: </strong>Maskless SGRT provided improved inter-fraction set-up accuracy, lower estimated PTV margin requirements based on setup deviations, and shorter set-up times compared with mask-based laser alignment for pelvic radiotherapy.</p>","PeriodicalId":21998,"journal":{"name":"Strahlentherapie und Onkologie","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148798036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Survival and patterns of recurrence in patients with nasopharyngeal carcinoma from a non-endemic region-A German multicenter analysis.","authors":"Justus Kaufmann, Isabel Krabbes, Eirini Nikolaidou, Nwabata Oji, Simone Ferdinandus, Julian Hlouschek, Georg Wurschi, Jan-Niklas Becker, Jana Schaule, Jörg-Andreas Müller, Laura Oebel, Felix Ehret, Christian Grad, Alexander Rühle","doi":"10.1007/s00066-026-02580-7","DOIUrl":"https://doi.org/10.1007/s00066-026-02580-7","url":null,"abstract":"<p><strong>Purpose: </strong>To determine oncological outcomes and patterns of recurrence of nasopharyngeal carcinoma (NPC) in a non-endemic population.</p><p><strong>Methods: </strong>MERLIN (DRKS00034782) is a retrospective study initiated by the Young DEGRO that included NPC patients who received definitive radiotherapy between 2004 and 2023. Overall survival (OS) and disease-free survival (DFS) were determined using Kaplan-Meier analyses, while the incidence of treatment failures was analyzed with death as a competing event. Prognostic variables were identified using Cox regression analyses.</p><p><strong>Results: </strong>Two hundred ninety-nine patients from 9 centers were analyzed; 274 (92%) were treated with concurrent systemic treatment, while 48 (16%) and 14 (5%) received induction and adjuvant chemotherapy. After a median follow-up of 62 months, 93 deaths, 40 local failures (LF), 19 regional failures (RF), and 41 distant failures (DF) were observed. Most LF (30/40), RF (15/19), and DF (38/41) occurred within the first 3 years after treatment. Five-year OS and DFS rates were 71% and 61%, while the 5‑year incidences of locoregional failures (LRF) and DF were 18% and 14%. In the multivariable analysis, age (HR, 1.03; 95% CI, 1.01-1.05), Karnofsky performance status (≤ 80% vs. ≥ 90%; HR, 1.97; 95%CI, 1.27-3.07), and AJCC/UICC stage (IV vs. I‑III; HR, 2.18; 95%CI, 1.42-3.35) were associated with DFS.</p><p><strong>Conclusion: </strong>The rates of LRF and DF in this cohort are similar, and the highest risk for disease progression is within the first 3 years after treatment. Future analyses are needed to assess potential improvements with the use of induction and adjuvant systemic therapy.</p>","PeriodicalId":21998,"journal":{"name":"Strahlentherapie und Onkologie","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148798057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stereotactic radiotherapy in brain metastases: SRS/FSRT paradox and preferences of radiation oncologists in Türkiye (TROD 10-010 study).","authors":"Berna Akkus Yildirim, Caglayan Selenge Beduk Esen, Sezin Yuce Sari, Enis Ozyar, Yildiz Guney","doi":"10.1007/s00066-026-02586-1","DOIUrl":"10.1007/s00066-026-02586-1","url":null,"abstract":"<p><strong>Purpose: </strong>Brain metastases (BM) are the most common intracranial malignancies. However, the lack of high-level evidence comparing single- and multi-fraction stereotactic radiotherapy (SRT) results in substantial practice variability. We aimed to assess fractionation preferences and clinical decision-making among radiation oncologists (ROs) in Turkey.</p><p><strong>Materials and methods: </strong>A 21-question nationwide survey was conducted among ROs performing stereotactic treatment for BM. Responses were analyzed by clinical experience (> 10 vs ≤ 10 years).</p><p><strong>Results: </strong>A total of 111 ROs participated; 77% had > 10 years of experience. Linac-based SRS was most commonly used (84%). Although 42% favored preoperative SRS, only 12% implemented it. The main factors influencing the choice of SRS over WBRT were number (42%) and volume (33%) of metastases. Junior ROs prioritized lesion number, whereas senior ROs adopted a more multifactorial approach. Most participants used both SRS and FSRT (57%). Fractionation decisions were primarily driven by lesion volume (83%), proximity to organs at risk (76%), size (75%), and location (74%). SRS was preferred for smaller, peripherally located lesions without prior WBRT.</p><p><strong>Conclusion: </strong>Fractionation strategies vary widely and are influenced by clinical experience, underscoring the need for prospective evidence and standardized guidance.</p>","PeriodicalId":21998,"journal":{"name":"Strahlentherapie und Onkologie","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148726865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DEGRO practical guidelines: radiotherapy of breast cancer-Regional nodal irradiation.","authors":"Vrushab Rao, Sagar Raut, Papuji Meher, Siddhartha Nanda","doi":"10.1007/s00066-026-02581-6","DOIUrl":"10.1007/s00066-026-02581-6","url":null,"abstract":"","PeriodicalId":21998,"journal":{"name":"Strahlentherapie und Onkologie","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148679961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carboplatin/Paclitaxel can be an effective alternative for cisplatin-ineligible patients with locally advanced HNSCC.","authors":"Stefan Gravemeyer, Jule Hermanns, David R Steike, Tom Schlusemann, Maximilian Oberste, Armands Riders, Gabriele Reinartz, Claudia Rudack, Hans T Eich","doi":"10.1007/s00066-026-02579-0","DOIUrl":"https://doi.org/10.1007/s00066-026-02579-0","url":null,"abstract":"<p><strong>Background: </strong>Despite considerable therapeutic advances, a significant evidence gap remains regarding optimal treatment strategies for cisplatin-unfit patients and whether carboplatin/paclitaxel represents a valid therapeutic alternative. This study investigates the treatment outcomes of patients receiving various platinum-based chemotherapy regimens.</p><p><strong>Methods: </strong>Between 2012 and 2022, 170 patients with LAHNSCC were included in the analysis. Overall survival (OS) and progression-free survival (PFS), as well as treatment-related toxicities, were evaluated.</p><p><strong>Results: </strong>The included patients were treated with intensity-modulated radiotherapy (IMRT) at a total dose of 59.4-72 Gy, along with 5-6 cycles of weekly platinum-based chemotherapy. 130 patients received cisplatin (40 mg/m² BSA), while 40 patients received carboplatin (AUC 1) and paclitaxel (40 mg/m² BSA). Median follow-up was 32 months. No significant difference was observed in median PFS (p = 0.14; HR 0.74 [0.44-1.26]) nor OS (p = 0.11; HR 0.62 [0.36-1.10]). Subgroup analysis showed that especially patients < 65 years and patients in the adjuvant setting benefit from the use of cisplatin.</p><p><strong>Conclusion: </strong>Definitive and postoperative radiochemotherapy for the treatment of LAHNSCC with concurrent administration of carboplatin/paclitaxel can be used as a safe and effective alternative but only for cisplatin-ineligible patients.</p>","PeriodicalId":21998,"journal":{"name":"Strahlentherapie und Onkologie","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148664451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The impact of uterine position during brachytherapy on treatment outcomes and toxicity in patients with cervical cancer.","authors":"Ecem Yigit, Melis Gultekin, Pantea Bayatfard, Sezin Yuce Sari, Fatih Biltekin, Ferah Yildiz","doi":"10.1007/s00066-026-02582-5","DOIUrl":"https://doi.org/10.1007/s00066-026-02582-5","url":null,"abstract":"<p><strong>Purpose: </strong>To evaluate the impact of uterine position during brachytherapy on dosimetric parameters, oncologic outcomes, and toxicity in cervical cancer patients treated with external beam radiotherapy (EBRT) followed by high-dose-rate intracavitary brachytherapy (HDR-ICBT).</p><p><strong>Methods: </strong>A retrospective analysis was conducted on 278 non-metastatic cervical cancer patients treated between 2012 and 2022. All received 45-50.4 Gy EBRT followed by 28 Gy HDR-ICBT in four fractions. Uterine position was documented for each ICBT fraction, and patients with inter-fraction variations were excluded.</p><p><strong>Results: </strong>In total, 251 patients met the inclusion criteria: 222 (88%) had an anteverted and 29 (12%) had a retroverted uterus. Median follow-up was 44 months (range: 1-134 months). The 2- and 5‑year overall survival rate was 82% and 71% for an anteverted vs. 77% and 77% for a retroverted uterus (p = 0.8). Local recurrence developed in 21 (10%) and three (11%) patients, respectively (p = 0.89). Median doses to the high- and intermediate-risk clinical target volumes (CTV) were higher with an anteverted uterus (91.3 vs. 89.8 Gy, p = 0.001; and 67.4 vs. 65.9 Gy, p = 0.044). A retroverted uterus was associated with higher rectum (76.3 vs. 79.7 Gy, p = 0.001) and bowel doses (66.4 vs. 73.7 Gy, p = 0.023), yet lower sigmoid doses (63.4 vs. 59.9 Gy, p = 0.005). Severe toxicity rates were similar, although late grade 1-2 gastrointestinal toxicity was more frequent in the retroverted group (4% vs. 17%, p = 0.019).</p><p><strong>Conclusion: </strong>A retroverted uterine position during ICBT was associated with lower CTV doses and higher rectum and bowel doses while oncologic outcomes and severe toxicity remained comparable.</p>","PeriodicalId":21998,"journal":{"name":"Strahlentherapie und Onkologie","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148670643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radiotherapy as an antihemorrhagic approach in gastric cancer: the RANTIGA study.","authors":"Valeria Epifani, Francesco Cellini, Luigina Graziosi, Rita Marina Niespolo, Giampaolo Montesi, Najla Slim, Alessio Gili, Nicola Simoni, Eliana La Rocca, Luca Nicosia, Vincenzo Burgio, Filippo Patti, Alessia Surgo, Carmen Molica, Pierfrancesco Franco, Cynthia Aristei, Marco Lupattelli","doi":"10.1007/s00066-026-02542-z","DOIUrl":"10.1007/s00066-026-02542-z","url":null,"abstract":"<p><strong>Introduction: </strong>Gastric bleeding is a major symptom of locally advanced gastric cancer and a significant cause of mortality. Management options include surgery, endoscopic interventions, embolization and radiotherapy (RT). Although palliative RT appears effective for hemorrhage control, evidences are limited to underpowered retrospective studies from Asia, with issues of patient heterogeneity and response evaluation criteria. This study is a multicenter retrospective analysis carried out across Italian radiation oncology centers to evaluate real-world outcomes of hemostatic RT in patients with bleeding gastric cancer.</p><p><strong>Methodology: </strong>Clinical and dosimetric data were retrospectively collected for patients with active bleeding gastric cancer treated across twelve Italian radiation oncology centers. The primary endpoint was to evaluate hemoglobin stabilization or improvement at four weeks post-treatment. Secondary outcomes included treatment parameters, acute toxicity profile and time to rebleeding.</p><p><strong>Results: </strong>Between January 2018 and October 2024, 100 patients receiving hemostatic RT were collected for the analysis. The median age was 77 years, 68% of cases had advanced disease and 41% of patients were pretreated with chemotherapy. The most frequently administered dose was 39 Gy BED10 (range: 9.6-53.1) with a schedule of 30 Gy in 10 fractions. The primary endpoint was achieved in 95/100 patients (95%) indicating stabilization or improvement in Hb levels without the need for post-treatment transfusions. Only 12 patients experienced acute toxicity, of whom 2 (3.3%) presenting grade 3 nausea. Rebleeding symptoms occurred in 38.5% of cases (median interval of 164 days).</p><p><strong>Conclusion: </strong>This national, retrospective, multicenter study suggests that palliative gastric RT is a feasible, effective and well-tolerated approach in this cohort of patients with bleeding gastric cancer, providing hemostatic control and stabilizing hemoglobin levels. Prospective trials are warranted to better define the role of RT, particularly in terms of dose and fractionation based on the disease setting and patient characteristics.</p>","PeriodicalId":21998,"journal":{"name":"Strahlentherapie und Onkologie","volume":" ","pages":"862-868"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13391449/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147875727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Duration of androgen deprivation therapy with radiotherapy for localized prostate cancer: is 36 months still necessary?]","authors":"Niklas Recknagel, Julia Heinzelbecker, Sebastian Adeberg","doi":"10.1007/s00066-026-02556-7","DOIUrl":"10.1007/s00066-026-02556-7","url":null,"abstract":"","PeriodicalId":21998,"journal":{"name":"Strahlentherapie und Onkologie","volume":" ","pages":"908-910"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148218984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dosimetric robustness of urethra sparing in ultrahypofractionated prostate SBRT using catheter-based motion tracking.","authors":"J Berchtold, M Schichl, N Annon-Eberharter, I M Messner, C Gaisberger, F Röder, F Wolf","doi":"10.1007/s00066-026-02547-8","DOIUrl":"10.1007/s00066-026-02547-8","url":null,"abstract":"<p><strong>Purpose: </strong>In ultrahypofractionated prostate stereotactic body radiation therapy (SBRT), genitourinary toxicity is the primary concern. Urethra sparing is a strategy to mitigate potential negative effects of higher single doses to the urethra and bladder neck. We report on the dosimetric robustness of urethra sparing using a catheter-based real-time monitoring device to track both interfractional variability and intrafractional motion.</p><p><strong>Methods: </strong>In 12 patients undergoing prostate ultrahypofractionated radiotherapy (UHFX), intrafractional prostate motion was monitored using a HypoCath catheter (Micropos Medical™, Gothenburg, Sweden), enabling urethra contouring on the planning CT and cone-beam (CB)CT images used for image-guided radiation therapy (IGRT). Dose coverage of both the urethra and the prostate clinical target volume (CTV) was calculated and compared between the planning CT and matched CBCTs. In addition, prostate motion was simulated and the cumulative dose coverage of prostate and urethra was calculated as a function of time.</p><p><strong>Results: </strong>The deviation between the planned and delivered urethral dose strongly correlated with elapsed time. Variations in the urethral curvature between planning CT and CBCT had only a minimal effect on the dose distribution. The combined effects of deviations in the urethral shape and prostate movement resulted in a mean dose deviation of 76 cGy for the urethral D1 of all fractions and patients. The patient who experienced the greatest prostate motion showed an increase in urethral D1 of 1.94 Gy (+5.2%).</p><p><strong>Conclusion: </strong>Urethra sparing is feasible and only marginally impaired by variations in urethral shape but is sensitive to longer treatment durations due to intrafractional movement. Direct visualization of the urethra is not essential for IGRT, but intrafractional motion control is recommended.</p>","PeriodicalId":21998,"journal":{"name":"Strahlentherapie und Onkologie","volume":" ","pages":"882-887"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13391749/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147989166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}