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Objective To investigate the effect of respiratory movement of different amplitude,period and direction on the dose distribution of target area in dynamic intensity modulated radiation therapy.Methods A total of 30 cases of lung cancer were selected and divided into three groups according to the volume size of the target area,including groups A (72.0-200.2 cm3),B (271.7-380.0 cm3) and C (498.9-684.9 cm3).The average volume was 151.5,327.1 and 583.3 cm3,respectively.Breathing motion simulation platform was used to drive the mode body with two-dimensional ionization chamber matrix along the Gun-Target direction,then turn the collimator to 0° and 90°,respectively.The doses were collected at the central level in different amplitudes of 0,4,8,12 and 15 mm,periodic respiratory movement at the intervals of 3,4 and 5 s and respiratory motion measurement with a cycle of 4 s 5 times.The difference of dose distribution between the collected dose and TPS output was analyzed by taking the absolute dose and γ-passing rate (3 mm/3％) as indicators.Results In the two-sided upward,respiratory movement reduced the dose at the medial edge of the target area and increased the dose at the lateral edge of the target area.The difference of γ-passing rate between respiration cycle was up to 3.54％ (t=2.301,P＜0.05),and when the respiration movement was more than 8 mm,the γ-passing rate was less than 90％ and decreased with the increase of amplitude.The difference of γ-passing rate between static and respiratory motion was negatively correlated with the volume of target area,and the average γ-passing rate of A,B and C three groups increased gradually.The γ-passing rate of 5 composited dose was higher than that of single dose,and the difference was statistically sigificant(t=-9.36--5.95,P＜0.05).Conclusions The dose distribution of dynamic IMRT target area is mainly influenced by respiration range and its own volume,and the respiration cycle has an effect on dose distribution under partial amplitude.After implementing the multiple doses,some single dose implementation errors can be eliminated.Physicians need to expand the target area reasonably according to the range of respiratory movement,and optimize the amount of marginal tissue in the target area in the direction of respiratory movement.For patients with small target volume and large respiratory movement,respiratory management technology should be adopted to improve the accuracy of target dose implementation.
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Objective To investigate the dosimetric effect of carbon fiber couch through virtual simulation in the XiO treatment planning system (TPS).Methods A treatment couch model of iBEAM evo Extension 650 was scanned with a big bore spiral CT and its contour was stored in the XiO TPS.The attenuation coefficient of couch was obtained by measuring the attenuated dose with and without a solid water phantom on the couch at different gantry angles (100°-180°).The optimal relative electron density (RED) values of the carbon fiber (CF) cover and foam core (FC) were adjusted according to the comparison between measured and simulated attenuation dose.The effects of the couch in the TPS on pass rate were evaluated by Octavius 4D phantom with 10 cases with lung cancer.Results The optimal RED values of CF and FC were 0.75 and 0.10 g/cm3,respectively.The measured attenuation error was the maximal at gantry angle of 120° (4.84％) without the treatment couch in the TPS.The average measured attenuation errors without the couch in the TPS dropped significantly from (2.54 ± 1.48) ％ to (-0.04 ± 0.36) ％ after inclusion of the treatment couch during dose calculation (Z =-3.621,P ＜ 0.05).The three-dimensional dose verification γ pass rate (3 mm/3％) without the couch increased significantly from (91.79± 1.25)％ to (94.74± 1.69)％ after inclusion of the couch in the dose calculation (t =6.027,P ＜ 0.05).Conclusions The effect of couch on the attenuation dose is significant.Inclusion of a virtual model of couch in XiO TPS can simulate the attenuation effect properly and improve the accuracy of dose calculation.
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Objective To verify and evaluate the prognostic models for extranodal natural killer/T-cell lymphoma, nasal type (ENKL). Methods ENKL patients in the 105th Hospital of PLA from January 1990 to December 2015 were retrospectively analyzed, and patients were followed to the August 2016 through telephone and medical records. The models were evaluated by C-index, and the prognostic ability of each factor was assessed by survival curves. Results A total of 76 patients met the inclusion criteria, with a median age of 41.9 years old (range, 14-74 years old), all patients received chemotherapy, and 49 received radiation therapy. During the median observation time (37.0 months), 37 patients died in a median of 28.4 months. The prognostic factors of Eastern Cooperative Oncology Group performance status (ECOG PS) score, level of lactate dehydrogenase (LDH) and Ann Arbor staging were the influencing factors of overall survival in the univariate survival analysis (all P<0.05), and only ECOG PS score was significant in the multivariate Cox regression (OR: 4.231, 95 ％ CI 2.172-8.240, P= 0.000). C-index of international prognostic index (IPI) was 0.541 (95 ％ CI 0.534- 0.555), and those of model with ECOG PS score, Ann Arbor staging, primary lesion invasion, LDH and age as the indicators and model with ECOG PS core, Ann Arbor staging, primary lesion invasion, LDH and hemoglobin as the indicators were both 0.726 (95 ％ CI 0.626-0.826). Conclusion Both model with ECOG PS score, Ann Arbor staging, primary lesion invasion, LDH and age as the indicators and model with ECOG PS core, Ann Arbor staging, primary lesion invasion, LDH and hemoglobin as the indicators can accurately predict the prognosis of patients with ENKL and are significantly better than the IPI model.
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Objective To investigate the feasibility of detector array in Monaco modeling for MLC parameters adjustment.Methods One parameter was fixed, and then the other parameter was changed.The γ pass rates of the test beams, namely 3ABUT, 7SegA, and FOUR L, were assessed to determine the values of leaf transmission and leaf offset.A total of 12 tumor cases from different anatomical sites were randomly selected.Two-dimensional dose verification (rack angle zero) of Step& Shot and dMLC plans as well as three-dimensional dose validation of VMAT plan were performed using Octavius 4D system.The γ pass rates were analyzed at a standard of 3%/3 mm.Meanwhile, the point dose verification for these three plans was analyzed to obtain the dose deviations.Results The values of leaf transmission and leaf offset were 0.0105 and-0.08 mm, respectively.The average γ pass rates (%) of Step& Shot, dMLC, and VMAT plans were 88.59±2.94, 87.81±3.28, and 87.45±2.24 before adjustment and 98.45±1.23, 98.9±1.01, and 96.03±1.66 after adjustment.In addition, the average dose deviations (%) according to the point dose verification were 0.85±0.75, 0.95±0.39, and 0.98±0.40 before adjustment and 0.97±0.57, 1.08±0.76, and 0.86±0.45 after adjustment.Conclusions Octavius detector 729 ionization chamber array is a feasible and reliable device in Monaco modeling for MLC parameters adjustment.
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Objective To investigate the gamma (γ) passing rates for volumetric-modulated arc therapy (VMAT) dosimetric verification with different techniques.Methods A total of 12 VMAT plans for the treatment of different anatomical sites in cancer patients were chosen.The Octavius 4D system was used to measure the dose distributions in two different settings:the gantry was rotating (three-dimensional (3D) and 2D γ-analysis) and the gantry was fixed at 0°(2D γ-analysis).The γ passing rates were analyzed with 3%/3 mm and 2%/2 mm criteria, using the paired t test or Wilcoxon signed-rank test.The 2D γ passing rates for different irradiation methods were calculated.Results For the 3D and 2D dose distributions obtained at a rotating gantry angle as well as the 2D dose distribution obtained at zero gantry angle, the average γ passing rates were 96.03%, 96.98%, and 98.90% for 3%/3 mm (P=0.227, P=0.000, P=0.003);82.08%, 84.04%, and 90.90% for 2%/2 mm (P=0.379, P=0.000, P=0.000).For the 2D dose distributions obtained with different irradiation methods, the average γ passing rate was 98.99% for 3%/3 mm and 93.68% for 2%/2 mm.Conclusions The VMAT dosimetric verification based on a 3D volumetric dosimeter at a rotating gantry position can be clinically useful for delivery quality assurance (QA), and can achieve the most reliable dose calculation for VMAT, which has more referential values.
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Objective To study the effect of amplitude of respiratory movements on dose distribution of static intensity-modulated radiotherapy (IMRT),and to provide a basis for dose correction against respiratory movements.Methods A two-dimensional matrix driven by the QUASAR program-controlled respiratory movement instrument was used to simulate human respiratory movements in the head/foot direction.The dose distribution was evaluated on the isocenter plane with different amplitudes of respiratory movements.The Verisoft software and absolute dose analysis were used to analyze dose distribution,percentage errors of absolute dose,and passing rates of radiation field for both collected data and planned dose distribution.Results In spite of little effect on dose distribution in target volume,respiratory movements increased the dose outside the marginal target volume along the movement direction.When the respiratory amplitude was lower than 6 mm,the passing rate of γdistribution met the requirement of clinical dose verification;when the respiratory amplitude was larger than 8 mm,the passing rate of γ distribution was reduced with the increasing respiratory amplitude and fell below the clinical standard.Conclusions Respiratory movements have a blurring effect on static IMRT.It is possible to introduce some compensation methods to static IMRT in the treatment of tumor with periodic respiratory movements.The normal tissue at the edge of target volume along the respiratory movement direction is exposed to a higher radiation dose than expected.Therefore,the radiation dose for the normal tissue around target volume should be made as low as possible in the radiotherapy plan.For the patients with relatively large respiratory amplitude,action should be taken to lower respiratory amplitude and elevate the radiation dose in target volume.
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Objective To study the effect of the respiratory amplitude on the dose distribution of volumetric modulated arc therapy (VMAT).Methods Respiratory motion simulation phantom (QUASAR) was used to simulate the respiratory movement from head to toe,and a two-dimensional ionization chamber matrix was used to collect the dose distribution in isocenter with different respiratory amplitude.Verisoft software and absolute dose analysis were used to analyze dose distribution,percentage errors of absolute dose in isocenter,passing rates of radiation field for the data collected,and results were compared to planned dosage.Results The effect on isocenter target dose of respiratory motion was below dose tolerance 5％ (t =-22.614--10.756,P ＜ 0.05).The respiratory movement made the dose on the edge of the target area higher,with fewer hot spots and more cold spots in the target area.As the respiratory amplitude increased,the effect of respiratory movement on the overall dose distribution in the target area was greater.The difference of the whole beam γ passing rate between 6,8,10 mm and stationary state was significant (t =3.095,8.685,14.096,P ＜ 0.05).The difference of target γ passing rate between 8,10 mm and stationary state was significant (t =6.081,9.841,P ＜0.05).Conclusions The respiratory movement could cause the dose transmission errors of VMAT,the error increased with increased range of motion.The actual radiation dose for normal tissues along the direction of respiratory movement on the target edge was higher than what was planned.
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Objective To study the feasibility of dose verification with Octavius 4D system in volumetric modulated arc therapy (VMAT).Methods Twenty patients were treated with the VMAT.Their treatment plans were performes and then acquired the measured data with the Octavius 4D system.In addition,the treatment plans are used in the CT phantom for Octavius 4D system,and acquire the simulated data.We use the γ pass rate to analysis the measured and simulated results for the conditions:the dose deviations are 2％3％5％,the displacement deviations are 2 mm/3 mm/5 mm and the thresholds are 5％ 10％,and got the Gamma pass rate and fitness of profile curve.Results The distributions of measured and simulated dose are matched well,and the fitness of profile curve are also matched well.The averaged Gamma pass rate is 97.78％ in the case 3 mm 3％ 10％.Conclusions Octavius 4D system can meet the dose verification for VMAT treatment.The measured plane is always following the rotating frame and perpendicular to the beam.
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<p><b>OBJECTIVE</b>To study the influence of the sequence of three-dimensional conformal radiotherapy (3DCRT) and transcatheter arterial chemoembolization (TACE) on the efficacy and toxicity of treatment in patients with hepatocellular carcinoma (HCC) with portal vein tumor thrombus (PVTT).</p><p><b>METHODS</b>A total of 65 patients who were diagnosed with primary HCC with PVTT were enrolled in the study from November 2008 to March 2012 and were randomly divided into the following two groups:group A,32 patients treated with 3DCRT followed by TACE; group B,33 patients treated with TACE followed by 3DCRT.</p><p><b>RESULTS</b>The total efficacy rates of groups A and B were 68.8% and 69.7% (x² =0.232, P < 0.793). The survival rates,effective percentage of PVTT and AFP remission rates were not significantly different between group A and group B.The exacerbation rate of liver function was significantly higher for group B than for group A (P < 0.05). No serious complication was found in the follow-up period for either group.</p><p><b>CONCLUSION</b>The combination of 3DCRT and TACE is a relatively effective local treatment for patients with primary HCC and PVTT.Compared with TACE followed by 3DCRT, 3DCRT followed by TACE may have a negative influence on liver function.</p>
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Humans , Arteries , Carcinoma, Hepatocellular , Chemoembolization, Therapeutic , Combined Modality Therapy , Liver Neoplasms , Portal Vein , Radiotherapy, Conformal , Survival Rate , Thrombosis , Treatment OutcomeABSTRACT
Objective To observe the efficacy and adverse effects of conventionally fractionated (CF) versus hypofractionated (HF) three-dimensional conformal radiotherapy (3DCRT) for hepatocellular carcinoma (HCC) with portal vein tumor thrombosis.Methods A retrospective analysis was performed on the clinical data of 65 patients with HCC suitable for 3DCRT from 2008 to 2012.These patients were randomly divided into HF group (n =32) and CF group (n =32).The HF group received 3DCRT at a total dose of 45-55 Gy (3-4 Gy/fraction,3-5 fractions/week),while the CF group at a total dose of 40-56 Gy (2 Gy/fraction,5 fractions/week).Results The follow-up rate was 100％.For the HF group and CF group,the short-term response rates were 72％ vs.55％ (P =0.034),the 1-year local control rates were 72％ vs.55％ (P=0.034),the 1-year overall survival rates were 59％ vs.45％ (P=0.042),and the numbers of individuals with grade 1-2 acute gastrointestinal reactions,deterioration of liver function,and radiation hepatitis were 14 vs.11,8 vs.8,and 1 vs.0,respectively (P =0.237).Conclusions HF 3DCRT is superior to CF 3DCRT in the treatment of HCC.
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Objective To analyse the efficacy of three-dimensional conformal radiotherapy(3D-CRT)for hepatic carcinomas.Methods 81 patients with advanced hepatic carcinoma were treated at every turn of 200-400 cGy to a total dose of 4800-5500 cGy.Average-dose was 4580 cGy.Following up time was 225 monthes.Recent effect was evaluated according to WHO tumor evaluation standard.Results 81 patients accomplished the treatment.The local response rate was 82.7 ％(67/81)after treatment with 21 cases CR,46 cases PR.The 1,2 year overall survival rates were 43 ％,26 ％.In the multivariate analysis,the recent effect,the total dose,metastasis,clinical staging,the diameter of the tumors and Child grade presages had statistical significance for overall survival(all P ＜ 0.05).Conclusion 3D-CRT is preferable therapeutic action for primary hepatic carcinomas and can prolong the survival term.
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Objective To evaluate the effects of respiratory on dose distributions in threedimensional conformal radiotherapy (3 DCRT) and intensity-modulated radiotherapy (IMRT).Methods The dose distributions were measured with a PTW 2D-ARRAY seven29 placed on a home-made moving platform to simulate the respirator.Dosimetric comparisions for 3DCRT and IMRT plans were performed by means of Gamma analysis with 3％ and 3 mm,respectively.Dose distribution measured for static treatment plans.Results The respiratory could reduce the target does and conformal index.The r pass rate (3％3 mm in 3 DCRT was greater than it in IMRT ((53.58 ± 0.74) ％,(30.71 ± 1.00) ％,t =57.91,P ＜ 0.01).The failed points were mainly near the field edge,but located in the whole target volumes for IMRT plans.Conclusions It is undesirable to use IMRT techniques for tumors with large motion amplitude.3DCRT can give a reliable dose distribution by reasonably selecting the PTV margin.