[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-420201-105":3,"detail-sidebar-cat-0-en-105":73,"doc-detail-420201-en":122},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":66,"head_meta":68,"extra_data":70,"updated_unix":72},105,"en","necessity-of-daily-igrt-dosimetric-study-of-beam-position-offsets-at-central-double-beam-junction-in-pediatric-craniospinal-irradiation","Necessity of Daily IGRT - Dosimetric Study of Beam Position Offsets at Central Double-beam Junction in Pediatric Craniospinal Irradiation","","Craniospinal irradiation (CSI) for pediatric patients carries the challenge of reproducing the original simulation posture across repeated sessions, because target volume expansion cannot fully offset setup variations. This study quantifies how beam position offsets at the central double-beam junction affect dose uncertainty during CSI radiotherapy. Positional shifts worsened conformity and homogeneity indices and increased deviation-related dose metrics at the junction. The findings support daily image-guided radiation therapy to reduce underdosing or overdosing risks.",{"@graph":14,"@context":65},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/healthcare/","Healthcare",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/document/necessity-of-daily-igrt-dosimetric-study-of-beam-position-offsets-at-central-double-beam-junction-in-pediatric-craniospinal-irradiation/420201/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/necessity-of-daily-igrt-dosimetric-study-of-beam-position-offsets-at-central-double-beam-junction-in-pediatric-craniospinal-irradiation/420201.png","ImageObject",300,407,{"name":42,"@type":43},"Mafia Boss","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-10-30","2026-09-28",true,{"@type":52,"interactionType":53,"userInteractionCount":55},"InteractionCounter",{"@type":54},"ViewAction",9,{"@type":57,"mainEntity":58},"FAQPage",[59],{"name":60,"@type":61,"acceptedAnswer":62},"What does the study recommend for clinical practice?","Question",{"text":63,"@type":64},"Opposing shifts of the brain and spinal fields can cause clinically important underdosing or overdosing at the junction. 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BMC Cancer (2026) 26:4 BMC Cancer  \n[https://doi.org/10.1186/s12885-025-15388-y](https://doi.org/10.1186/s12885-025-15388-y)  \nRESEARCH Open Access  \nNecessity of daily IGRT? Dosimetric study of beam position offsets at central doublebeam junction in pediatric craniospinal irradiation  \nBo Gao 1, Zaojie Yao 1, Lizhen Wu 1, Kongfeng Shao 1, Xijin Lin 1, Qiandong Liang 1, Xizhen Huang 1, Haiyan Chen 1,2 and Zhanquan Lei 1*  \nAbstract  \nBackground Craniospinal irradiation (CSI) is an essential treatment modality for pediatric patients with tumors at high risk of leptomeningeal spread. However, accurate reproduction of the original simulation posture is difficult in subsequent CSI sessions as expansion of the target volume cannot fully compensate for variations, potentially resulting in dose uncertainties caused by the beam junction.  \nPurpose This study aimed to evaluate the impact of offsets in beam positions on dose uncertainty at the central double-beam junction during CSI radiotherapy.  \nMethods To compute the dose distribution in different positional offsets, the relative positions ofthe beams and CT images of the brain and spine beam centers were adjusted according to the original treatment plan of individual patients. Four parameters were calculated to assess the quality of the radiotherapy plan: the conformity index (CI), homogeneity index (HI), percentage of 1-V95%, and percentage of V110% at the planning target volume (PTV) at the beam junction.  \nResults The quality parameters (CI, HI, 1-V95%, V110%) were observed to deteriorate with increasing positional offsets. Overall, higher absolute values of beam center offset were associated with poorer dose distributions at the beam junction. Movement along the craniospinal axis toward the brain was defined as positive, while movement toward the spine was defined as negative. Shifting of the brain beams by + 3 mm and the spine beams by-3 mm resulted in an average CI value of 0 . 50, compared to 0.76 in the non-offset scenario, while the average HI was 0.33 versus 0.11 and the average 1-V95% value was 41.05% compared to 0.52% in the reference plan. When the brain beams were shifted by-3 mm and the spine beams by + 3 mm, the average V110% was 62.75%, compared to 2.01% without offset. Considering all beam offset scenarios, the worst-case doses to organs at risk were a maximum dose 7.78 Gy to the lens and average doses of 10 . 01, 8 . 58, 8 .46, and 5.57 Gy to the parotid gland, thyroid gland, heart, and kidneys, respectively, while the lung V5 was 47% .  \n*Correspondence: Zhanquan Lei [244902263@qq.com](244902263@qq.com)  \nFull list of author information is available at the end of the article  \n© The Author(s) 2025. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit [http://creati](http://creati)[vecommons.org/l](vecommons.org/l)icenses/by-nc-nd/4.0/.  \nGao et al. BMC Cancer (2026) 26:4 Page 2 of 13  \nConclusion Greater discrepancies in beam positioning during CSI radiotherapy result in poorer dose distributions at the beam junction. Therefore, opposing shifts of th","cbCaisLc1HVR39RU","https://ap.wps.com/l/cbCaisLc1HVR39RU","pdf",4264791,13,"English","# Abstract\n# Introduction\n# Methods\n# Results\n# Conclusion","[{\"question\":\"What does the study recommend for clinical practice?\",\"answer\":\"Opposing shifts of the brain and spinal fields can cause clinically important underdosing or overdosing at the junction. Therefore, daily image-guided radiation therapy is recommended for CSI.\"}]","Necessity of Daily IGRT - Dosimetric Study of Beam Position Offsets at Central Double-beam Junction in Pediatric Craniospinal Irradiation | PDF",1790619910,33]