scholarly journals The Influence of SSO on the Optimization Result of Nasopharynx Carcinoma Plan

2021 ◽  
Author(s):  
Xiaolong HUA ◽  
Jianhe YU ◽  
Lu WANG ◽  
Jiaqi DAI ◽  
Qun REN ◽  
...  
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Organs At Risk ◽  
Planning System ◽  
Treatment Planning System ◽  
Target Area ◽  
Delivery Time ◽  
Parotid Glands ◽  
Similar Dose ◽  
Significant Difference ◽  
Better Than

Abstract PurposeTo study the influence of Monaco 5.4 treatment planning system (TPS) on the dosimetry of radiotherapy for nasopharynx carcinoma (NPC) under the condition of different segment shape optimization (SSO) times.MethodsFifteen patients with T3-4N0-2M0 stage nasopharyngeal carcinoma were enrolled, and each case was designed with SSO of 3, 5, 7 and 10 times respectively. The dose results of the target area and the major organs at risk (OAR) were statistically analyzed by DVH statistics; moreover, the isodose lines of 70Gy, 60Gy and 54Gy were intercepted at the same plane in the transverse, coronal and sagittal views and the segment shapes were compared at the angle of 30°, 120°, 240° and 330° in beam eye view (BEV); In addition, optimization time (OT), delivery time (DT), segments# and MU# were obtained and analyzed by optimization console; the plans were verified and analyzed by using ArcCheck phantom.ResultsFor target area D2, the results of the SSO7 group and the SSO10 group were similar and both better than those of SSO3 and SSO5 groups, and the D2 results of the SSO3 group were notable higher than those of the other three groups; for the major OARs, the results of the maximum dose of spinal cord, brain stem, and lens and the mean dose and V30 of parotid glands showed the same trend. It showed that SSO7 and SSO10 share similar dose results, too which are notable better than the similar dose results shared by SSO3 and SSO5; in the dose deprogram distribution of 70Gy, 60Gy and 54Gy, partial 70Gy dose spillover occurred in both groups SSO3 and SSO5 and it was more obvious in group SSO3. While there was a no significant dose spillover in group SSO7 and group SSO10; in the sub-field alignment comparison under the same angle, the alignment became more complicated and the sub-fields were smaller as the number of SSO increased; the results of segment#, MU# and plan delivery time between different SSO groups were slightly different, while the plan optimization time changed significantly. The difference between group SSO3 and group SSO10 was more than 500s; the results were compared in ArcCheck, there was no significant difference between the groups.ConclusionsThe user-defined SSO function of Monaco 5.4 TPS effectively balances the relationship between plan design efficiency and plan quality. When SSO is 7, it is better value for efficiency and quality in clinical radiotherapy for nasopharyngeal carcinoma.

scholarly journals The Influence of SSO on the Optimization Result of Nasopharynx Carcinoma Plan

2021 ◽  
Author(s):  
Xiaolong HUA ◽  
Jianhe YU ◽  
Lu WANG ◽  
Li CHEN ◽  
Yanshu MU ◽  
...  
Keyword(s):  
Organs At Risk ◽  
Planning System ◽  
Treatment Planning System ◽  
Target Area ◽  
Delivery Time ◽  
Parotid Glands ◽  
Similar Dose ◽  
Significant Difference ◽  
Clinical Radiotherapy ◽  
Better Than

Abstract PurposeTo study the influence of Monaco 5.4 treatment planning system (TPS) on the dosimetry of radiotherapy for nasopharynx carcinoma (NPC) under the condition of different segment shape optimization (SSO) times.MethodsFifteen patients with T3-4N0-2M0 stage NPC were enrolled, and each case was designed with SSO of 3, 5, 7 and 10 times respectively. The dose results of the target area and the major organs at risk (OARs) were statistically analyzed by DVH statistics; moreover, the isodose lines of 70Gy, 60Gy and 54Gy were intercepted at the same plane in the transverse, coronal and sagittal views and the segment shapes were compared at the angle of 30°, 120°, 240° and 330° in beam eye view (BEV); In addition, optimization time (OT), delivery time (DT), segments# and monitor unit (MU#) were obtained and analyzed by optimization console; the plans were verified and analyzed by using ArcCheck phantom.ResultsFor target area D2, the results of the SSO7 group and the SSO10 group were similar and both better than those of SSO3 and SSO5 groups, and the D2 results of the SSO3 group were notable higher than those of the other three groups; for the major OARs, the results of the maximum dose of spinal cord, brain stem, and lens and the mean dose and V30 of parotid glands showed the same trend. It showed that SSO7 and SSO10 share similar dose results, too which are notable better than the similar dose results shared by SSO3 and SSO5; in the dose deprogram distribution of 70Gy, 60Gy and 54Gy, partial 70Gy dose spillover occurred in both groups SSO3 and SSO5 and it was more obvious in group SSO3. While there was a no significant dose spillover in group SSO7 and group SSO10; in the sub-field alignment comparison under the same angle, the alignment became more complicated and the sub-fields were smaller as the number of SSO increased; the results of segment#, MU# and plan delivery time between different SSO groups were slightly different, while the plan optimization time changed significantly. The difference between group SSO3 and group SSO10 was more than 500s; the results were compared in ArcCheck, there was no significant difference between the groups.ConclusionsThe user-defined SSO function of Monaco 5.4 TPS effectively balances the relationship between plan design efficiency and plan quality. When SSO is 7, it is better value for efficiency and quality in clinical radiotherapy for NPC.

scholarly journals Automatic Planning for Nasopharyngeal Carcinoma Based on Progressive Optimization in RayStation Treatment Planning System

2020 ◽  
Vol 19 ◽  
pp. 153303382091571
Author(s):  
Yiwei Yang ◽  
Kainan Shao ◽  
Jie Zhang ◽  
Ming Chen ◽  
Yuanyuan Chen ◽  
...  
Keyword(s):  
At Risk ◽  
Nasopharyngeal Carcinoma ◽  
Organs At Risk ◽  
Planning System ◽  
Treatment Planning System ◽  
Conformity Index ◽  
Homogeneity Index ◽  
Automatic Planning ◽  
The Difference ◽  
Better Than

Objective: To evaluate and quantify the planning performance of automatic planning (AP) with manual planning (MP) for nasopharyngeal carcinoma in the RayStation treatment planning system (TPS). Methods: A progressive and effective design method for AP of nasopharyngeal carcinoma was realized through automated scripts in this study. A total of 30 patients with nasopharyngeal carcinoma with initial treatment was enrolled. The target coverage, conformity index (CI), homogeneity index (HI), organs at risk sparing, and the efficiency of design and execution were compared between automatic and manual volumetric modulated arc therapy (VMAT) plans. Results: The results of the 2 design methods met the clinical dose requirement. The differences in D95 between the 2 groups in PTV1 and PTV2 showed statistical significance, and the MPs are higher than APs, but the difference in absolute dose was only 0.21% and 0.16%. The results showed that the conformity index of planning target volumes (PTV1, PTV2, PTVnd and PGTVnx+rpn [PGTVnx and PGTVrpn]), homogeneity index of PGTVnx+rpn, and HI of PTVnd in APs are better than that in MPs. For organs at risk, the APs are lower than the MPs, and the difference was statistically significant ( P < .05). The manual operation time in APs was 83.21% less than that in MPs, and the computer processing time was 34.22% more. Conclusion: IronPython language designed by RayStation TPS has clinical application value in the design of automatic radiotherapy plan for nasopharyngeal carcinoma. The dose distribution of tumor target and organs at risk in the APs was similar or better than those in the MPs. The time of manual operation in the plan design showed a sharp reduction, thus significantly improving the work efficiency in clinical application.

scholarly journals Consistency Study of Multiparametric Magnetic Resonance and Computed Tomography Targeting in Targeted Radiotherapy for Prostate Cancer

2020 ◽  
Author(s):  
Zhen Xu ◽  
Xiao-Dong Li ◽  
Lu Fu ◽  
Yong-Hua Yu
Keyword(s):  
Prostate Cancer ◽  
Computed Tomography ◽  
Magnetic Resonance ◽  
Organs At Risk ◽  
Target Volume ◽  
Planning System ◽  
Treatment Planning System ◽  
Target Area ◽  
Target Delineation ◽  
Significant Difference

Abstract Background: To compare the difference of location by computed tomography (CT) and multiparametric magnetic resonance imaging (mpMRI) on the target delineation and volume for organs at risk (OARs) among patients with prostate cancer. Methods: T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), and CT were performed among 11 patients who received radiotherapy for prostate cancer at our center between August 2018 and December 2019. The target areas were delineated using the Eclipse system, and the radiotherapy plans were made based on the treatment planning system (TPS) to compare target volume and dose-volume histogram (DVH) relative to rectum and bladder. Results: The clinical target volume (CTV) of T1WI and T2WI decreased by 18.8% (P=0.001) and 22.72% (P=0.003), respectively, compared with CT. The planning target volume (PTV) on T1WI and T2WI were 20.45% (P=0.015) and 22.31% (P= 0.008) smaller than that defined by CT. There was no significant difference in either CTV or PTV between the areas outlined on T1WI and T2WI. The DVH resulting from CT and MRI comparisons showed that the rectum and bladder dose levels were lower with MRI images compared with CT. It should be noted that at the lateral directions, the range of outlining on T2WI sequence were significantly smaller than others. Conclusion: Target planning based on mpMRI (T1WI, T2WI) is more precise than CT, which can significantly reduce the range of the target area and the volume of rectum and bladder exposed to high levels of radiation, improve the fitness and radiographic accuracy of the target area, especially on T2WI.

scholarly journals Dosimetric evaluation of three commercial radiotherapy planning systems for lung cancer and nasopharyngeal carcinoma cases

2020 ◽  
Author(s):  
Wan-jia Zheng ◽  
Ming-li Wang ◽  
Jun Zhang ◽  
Yi-mei Liu ◽  
Li Chen ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Spinal Cord ◽  
Nasopharyngeal Carcinoma ◽  
Treatment Time ◽  
Maximum Dose ◽  
Organs At Risk ◽  
Radiotherapy Planning ◽  
Planning Systems ◽  
Significant Difference ◽  
Better Than

Abstract Purpose: To identify planning systems and techniques suitable for different sites tumors by analyzing dosimetric differences using three commercial radiotherapy planning systems: Tomotherapy, Monaco and Eclipse.Methods: We retrospectively analyzed 20 lung cancer and 8 nasopharyngeal carcinoma (NPC), and each patient plans were designed using the three systems. The dose distribution of the target and organs at risk (OARs) were compared, and monitor unit (MU) and treatment time were also evaluated.Results: For lung cancer, mean dose of PGTV, PTV1 and PTV2 in Monaco and Tomo plans were lower than Eclipse plan. PTV2 CI in Monaco and Eclipse plans were better than Tomo plans (p=0.002, p=0.022). Monaco and Tomo plans were better than Eclipse plan regarding to mean dose and V15Gy of lungs; the lowest lungs V20Gy and V30Gy were provided by Tomo plan. The esophagus, heart and SpinalCord_03 dose were lowest in Monaco plan, and the maximum dose and V45Gy of SpinalCord_03 were 592.1cGy and 1.37% lower than Eclipse plan, respectively. For NPC, mean dose of PGTV, PTV1 and PTV2 in Eclipse plan were superior to Tomo plan (p=0.008, p=0.000, p=0.003); PTV2 V95% in Tomo plan was increased by 1.64% than Eclipse plan. There was no significant difference between Monaco and Eclipse plans. Tomo plan showed better spinal cord and brainstem protection, with spinal cord max dose 249.38cGy lower than Eclipse plan and 555cGy lower than Monaco plan, respectively.Conclusion: Although the three plans reflected their respective advantages in different aspects, in general, the Monaco plan (VMAT) was the best choice for lung cancer, and for the more advanced nasopharyngeal carcinoma, the Tomo plan (HT) was superior to the other two plans.

scholarly journals Application of dose-volume histogram prediction in biologically related models for nasopharyngeal carcinomas treatment planning

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Wufei Cao ◽  
Yongdong Zhuang ◽  
Lixin Chen ◽  
Xiaowei Liu
Keyword(s):  
Spinal Cord ◽  
At Risk ◽  
Treatment Planning ◽  
Organs At Risk ◽  
Planning System ◽  
Treatment Planning System ◽  
Dose Volume Histogram ◽  
Parotid Glands ◽  
Dose Volume ◽  
Dose Sparing

Abstract Purpose In this study, we employed a gated recurrent unit (GRU)-based recurrent neural network (RNN) using dosimetric information induced by individual beam to predict the dose-volume histogram (DVH) and investigated the feasibility and usefulness of this method in biologically related models for nasopharyngeal carcinomas (NPC) treatment planning. Methods and materials One hundred patients with NPC undergoing volumetric modulated arc therapy (VMAT) between 2018 and 2019 were randomly selected for this study. All the VMAT plans were created using the Monaco treatment planning system (Elekta, Sweden) and clinically approved: > 98% of PGTVnx received the prescribed doses of 70 Gy, > 98% of PGTVnd received the prescribed doses of 66 Gy and > 98% of PCTV received 60 Gy. Of these, the data from 80 patients were used to train the GRU-RNN, and the data from the other 20 patients were used for testing. For each NPC patient, the DVHs of different organs at risk were predicted by a trained GRU-based RNN using the information given by individual conformal beams. Based on the predicted DVHs, the equivalent uniform doses (EUD) were calculated and applied as dose constraints during treatment planning optimization. The regenerated VMAT experimental plans (EPs) were evaluated by comparing them with the clinical plans (CPs). Results For the 20 test patients, the regenerated EPs guided by the GRU-RNN predictive model achieved good consistency relative to the CPs. The EPs showed better consistency in PTV dose distribution and better dose sparing for many organs at risk, and significant differences were found in the maximum/mean doses to the brainstem, brainstem PRV, spinal cord, lenses, temporal lobes, parotid glands and larynx with P-values < 0.05. On average, compared with the CPs, the maximum/mean doses to these OARs were altered by − 3.44 Gy, − 1.94 Gy, − 1.88 Gy, 0.44 Gy, 1.98 Gy, − 1.82 Gy and 2.27 Gy, respectively. In addition, significant differences were also found in brainstem and spinal cord for the dose received by 1 cc volume with 4.11 and 1.67 Gy dose reduction in EPs on average. Conclusion The GRU-RNN-based DVH prediction method was capable of accurate DVH prediction. The regenerated plans guided by the predicted EUDs were not inferior to the manual plans, had better consistency in PTVs and better dose sparing in critical OARs, indicating the usefulness and effectiveness of biologically related model in knowledge-based planning.

Volumetric modulated arc therapy: a dosimetric comparison with dynamic IMRT and step-and-shoot IMRT

2019 ◽  
Vol 19 (4) ◽  
pp. 393-398 ◽  
Author(s):  
Payal Raina ◽  
Sudha Singh ◽  
Rajanigandha Tudu ◽  
Rashmi Singh ◽  
Anup Kumar
Keyword(s):  
Organs At Risk ◽  
Volumetric Modulated Arc Therapy ◽  
Intensity Modulated Radiation Therapy ◽  
Target Volume ◽  
Planning System ◽  
Treatment Planning System ◽  
Conformity Index ◽  
Delivery Time ◽  
Arc Therapy ◽  
Step And Shoot

AbstractAim:The aim of this study was to compare volumetric modulated arc therapy (VMAT) with dynamic intensity-modulated radiation therapy (dIMRT) and step-and-shoot IMRT (ssIMRT) for different treatment sites.Materials and methods:Twelve patients were selected for the planning comparison study. This included three head and neck, three brain, three rectal and three cervical cancer patients. Total dose of 50 Gy was given for all the plans. Plans were done for Elekta synergy with Monaco treatment planning system. All plans were generated with 6 MV photons beam. Plan evaluation was based on the ability to meet the dose volume histogram, dose homogeneity index, conformity index and radiation delivery time, and monitor unit needs to deliver the prescribed dose.Results:The VMAT and dIMRT plans achieved the better conformity (CI98% = 0·965 ± 0·023) and (CI98% = 0·939 ± 0·01), respectively, while ssIMRT plans were slightly inferior (CI98% = 0·901 ± 0·038). The inhomogeneity in the planning target volume (PTV) was highest with ssIMRT with HI equal to 0·097 ± 0·015 when compared to VMAT with HI equal to 0·092 ± 0·0369 and 0·095 ± 0·023 with dIMRT. The integral dose is found to be inferior with VMAT 105·31 ± 53·6 (Gy L) when compared with dIMRT 110·75 ± 52·9 (Gy L) and ssIMRT 115 38 ± 55·1(Gy L). All the techniques respected the planning objective for all organs at risk. The delivery time per fraction for VMAT was much lower than dIMRT and ssIMRT.Findings:Our results indicate that dIMRT and VMAT provide better sparing of normal tissue, homogeneity and conformity than ssIMRT with reduced treatment delivery time.

scholarly journals Application of Dose-Volume Histogram Prediction in Biologically Related Models for Nasopharyngeal Carcinomas Treatment Planning

2020 ◽  
Author(s):  
Wufei Cao ◽  
Yongdong Zhuang ◽  
Lixin Chen ◽  
Xiaowei Liu
Keyword(s):  
Spinal Cord ◽  
At Risk ◽  
Treatment Planning ◽  
Organs At Risk ◽  
Planning System ◽  
Treatment Planning System ◽  
Dose Volume Histogram ◽  
Parotid Glands ◽  
Dose Volume ◽  
Dose Sparing

Abstract Purpose: In this study, we employed a gated recurrent unit (GRU)-based recurrent neural network (RNN) using dosimetric information induced by individual beam to predict the dose-volume histogram (DVH) and investigated the feasibility and usefulness of this method in biologically related models for nasopharyngeal carcinomas (NPC) treatment planning.Methods and Materials: One hundred patients with NPC undergoing volumetric modulated arc therapy (VMAT) between 2018 and 2019 were randomly selected for this study. All the VMAT plans were created using the Monaco treatment planning system (Elekta, Sweden) and clinically approved: >98% of PGTVnx received the prescribed doses of 70 Gy, >98% of PGTVnd received the prescribed doses of 66 Gy and >98% of PCTV received 60 Gy. Of these, the data from 80 patients were used to train the GRU-RNN, and the data from the other 20 patients were used for testing. For each NPC patient, the DVHs of different organs at risk were predicted by a trained GRU-based RNN using the information given by individual conformal beams. Based on the predicted DVHs, the equivalent uniform doses (EUD) were calculated and applied as dose constraints during treatment planning optimization. The regenerated VMAT experimental plans (EPs) were evaluated by comparing them with the clinical plans (CPs).Results: For the 20 test patients, the regenerated EPs guided by the GRU-RNN predictive model achieved good consistency relative to the CPs. The EPs showed better consistency in PTV dose distribution and better dose sparing for many organs at risk, and significant differences were found in the maximum/mean doses to the brainstem, brainstem PRV, spinal cord, lenses, temporal lobes, parotid glands and larynx with P-values <0.05. On average, compared with the CPs, the maximum/mean doses to these OARs were altered by -3.44 Gy, -1.94 Gy, -1.88 Gy, 0.44 Gy, 1.98 Gy, -1.82 Gy and 2.27 Gy, respectively. In addition, significant differences were also found in brainstem and spinal cord for the dose received by 1cc volume with 4.11 and 1.67 Gy dose reduction in EPs on average.Conclusion: The GRU-RNN-based DVH prediction method was capable of accurate DVH prediction. The regenerated plans guided by the predicted EUDs were not inferior to the manual plans, had better consistency in PTVs and better dose sparing in critical OARs, indicating the usefulness and effectiveness of biologically related model in knowledge-based planning.

scholarly journals Evaluation of plan robustness on the dosimetry of volumetric arc radiotherapy (VMAT) with set-up uncertainty in Nasopharyngeal carcinoma (NPC) radiotherapy

2022 ◽  
Vol 17 (1) ◽  
Author(s):  
Zhen Ding ◽  
Xiaoyong Xiang ◽  
Qi Zeng ◽  
Jun Ma ◽  
Zhitao Dai ◽  
...  
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Evaluation Method ◽  
Biological Evaluation ◽  
Planning System ◽  
Treatment Planning System ◽  
Tumor Control ◽  
Tumor Control Probability ◽  
Parotid Glands ◽  
The Mean ◽  
Set Up

Abstract Purpose To evaluate the sensitivity to set up the uncertainty of VMAT plans in Nasopharyngeal carcinoma (NPC) treatment by proposing a plan robustness evaluation method. Methods 10 patients were selected for this study. A 2-arc volumetric-modulated arc therapy (VMAT) plan was generated for each patient using Varian Eclipse (13.6 Version) treatment planning system (TPS). 5 uncertainty plans (U-plans) were recalculated based on the first 5 times set-up errors acquired from cone-beam computer tomography (CBCT). The dose differences of the original plan and perturbed plan corresponded to the plan robustness for the structure. Tumor control probability (TCP) and normal tissues complication probability (NTCP) were calculated for biological evaluation. Results The mean dose differences of D98% and D95% (ΔD98% and ΔD95%) of PTVp were respectively 3.30 Gy and 2.02 Gy. The ΔD98% and ΔD95% of CTVp were 1.12 Gy and 0.58 Gy. The ΔD98% and ΔD95% of CTVn were 1.39 Gy and 1.03 Gy, distinctively lower than those in PTVn (2.8 Gy and 2.0 Gy). The CTV-to-PTV margin increased the robustness of CTVs. The ΔD98% and ΔD95% of GTVp were 0.56 Gy and 0.33 Gy. GTVn exhibited strong robustness with little variation of D98% (0.64 Gy) and D95% (0.39 Gy). No marked mean dose variations of Dmean were seen. The mean reduction of TCP (ΔTCP) in GTVp and CTVp were respectively 0.4% and 0.3%. The mean ΔTCPs of GTVn and CTVn were 0.92% and 1.3% respectively. The CTV exhibited the largest ΔTCP (2.2%). In OARs, the brain stem exhibited weak robustness due to their locations in the vicinity of PTV. Bilateral parotid glands were sensitive to set-up uncertainty with a mean reduction of NTCP (ΔNTCP) of 6.17% (left) and 7.70% (right). The Dmax of optical nerves and lens varied slightly. Conclusion VMAT plans had a strong sensitivity to set-up uncertainty in NPC radiotherapy, with increasing risk of underdose of tumor and overdose of vicinal OARs. We proposed an effective method to evaluate the plan robustness of VMAT plans. Plan robustness and complexity should be taken into account in photon radiotherapy.

scholarly journals A Comparative Study of Auto-contouring Softwares in Delineation of Organs at Risk in Lung Cancer and Rectal Cancer

2021 ◽  
Author(s):  
weijun chen ◽  
Cheng Wang ◽  
Wenming Zhan ◽  
Yongshi Jia ◽  
Fangfang Ruan ◽  
...  
Keyword(s):  
Lung Cancer ◽  
At Risk ◽  
Rectal Cancer ◽  
Organs At Risk ◽  
Similarity Index ◽  
Slight Modification ◽  
Ct Images ◽  
Target Area ◽  
Ct Image ◽  
Significant Difference

Abstract Background:Radiotherapy requires the target area and the organs at risk to be contoured on the CT image of the patient. During the process of organs-at-Risk (OAR) of the chest and abdomen, the doctor needs to contour at each CT image. The delineations of large and varied shapes are time-consuming and laborious.This study aims to evaluate the results of two automatic contouring software on OAR definition of CT images of lung cancer and rectal cancer patients. Methods: The CT images of 15 patients with rectal cancer and 15 patients with lung cancer were selected separately, and the organs at risk were outlined by the same experienced doctor as references, and then the same datasets were automatically contoured based on AiContour®© (Manufactured by Linking MED, China) and Raystation®© (Manufactured by Raysearch, Sweden) respectively. Overlap index (OI), Dice similarity index (DSC) and Volume difference (DV) were evaluated based on the auto-contours, and independent-sample t-test analysis is applied to the results. Results: The results of AiContour®© on OI and DSC were better than that of Raystation®© with statistical difference. There was no significant difference in DV between the results of two software. Conclusions: With AiContour®©, auto-contouring results of most organs in the chest and abdomen are good, and with slight modification, it can meet the clinical requirements for planning. With Raystation®©, auto-contouring results in most OAR is not as good as AiContour®©, and only the auto-contouring results of some organs can be used clinically after modification.

scholarly journals Actual Anatomical and Dosimetric Changes of Parotid Glands in Nasopharyngeal Carcinoma Patients during Intensity Modulated Radiation Therapy

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Gang Ren ◽  
Shou-Ping Xu ◽  
Lei Du ◽  
Lin-Chun Feng ◽  
Bao-Lin Qu ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Nasopharyngeal Carcinoma ◽  
Volume Change ◽  
Helical Tomotherapy ◽  
Intensity Modulated Radiation Therapy ◽  
Planning System ◽  
Parotid Glands ◽  
Intensity Modulated ◽  
Data Comparison ◽  
Clinical Benefits

The goal of this study was to evaluate the actual anatomical and dosimetric changes of parotid glands in nasopharyngeal carcinoma patients during intensity modulated radiation therapy. With helical tomotherapy, its planning system, and adaptive software, weekly anatomical and dosimetric changes of parotid glands in 35 NPC patients were evaluated. Interweekly parotid volume varied significantly (P<0.03). The rate of volume change reached the highest level at the 16th fraction. The averageV1increased by 32.2 (left) and 28.6 (right), and the averageD50increased by 33.9 (left) and 24.93 (right), respectively. Repeat data comparison indicated that theV1andD50varied significantly among different fractions (both withP=0.000). The variation of parotid volume was inversely correlated with that of theV1andD50(both withP=0.000). In conclusion, parotid volume and actual dose vary significantly in NPC patients during IMRT. Replanning at the end of the fourth week of IMRT may have clinical benefits.

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