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1.
Article in Chinese | WPRIM | ID: wpr-974369

ABSTRACT

Objective To investigate the dose calculation accuracy of two algorithms in Monaco TPS for self-made phantoms with different cavity thickness, and analyze the influence of phantoms with different cavity thickness on dose verification of upper esophageal cancer. Methods The phantoms with different cavity thickness were placed on the simulated CT positioning machine to scan and acquire images. In Monaco TPS, the irradiation fields with energy of 6 MV, 100 MU and different square field sizes were added to the acquired images. The dose of the cavity of the ionization chamber was calculated by two algorithms, and measured on the accelerator by dosimeter under the same conditions. At the same time, 20 patients with upper esophageal cancer who received dynamic intensity modulation in fixed field were randomly selected and included in the study, and two algorithms were used for dose verification on phantoms with different cavity thickness. The results were statistically analyzed by SPSS 22.0 software. Results The maximum deviations between the calculated values and the measured values were 0.66% and −1.8%, in the calculation of phantoms with different cavity thickness by algorithms of Monte Carlo and Pencil Beam. In Monte Carlo algorithm, the result of RD pair t test is P > 0.05. Paired t test of AD (0 mm, 10 mm), (5 mm, 10 mm) and (10 mm, 20 mm) groups showed no significant difference (P < 0.05). The maximum deviation was 1.1%, and the rest groups were not statisticely significant (P > 0.05); In Pencil Beam algorithm the t test results of RD (0 mm, 20 mm) and (5 mm, 20 mm) pairs were (P < 0.05), the maximum deviation was 0.58%, and the rest groups were (P > 0.05). In AD group, (P < 0.05), the maximum deviation was 2.78%; The paired t test between the two algorithms was (P < 0.05), and the maximum deviations in RD and AD groups were 2.49% and 4.14%, respectively. Conclusion Monte Carlo algorithm has accurate calculation and high gamma pass rate of dose verification, and there is no clinical difference in gamma pass rate of dose verification among phantoms with different cavity thickness, pencil Beam algorithm is not recommended in cavity phantom calculation.

2.
Article in Chinese | WPRIM | ID: wpr-868395

ABSTRACT

Objective To compare the dosimetric differences of volumetric modulated arc therapy (VMAT) plans optimized with 3 different fluence smoothing parameters using Monaco treatment planning system.Methods A total of 15 patients with middle and upper esophageal carcinoma were planned with Low fluence smoothing (Low),Medium fluence smoothing (Medium) and High fluence smoothing (High) during VMAT optimization.The dosimetric differences in D95,D conformity index (CI),homogeneity index (HI) of targets,dose volume histogram (DVH) of organs at risk (OARs),and monitor unit (MU) were compared.Results There were no significant differences in D95,D CI and HI of targets,as well as in V40 and D of the heart,V10,V20 and D of the lung,and segment number among plans optimized with different fluence smoothing techniques (P>0.05).Plans with high fluence smoothing achieved less V30 of heart,Dmax of cord PRV (t=-2.167,-0.999,P<0.05),lower MU (t=-3.148,-6.692,P<O.05),but increased V5 of both lungs (t=1.306,-2.027,P<O.05)compared with plans with Medium and Low fluence smoothing.Plans with low fluence smoothing irradiated higher dose to the V30 and D to heart (t=O.411,0.589,0.013,P<0.05),but less V5 of the lungs (t=O.423,P<0.05) compared with plans with medium fluence smoothing.Conclusions All VMAT plans with 3 different fluence smoothing can meet the clinical requirements.VMAT plans optimized with high fluence smoothing are recommended in the treatment of patients middle and upper thoracic esophageal carcinoma.

3.
Article in Chinese | WPRIM | ID: wpr-798775

ABSTRACT

Objective@#To compare the dosimetric differences of volumetric modulated arc therapy (VMAT) plans optimized with 3 different fluence smoothing parameters using Monaco treatment planning system.@*Methods@#A total of 15 patients with middle and upper esophageal carcinoma were planned with Low fluence smoothing (Low), Medium fluence smoothing (Medium) and High fluence smoothing(High) during VMAT optimization. The dosimetric differences in D95, Dmean, conformity index (CI), homogeneity index (HI) of targets, dose volume histogram (DVH) of organs at risk (OARs), and monitor unit (MU) were compared.@*Results@#There were no significant differences in D95, Dmean, CI and HI of targets, as well as in V40 and Dmean of the heart, V10, V20 and Dmean of the lung , and segment number among plans optimized with different fluence smoothing techniques (P>0.05). Plans with high fluence smoothing achieved less V30 of heart, Dmax of cord PRV(t=-2.167, -0.999, P<0.05), lower MU (t=-3.148, -6.692, P<0.05), but increased V5 of both lungs (t=1.306, -2.027, P<0.05) compared with plans with Medium and Low fluence smoothing. Plans with low fluence smoothing irradiated higher dose to the V30 and Dmean to heart (t=0.411, 0.589, 0.013, P<0.05), but less V5 of the lungs (t=0.423, P<0.05) compared with plans with medium fluence smoothing.@*Conclusions@#All VMAT plans with 3 different fluence smoothing can meet the clinical requirements. VMAT plans optimized with high fluence smoothing are recommended in the treatment of patients middle and upper thoracic esophageal carcinoma.

4.
Practical Oncology Journal ; (6): 34-38, 2014.
Article in Chinese | WPRIM | ID: wpr-498925

ABSTRACT

Objective To compare the dosimetry between three -dimensional conformal radiotherapy (3DCRT)and intensity -modulated radiotherapy(IMRT)in the treatment of upper thoracic esophageal carcino-ma,and to provide references to choose radiotherapy program for clinical physician .Methods twenty-five cases with upper esophageal carcinoma (clinical stageⅠ~Ⅲstage)were treated by 3DCRT and IMRT at the concentra three-dimensional radiation treatment planning system .The different exposure doses between target area and effected organs were compared by dose volume histogram ( DVH) with the planed target volume ( PTV) ,which must reach 95% of the prescriptive doses.Results Two different radiotherapy plans of IMRT and 3DCRT:V95, (99.91 ±0.14)%,(95.73 ±4.14)% respectively,P0.05;targeting minimum dose(Dmin)were(5 458.88 ±184.06) cGy,(4541.60 ±599.0)cGy,P0.05;Lung V10 (35.39 ±11.41)%,(29.0 ±8.80)%,P<0.05,Lung V5(44.95 ±15.55)%,(37.27 ±11.93)%,P<0.05. Conclusion Intensity-modulated radiotherapy is better than 3DCRT technology in showing PTV volume ,target conformal degrees and the mean index ,spinal cord protection ,However ,The risk of lung injury could be increased with the enlarged area of low -dose irradiation in lung .

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