Medical Dosimetry最新文献

{"title":"Two novel stereotactic radiotherapy methods for locally advanced, previously irradiated head and neck cancers patients","authors":"Damodar Pokhrel PhD,&nbsp;Josh Misa BS,&nbsp;Shane McCarthy MS,&nbsp;Eddy S. Yang MD, PhD","doi":"10.1016/j.meddos.2023.09.003","DOIUrl":"10.1016/j.meddos.2023.09.003","url":null,"abstract":"<div><p><span>To determine the feasibility and utility of conebeam CT-guided stereotactic radiotherapy<span><span> for locally recurrent, previously irradiated head and neck cancer<span> (HNC) patients on the Halcyon, a ring delivery system (RDS). This research aims to quantify plan quality, treatment delivery accuracy, and overall efficacy by comparing against novel clinical </span></span>TrueBeam<span><span> HyperArc method. Ten recurrent HNC patients who were treated at our institution on TrueBeam (6MV-FFF) for 30 to 40 Gy in 3 to 5 fractions with noncoplanar HyperArc plans were re-planned on Halcyon (6MV-FFF). These plans were re-planned with the same Acuros-based dose engine. Additionally, we used site-specific full/partial coplanar VMAT arcs. PTV coverage, mean dose to </span>GTV<span>, maximum dose to organs-at-risk (OAR), beam-on time (BOT), and quality assurance (QA) results were investigated and compared. Halcyon provided highly conformal HNC SRT plans with slightly superior mean PTVD99 coverage (96.7% </span></span></span></span><em>vs</em> 95.5%, <em>p</em> = 0.071), and slightly lower mean GTV dose (37.8 Gy <em>vs</em> 38.2 Gy, <em>p</em> = 0.241) when compared to the HyperArc plans. Differences in plan conformality and maximum dose to OARs were statistically insignificant. Due to Halcyon's coplanar geometry, D2cm was significantly higher (<em>p</em> = 0.001) but Halcyon did result in a reduced normal brain dose by 1 Gy on average and up to 5.2 Gy in some cases. Halcyon provided similar patient-specific QA pass rates with a 2%/2mm gamma criteria (98.2% <em>vs</em> 98.5%) and independent in-house Monte Carlo second check results (97.7% <em>vs</em> 98.2%), suggesting identical treatment delivery accuracy. Halcyon plans resulted in slightly longer beam-on time (3.16 vs 2.30 minutes, <em>p</em> = 0.010), however door-to-door patient time is expected to be &lt;10 minutes. Compared to clinical TrueBeam HyperArc, Halcyon SRT plans provided similar plan quality and treatment delivery accuracy with a potentially faster overall treatment using fully automated patient setup and verification. Rapid delivery of recurrent HNC SRT may reduce intrafraction motion errors while also improving patient compliance and comfort. To provide high-quality of HNC SRT similar to HyperArc, we recommend Halcyon users consider commissioning this novel method. This method will be useful for remote and underserved patient cohorts including Halcyon-only clinics as well.</p></div>","PeriodicalId":49837,"journal":{"name":"Medical Dosimetry","volume":"49 2","pages":"Pages 114-120"},"PeriodicalIF":1.2,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49693440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hypoglossal nerve delineation in nasopharyngeal carcinoma patients may reduce the radiation dose and damage to the nerve","authors":"Fen Chen MD ,&nbsp;Yee-Min Jen MD, PhD ,&nbsp;Kui He MSc ,&nbsp;Zhao-sheng Yin MD ,&nbsp;Jih-Chin Lee MD ,&nbsp;Wen-Yen Huang MD ,&nbsp;Yong-Hong Tang MD","doi":"10.1016/j.meddos.2023.09.001","DOIUrl":"10.1016/j.meddos.2023.09.001","url":null,"abstract":"<div><p><span><span>This study aims to establish a delineation guideline for the contouring of the hypoglossal nerve by dividing the nerve into different segments, and to test the possibility of a </span>radiation dose reduction<span> to the hypoglossal nerve in NPC patients receiving </span></span>radiotherapy<span><span>. Twenty NPC patients were selected arbitrarily. The hypoglossal nerves were delineated using </span>anatomic landmarks<span> and divided into the cisternal, intracanalicular, carotid, and transverse segments. The tumor coverage by radiation and dose-volume parameters of the nerve with and without various dose constraints to the hypoglossal nerve were compared. The hypoglossal nerve, which is invisible on CT images, can be delineated accurately with the assistance of several anatomic landmarks. Without a dose constraint to the hypoglossal nerve, the carotid space, intracanalicular, and transverse segments had high radiation dose-volumes. The dose-volume to the nerve, however, can be reduced when the nerve was defined and a dose constraint was given. The delineation of the hypoglossal nerve with its different segments is feasible. The carotid space, intracanalicular, and transverse segments received the highest dose, where the nerve damage was most likely located. The dose to the nerve can be reduced to less than 70 Gy using the intensity-modulated radiotherapy technique.</span></span></p></div>","PeriodicalId":49837,"journal":{"name":"Medical Dosimetry","volume":"49 2","pages":"Pages 102-108"},"PeriodicalIF":1.2,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49684259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrated feathering for craniospinal irradiation improves patient safety and departmental efficiency","authors":"Amy S. Harrison PhD,&nbsp;Angelia Landers PhD,&nbsp;Virginia Nettleton,&nbsp;Katelyn Palermo BS,&nbsp;Yelena Vakhnenko BS,&nbsp;Wenyin Shi MD, PhD","doi":"10.1016/j.meddos.2023.08.008","DOIUrl":"10.1016/j.meddos.2023.08.008","url":null,"abstract":"<div><p><span><span>This paper presents to the dosimetrist audience an integrated feathering technique for craniospinal irradiation which improves </span>dosimetry<span>, physics, physician and therapist efficiencies while increasing </span></span>patient safety<span> and decreasing portal imaging time. This technique has been presented by other authors in physics journals stressing technical and quality assurance aspects, this article is presented to the treatment<span> planners with a focus on the planning process including field design and weighting, efficiency improvements and patient safety.</span></span></p></div>","PeriodicalId":49837,"journal":{"name":"Medical Dosimetry","volume":"49 2","pages":"Pages 77-80"},"PeriodicalIF":1.2,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41155661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel hybrid treatment planning approach for irradiation a pediatric craniospinal axis","authors":"Dr. Christian Ziemann ,&nbsp;Florian Cremers ,&nbsp;Laura Motisi ,&nbsp;Dirk Albers ,&nbsp;Miller MacPherson ,&nbsp;Dirk Rades","doi":"10.1016/j.meddos.2023.08.011","DOIUrl":"10.1016/j.meddos.2023.08.011","url":null,"abstract":"&lt;div&gt;&lt;p&gt;This study presents a new treatment planning approach merging 3D-CRT and VMAT fields into a hybrid treatment plan (HybTP), in order to achieve an optimum dose coverage of the planning target volume (PTV) and protection of OAR. Craniospinal axis irradiation (CSI) treated with 3D conformal radiotherapy (3D-CRT) is associated with high doses to the heart and eye lenses but provides better sparing of lungs and kidneys compared to volumetric modulated arc therapy (VMAT). VMAT treatment spares eye lenses and the heart, but lungs and kidneys are not as effective as 3D-CRT. Thus, a combination of both techniques (HybTP) may be optimal in sparing all these organs at risk (OAR). The results of HybTP are compared with helical tomotherapy (HT), intensity modulated radio therapy (IMRT), VMAT, and 3D-CRT plans. Hybrid, HT, VMAT, IMRT, and 3D-CRT treatment plans for a male child (age 6 years) with medulloblastoma were created and compared. A total dose of 35.2 Gy (PTV) with a dose per fraction of 1.6 Gy was prescribed. The following dose acceptance criteria were defined:&lt;/p&gt;&lt;ul&gt;&lt;li&gt;&lt;span&gt;(1)&lt;/span&gt;&lt;span&gt;&lt;p&gt;Mean PTV dose should be 100% of the prescribed dose, while the maximum dose should not exceed 107%.&lt;/p&gt;&lt;/span&gt;&lt;/li&gt;&lt;li&gt;&lt;span&gt;(2)&lt;/span&gt;&lt;span&gt;&lt;p&gt;At least 98% of the PTV should receive 95% of the prescribed dose.&lt;/p&gt;&lt;/span&gt;&lt;/li&gt;&lt;li&gt;&lt;span&gt;(3)&lt;/span&gt;&lt;span&gt;&lt;p&gt;The cribriform plate should be covered by the 95% isodose line.&lt;/p&gt;&lt;/span&gt;&lt;/li&gt;&lt;li&gt;&lt;span&gt;(4)&lt;/span&gt;&lt;span&gt;&lt;p&gt;The acceptance criteria for the OARs were: lenses &lt;em&gt;D&lt;sub&gt;max&lt;/sub&gt;&lt;/em&gt;&lt;10 Gy, lungs &lt;em&gt;D&lt;sub&gt;mean&lt;/sub&gt;&lt;/em&gt;&lt;7 Gy, kidneys &lt;em&gt;D&lt;sub&gt;mean&lt;/sub&gt;&lt;/em&gt;&lt;15 Gy, heart &lt;em&gt;D&lt;sub&gt;mean&lt;/sub&gt;&lt;/em&gt;&lt;26 Gy, and heart &lt;em&gt;V&lt;sub&gt;25&lt;/sub&gt;&lt;/em&gt;&lt;10%.&lt;/p&gt;&lt;/span&gt;&lt;/li&gt;&lt;/ul&gt;&lt;p&gt;The plans were compared regarding dose homogeneity index (HI) and conformity index (CI), PTV coverage, (particularly at cribriform plate) and doses at OARs. Best conformity was achieved with HT (CI = 0.98) followed by VMAT (CI = 0.96), IMRT (CI = 0.91), HybTP (CI = 0.86), and 3D-CRT (CI = 0.83). The homogeneity index varied marginally. For both HT and IMRT the HI was 0.07, and for 3D-CRT, VMAT and HybTP the HI was between 0.13 and 0.15. The cribriform plate was sufficiently covered by HybTP, VMAT, and 3D-CRT. The dose acceptance criteria for OARs were met by HT and HybTP. VMAT did not meet the criteria for lung (&lt;em&gt;D&lt;sub&gt;mean&lt;/sub&gt;&lt;/em&gt; = right 10.4 Gy/left 10.2 Gy), 3D-CRT did not meet the criteria for eye lenses (&lt;em&gt;D&lt;sub&gt;max&lt;/sub&gt;&lt;/em&gt; = right 32.3 Gy/left 33.1), and heart (&lt;em&gt;V&lt;sub&gt;25&lt;/sub&gt;&lt;/em&gt;≈44%) and IMRT did not meet the criteria for lung (&lt;em&gt;D&lt;sub&gt;mean&lt;/sub&gt;&lt;/em&gt; = right 11.1 Gy/left 11.2 Gy) and eye lenses (&lt;em&gt;D&lt;sub&gt;max&lt;/sub&gt;&lt;/em&gt; = right 12.2 Gy/left 13.1). HybTP meets all defined acceptance criteria and has proved to be a reasonable alternative for CSI. With HybTP that combines VMAT at the brain and heart with 3D-CRT posterior spinal fields (to spare lungs and kidneys), both appropriate coverage of the PTV","PeriodicalId":49837,"journal":{"name":"Medical Dosimetry","volume":"49 2","pages":"Pages 93-101"},"PeriodicalIF":1.2,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0958394723000766/pdfft?md5=037d95a42c17a31f394e7344d19f5276&pid=1-s2.0-S0958394723000766-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41160280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Technical Report: Efficient constancy evaluation of the Eclipse treatment planning system's photon and electron dose calculation algorithms aided by the third-party ClearCheck software","authors":"Eric Lobb MS","doi":"10.1016/j.meddos.2023.08.009","DOIUrl":"10.1016/j.meddos.2023.08.009","url":null,"abstract":"<div><p>Our institutional approach to performing periodic constancy checks on dose calculations for the Varian Eclipse treatment planning system<span> is described, including details of how the Radformation ClearCheck software is leveraged for highly efficient results analysis. Photon- and electron-specific synthetic phantoms are created which allow all modality-specific fields to be spatially separated and calculated in a single plan, with field-specific structures encompassing individual irradiated volumes facilitating field-specific dose distribution<span> evaluations. Plan comparison templates in ClearCheck allow for the near-instantaneous evaluation of 116 and 165 individual calculation metrics for photon and electron fields, respectively. The methodology is further applied to the Radformation ClearCalc finite-size pencil beam and electron algorithms for secondary algorithm validation. The total time required for constancy evaluations of 6 primary algorithms and 4 secondary algorithms is less than one hour, with much of that time used for passive dose calculation.</span></span></p></div>","PeriodicalId":49837,"journal":{"name":"Medical Dosimetry","volume":"49 2","pages":"Pages 81-84"},"PeriodicalIF":1.2,"publicationDate":"2023-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41179072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dosimetric comparison between RapidArc and HyperArc in hippocampal-sparing whole-brain radiotherapy with a simultaneous integrated boost","authors":"Jeongho Kim PhD ,&nbsp;Tae Gyu Kim MD ,&nbsp;Byungdo Park PhD ,&nbsp;Hyunjung Kim MD ,&nbsp;Yun Gyu Song MD ,&nbsp;Hyoun Wook Lee MD ,&nbsp;Young Zoon Kim MD ,&nbsp;Jun Ho Ji MD ,&nbsp;Seok-Hyun Kim MD ,&nbsp;Sung Min Kim MD ,&nbsp;Jun Ho Lee MD ,&nbsp;Haeyoung Kim MD","doi":"10.1016/j.meddos.2023.08.007","DOIUrl":"10.1016/j.meddos.2023.08.007","url":null,"abstract":"<div><p><span>The HyperArc technique is known for generating high-quality radiosurgical treatment plans for intracranial lesions or hippocampal-sparing whole-brain </span>radiotherapy<span><span> (WBRT). However, there is no reported feasibility of using the HyperArc technique in hippocampal-sparing WBRT with a simultaneous integrated boost (SIB). This study aimed to compare dosimetric parameters of 2 commercially-available volumetric-modulated arc radiotherapy techniques, HyperArc and </span>RapidArc<span>, when using hippocampal-sparing WBRT with a SIB to treat brain metastases.</span></span></p><p><span>Treatment plans using HyperArc and RapidArc techniques were generated retrospectively for 19 previously treated patients (1 to 3 brain metastases). The planning target volumes for the whole brain (excluding the hippocampal avoidance region; PTV</span>_WB<span>) and metastases (PTV</span>_met) were prescribed 25 and 45 Gy, respectively, in 10 fractions. Each plan included homogeneous and inhomogeneous delivery to the PTV_met. Dosimetric parameters for the target (conformity index [CI], homogeneity index [HI], target coverage [D_95%]), and nontarget organs at risk were compared for the HyperArc and RapidArc plans.</p><p>For homogeneous delivery, dosimetric parameters, including mean CI, HI, and target coverage in PTV_WB and PTV_met, were superior for HyperArc than RapidArc plans (all <em>p</em> &lt; 0.01). The PTV_WB and PTV_met target coverage for HyperArc plans was significantly greater than for RapidArc plans (96.17% <em>vs</em> 93.38%, <em>p</em> &lt; 0.01; 94.02% <em>vs</em> 92.21%, <em>p</em> &lt; 0.01, respectively). HyperArc plans had significantly lower mean hippocampal D_max and D_min values than RapidArc plans (D_max: 15.53 Gy <em>vs</em>, 16.71 Gy, <em>p</em> &lt; 0.01; D_min: 8.33 Gy <em>vs</em> 8.93 Gy, <em>p</em> &lt; 0.01, respectively). Similarly, inhomogeneous delivery of hyperArc produced a superior target and lower hippocampal dosimetric parameters than RapidArc, except for the HI of PTV_met (all <em>p</em> &lt; 0.01).</p><p>HyperArc generated superior conformity and target coverage with lower hippocampal doses than RapidArc. HyperArc could be an attractive technique for hippocampal-sparing WBRT with an SIB.</p></div>","PeriodicalId":49837,"journal":{"name":"Medical Dosimetry","volume":"49 2","pages":"Pages 69-76"},"PeriodicalIF":1.2,"publicationDate":"2023-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10634587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Proton versus photon comprehensive nodal breast irradiation","authors":"Kelly McKenna CMD, BS RT(T)","doi":"10.1016/j.meddos.2023.08.005","DOIUrl":"10.1016/j.meddos.2023.08.005","url":null,"abstract":"<div><p><span><span><span>Comprehensive nodal breast irradiation is traditionally treated utilizing 3DCRT planning with a three or four field technique. While the three or four field photon technique may be the </span>standard of care<span> for comprehensive nodal breast treatment, the ipsilateral lung dose and heart mean can often be of concern dependent on patient's </span></span>anatomy<span>. Standard dose constraints (200cGy x25) per the Alliance A221505 trial strive to maintain the ipsilateral V20&lt;35% and heart mean &lt;3Gy. Double scattering proton therapy treatment has a significant advantage over photons in reducing the ipsilateral lung and heart dose due the Spread-Out </span></span>Bragg Peak and rapid dose drop off. Proton therapy in comprehensive nodal breast irradiation can be beneficial when dose constraints are exceeding in a photon plan or in the re-irradiation setting. Within this study, a comparison of ipsilateral lung and heart mean doses will be evaluated using both photon three/four field technique and double scattering proton therapy technique. A decreased ipsilateral lung V20 can be correlated to all proton plans that were conducted in the study. In all but one patient there was a decrease in the heart mean as well, which was due to patient anatomy.</p></div>","PeriodicalId":49837,"journal":{"name":"Medical Dosimetry","volume":"48 4","pages":"Pages 312-314"},"PeriodicalIF":1.2,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10273930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From protons to Picasso: recreating famous paintings using proton beams as a “Paintbrush”","authors":"Lee Xu","doi":"10.1016/j.meddos.2023.08.006","DOIUrl":"10.1016/j.meddos.2023.08.006","url":null,"abstract":"<div><p><span>In pencil-beam-scanning proton therapy<span><span>, the dose is painted spot-by-spot, layer-by-layer, allowing for significantly more control compared to conventional radiation. This work intends to showcase the impressive ability of intensity-modulated proton therapy (IMPT) to shape complex dose distributions<span> by recreating some of history's most renowned artworks as treatment plans. Five (5) well-recognized paintings were recreated in our clinical </span></span>treatment planning system using a water phantom as a “canvas” and radiation dose as “paint.” For each “painting,” colors were assigned to various isodose levels, and the treatment plans were inversely optimized to achieve the desired tones. Using the above methods, we were able to recreate </span></span><em>The Starry Night</em> by Vincent Van Gogh, <em>Girl with a Pearl Earring</em> by Johannes Vermeer, and <em>The Scream</em><span> by Edvard Munch, among others. The results of this work have potential applications in patient<span> education, medical education, and medical physics education by providing a unique and interesting platform for learning.</span></span></p></div>","PeriodicalId":49837,"journal":{"name":"Medical Dosimetry","volume":"49 1","pages":"Pages 56-60"},"PeriodicalIF":1.2,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10145020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vertebral artery sparing volumetric modulated arc therapy in nasopharyngeal carcinoma","authors":"Szu-Huai Lu MS ,&nbsp;Hao-Ting Lan MS ,&nbsp;Yi-Chun Tsai MS ,&nbsp;Ya-Fang Chen MD ,&nbsp;Shih-Fan Lai MD ,&nbsp;Hsiang-Kuang Liang MD ,&nbsp;Bing-Shen Huang MD ,&nbsp;Wan-Yu Chen MD, PhD ,&nbsp;Chun-Wei Wang MD, PhD","doi":"10.1016/j.meddos.2023.08.004","DOIUrl":"10.1016/j.meddos.2023.08.004","url":null,"abstract":"<div><p><span><span><span>Vascular stenosis is a late radiation complication that develops in long-term survivors of nasopharyngeal carcinoma. </span>Vertebral arteries<span> (VAs) are major vessels responsible for posterior circulation. In this study, we evaluated the feasibility of VA-sparing volumetric modulated arc therapy (VMAT) techniques. A total of 20 patients with nasopharyngeal carcinoma treated by a </span></span>TrueBeam linear accelerator were enrolled in this study. The original VMAT plan was designed without the contouring of VAs as organs at risk (OARs). The same image set of the original VMAT plan was used to contour the VAs for each patient. A new VA-sparing VMAT plan was developed by avoiding VAs as OARs. Finally, a paired t-test was used to compare the dosimetric differences. The VA-sparing VMAT plan had similar target coverage and dose to those of other OARs. The VA-sparing plan yielded a significantly low VA dose from 53 to 40 Gy, with V35Gy changing from 97% to 56%, V50Gy changing from 67% to 35%, and V63Gy changing from 15% to approximately 7%–10% (</span><em>p</em> &lt; 0.001 for all comparisons). VAs should be correctly identified as OARs. Photon VMAT with VA sparing can help substantially decrease the VA dose.</p></div>","PeriodicalId":49837,"journal":{"name":"Medical Dosimetry","volume":"48 4","pages":"Pages 304-311"},"PeriodicalIF":1.2,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10172937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From organ at risk to target organ: Dosimetric comparison of myocardial stereotactic ablative body radiotherapy between helical tomotherapy and volumetric arc therapy for refractory ventricular tachycardia","authors":"Hüseyin Furkan Öztürk MD ,&nbsp;Suheyla Aytaç Arslan MD ,&nbsp;Zerrin Gani MSci ,&nbsp;Dursun Aras MD ,&nbsp;Yılmaz Tezcan MD","doi":"10.1016/j.meddos.2023.08.001","DOIUrl":"10.1016/j.meddos.2023.08.001","url":null,"abstract":"<div><p><span><span>Ventricular tachycardia (VT) is an important type of </span>arrhythmia<span> with a risk of sudden death. Although implanted cardiac defibrillation<span><span> and radiofrequency ablation are used together with medical treatments for VT, the </span>treatment<span><span> options are limited in cases that do not respond to them. Stereotactic ablative body radiotherapy (SABR) applied to VT substrates in resistant cases is an emerging treatment with positive results. Such clinical results have increased the interest in this subject. However, the ideal treatment device and method have not yet been described for this therapy, which is generally applied at a single fraction using various devices and methods. Herein, treatment planning was conducted for a total of 8 patients (11 VT substrates) using the Varian </span>TrueBeam<span> EDGE and TomoTherapy<span> Radixact devices at a single center, and the results were compared dosimetrically. The Wilcoxon-signed rank test was used for the statistical analysis, and mean values were expressed as medians and interquartile ranges (IQRs). In the volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) plans, the plan coverages and conformity indexes were similar; meanwhile, the homogeneity indexes were 0.10 (IQR = 0.05) and 0.07 (IQR = 0.05), respectively, and were significantly better in the HT plan (</span></span></span></span></span></span><em>p</em><span> = 0.02). The gradient indexes were 3.18 (IQR = 0.8) and 5.33 (IQR = 3.68) in the VMAT and HT plans, respectively, and were significantly better in the VMAT plan. For the organs at risk, similar doses were observed. The maximum doses<span> for the stomach and esophagus and the mean doses for the left lung and both lungs were significantly lower in the VMAT plan. Similarly, the maximum and mean doses for the cardiac substructures and great vessels were significantly lower in the VMAT plan. More homogeneous plans were obtained in HT, while a faster dose reduction and lower critical organ dose were observed in VMAT. Reasonable myocardial SABR plans could be obtained with both techniques. The effects of the dosimetric differences on the clinical outcomes should be evaluated in prospective clinical studies.</span></span></p></div>","PeriodicalId":49837,"journal":{"name":"Medical Dosimetry","volume":"48 4","pages":"Pages 293-298"},"PeriodicalIF":1.2,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10170775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}