Physics and Imaging in Radiation Oncology最新文献

{"title":"Benefit of range uncertainty reduction in robust optimisation for proton therapy of brain, head-and-neck and breast cancer patients","authors":"Ivanka Sojat Tarp,&nbsp;Vicki Trier Taasti,&nbsp;Maria Fuglsang Jensen,&nbsp;Anne Vestergaard,&nbsp;Kenneth Jensen","doi":"10.1016/j.phro.2024.100632","DOIUrl":"10.1016/j.phro.2024.100632","url":null,"abstract":"<div><h3>Background and Purpose</h3><p>The primary cause of range uncertainty in proton therapy is inaccuracy in estimating the stopping-power ratio from computed tomography. This study examined the impact on dose-volume metrics by reducing range uncertainty in robust optimisation for a diverse patient cohort and determined the level of range uncertainty that resulted in a relevant reduction in doses to organs-at-risk (OARs).</p></div><div><h3>Materials and Methods</h3><p>The effect of reducing range uncertainty on OAR doses was evaluated by robustly optimising six proton plans with varying range uncertainty levels (ranging from 3.5% in the original plan to 1.0%), keeping setup uncertainty fixed. All plans used the initial clinical treatment plan’s beam directions and optimisation objectives and were optimised until a clinically acceptable plan was achieved across all setup and range scenarios. The effect of reduced range uncertainty on dose-volume metrics for OARs near the target was evaluated. This study included 30 brain cancer patients, as well as five head-and-neck and five breast cancer patients, investigating the relevance of reducing range uncertainty when different setup uncertainties were used.</p></div><div><h3>Results</h3><p>Lowering range uncertainty slightly reduced the nominal dose to surrounding tissue. For body volume receiving 80% of the prescribed dose, reducing range uncertainty from 3.5% to 2.0% resulted in a median decrease of 4 cm³ for the brain, 17 cm³ for head-and-neck, and 27 cm³ for breast cancer patients.</p></div><div><h3>Conclusions</h3><p>Reducing range uncertainty in robust optimisation showed a reduction in dose to OARs. The clinical relevance depends on the affected organs and the clinical dose constraints.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"31 ","pages":"Article 100632"},"PeriodicalIF":3.4,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624001027/pdfft?md5=40ea3b02cd9b1b02dc1f30a7b0acf9f4&pid=1-s2.0-S2405631624001027-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142048381","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":"Correlation between local instantaneous dose rate and oxygen pressure reduction during proton pencil beam scanning irradiation","authors":"Eleni Kanouta ,&nbsp;Jacob Graversen Johansen ,&nbsp;Sara Poulsen ,&nbsp;Line Kristensen ,&nbsp;Brita Singers Sørensen ,&nbsp;Cai Grau ,&nbsp;Morten Busk ,&nbsp;Per Rugaard Poulsen","doi":"10.1016/j.phro.2024.100614","DOIUrl":"10.1016/j.phro.2024.100614","url":null,"abstract":"<div><h3>Background and purpose</h3><p>Oxygen dynamics may be important for the tissue-sparing effect observed at ultra-high dose rates (FLASH sparing effect). This study investigated the correlation between local instantaneous dose rate and radiation-induced oxygen pressure reduction during proton pencil beam scanning (PBS) irradiations of a sample and quantified the oxygen consumption g-value.</p></div><div><h3>Materials and methods</h3><p>A 0.2 ml phosphorescent sample (1 μM PtG4 Oxyphor probe in saline) was irradiated with a 244 MeV proton PBS beam. Four irradiations were performed with variations of a PBS spot pattern with 5 × 7 spots. During irradiation, the partial oxygen pressure (pO₂) was measured with 4.5 Hz temporal resolution with a phosphorometer (Oxyled) that optically excited the probe and recorded the subsequently emitted light. A calibration was performed to calculate the pO₂ level from the measured phosphorescence lifetime. A fiber-coupled scintillator simultaneously measured the instantaneous dose rate in the sample with 50 kHz sampling rate. The oxygen consumption g-value was determined on a spot-by-spot level and using the total pO₂ change for full spot pattern irradiation.</p></div><div><h3>Results</h3><p>A high correlation was found between the local instantaneous dose rate and pO₂ reduction rate, with a correlation coefficient of 0.96–0.99. The g-vales were 0.18 ± 0.01 mmHg/Gy on a spot-by-spot level and 0.17 ± 0.01 mmHg/Gy for full spot pattern irradiation.</p></div><div><h3>Conclusions</h3><p>The pO₂ reduction rate was directly related to the local instantaneous dose rate per delivered spot in PBS deliveries. The methodology presented here can be applied to irradiation at ultra-high dose rates with modifications in the experimental setup.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"31 ","pages":"Article 100614"},"PeriodicalIF":3.4,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624000848/pdfft?md5=208a49b4c62262ac9e7dcbf5e7a6ba13&pid=1-s2.0-S2405631624000848-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141853451","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":"A treatment-site-specific evaluation of commercial synthetic computed tomography solutions for proton therapy","authors":"Ping Lin Yeap ,&nbsp;Yun Ming Wong ,&nbsp;Kang Hao Lee ,&nbsp;Calvin Wei Yang Koh ,&nbsp;Kah Seng Lew ,&nbsp;Clifford Ghee Ann Chua ,&nbsp;Andrew Wibawa ,&nbsp;Zubin Master ,&nbsp;James Cheow Lei Lee ,&nbsp;Sung Yong Park ,&nbsp;Hong Qi Tan","doi":"10.1016/j.phro.2024.100639","DOIUrl":"10.1016/j.phro.2024.100639","url":null,"abstract":"<div><h3>Background and purpose</h3><p>Despite the superior dose conformity of proton therapy, the dose distribution is sensitive to daily anatomical changes, which can affect treatment accuracy. This study evaluated the dose recalculation accuracy of two synthetic computed tomography (sCT) generation algorithms in a commercial treatment planning system.</p></div><div><h3>Materials and methods</h3><p>The evaluation was conducted for head-and-neck, thorax-and-abdomen, and pelvis sites treated with proton therapy. Thirty patients with two cone-beam computed tomography (CBCT) scans each were selected. The sCT images were generated from CBCT scans using two algorithms, Corrected CBCT (corrCBCT) and Virtual CT (vCT). Dose recalculations were performed based on these images for comparison with “ground truth” deformed CTs.</p></div><div><h3>Results</h3><p>The choice of algorithm influenced dose recalculation accuracy, particularly in high dose regions. For head-and-neck cases, the corrCBCT method showed closer agreement with the “ground truth”, while for thorax-and-abdomen and pelvis cases, the vCT algorithm yielded better results (mean percentage dose discrepancy of 0.6 %, 1.3 % and 0.5 % for the three sites, respectively, in the high dose region). Head-and-neck and pelvis cases exhibited excellent agreement in high dose regions (2 %/2 mm gamma passing rate &gt;98 %), while thorax-and-abdomen cases exhibited the largest differences, suggesting caution in sCT algorithm usage for this site. Significant systematic differences were observed in the clinical target volume and organ-at-risk doses in head-and-neck and pelvis cases, highlighting the importance of using the correct algorithm.</p></div><div><h3>Conclusions</h3><p>This study provided treatment site-specific recommendations for sCT algorithm selection in proton therapy. The findings offered insights for proton beam centers implementing adaptive radiotherapy workflows.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"31 ","pages":"Article 100639"},"PeriodicalIF":3.4,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S240563162400109X/pdfft?md5=ba78c750d5b28de5c476ae16c45a73a8&pid=1-s2.0-S240563162400109X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142129785","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":"Comparison of stereotactic radiotherapy and protons for uveal melanoma patients","authors":"Emmanuelle Fleury ,&nbsp;Jean-Philippe Pignol ,&nbsp;Emine Kiliç ,&nbsp;Maaike Milder ,&nbsp;Caroline van Rij ,&nbsp;Nicole Naus ,&nbsp;Serdar Yavuzyigitoglu ,&nbsp;Wilhelm den Toom ,&nbsp;Andras Zolnay ,&nbsp;Kees Spruijt ,&nbsp;Marco van Vulpen ,&nbsp;Petra Trnková ,&nbsp;Mischa Hoogeman","doi":"10.1016/j.phro.2024.100605","DOIUrl":"https://doi.org/10.1016/j.phro.2024.100605","url":null,"abstract":"<div><h3>Background and purpose</h3><p>Uveal melanoma (UM) is the most common primary ocular malignancy. We compared fractionated stereotactic radiotherapy (SRT) with proton therapy, including toxicity risks for UM patients.</p></div><div><h3>Materials and methods</h3><p>For a total of 66 UM patients from a single center, SRT dose distributions were compared to protons using the same planning CT. Fourteen dose-volume parameters were compared in 2-Gy equivalent dose per fraction (EQD2). Four toxicity profiles were evaluated: maculopathy, optic-neuropathy, visual acuity impairment (Profile I); neovascular glaucoma (Profile II); radiation-induced retinopathy (Profile III); and dry-eye syndrome (Profile IV). For Profile III, retina Mercator maps were generated to visualize the geographical location of dose differences.</p></div><div><h3>Results</h3><p>In 9/66 cases, (14 %) proton plans were superior for all dose-volume parameters. Higher T stages benefited more from protons in Profile I, especially tumors located within 3 mm or less from the optic nerve. In Profile II, only 9/66 cases resulted in a better proton plan. In Profile III, better retina volume sparing was always achievable with protons, with a larger gain for T3 tumors. In Profile IV, protons always reduced the risk of toxicity with a median RBE-weighted EQD2 reduction of 15.3 Gy.</p></div><div><h3>Conclusions</h3><p>This study reports the first side-by-side imaging-based planning comparison between protons and SRT for UM patients. Globally, while protons appear almost always better regarding the risk of optic-neuropathy, retinopathy and dry-eye syndrome, for other toxicity like neovascular glaucoma, a plan comparison is warranted. Choice would depend on the prioritization of risks.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"31 ","pages":"Article 100605"},"PeriodicalIF":3.4,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624000757/pdfft?md5=31bfef88b971c8f260126a467af2f91c&pid=1-s2.0-S2405631624000757-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141541856","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":"RadDeploy: A framework for integrating in-house developed software and artificial intelligence models seamlessly into radiotherapy workflows","authors":"Mathis Ersted Rasmussen ,&nbsp;Casper Dueholm Vestergaard ,&nbsp;Jesper Folsted Kallehauge ,&nbsp;Jintao Ren ,&nbsp;Maiken Haislund Guldberg ,&nbsp;Ole Nørrevang ,&nbsp;Ulrik Vindelev Elstrøm ,&nbsp;Stine Sofia Korreman","doi":"10.1016/j.phro.2024.100607","DOIUrl":"https://doi.org/10.1016/j.phro.2024.100607","url":null,"abstract":"<div><p>The use of and research in automation and artificial intelligence (AI) in radiotherapy is moving with incredible pace. Many innovations do, however, not make it into the clinic. One technical reason for this may be the lack of a platform to deploy such software into clinical practice. We suggest RadDeploy as a framework for integrating containerized software in clinical workflows outside of treatment planning systems. RadDeploy supports multiple DICOM as input for model containers and can run model containers asynchronously across GPUs and computers. This technical note summarizes the inner workings of RadDeploy and demonstrates three use-cases with varying complexity.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"31 ","pages":"Article 100607"},"PeriodicalIF":3.4,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624000770/pdfft?md5=07c43a38a273144b17afee3cbb741fc9&pid=1-s2.0-S2405631624000770-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141541857","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":"Individualized 3D-printed applicators for magnetic resonance imaging-guided brachytherapy in nasal vestibule cancer","authors":"Mischa de Ridder ,&nbsp;Milena Smolic ,&nbsp;Maarten Kastelijns ,&nbsp;Samantha Kloosterman ,&nbsp;Stefan van der Vegt ,&nbsp;Johannes A. Rijken ,&nbsp;Ina M. Jürgenliemk-Schulz ,&nbsp;Homan Dehnad ,&nbsp;Petra S. Kroon ,&nbsp;Marinus A. Moerland","doi":"10.1016/j.phro.2024.100629","DOIUrl":"10.1016/j.phro.2024.100629","url":null,"abstract":"<div><h3>Background and purpose</h3><p>Brachytherapy is treatment of choice for early stage nasal vestibule cancer. Over the years improvements were achieved by means of image guided target definition, interstitial implant techniques and also individual mold techniques. The aim of this study was to improve the technique of the implant so that the need for interstitial catheters can be limited by making use of patient individualized 3D-printed applicators.</p></div><div><h3>Materials and Methods</h3><p>In 19 patients 3D-printed applicators were used to deliver pulse dose rate (PDR) brachytherapy. All patients underwent computed tomography (CT) and magnetic resonance imaging (MRI). A pre-plan with tumor delineation and manually optimized catheter positions to achieve tumor coverage was made. Based on the pre-plan a 3D-printed applicator was manufactured. Dose was evaluated by several indices: Conformity Index, Healthy Tissues Conformity Index, Dose Homogeneity Index, Dose non-uniformity ratio, Conformal index and high dose (HD) index.</p></div><div><h3>Results</h3><p>A high target coverage was achieved, with a median V100%_CTV of 99.1 % (range, 81.8–100 %) and median CI of 0.99 (range, 0.82–1.00), as well as a median V0.7Gy_GTV of 100 % (range, 93.0–100 %). The median HD was 0.39 (range, 0.20–0.83). Interstitial catheters were needed in 12 patients. None of the patients developed grade ≥ II toxicity within the median follow up of 18 months.</p></div><div><h3>Conclusions</h3><p>This study shows that using 3D-printed applicators limits the need for interstitial catheters and also limits the high doses in normal tissue.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"31 ","pages":"Article 100629"},"PeriodicalIF":3.4,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S240563162400099X/pdfft?md5=e60301b7e39f906cb6252499405c2c3b&pid=1-s2.0-S240563162400099X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142048390","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":"Inter-fraction motion robustness in a prospective phase II trial on dose-escalated proton reirradiation for locally recurrent rectal cancer","authors":"Christina G. Truelsen ,&nbsp;Heidi S. Rønde ,&nbsp;Jesper F. Kallehauge ,&nbsp;Laurids Ø. Poulsen ,&nbsp;Birgitte M. Havelund ,&nbsp;Bodil G. Pedersen ,&nbsp;Lene H. Iversen ,&nbsp;Karen-Lise G. Spindler ,&nbsp;Camilla S. Kronborg","doi":"10.1016/j.phro.2024.100634","DOIUrl":"10.1016/j.phro.2024.100634","url":null,"abstract":"<div><h3>Background and purpose</h3><p>Intensity modulated proton therapy (IMPT) enables generation of conformal dose plans with organ at risk (OAR) sparing potential. However, pelvic IMPT robustness is challenged by inter-fraction motion caused by constant anatomical variations. In this study, the dosimetric impact of inter-fraction motion on target coverage and dose to OAR was quantified in the prospective phase II study ReRad-II on dose-escalated proton reirradiation for locally recurrent rectal cancer (LRRC).</p></div><div><h3>Materials and methods</h3><p>The inter-fraction motion robustness was assessed for the initial twelve patients enrolled in the ReRad-II study. Patients with resectable LRRC were assessed for neoadjuvant IMPT (55 Gy(RBE)/44Fx) and unresectable recurrences for definitive IMPT (57.5–65 Gy(RBE)/ 46-52Fx). Target coverage and dose to OAR were assessed for robustly optimised three-field IMPT, on 12 plan computerized tomography (CT) scans (pCT) − and 47 repetitive control CT scans (cCTs) during the treatment. The target coverage and doses to OAR were re-calculated on each cCT and the mean dose ratio (pCT/cCT-ratio) and target coverage (V_95%) was evaluated.</p></div><div><h3>Results</h3><p>The target coverage was robust with a mean dose pCT/cCT-ratio of 1.00 (+/-1%). The V_95% target coverage for every cCT were above the accepted worst-case scenario in the robust evaluation. Considerable variation in bladder-, bowel bag-, and bowel loop volume was observed. The OAR with the largest variation in ratio was the bladder (pCT/cCT-ratio: 1.3 (range: 0.5–4.7).</p></div><div><h3>Conclusions</h3><p>IMPT for dose-escalated reirradiation of LRRC provided anatomically robust target coverage despite OAR changes. Inter-fraction motion resulted in OAR doses varying within clinically acceptable range.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"31 ","pages":"Article 100634"},"PeriodicalIF":3.4,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624001040/pdfft?md5=731e13668a424ef4ff17ecc41f64328a&pid=1-s2.0-S2405631624001040-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142099478","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":"Individual lymph node position variation for rectal cancer patients treated with long course chemoradiotherapy","authors":"Dennis Tideman Arp ,&nbsp;Ane L. Appelt ,&nbsp;Rasmus Froberg Brøndum ,&nbsp;Rasa Mikalone ,&nbsp;Martin Skovmos Nielsen ,&nbsp;Laurids Østergaard Poulsen","doi":"10.1016/j.phro.2024.100599","DOIUrl":"10.1016/j.phro.2024.100599","url":null,"abstract":"<div><h3>Background and purpose</h3><p>Delivery of high precision radiotherapy lymph node boosts requires detailed information on the interfraction positional variation of individual lymph nodes. In this study we characterized interfraction positional shifts of suspected malignant lymph nodes for rectal cancer patients receiving long course radiotherapy. Furthermore, we investigated parameters which could affect the magnitude of the position variation.</p></div><div><h3>Materials and Methods</h3><p>Fourteen patients from a prospective clinical imaging study with a total of 61 suspected malignant lymph nodes in the mesorectum, presacral, and lateral regions, were included. The primary gross tumor volume (GTV_p) and all suspected malignant lymph nodes were delineated on six magnetic resonance imaging scans per patient. Positional variation was calculated as systematic and random errors, based on shifts of center-of-mass, and estimated relative to either bony structures or the GTV_p using a hierarchical linear mixed model.</p></div><div><h3>Results</h3><p>Depending on location and direction, systematic and random variations (relative to bony structures) were within 0.6–2.8 mm and 0.6–2.9 mm, respectively. Systematic and random variations increased when evaluating position relative to GTV_p (median increase of 0.6 mm and 0.5 mm, respectively). Correlations with scan time-point and relative bladder volume were found in some directions.</p></div><div><h3>Conclusions</h3><p>Using linear mixed modeling, we estimated systematic and random positional variation for suspected malignant lymph nodes in rectal cancer patients treated with long course radiotherapy. Statistically significant correlations of the magnitude of the lymph node shifts were found related to scan time-point and relative bladder volume.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"31 ","pages":"Article 100599"},"PeriodicalIF":3.7,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624000691/pdfft?md5=e162444edd7de337c124c09d2fcd281e&pid=1-s2.0-S2405631624000691-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141397027","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":"Geometrical accuracy of magnetic resonance imaging for ocular proton therapy planning","authors":"Lisa Klaassen ,&nbsp;Corné Haasjes ,&nbsp;Martijn Hol ,&nbsp;Patricia Cambraia Lopes ,&nbsp;Kees Spruijt ,&nbsp;Christal van de Steeg-Henzen ,&nbsp;Khanh Vu ,&nbsp;Pauline Bakker ,&nbsp;Coen Rasch ,&nbsp;Berit Verbist ,&nbsp;Jan-Willem Beenakker","doi":"10.1016/j.phro.2024.100598","DOIUrl":"https://doi.org/10.1016/j.phro.2024.100598","url":null,"abstract":"<div><h3>Background &amp; purpose</h3><p>Magnetic resonance imaging (MRI) is increasingly used in treatment preparation of ocular proton therapy, but its spatial accuracy might be limited by geometric distortions due to susceptibility artefacts. A correct geometry of the MR images is paramount since it defines where the dose will be delivered. In this study, we assessed the geometrical accuracy of ocular MRI.</p></div><div><h3>Materials &amp; methods</h3><p>A dedicated ocular 3 T MRI protocol, with localized shimming and increased gradients, was compared to computed tomography (CT) and X-ray images in a phantom and in 15 uveal melanoma patients. The MRI protocol contained three-dimensional T2-weighted and T1-weighted sequences with an isotropic reconstruction resolution of 0.3–0.4 mm. Tantalum clips were identified by three observers and clip-clip distances were compared between T2-weighted and T1-weighted MRI, CT and X-ray images for the phantom and between MRI and X-ray images for the patients.</p></div><div><h3>Results</h3><p>Interobserver variability was below 0.35 mm for the phantom and 0.30(T1)/0.61(T2) mm in patients. Mean absolute differences between MRI and reference were below 0.27 ± 0.16 mm and 0.32 ± 0.23 mm for the phantom and in patients, respectively. In patients, clip-clip distances were slightly larger on MRI than on X-ray images (mean difference T1: 0.11 ± 0.38 mm, T2: 0.10 ± 0.44 mm). Differences did not increase at larger distances and did not correlate to interobserver variability.</p></div><div><h3>Conclusions</h3><p>A dedicated ocular MRI protocol can produce images of the eye with a geometrical accuracy below half the MRI acquisition voxel (&lt;0.4 mm). Therefore, these images can be used for ocular proton therapy planning, both in the current model-based workflow and in proposed three-dimensional MR-based workflows.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"31 ","pages":"Article 100598"},"PeriodicalIF":3.7,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S240563162400068X/pdfft?md5=575c62f2ecc72ab6cd84680303b9ce94&pid=1-s2.0-S240563162400068X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141324835","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":"Bringing online adaptive radiotherapy to a standard C-arm linac","authors":"Maureen L. Groot Koerkamp,&nbsp;Gijsbert H. Bol,&nbsp;Petra S. Kroon,&nbsp;Lean L. Krikke,&nbsp;Tessa Harderwijk,&nbsp;Annelies J. Zoetelief,&nbsp;Annick Scheeren,&nbsp;Stefan van der Vegt,&nbsp;Annika Plat,&nbsp;Jochem Hes,&nbsp;Ineke B.A. van Gasteren,&nbsp;Esmee R.T. Renders,&nbsp;Reijer H.A. Rutgers,&nbsp;Saskia W. Kok,&nbsp;Joost van Kaam,&nbsp;Geja J. Schimmel-de Kogel,&nbsp;Gonda G. Sikkes,&nbsp;Dennis Winkel,&nbsp;Michael J. van Rijssel,&nbsp;André J.M. Wopereis,&nbsp;Bas W. Raaymakers","doi":"10.1016/j.phro.2024.100597","DOIUrl":"10.1016/j.phro.2024.100597","url":null,"abstract":"<div><p>Current online adaptive radiotherapy (oART) workflows require dedicated equipment. Our aim was to develop and implement an oART workflow for a C-arm linac which can be performed using standard clinically available tools. A workflow was successfully developed and implemented. Three patients receiving palliative radiotherapy for bladder cancer were treated, with 33 of 35 total fractions being delivered with the cone-beam computed tomography (CBCT)-guided oART workflow. Average oART fraction duration was 24 min from start of CBCT acquisition to end of beam on. This work shows how oART could be performed without dedicated equipment, broadening oART availability for application at existing treatment machines.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"31 ","pages":"Article 100597"},"PeriodicalIF":3.7,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624000678/pdfft?md5=012d148b2ed045edeb2c4dac4267f4f1&pid=1-s2.0-S2405631624000678-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141411169","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}