Physics and Imaging in Radiation Oncology最新文献

{"title":"Treatment planning for very high energy electrons: Studies that indicate the potential of the modality","authors":"James L. Bedford,&nbsp;Uwe Oelfke","doi":"10.1016/j.phro.2024.100670","DOIUrl":"10.1016/j.phro.2024.100670","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Radiotherapy using Very High Energy Electrons (VHEE) has the potential to reduce dose to organs at risk compared to photons. This article therefore reviews treatment planning for VHEE, to clarify the potential benefit of the modality.</div></div><div><h3>Materials and methods</h3><div>Articles on VHEE were identified and those which focused on treatment planning were manually selected, particularly those which contained results on patient datasets. Benefits in absorbed dose to organs at risk were converted to percentages of prescription dose so as to provide uniform, clinically relevant reporting.</div></div><div><h3>Results</h3><div>Increased beam energy was found to reduce electron scatter and give rise to a narrower penumbra but lead to a rather constant depth dose curve, which was not as useful for sparing normal tissues as that of protons. The sharp penumbra of VHEE was of benefit in treatment planning for producing treatment plans with conformal dose shaping, with improved dose to critical structures being demonstrated for several treatment sites. Mean dose to critical structures, relative to the prescribed dose, was in the order of 0–10% lower than photons and 0–10% higher than protons. The delivery technology and dose distributions were also promising for radiotherapy with ultra-high dose rate (FLASH).</div></div><div><h3>Conclusion</h3><div>At present, the potential clinical benefit of VHEE relative to photons or protons is small. Further studies are needed to more precisely quantify the relative performance of broad beams versus pencil beam scanning and to investigate treatment sites that might benefit maximally from the use of VHEE beams.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"32 ","pages":"Article 100670"},"PeriodicalIF":3.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automatic segmentation for magnetic resonance imaging guided individual elective lymph node irradiation in head and neck cancer patients","authors":"Floris C.J. Reinders ,&nbsp;Mark H.F. Savenije ,&nbsp;Mischa de Ridder ,&nbsp;Matteo Maspero ,&nbsp;Patricia A.H. Doornaert ,&nbsp;Chris H.J. Terhaard ,&nbsp;Cornelis P.J. Raaijmakers ,&nbsp;Kaveh Zakeri ,&nbsp;Nancy Y. Lee ,&nbsp;Eric Aliotta ,&nbsp;Aneesh Rangnekar ,&nbsp;Harini Veeraraghavan ,&nbsp;Marielle E.P. Philippens","doi":"10.1016/j.phro.2024.100655","DOIUrl":"10.1016/j.phro.2024.100655","url":null,"abstract":"<div><h3>Background and purpose</h3><div>In head and neck squamous cell carcinoma (HNSCC) patients, the radiation dose to nearby organs at risk can be reduced by restricting elective neck irradiation from lymph node levels to individual lymph nodes. However, manual delineation of every individual lymph node is time-consuming and error prone. Therefore, automatic magnetic resonance imaging (MRI) segmentation of individual lymph nodes was developed and tested using a convolutional neural network (CNN).</div></div><div><h3>Materials and methods</h3><div>In 50 HNSCC patients (UMC-Utrecht), individual lymph nodes located in lymph node levels Ib-II-III-IV-V were manually segmented on MRI by consensus of two experts, obtaining ground truth segmentations. A 3D CNN (nnU-Net) was trained on 40 patients and tested on 10. Evaluation metrics were Dice Similarity Coefficient (DSC), recall, precision, and F1-score. The segmentations of the CNN was compared to segmentations of two observers. Transfer learning was used with 20 additional patients to re-train and test the CNN in another medical center.</div></div><div><h3>Results</h3><div>nnU-Net produced automatic segmentations of elective lymph nodes with median DSC: 0.72, recall: 0.76, precision: 0.78, and F1-score: 0.78. The CNN had higher recall compared to both observers (p = 0.002). No difference in evaluation scores of the networks in both medical centers was found after re-training with 5 or 10 patients.</div></div><div><h3>Conclusion</h3><div>nnU-Net was able to automatically segment individual lymph nodes on MRI. The detection rate of lymph nodes using nnU-Net was higher than manual segmentations. Re-training nnU-Net was required to successfully transfer the network to the other medical center.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"32 ","pages":"Article 100655"},"PeriodicalIF":3.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of deep learning-based target auto-segmentation for Magnetic Resonance Imaging-guided cervix brachytherapy","authors":"Rita Simões,&nbsp;Eva C. Rijkmans,&nbsp;Eva E. Schaake,&nbsp;Marlies E. Nowee,&nbsp;Sandra van der Velden,&nbsp;Tomas Janssen","doi":"10.1016/j.phro.2024.100669","DOIUrl":"10.1016/j.phro.2024.100669","url":null,"abstract":"<div><h3>Background and purpose</h3><div>The target structures for cervix brachytherapy are segmented by radiation oncologists using imaging and clinical information. At the first fraction, this is performed manually from scratch. For subsequent fractions the first fraction segmentations are rigidly propagated and edited manually. This process is time-consuming while patients wait immobilized. In this work, we evaluate the potential clinical impact of using population-based and patient-specific auto-segmentations as a starting point for target segmentation of the second fraction.</div></div><div><h3>Materials and method</h3><div>For twenty-eight patients with locally advanced cervical cancer, treated with MRI-guided brachytherapy, auto-segmentations were retrospectively generated for the second fraction image using two approaches: 1) population-based model, 2) patient-specific models fine-tuned on first fraction information. A radiation oncologist manually edited the auto-segmentations to assess model-induced bias. Pairwise geometric and dosimetric comparisons were performed for the automatic, edited and clinical structures. The time spent editing the auto-segmentations was compared to the current clinical workflow.</div></div><div><h3>Results</h3><div>The edited structures were more similar to the automatic than to the clinical structures. The geometric and dosimetric differences between the edited and the clinical structures were comparable to the inter-observer variability investigated in literature. Editing the auto-segmentations was faster than the manual segmentation performed during our clinical workflow. Patient-specific auto-segmentations required less edits than population-based structures.</div></div><div><h3>Conclusions</h3><div>Auto-segmentation introduces a bias in the manual delineations but this bias is clinically irrelevant. Auto-segmentation, particularly patient-specific fine-tuning, is a time-saving tool that can improve treatment logistics and therefore reduce patient burden during the second fraction of cervix brachytherapy.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"32 ","pages":"Article 100669"},"PeriodicalIF":3.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monte Carlo simulated correction factors for high dose rate brachytherapy postal dosimetry audit methodology","authors":"Krzysztof Chelminski ,&nbsp;Alexis Dimitriadis ,&nbsp;Roua Abdulrahim ,&nbsp;Pavel Kazantsev ,&nbsp;Evelyn Granizo-Roman ,&nbsp;Jonathan Kalinowski ,&nbsp;Shirin Abbasi Enger ,&nbsp;Godfrey Azangwe ,&nbsp;Mauro Carrara ,&nbsp;Jamema Swamidas","doi":"10.1016/j.phro.2024.100657","DOIUrl":"10.1016/j.phro.2024.100657","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>Full-scatter conditions in water are impractical for postal dosimetry audits in brachytherapy. This work presents a method to obtain correction factors that account for deviations from full-scatter water-equivalent conditions for a small plastic phantom.</div></div><div><h3>Material and Methods</h3><div>A 16 × 8 × 3 cm phantom (PMMA) with a radiophotoluminescent dosimeter (RPLD) at the centre and two catheters on either side was simulated using Monte Carlo (MC) to calculate correction factors accounting for the lack of scatter, non-water equivalence of the RPLD and phantom, source model and backscatter for HDR ⁶⁰Co and ¹⁹²Ir sources.</div></div><div><h3>Results</h3><div>The correction factors for non-water equivalence, lack of full scatter, and the use of PMMA were 1.062 ± 0.013, 1.059 ± 0.008 and 0.993 ± 0.009 for ¹⁹²Ir and 1.129 ± 0.005, 1.009 ± 0.005 and 1.005 ± 0.005 for ⁶⁰Co respectively. Water-equivalent backscatter thickness of 5 cm was found to be adequate and increasing thickness of backscatter did not have an influence on the RPLD dose. The mean photon energy in the RPLD for four HDR ¹⁹²Ir sources was 279 ± 2 keV in full scatter conditions and 295 ± 1 keV in the audit conditions. For ⁶⁰Co source the corresponding mean energies were 989 ± 1 keV and 1022 ± 1 keV respectively.</div></div><div><h3>Conclusions</h3><div>Correction factors were obtained through the MC simulations for conditions deviating from TG-43, including the amount of back scatter, and the optimum audit set up. Additionally, the influence of different source models on the correction factors was negligible and demonstrates their generic applicability.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"32 ","pages":"Article 100657"},"PeriodicalIF":3.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142560794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"External validation of a multimodality deep-learning normal tissue complication probability model for mandibular osteoradionecrosis trained on 3D radiation distribution maps and clinical variables","authors":"Laia Humbert-Vidan ,&nbsp;Christian R. Hansen ,&nbsp;Vinod Patel ,&nbsp;Jørgen Johansen ,&nbsp;Andrew P. King ,&nbsp;Teresa Guerrero Urbano","doi":"10.1016/j.phro.2024.100668","DOIUrl":"10.1016/j.phro.2024.100668","url":null,"abstract":"<div><h3>Background and purpose</h3><div>While the inclusion of spatial dose information in deep learning (DL)-based normal-tissue complication probability (NTCP) models has been the focus of recent research studies, external validation is still lacking. This study aimed to externally validate a DL-based NTCP model for mandibular osteoradionecrosis (ORN) trained on 3D radiation dose distribution maps and clinical variables.</div></div><div><h3>Methods and materials</h3><div>A 3D DenseNet-40 convolutional neural network (3D-mDN40) was trained on clinical and radiation dose distribution maps on a retrospective class-balanced matched cohort of 184 subjects. A second model (3D-DN40) was trained on dose maps only and both DL models were compared to a logistic regression (LR) model trained on DVH metrics and clinical variables. All models were externally validated by means of their discriminative ability and calibration on an independent dataset of 82 subjects.</div></div><div><h3>Results</h3><div>No significant difference in performance was observed between models. In internal validation, these exhibited similar Brier scores around 0.2, Log Loss values of 0.6–0.7 and ROC AUC values around 0.7 (internal) and 0.6 (external). Differences in clinical variable distributions and their effect sizes were observed between internal and external cohorts, such as smoking status (0.6 vs. 0.1) and chemotherapy (0.1 vs. −0.5), respectively.</div></div><div><h3>Conclusion</h3><div>To our knowledge, this is the first study to externally validate a multimodality DL-based ORN NTCP model. Utilising mandible dose distribution maps, these models show promise for enhancing spatial risk assessment and guiding dental and oncological decision-making, though further research is essential to address overfitting and domain shift for reliable clinical use.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"32 ","pages":"Article 100668"},"PeriodicalIF":3.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accuracy, repeatability, and reproducibility of water-fat magnetic resonance imaging in a phantom and healthy volunteer","authors":"Anouk Corbeau ,&nbsp;Pien van Gastel ,&nbsp;Piotr A. Wielopolski ,&nbsp;Nick de Jong ,&nbsp;Carien L. Creutzberg ,&nbsp;Uulke A. van der Heide ,&nbsp;Stephanie M. de Boer ,&nbsp;Eleftheria Astreinidou","doi":"10.1016/j.phro.2024.100651","DOIUrl":"10.1016/j.phro.2024.100651","url":null,"abstract":"<div><div>Bone marrow (BM) damage due to chemoradiotherapy can increase BM fat in cervical cancer patients. Water-fat magnetic resonance (MR) scans were performed on a phantom and a healthy female volunteer to validate proton density fat fraction accuracy, reproducibility, and repeatability across different vendors, field strengths, and protocols. Phantom measurements showed a high accuracy, high repeatability, and excellent reproducibility. Volunteer measurements had an excellent intra- and interreader reliability, good repeatability, and moderate to good reproducibility. Water-fat MRI show potential for quantification of longitudinal vertebral BM fat changes. Further studies are needed to validate and extend these findings for broader clinical applicability.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"32 ","pages":"Article 100651"},"PeriodicalIF":3.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparing robust proton versus online adaptive photon radiotherapy for short-course treatment of rectal cancer","authors":"Johanna A. Hundvin ,&nbsp;Unn Hege Lilleøren ,&nbsp;Alexander Valdman ,&nbsp;Bruno Sorcini ,&nbsp;John Alfred Brennsæter ,&nbsp;Camilla G. Boer ,&nbsp;Helge E.S. Pettersen ,&nbsp;Kathrine R. Redalen ,&nbsp;Inger Marie Løes ,&nbsp;Sara Pilskog","doi":"10.1016/j.phro.2024.100663","DOIUrl":"10.1016/j.phro.2024.100663","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Image-guided proton beam therapy (IG-PBT) and cone-beam CT (CBCT)-based online adaptive photon radiotherapy (oART) have potentials to restrict radiation toxicity. They are both hypothesised to reduce therapy limiting bowel toxicity in the multimodality treatment of locally advanced rectal cancer (LARC). This study aimed to quantify the difference in relevant dose-volume metrics for these modalities.</div></div><div><h3>Material and Methods</h3><div>Six-degrees-of-freedom IG-PBT and oART short-course radiotherapy (SCRT) were simulated for 18 LARC patients. Relative biological effectiveness (RBE) was 1.1 for IG-PBT. Delivered dose was evaluated using post-CBCTs. Target coverage was considered robust if average dose to 99% of the clinical target volume was <span><math><mrow><mo>≥</mo></mrow></math></span> 95% of the prescription. Organ at risk (OAR) doses were compared using dose-volume histograms and severe bowel toxicity estimated using dose–response modelling.</div></div><div><h3>Results</h3><div>Target coverage was robust in all patients for oART and all but one patient for IG-PBT. For the main OARs, IG-PBT increased the volume exposed to <span><math><mrow><mo>≥</mo></mrow></math></span> 15 Gy (RBE), but reduced volumes exposed to lower doses. Both low- and high-dose exposure to bowel loops were significantly different between the modalities (median (interquartile range) IG-PBT-V_8.9Gy(RBE) = 92 (51–156) cm³, oART-V_8.9Gy(RBE) = 166 (107–234) cm³, p &lt; 0.001; IG-PBT-V_23Gy(RBE) = 62 (25–106) cm³, oART-V_23Gy(RBE) = 38 (18–75) cm³, p &lt; 0.001), translating into similar total grade ≥ 3 bowel toxicity risk.</div></div><div><h3>Conclusion</h3><div>IG-PBT and oART delivered comparable and satisfying target coverage in SCRT for LARC with similar estimated risk of severe bowel toxicity. Volumes of OAR exposed to 15 Gy (RBE) or more were reduced by oART, while IG-PBT reduced the volumes receiving doses below this level.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"32 ","pages":"Article 100663"},"PeriodicalIF":3.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development and international multicentre pilot testing of a postal dosimetry audit methodology for high dose rate brachytherapy","authors":"Alexis Dimitriadis,&nbsp;Anna Becker,&nbsp;Krzysztof Chelminski,&nbsp;Pavel Kazantsev,&nbsp;Egor Titovich,&nbsp;Godfrey Azangwe,&nbsp;Liset de la Fuente Rosales,&nbsp;Benjamin Kellogg,&nbsp;Mauro Carrara,&nbsp;Jamema Swamidas","doi":"10.1016/j.phro.2024.100665","DOIUrl":"10.1016/j.phro.2024.100665","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>Dosimetry audits are essential for reducing errors in brachytherapy. A postal dosimetry audit methodology was developed and tested in an international multicentre pilot, to assess the accuracy of the Reference Air Kerma Rate of ¹⁹²Ir and ⁶⁰Co brachytherapy sources.</div></div><div><h3>Materials and Methods</h3><div>A compact phantom made of polymethyl methacrylate was developed to accommodate two catheters, a radiophotoluminescence dosimeter (RPLD) for dose measurements and a Gafchromic (RTQA2) film strip for source position verification. Deviations of the audit setup from TG-43 conditions were quantified experimentally and compared to previous Monte Carlo (MC) simulations. A measurement uncertainty budget was estimated for the RPLD analysis. The methodology was tested in an international pilot study consisting of 59 dosimeter sets among 48 centres from 11 countries.</div></div><div><h3>Results</h3><div>The experimental correction factors showed good agreement with previous MC simulations, and the total correction factor accounting for non-water equivalence, lack of scatter and beam quality was found to be 1.029 ± 0.009 for ¹⁹²Ir and 1.059 ± 0.007 for ⁶⁰Co sources, to be employed in audit measurement. The total uncertainty budget was estimated to be 2.24 % (k = 1). In the multicentre study, the ratio between measured and reported user dose ranged from 0.968 to 1.049, with all irradiated dosimeter sets within ± 5 %, and 54 out of 59 within ± 3 %.</div></div><div><h3>Conclusions</h3><div>The methodology was tested in an international multicentre pilot study and has shown good performance validating the uncertainty budget.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"32 ","pages":"Article 100665"},"PeriodicalIF":3.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-institutional experience treating patients with cardiac devices on a 1.5 Tesla magnetic resonance-linear accelerator and workflow development for thoracic treatments","authors":"Rick Keesman ,&nbsp;Erik van der Bijl ,&nbsp;Linda G.W. Kerkmeijer ,&nbsp;Neelam Tyagi ,&nbsp;Osman Akdag ,&nbsp;Jochem W.H. Wolthaus ,&nbsp;Sandrine M.G. van de Pol ,&nbsp;Juus L. Noteboom ,&nbsp;Martijn P.W. Intven ,&nbsp;Martin F. Fast ,&nbsp;Astrid L.H.M.W. van Lier","doi":"10.1016/j.phro.2024.100680","DOIUrl":"10.1016/j.phro.2024.100680","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Patients with cardiac implantable electronic devices (CIED patients) are often ineligible for online magnetic resonance-guided radiotherapy (MRgRT), most likely due to the absence of established guidelines. Existing radiotherapy (RT) and magnetic resonance imaging (MRI) guidelines offer an opportunity to construct MRgRT protocols, promoting equitable access. Our objective was to present such a workflow, share multi-institutional experiences treating CIED patients with MRgRT on a 1.5 T magnetic resonance-linear accelerator (MR-linac), and investigate geometric accuracy and electrocardiogram (ECG) monitoring for thoracic treatment.</div></div><div><h3>Materials and methods</h3><div>A risk analysis identified strategies for safe MRgRT for CIED patients. At three institutions, 21 pelvic and abdominal patients were treated. Patient records were analyzed for adverse events. Geometric accuracy was investigated using B₀-mapping with a phantom simulating moving lung and cardiac lesions near a CIED. Volunteer measurements evaluated the effects of patient positioning and MRI sequences on ECG signal distortion.</div></div><div><h3>Results</h3><div>MRI and RT workflows were adaptable to MRgRT. No adverse events were recorded. B₀-maps showed a maximum mean difference between static and dynamic phantom configurations of 0.1 mm, increasing to 0.4 mm distortion in the presence of a CIED. ECG readings exhibited severe distortions during scanning, hampering heart rhythm detection for most MRI sequences.</div></div><div><h3>Conclusions</h3><div>CIED patients can safely undergo treatment on a 1.5 T MR-linac following RT and MRI guidelines. For targets near CIEDs, a B₀-mapping procedure was considered accurate enough to determine MRgRT eligibility. Pulse oximetry is recommended for cardiac monitoring during MRI scanning due to ECG signal distortion.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"32 ","pages":"Article 100680"},"PeriodicalIF":3.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Palliative radiotherapy of soft tissue tumoral masses based on diagnostic instead of planning computed tomography scans","authors":"Satu Strengell ,&nbsp;Suvi Larjavaara ,&nbsp;Mikko Tenhunen,&nbsp;Anu Anttonen","doi":"10.1016/j.phro.2024.100682","DOIUrl":"10.1016/j.phro.2024.100682","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Radiotherapy (RT) treatment planning is based on a planning computed tomography scan (pCT), while the decision to treat is often already established on a diagnostic CT scan (dCT). The objective of this study was to evaluate the usage of dCT for palliative radiation planning of soft tissue tumoral masses (STTMs), removing the need for a pCT scan and associated attendances.</div></div><div><h3>Materials and methods</h3><div>RT planning was performed retrospectively to 38 STTMs of 7 anatomical sites using volumetric modulated arc therapy techniques in dCT and transferred to pCT. The dose of clinical target volumes (CTV), D(95 %,50 %), were compared between the plans. The patient setup was assessed in cone-beam CT scans.</div></div><div><h3>Results</h3><div>The differences of D(95 %,50 %) between dCT and pCT plans were the lowest in the STTMs of the thoracic cage (0.9 %,0.9 %), STTMs in the inguinal area (0.8 %,1.3 %) and in mediastinal masses associated with superior vena cava syndrome (SVCS) (1.1 %,1.3 %), while the differences increased for other sites. The patient setup was acceptable for 88 % of mediastinal masses associated with SVCS and ≤ 60 % of cases in other sites comparing pCT and CBCT images with a strict margin of 6 mm, but all cases fitted to increased 2 cm margin.</div></div><div><h3>Conclusions</h3><div>This study demonstrated the possibility of using dCT scans for palliative RT planning of STTMs for mediastinal masses associated with SVCS and for STTMs in the thoracic cage and in the inguinal area, indicating the potential feasibility of this procedure for clinical use.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"32 ","pages":"Article 100682"},"PeriodicalIF":3.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}