Anatomical change during radiotherapy for head and neck cancer, and its effect on delivered dose to the spinal cord

Abstract

Differences between delivered and planned spinal cord D are small in patients treated with daily IG. Even patients experiencing substantial weight loss or anatomical change during treatment do not require adaptive replanning for spinal cord safety.

Analysis of dose using CBCT and synthetic CT during head and neck radiotherapy: A single centre feasibility study

“…Anatomical changes can be well visualised on CBCT to evaluate changes in tar- get volume, patient contour variation (caused by weight loss, tumour changes etc.) and shifts in delineated planning volumes [8,16,25,28]. One patient within this study had bolus in situ during their CBCT scans but not on their pCT.…”

Dosimetric impact of weight loss and anatomical changes at organs at risk during intensity-modulated radiotherapy for head-and-neck cancer

“…Head and neck (H&N) cancer treatment using IMRT is complex and consequences in inconsistencies between planned and measured doses using Thermoluminescent Dosimetry (TLD), especially approximately critical structures (Chung et al, 2005;Noble et al, 2019). Treatment of nasopharyngeal tumors using intensity-modulated radiation therapy (IMRT) requires highly accurate techniques to keep the radiation to organs at risk (OAR) such as; optic nerves, eyes, spinal cord, parotid gland, and other sensitive structures, at low doses below tolerance and constraint doses.…”

“…The anatomy of both the patient's tumor and OAR can vary significantly during a course of treatment (Chen, Bai, Pan, Xu, & Chen, 2017;Han, Chen, Liu, Schultheiss, & Wong, 2008;Hansen, Bucci, Quivey, Weinberg, & Xia, 2006;Hawkins et al, 2018;Noble et al, 2019;Ottosson, Zackrisson, Kjellén, Nilsson, & Laurell, 2013;Robar et al, 2007). Consequently, differences between planned radiation dose and that which is actually delivered to any structure may vary accordingly (Hawkins et al, 2018;Noble et al, 2019;Shelley et al, 2017). Current radiotherapy (RT) treatments are planned using a CT scan at a single pretreatment time point to delineate the PTV and OARs, without taking into account the occurrence of anatomic changes during the course of fractionated RT.…”

“…Current radiotherapy (RT) treatments are planned using a CT scan at a single pretreatment time point to delineate the PTV and OARs, without taking into account the occurrence of anatomic changes during the course of fractionated RT. In this context, adaptive RT (adapting treatment delivery based on changes in tumor and/or normal tissues during course of RT) should be considered to modify the complex geometry of IMRT plan and account for these changes (Hansen et al, 2006;Hawkins et al, 2018;Noble et al, 2019).…”

“…Incorrect positioning and patient weight loss during treatment may lead to an increase in the dose supplied to normal tissues and may cause geographical tumor area misses. A crucial dose-limiting OAR for H&N cancer radiotherapy is the parotid gland, with its close proximity to nasopharyngeal tumors; through its impact on infections, speech, and swallowing (Menke et al, 1994;Minniti et al, 2011;Noble et al, 2019;Sweeney et al, 1998;Tsai et al, 1999;Verellen, Linthout, Van Den Berge, Bel, & Storme, 1997).…”