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[What is the impact of IMRT of nasopharyngeal carcinomas on glandular structures?] Mnejja W,Daoud H,Fourati N,Sahnoun T,Siala W,Farhat L,Daoud J Cancer radiotherapie : journal de la Societe francaise de radiotherapie oncologique PURPOSE:The aim of this work is to evaluate the anatomical changes of the glandular structures during the NPC IMRT and to study their dosimetric impacts. PATIENTS AND METHODS:Twenty patients receiving IMRT for NPC were included. For each patient, a second dosimetric CT was performed at a dose of 38Gy, which was fused with the initial planning dosimetric CT. We calculated the volume percent change, the positional and dosimetric variation between the 2 scanners for the glandular structures (parotid, submaxillary, thyroid and pituitary). RESULTS:We observed a decrease in the volume of right and left parotids (-27.9% and -27.54%). It was correlated with the initial dose planned at its level. For the sub maxillary glands, the decrease was -36.1% on the right and -27.28% on the left. The value of reduction of the thyroid gland was -18.01%. A medial supra-millimeter migration of 2 and 1.15mm was found for right and left parotid glands respectively, correlated with GTV N reduction volume. We found a significant increase in mean doses for the parotid glands. It was 1.8±2.3Gy for the right and 1.5±2.7Gy for the left. For the right sub maxillary gland, the increase was about 0.35±2Gy and 3.79±5.2Gy for the thyroid. CONCLUSION:The modifications observed for glandular structures during NPC IMRT can explain the different toxicities caused by radiation. It seems also that a careful adaptation of the treatment plan should be considered during therapy. 10.1016/j.canrad.2019.06.015
Study of the dose-volume parameters variation in tumor target volumes and organs at risk during nasopharyngeal carcinoma radiotherapy applying deformation registration. Translational cancer research BACKGROUND:During intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC), the volume of the target volume and the organs at risk (OARs) will change constantly, which may lead to differences between the actual dose received and the initial planned dose. In this study, the cumulative dose of the two plans was obtained by deformable registration. This study provides an approach to evaluate the dose volume of IMRT for the NPC objective. METHODS:From July 2014 to May 2018, eighteen NPC patients who accepted simultaneous integrated boost IMRT were enrolled. All patients underwent simulation CT (CT) and replanning CT (CT) scans after 20-25 fractions of radiation therapy. The treatment plans were designed on CT and CT with the name of Plan and Plan, respectively. The Plan and Plan were obtained after registering from CT to CT using rigidity and deformation technology by Velocity. Then the dose-volume indices of the tumor target volumes and OARs at Plan, Plan, Plan and Plan were compared. RESULTS:The gross tumor volume (GTV) and the left and right parotid gland volumes decreased by 20.8% (P<0.001), 36.8% (P<0.001) and 37.5% (P<0.001), respectively, from CT to CT. There was no significant difference in the dose-volume index on the GTV and plan gross tumor volume (PGTV) between Plan and Plan. The V of the left and right parotid gland and the D of the brainstem, left and right eyeballs, left and right lens, and left and right optic nerves were all lower in Plan than in Plan (the average decrease was 17.0% to 60.1%). The differences in some dose-volume parameters (including D, D of the GTV and PGTV, D of the parotid glands, D of the lens and optic nerves) between Plan and Plan were less than 5%. The differences in some dose-volume parameters (including D, D of the GTV and PGTV, D, D and V of the parotid glands, D of lens and optic nerves) between Plan and Plan were less than 10%. The Dyce Similarity Coefficient of the target volume and OARs after deformation registration were higher than that after rigid registration. CONCLUSIONS:The volume of the GTV and parotid glands were decreased during the IMRT for NPC. The dose-volume indices of the GTV and the OARs in Plan were similar to those in Plan. Therefore, the dose-volume indices of Plan can be used to evaluate the efficacy of radiotherapy and to predict radioactive damage. 10.21037/tcr.2019.11.06
Quality of life and survival outcome for patients with nasopharyngeal carcinoma treated by volumetric-modulated arc therapy versus intensity-modulated radiotherapy. Huang Tai-Lin,Tsai Ming-Hsien,Chuang Hui-Ching,Chien Chih-Yen,Lin Yu-Tsai,Tsai Wen-Ling,Fang Fu-Min Radiation oncology (London, England) BACKGROUND:To evaluate the longitudinal changes of quality of life (QoL) and survival in patients with nasopharyngeal carcinoma (NPC) treated by volumetric-modulated arc therapy (VMAT) versus intensity-modulated radiotherapy (IMRT). METHODS:One hundred and forty non-distant metastatic NPC patients treated by VMAT (n = 66) or IMRT (n = 74) with simultaneously integrated boost between March 2013 and December 2015 at a single institute were analyzed. QoL was prospectively assessed by the EORTC QLQ-C30 and HN35 questionnaires at the four time points: before RT, RT 42.4 Gy (20 fractions), and 3, 12 months after RT. RESULTS:The 3-year locoregional relapse-free survival, distant metastasis-free survival, failure-free survival, and overall survival rates were 96.6, 89.4, 86.1%, and 87.4 for the VMAT group, respectively, compared with 91.4, 90.0, 79.8, and 91.3% for the IMRT group (p value > 0.05). The pattern of QoL changes was similar between the VMAT and IMRT group. No statistically or clinically significant difference in all the QoL scales was observed between VMAT and IMRT group at each time point. Compared to before RT, we observed statistically (p<0.05) and clinically (difference of mean scores≧10) better outcome in global QoL and social functioning, but worse head and neck symptomatic outcome in swallowing, taste/smell, opening mouth, dry mouth, and sticky saliva at the time point of 1 year after RT for both groups. CONCLUSION:The study provides the evidence that the tumor control, survival and changes of QoL is compatible for NPC patients treated by VMAT versus IMRT. 10.1186/s13014-020-01532-4
Quantifying the dosimetric effects of neck contour changes and setup errors on the spinal cord in patients with nasopharyngeal carcinoma: establishing a rapid estimation method. Journal of radiation research The purpose of this study was to quantify the effect of neck contour changes and setup errors on spinal cord (SC) doses during the treatment of nasopharyngeal carcinoma (NPC) and to establish a rapid dose estimation method. The setup errors and contour changes in 60 cone-beam computed tomography (CBCT) images of 10 NPC patients were analysed in different regions of the neck (C1-C3, C4-C5 and C6-C7). The actual delivered dose to the SC was calculated using the CBCT images, and univariate simulations were performed using the planning CT to evaluate the dose effects of each factor, and an index ${\mathrm{Dmax}}_{\mathrm{displaced}}$ was introduced to estimate the SC dose. Compared with the planned dose, the mean (maximum) Dmax increases in the C1-C3, C4-C5 and C6-C7 regions of the SC were 2.1% (12.3%), 1.8% (8.2%) and 2.5% (9.2%), respectively. The simulation results showed that the effects of setup error in the C1-C3, C4-C5 and C6-C7 regions were 1.5% (9.7%), 0.9% (8.2%) and 1.3% (6.3%), respectively, and the effects of contour change were 0.4% (1.7%), 0.7% (2.5%) and 1.5% (4.9%), respectively. The linear regression model can be used to estimate the dose effect of contour changes (R2 > 0.975) and setup errors (R2 = 0.989). Setup errors may lead to a significant increase in the SC dose in some patients. This study established a rapid dose estimation method, which is of great significance for the daily dose evaluation and the adaptive re-planning trigger of the SC. 10.1093/jrr/rrac009