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Materials and methods: A retrospective cohort of patients with intracranial neoplasms treated between December 2022 and December 2024 with curative radiotherapy using on-board kV CBCT was analyzed. Translational and rotational displacements were recorded to compute CTV-to-PTV margins. Results and conclusions are based on the reported CBCT-matching performance and margin comparisons, supporting reduced margins with enhanced daily image guidance.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/setup-errors-during-curative-radiation-therapy-in-intracranial-neoplasms-is-a-5-mm-ptv-margin-an-overestimation/442895/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/setup-errors-during-curative-radiation-therapy-in-intracranial-neoplasms-is-a-5-mm-ptv-margin-an-overestimation/442895.png","ImageObject",300,407,{"name":92,"@type":93},"anakgang17","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-31","2026-09-29",true,{"@type":102,"interactionType":103,"userInteractionCount":34},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What was the study objective regarding PTV margin in intracranial neoplasms?","Question",{"text":112,"@type":113},"The study aimed to identify an ideal CTV-to-PTV margin using the Van Herk formula by auditing six-dimensional setup errors in patients receiving curative brain radiotherapy.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How were setup errors measured in the materials and methods?",{"text":117,"@type":113},"Patients treated between December 2022 and December 2024 with on-board kV CBCT were included. Translational (3) and rotational (3) displacements were retrieved using the offline review feature of the radiation planning and delivery software.",{"name":119,"@type":110,"acceptedAnswer":120},"What do the results indicate about a 5 mm institutional PTV margin?",{"text":121,"@type":113},"Using Van Herk calculations, the CTV-to-PTV margins were 0.28, 0.37, and 0.34 cm across lateral, longitudinal, and vertical axes, which were well below the institutional 5 mm margin. The authors conclude that a reduced PTV margin of 4 mm is sufficient.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},442895,1790826454,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":34,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":29,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":143,"read_time":144,"preview_page_count":4},962090883568,"https://ap-avatar.wpscdn.com/davatar_a8503ba1806abce46bf441b54a3ca4cd","© 2025 Greater Poland Cancer Centre. Published by Via Medica.  \nAll rights reserved. e-ISSN 2083–4640  \nISSN 1507–1367  \nISSN: 1507–1367  \nRESEARCH PAPER  \nReports of Practical Oncology and Radiotherapy 2025, Volume 30, Number 5, pages: 657–662  \nDOI: 10.5603/rpor.108087  \nSubmitted: 30.03.2025  \nAccepted: 12.08.2025  \nSetup errors during curative radiation therapy in intracranial neoplasms—is a 5 MM PTV margin an overestimation?  \nAswin Chandran Veluthattil, Nithiyaanandan Natarajan, Anjali Thiruthiyil  \nDepartment of Radiation Oncology, PSG Institute of Medical Sciences and Research, Coimbatore, Tamil Nadu, India  \nABSTRACT  \nBackground: The aim of the study was to determine an ideal planning target volume (PTV) margin using the Van Herks formula by auditing and reporting the setup errors in 6 dimensions of patients undergoing curative radiation therapy to the brain in a newly set up Radiation Oncology Department in Southern India.  \nMaterials and methods: All patients with intracranial neoplasms who underwent curative intracranial radiotherapy with an on board kV cone beam computed tomography (CBCT) in our department between December 2022 and December 2024 were selected for this retrospective analysis. Displacements in each direction—3 translational and 3 rotational—were retrieved and recorded using the offline review feature of the radiation planning and delivery software. Clinical target volume (CTV) to PTV margin was calculated using the Van Herk formula (2.5 Σ + 0.7 σ) in the translational axes.  \nResults: We evaluated 474 on-board CBCT images of 21 patients who had undergone curative intracranial fractionated external beam radiotherapy (EBRT). Matching the CBCT and simulation CT was done and verified by 2 expert radiation oncologists. The mean setup errors in the lateral, longitudinal and vertical axes were 0.03,–0.01, and –0.06 cm, respectively, and the mean rotational errors for roll, pitch and yaw were 0.1, 0.2, and –0.28 degrees, respectively. Using the Van Herk formula, the calculated CTV to PTV margins in the lateral, longitudinal and vertical axes were 0.28, 0.37, and 0.34 cm, respectively. This was well below the institutional PTV margin of 5 mm.  \nConclusions: The results showed that a reduced PTV Margin of 4mm is sufficient in intracranial malignancies. Daily Online image matching with a 6D couch further enhances the accuracy of the treatment.  \nKeywords: random error; systematic error; PTV margin Rep Pract Oncol Radiother 2025;30(5):657–662  \nIntroduction  \nIntracranial neoplasms have a worldwide yearly incidence of 321,476 as per the latest statistics [1] . It ranks 12th overall in the number of deaths and 19th overall in terms of incidence. Although surgical interventions have been the mainstay of treatment of these tumors, radiation therapy has played an important adjunctive role. Fractionated external beam radiotherapy generally delivered over 5–6 weeks  \nis part of the treatment protocol of many benign and malignant intracranial neoplasms.  \nThe use of radiation in these neoplasms comes with its own challenges, the most serious of which is radiation necrosis — a late toxicity leading to neurological damage which is extremely difficult to treat [2] . Limiting radiation dose-volume parameters often helps in decreasing this side effect thereby improving the neurological functioning and quality of life of the patients [3] . Limiting  \nAddress for correspondence: Dr. Aswin Chandran Veluthattil, Assist. Prof., Department of Radiation Oncology, PSGIMSR, Coimbatore, Tamil Nadu, India, tel: (+91) 7639465597; e-mail: [chandiru@gmail.com](chandiru@gmail.com)  \nThis article is available in open access under Creative Common Attribution-Non-Commercial-No Derivatives 4.0 International (CC BY-NC-ND 4.0) license, allowing to download articles and share them with others as long as they credit the authors and the publisher, but without permission to change them in any way or use them commercially  \n[https://journals.viame","cbCaiowlWLBQOafL","https://ap.wps.com/l/cbCaiowlWLBQOafL","pdf",486773,"English","# Abstract\n# Introduction\n# Materials and methods\n# Results\n# Conclusions","[{\"question\":\"What was the study objective regarding PTV margin in intracranial neoplasms?\",\"answer\":\"The study aimed to identify an ideal CTV-to-PTV margin using the Van Herk formula by auditing six-dimensional setup errors in patients receiving curative brain radiotherapy.\"},{\"question\":\"How were setup errors measured in the materials and methods?\",\"answer\":\"Patients treated between December 2022 and December 2024 with on-board kV CBCT were included. Translational (3) and rotational (3) displacements were retrieved using the offline review feature of the radiation planning and delivery software.\"},{\"question\":\"What do the results indicate about a 5 mm institutional PTV margin?\",\"answer\":\"Using Van Herk calculations, the CTV-to-PTV margins were 0.28, 0.37, and 0.34 cm across lateral, longitudinal, and vertical axes, which were well below the institutional 5 mm margin. The authors conclude that a reduced PTV margin of 4 mm is sufficient.\"}]","Setup errors during curative radiation therapy in intracranial neoplasms - is a 5 MM PTV margin an overestimation? | PDF",1790702014,15]