Physics and Imaging in Radiation Oncology最新文献

{"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}

{"title":"Characterization of spatial integrity with active and passive implants in a low-field magnetic resonance linear accelerator scanner","authors":"Bertrand Pouymayou ,&nbsp;Yoel Perez-Haas ,&nbsp;Florin Allemann ,&nbsp;Ardan M. Saguner ,&nbsp;Nicolaus Andratschke ,&nbsp;Matthias Guckenberger ,&nbsp;Stephanie Tanadini-Lang ,&nbsp;Lotte Wilke","doi":"10.1016/j.phro.2024.100576","DOIUrl":"https://doi.org/10.1016/j.phro.2024.100576","url":null,"abstract":"<div><h3>Background and Purpose</h3><p>Standard imaging protocols can guarantee the spatial integrity of magnetic resonance (MR) images utilized in radiotherapy. However, the presence of metallic implants can significantly compromise this integrity. Our proposed method aims at characterizing the geometric distortions induced by both passive and active implants commonly encountered in planning images obtained from a low-field 0.35 T MR-linear accelerator (LINAC).</p></div><div><h3>Materials and Methods</h3><p>We designed a spatial integrity phantom defining 1276 control points and covering a field of view of 20x20x20 cm³. This phantom was scanned in a water tank with and without different implants used in hip and shoulder arthroplasty procedures as well as with active cardiac stimulators. The images were acquired with the clinical planning sequence (balanced steady-state free-precession, resolution 1.5x1.5x1.5 mm³). Spatial integrity was assessed by the Euclidian distance between the control point detected on the image and their theoretical locations. A first plane free of artefact (FPFA) was defined to evaluate the spatial integrity beyond the larger banding artefact.</p></div><div><h3>Results</h3><p>In the region extending up to 20 mm from the largest banding artefacts, the tested passive and active implants could cause distortions up to 2 mm and 3 mm, respectively. Beyond this region the spatial integrity was recovered and the image could be considered as unaffected by the implants.</p></div><div><h3>Conclusions</h3><p>We characterized the impact of common implants on a low field MR-LINAC planning sequence. These measurements could support the creation of extra margin while contouring organs at risk and target volumes in the vicinity of implants.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"30 ","pages":"Article 100576"},"PeriodicalIF":3.7,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624000460/pdfft?md5=10e38f5c685d8b0ecd54d8a274d223f9&pid=1-s2.0-S2405631624000460-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140605906","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":"Treatment planning evaluation and experimental validation of the magnetic resonance-based intrafraction drift correction","authors":"Madelon van den Dobbelsteen,&nbsp;Sara L. Hackett,&nbsp;Bram van Asselen,&nbsp;Stijn Oolbekkink,&nbsp;Bas W. Raaymakers,&nbsp;Johannes C.J. de Boer","doi":"10.1016/j.phro.2024.100580","DOIUrl":"10.1016/j.phro.2024.100580","url":null,"abstract":"<div><h3>Background and purpose</h3><p>MRI-guided online adaptive treatments can account for interfractional variations, however intrafraction motion reduces treatment accuracy. Intrafraction plan adaptation methods, such as the Intrafraction Drift Correction (IDC) or sub-fractionation, are needed. IDC uses real-time automatic monitoring of the tumor position to initiate plan adaptations by repositioning segments. IDC is a fast adaptation method that occurs only when necessary and this method could enable margin reduction. This research provides a treatment planning evaluation and experimental validation of the IDC.</p></div><div><h3>Materials and methods</h3><p>An in silico treatment planning evaluation was performed for 13 prostate patients mid-treatment without and with intrafraction plan adaptation (IDC and sub-fractionation). The adaptation methods were evaluated using dose volume histogram (DVH) metrics. To experimentally verify IDC a treatment was mimicked whereby a motion phantom containing an EBT3 film moved mid-treatment, followed by repositioning of segments. In addition, the delivered treatment was irradiated on a diode array phantom for plan quality assurance purposes.</p></div><div><h3>Results</h3><p>The planning study showed benefits for using intrafraction adaptation methods relative to no adaptation, where the IDC and sub-fractionation showed consistently improved target coverage with median target coverages of 100.0%. The experimental results verified the IDC with high minimum gamma passing rates of 99.1% and small mean dose deviations of maximum 0.3%.</p></div><div><h3>Conclusion</h3><p>The straightforward and fast IDC technique showed DVH metrics consistent with the sub-fractionation method using segment weight re-optimization for prostate patients. The dosimetric and geometric accuracy was shown for a full IDC workflow using film and diode array dosimetry.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"30 ","pages":"Article 100580"},"PeriodicalIF":3.7,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624000502/pdfft?md5=c8011bab47fdb66631d638a672a9c9a5&pid=1-s2.0-S2405631624000502-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140764359","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":"Robustness analysis of dynamic trajectory radiotherapy and volumetric modulated arc therapy plans for head and neck cancer","authors":"Hannes A. Loebner ,&nbsp;Jenny Bertholet ,&nbsp;Paul-Henry Mackeprang ,&nbsp;Werner Volken ,&nbsp;Olgun Elicin ,&nbsp;Silvan Mueller ,&nbsp;Gian Guyer ,&nbsp;Daniel M. Aebersold ,&nbsp;Marco F.M. Stampanoni ,&nbsp;Michael K. Fix ,&nbsp;Peter Manser","doi":"10.1016/j.phro.2024.100586","DOIUrl":"10.1016/j.phro.2024.100586","url":null,"abstract":"<div><h3>Background and purpose</h3><p>Dynamic trajectory radiotherapy (DTRT) has been shown to improve healthy tissue sparing compared to volumetric arc therapy (VMAT). This study aimed to assess and compare the robustness of DTRT and VMAT treatment-plans for head and neck (H&amp;N) cancer to patient-setup (PS) and machine-positioning uncertainties.</p></div><div><h3>Materials and methods</h3><p>The robustness of DTRT and VMAT plans previously created for 46 H&amp;N cases, prescribed 50–70 Gy to 95 % of the planning-target-volume, was assessed. For this purpose, dose distributions were recalculated using Monte Carlo, including uncertainties in PS (translation and rotation) and machine-positioning (gantry-, table-, collimator-rotation and multi-leaf collimator (MLC)). Plan robustness was evaluated by the uncertainties’ impact on normal tissue complication probabilities (NTCP) for xerostomia and dysphagia and on dose-volume endpoints. Differences between DTRT and VMAT plan robustness were compared using Wilcoxon matched-pair signed-rank test (<span><math><mi>α</mi></math></span> = 5 %).</p></div><div><h3>Results</h3><p>Average NTCP for moderate-to-severe xerostomia and grade ≥ II dysphagia was lower for DTRT than VMAT in the nominal scenario (0.5 %, p = 0.01; 2.1 %, p &lt; 0.01) and for all investigated uncertainties, except MLC positioning, where the difference was not significant. Average differences compared to the nominal scenario were <span><math><mo>≤</mo></math></span> 3.5 Gy for rotational PS (<span><math><mo>≤</mo></math></span> 3°) and machine-positioning (<span><math><mo>≤</mo></math></span> 2°) uncertainties, &lt;7 Gy for translational PS uncertainties (<span><math><mo>≤</mo></math></span> 5 mm) and &lt; 20 Gy for MLC-positioning uncertainties (<span><math><mo>≤</mo></math></span> 5 mm).</p></div><div><h3>Conclusions</h3><p>DTRT and VMAT plan robustness to the investigated uncertainties depended on uncertainty direction and location of the structure-of-interest to the target. NTCP remained on average lower for DTRT than VMAT even when considering uncertainties.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"30 ","pages":"Article 100586"},"PeriodicalIF":3.7,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624000563/pdfft?md5=27937f4f3eb2aacacce30fcc8d8a8d9d&pid=1-s2.0-S2405631624000563-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141036885","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":"Interobserver variation in tumor delineation of liver metastases using Magnetic Resonance Imaging","authors":"Julia E. Peltenburg ,&nbsp;Ali Hosni ,&nbsp;Rana Bahij ,&nbsp;Simon Boeke ,&nbsp;Pètra M. Braam ,&nbsp;William A. Hall ,&nbsp;Martijn P.W. Intven ,&nbsp;Luca Nicosia ,&nbsp;Jan-Jakob Sonke ,&nbsp;Marnix Witte ,&nbsp;Marlies E. Nowee ,&nbsp;Tomas Janssen","doi":"10.1016/j.phro.2024.100592","DOIUrl":"https://doi.org/10.1016/j.phro.2024.100592","url":null,"abstract":"<div><h3>Background and purpose</h3><p>Magnetic Resonance Imaging (MRI) guided stereotactic body radiotherapy (SBRT) of liver metastases is an upcoming high-precision non-invasive treatment. Interobserver variation (IOV) in tumor delineation, however, remains a relevant uncertainty for planning target volume (PTV) margins. The aims of this study were to quantify IOV in MRI-based delineation of the gross tumor volume (GTV) of liver metastases and to detect patient-specific factors influencing IOV.</p></div><div><h3>Materials and methods</h3><p>A total of 22 patients with liver metastases from three primary tumor origins were selected (colorectal(8), breast(6), lung(8)). Delineation guidelines and planning MRI-scans were provided to eight radiation oncologists who delineated all GTVs. All delineations were centrally peer reviewed to identify outliers not meeting the guidelines. Analyses were performed both in- and excluding outliers. IOV was quantified as the standard deviation (SD) of the perpendicular distance of each observer’s delineation towards the median delineation. The correlation of IOV with shape regularity, tumor origin and volume was determined.</p></div><div><h3>Results</h3><p>Including all delineations, average IOV was 1.6 mm (range 0.6–3.3 mm). From 160 delineations, in total fourteen single delineations were marked as outliers after peer review. After excluding outliers, the average IOV was 1.3 mm (range 0.6–2.3 mm). There was no significant correlation between IOV and tumor origin or volume. However, there was a significant correlation between IOV and regularity (Spearman’s ρ_s = -0.66; p = 0.002).</p></div><div><h3>Conclusion</h3><p>MRI-based IOV in tumor delineation of liver metastases was 1.3–1.6 mm, from which PTV margins for IOV can be calculated. Tumor regularity and IOV were significantly correlated, potentially allowing for patient-specific margin calculation.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"30 ","pages":"Article 100592"},"PeriodicalIF":3.7,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624000629/pdfft?md5=7858fc9860d9c4f0cacba04c519b5143&pid=1-s2.0-S2405631624000629-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141240196","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":"Dose-volume metric-based prediction of radiotherapy-induced lymphocyte loss in patients with non-small-cell lung cancer treated with modern radiotherapy techniques","authors":"Zuzanna Nowicka ,&nbsp;Kasper Kuna ,&nbsp;Mateusz Łaszczych ,&nbsp;Małgorzata Łazar-Poniatowska ,&nbsp;Bartosz Kamil Sobocki ,&nbsp;Konrad Stawiski ,&nbsp;Michał Dąbrowski ,&nbsp;Konrad Bruski ,&nbsp;Adam Zięba ,&nbsp;Mateusz Pajdziński ,&nbsp;Emilia Staniewska ,&nbsp;Marcin Miszczyk ,&nbsp;Harald Paganetti ,&nbsp;Wojciech Fendler ,&nbsp;Bartłomiej Tomasik","doi":"10.1016/j.phro.2024.100593","DOIUrl":"https://doi.org/10.1016/j.phro.2024.100593","url":null,"abstract":"<div><h3>Background and Purpose</h3><p>Radiation-induced lymphopenia (RIL) is a common side effect of radiotherapy (RT) that may negatively impact survival. We aimed to identify RIL predictors in patients with non-small-cell lung cancer (NSCLC) treated intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT).</p></div><div><h3>Materials and Methods</h3><p>We retrospectively analysed data of 306 patients who underwent radical RT for NSCLC. Absolute lymphocyte count (ALC) loss was evaluated for each patient by fitting an exponential decay curve to data from first 45 days since treatment start, and percentage ALC loss relative to baseline was calculated based on area under the decay curve and baseline ALC. We compared IMRT and VMAT treatment plans and used linear regression to predict ALC loss.</p></div><div><h3>Results</h3><p>ALC decreased during RT in the whole patient group, while neutrophil counts remained stable and decreased only in those treated with concurrent chemoradiotherapy (CRT). Percentage ALC loss ranged between 11 and 78 % and was more strongly than lymphocyte nadir correlated with dose-volume metrics for relevant normal structures. We found evidence for the association of high radiation dose to the lungs, heart and body with percentage ALC loss, with lung volume exposed to 20–30 Gy being most important predictors in patients treated with IMRT. A multivariable model based on CRT use, baseline ALC and first principal component (PC1) of the dose-volume predictors showed good predictive performance (bias-corrected R² of 0.40).</p></div><div><h3>Conclusion</h3><p>Percentage lymphocyte loss is a robust measure of RIL that is predicted by baseline ALC, CRT use and dose-volume parameters to the lungs, heart and body.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"30 ","pages":"Article 100593"},"PeriodicalIF":3.7,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624000630/pdfft?md5=70b73048e1aff2093b500bd187376da5&pid=1-s2.0-S2405631624000630-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141240199","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 deep learning based dynamic arc radiotherapy photon dose engine trained on Monte Carlo dose distributions","authors":"Marnix Witte,&nbsp;Jan-Jakob Sonke","doi":"10.1016/j.phro.2024.100575","DOIUrl":"https://doi.org/10.1016/j.phro.2024.100575","url":null,"abstract":"<div><h3>Background and purpose</h3><p>Despite hardware acceleration, state-of-the-art Monte Carlo (MC) dose engines require considerable computation time to reduce stochastic noise. We developed a deep learning (DL) based dose engine reaching high accuracy at strongly reduced computation times.</p></div><div><h3>Materials and methods</h3><p>Radiotherapy treatment plans and computed tomography scans were collected for 350 treatments in a variety of tumor sites. Dose distributions were computed using a MC dose engine for <span><math><mrow><mo>∼</mo></mrow></math></span>30,000 separate segments at 6 MV and 10 MV beam energies, both flattened and flattening filter free. For dynamic arcs these explicitly incorporated the leaf, jaw and gantry motions during dose delivery. A neural network was developed, combining two-dimensional convolution and recurrence using 64 hidden channels. Parameters were trained to minimize the mean squared log error loss between the MC computed dose and the model output. Full dose distributions were reconstructed for 100 additional treatment plans. Gamma analyses were performed to assess accuracy.</p></div><div><h3>Results</h3><p>DL dose evaluation was on average 82 times faster than MC computation at a 1 % accuracy setting. In voxels receiving at least 10 % of the maximum dose the overall global gamma pass rate using a 2 % and 2 mm criterion was 99.6 %, while mean local gamma values were accurate within 2 %. In the high dose region over 50 % of maximum the mean local gamma approached a 1 % accuracy.</p></div><div><h3>Conclusions</h3><p>A DL based dose engine was implemented, able to accurately reproduce MC computed dynamic arc radiotherapy dose distributions at high speed.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"30 ","pages":"Article 100575"},"PeriodicalIF":3.7,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624000459/pdfft?md5=9b69a16f8acbb3663eeeb7983084265d&pid=1-s2.0-S2405631624000459-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140551739","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}