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Objective:To investigate the effects of CT images reconstructed using different field of view (FOV) sizes on the automatic segmentation of organs at risk and dose calculation accuracy in radiotherapy after radical mastectomy.Methods:Under the same scanning conditions, CT values-electron density conversion curves were established by reconstructing the original CT images of a phantom placed at the isocenter and extended FOV (eFOV) positions using FOV sizes of 50, 60, 70 and 80 cm. Then, these curves were compared. A standard phantom with a known volume was scanned, and the automatic segmentation result of the phantom on CT images reconstructed using different FOV sizes was compared. A total of 30 patients in Guangdong Second Provincial General Hospital from January 2020 to June 2022 with breast cancer were randomly selected. Through simulated positioning, their CT images were reconstructed using different FOV sizes for the purpose of automatic segmentation of organs at risk, followed by comparison between the outcomes of automatic segmentation and physicians′segmentation. The treatment plan established based on CT images reconstructed using a FOV size of 50 cm (FOV 50 images for short) was applied to CT images reconstructed using FOV sizes of 60, 70 and 80 cm (FOV 60, FOV 70 and FOV 80 images for short) for dose calculation, and the dose calculation result were compared. Results:The CT values - electron density conversion curves derived from CT images reconstructed using different FOV sizes were roughly consistent. At the isocenter, the difference between the segmented volume and actual volume of the standard phantom increased up to a maximum of 6 cm 3 (4.8%) with an increase in the FOV size. As indicated by the automatic segmentation result, the segmentation accuracy of the spinal cord, trachea, esophagus, thyroid, healthy mammary gland, and skin decreased with an increase in the FOV size ( t = -28.43-8.23, P < 0.05). The comparison of dose calculated based on CT images reconstructed using different FOV sizes showed that there was no statistically significant differences( P>0.05) in the dose to target volume ( V95) and the maximum and average doses in the supraclavicular lymph node region, as well as the dose to organs at risk. The coverage for planned target volume decreased with an increase in the FOV size, with a maximum difference of 4.06%. Conclusions:It is recommended that, for radiotherapy after radical mastectomy, FOV 50 images should be selected for the automatic segmentation of organs at risk, CT-values-electron density conversion curves should be established based on the electron density phantom images of the eFOV region, and the eFOV 80 images should be preferred for dose calculation.
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Objective A self-made tiltable treatment couch was adopted for CT simulation positioning and radiotherapy to evaluate the feasibility and effectiveness to minimize the setup errors. Methods Twenty-two patients with thoracic and abdominal tumors receiving radiotherapy in Department of Radiation Oncology,Peking Union Medical College between March and September 2016 were recruited in this study. All patients were randomly divided into the experimental(n=11)and control groups(n=11).In the study group,the tiltable treatment couch was adopted to switch the patients from the standing position to the supine position,and conventional supine position was utilized in the control group. All patients received CT positioning under spontaneous breathing. Image registration was performed according to the standard recommendations of IGRT group. The image registration data for the translational and rotation errors of CBCT were recorded and analyzed. The setup errors were calculated by four-parameter model between two groups. Results In the experimental group,the translational error of the x direction was(-0.012±0.128)cm with a variation range of(0.29-0.70 cm),(0.272±0.123)cm for the y direction(0.23-0.70 cm)and(0.089± 0.105)cm for the z direction(0.14-0.53 cm),respectively. In the control group,the translational error of the x direction was(0.006±0.198)cm(0.27-0.75 cm),(-0.108±0.396)cm for the y direction(0.56-2.08 cm)and(- 0.096± 0.176)cm for the z direction(0.34-0.89 cm), respectively. Conclusions Application of the self-made tiltable treatment couch can enhance the setup reproducibility and reduce the setup errors,especially in the y direction during radiotherapy for the thoracic and abdominal tumors.
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Objective To evaluate the dosimetric difference between fixed-field static intensity-modulated radiotherapy (IMRT), fixed-field dynamic multileaf collimator (DMLC), and volumetric modulated arc therapy (VMAT), all of which involve supraclavicular and infraclavicular regions, in breast cancer patients after breast-conserving surgery.Methods This study included 14 female patients with breast cancer who received radiotherapy after breast-conserving surgery in our hospital from October 2012 to April 2016.The radiation field included the chest wall and supraclavicular and infraclavicular regions.IMRT, DMLC, and VMAT plans were generated for each patient while using identical optimization conditions.The doses to planning target volume (PTV) and organs at risk (OARs) were compared based on dose-volume histogram (DVH);one-way analysis of variance or nonparametric Wilcoxon rank test was used for comparison.Results For the dose distribution of PTV, VMAT achieved the best V95, V98, CI, and HI (P<0.009).Concerning the doses to OARs, VMAT achieved the best V5, V20, and Dmean of the ipsilateral lung and the best V5 and Dmean of the contralateral lung (P<0.022).Dmean of the spinal cord was significantly lower in VMAT than in IMRT and DMLC (P=0.004).Conclusions VMAT is preferred for the patients with breast cancer to be treated with radiotherapy involving supraclavicular and infraclavicular regions after breast-conserving surgery.It can improve the dose distribution of target and reduce the doses to organs at risk and radiotherapy toxicities.
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Objective To compare the clinical effect of two ways of the closed reduction internal fixation and open reduction internal fixation in the treatment of joint injury.Methods According to the digital table,84 patients with joint injury were randomly divided into control group and treatment group,42 cases in each group.The control group was given closed reduction and internal fixation,and the treatment group was given open reduction and internal fixation.Results The total time of operation,postoperative hospitalization time,postoperative joint function recovery time of the treatment group were (78.51 ±10.20)min,(13.35 ±2.46)d,(88.43 ±5.27)d,those of the control group were (118.73 ±25.71)min,(19.72 ±3.57)d,(107.42 ±10.33)d,the differences were statistically signifi-cant(t =9.424,9.522,10.613;P =0.000,0.000,0.000).The excellent and good rate of the treatment group was 90.48%,which was higher than 71.43% of the control group,the difference was statistically significant(χ2 =4.941, P =0.026).The treatment group had 1 case of adverse reaction,the control group had 8 cases of adverse reaction, there was statistically significant difference between the two groups(χ2 =6.098,P =0.014).After treatment,the VAS pain score in the treatment group was (2.11 ±0.68)points,which was lower than (4.98 ±1.35)points in the control group,the difference was statistically significant(t =12.305,P =0.000).Conclusion The application effect of closed reduction and internal fixation for patients with joint injury disease is very obvious.
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Objective To seek a optimization method for lung cancer planning with Helical TomoTherapy for reducing the low dose area of total lung.Methods CT images of thirty patients with unilateral lung cancer were selected.Seven plans (Groups A,B,C,D,E,F and G) were generated for each patient using an identical optimization procedure with the conditions that implemented contralateral lung with unblocked (control group),1/4 directional block,1/2 directional block,directional block,1/4 complete block,1/2 complete block and complete block,respectively.The benefits in different schemes of reducing the low dose area of normal lung tissue were estimated,in order to provide a reference treatment plan scheme in clinical.Results Groups B,C,D and E had less influence on the target than that of group A.And there were no statistical difference between the target dosimetric parameters.The median dose and average dose of group F were increased within 0.5 Gy.The conformal index of group G had great influence on the target.The low dose area of total lung were reduced effectively in Groups C,D,E,F and G,the average decrease of V5 and V10 was 8.06％-45.26％ and 6.21％-33.95％,respectively.The V20 decreased by 1.71％-3.78％ in directional block group,while V20 increased in complete block group (2.07％-5.07％).The single treatment time was increased by 8.51％-79.22％.Conclusions The results showed that the low dose area of total lung was higher for the plan without any block limitation.It could reduce the low dose area of total lung with directional block.We should lengthen the blocking arc of contralateral lung with directional block based on the fractional treatment time and the patient's physical condition.A certain arc of contralateral lung with complete block could effectively reduce low dose area.When complete block was used,it is suggested that the arc was no more than half of the contralateral lung.
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Objective To study the dosimetry and safety of the non-coplanar IMRT plan for advanced lung cancer.Methods The two groups IMRT plans were designed with coplanar (5,7F) and non-coplanar field (5,7F-n) for patients.To compare the dosimetry of two groups and perform 4 patients F7-n IMRT plan.Results With the increase of the fields in each group PTV's CI were improved (all P =0.000),especially the 7F-n plan PTV's Dmean,Dmax,V95％ and HI also were improved (P=0.001,0.001,0.009,0.000) ; in the coplanar group each lung' s V5 increased (P =0.000,0.002,0.000) and whole lung's Dmean increased (P =0.000),but non-coplanar group whole lung's and contralateral lung's V5 reduce (P =0.001,0.005).Between the groups,7F-n plan PTV's indicators were all improved to compared with 5F plan (all P =0.000),and each lung's V20 reduced (all P =0.000),and whole lung's Dmean,V30,contralateral lung' s V5 reduced (P =0.000,0.001,0.000),and spinal cord' s Dmax also reduced (P =0.033),but ipsilateral lung's V5 and heart's Dmean increased (P =0.000,0.003);with compared to 7F plan,the 7F-n's ipsilateral lung's V5 and heart's Dmean also increased (P =0.000,0.048),but whole lung' s and contralateral lung's V5 decreased (all P =0.000).Four patients were performed successfully non-coplanar IMRT treatment,no collision occurred.Conclusions 7 fields non-coplanar IMRT plan not only improve the dose distribution of PTV,but also effectively control the volume of low dose lung increase,lung V20 and Dmean reduce too.Thus recommended to use this design in patients with advanced lung cancer for radiotherapy
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Objective To investigate the effects of reducing the auditory organ dose by limitation of sub regional auditory organ in IMRT plan. Methods Total 223 cases of nasopharyngeal carcinoma patients were divided into group A and group B. In group A, the IMRT plans of 114 patients were designed by limiting overall auditory organ dose. In group B, the IMRT plans of 109 patients were designed by limiting sub regional auditory organ dose. According to the Clinical prescription, the IMRT plans were designed. Paried t?test was difference between groups. Results By comparing the two groups of auditory organ dose, in all stages, the tympanic cavity Dmean average in group B decreased by T1 vs. 17?? 7%,T2 vs. 22?? 4%,T3 vs. 15?? 7% and T4 vs. 14?? 2% ( P= 0?? 000,0?? 000,0?? 000,0?? 000);cochlea Dmean average decreased by T1 vs. 11?? 0%, T2 vs. 20?? 1%, T3 vs. 10?? 0% and T4 vs. 9?? 0%(P= 0?? 004,0?? 000,0?? 007,0?? 036);vestibule Dmean average decreased by T1 vs. 22?? 6%, T2 vs. 31?? 8%, T3 vs. 20?? 6% and T4 vs. 21?? 4%, significantly less than in group A (P= 0?? 000,0?? 000,0?? 000,0?? 000). The bony portion of eustachian tube Dmean average in group B decreased were not significantly less than in group A (decreased by 3?? 4%,6?? 8%,3?? 6%,0?? 1%;P= 0?? 291, 0?? 006,0?? 155,0?? 963). Conclusions In IMRT plan, optimization on dose limitation of sub regional auditory organs were used to reduce the auditory organ dose and decrease the radiation damage to auditory organ.
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Objective To study the probability safety assessment to analyze and evaluate radiation error risk in the external beam radiotherapy,so as to establish and strengthen the control and management of the radiotherapy process,continuous improvement of quality control and quality management.Methods To build the whole of radiotherapy flow chart and process tree,using the decision tree model to determine critical control points in the whole process,making risk assessment chart and analyzing 4 patients with potential safety hazards error.Results The whole process is divided into 22 missions in 3 functional areas,the entire cover 15 branches and 59 key and 11 key control point.The enumeration of error as risks and critical control points has certain correlation.Conclusions Probabilistic safety assessment method have strengthened manage,analyze and control to risk,and all these provide the basis for developing and improving radiotherapy process control management.Radiotherapy quality management for future multidisciplinary and high-level management personnel who take up provides a prospective study.
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Objective To investigate the dose calculation accuracy and feasibility of using kilovoltage cone-beam CT (KVCBCT) for esophageal cancer radiotherapy.Methods Hounsfield unit (HU) values and profile along the horizontal line of Catphan (R) 600 phantom in KVCBCT images acquired on Trilogy linear accelerator were compared to those in the planning CT.The KVCBCT value-density calibration curve was established.The intensity modulated radiotherapy plans were created on the planning CT images and copied to KVCBCT images.The dose distribution was recalculated by means of the KVCBCT value-density calibration curve in the treatment planning system.The dosimetric comparisons were performed between the KVCBCT and planning CT plans on the phantom and 10 patients with esophageal cancer.ResultsThe KVCBCT value was stable with a maximum variation of 1.6％,and there was no significant time trend.CT value profiles showed good agreement within 1％ variation except the peripheral regions.The dosimetric differences were less than 1.33％and 3.65％for the phantom case and the patient ones,respectively.The dose distribution comparison was also in good agreements.Conclusions The accurate dose caleulation based on KVCBCT for esophageal cancer is feasible.The KVCBCT images can be used for monitoring the dosimetric changes during the treatment.
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Scatter coincident events are the important factor that affects the quality of positron emission tomography (PET) images. In this paper, according to the characters of projection data, a scatter correction method which uses maximum likelihood expectation maximization (MLEM) algorithm based on poisson model is proposed. We compared the sinograms and reconstructed images corrected by MLEM algorithm and deconvolution method respectively. The results indicate that the algorithm proposed in this paper increases the contrast of images while correcting scatter. It is better than the traditional method.
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Algorithmes , Traitement d'image par ordinateur , Méthodes , Dynamique non linéaire , Loi de Poisson , Tomographie par émission de positons , Méthodes , Diffusion de rayonnementsRÉSUMÉ
AIM: The effects of selenium dioxide (SeO_2) on proliferation, apoptosis, intracellular reactive oxygen species (ROS) and Ca~(2+) levels in three leukemia cell lines NB4, K562 and HL-60 were investigated. METHODS: Three leukemia cell lines were treated with 3-30 ?mol/L SeO_2. Flow cytometry was used to detect apoptosis rate, and analyze the changes of ROS and Ca~(2+) level within cells. RESULTS: SeO_2 at 10 and 30 ?mol/L inhibited proliferation in three leukemia cell lines. Treatment with 30 ?mol/L SeO_2 for 48 h induced 54.0%, 46.5%, 49.6% apoptosis in NB4, K562, and HL-60 cells, respectively, and also markedly decreased ROS and Ca~(2+) levels among three cell lines. The rate of ROS positive cells in NB4 and HL-60 decreased with the increase in SeO_2 concentrations. ROS was clearly reduced with 30 ?mol/L SeO_2 in K562. Ca~(2+) levels were tardily declined with 10, 30 ?mol/L SeO_2 in NB4 and HL-60 cells. Ca~(2+) levels were clearly reduced with 30 ?mol/L SeO_2 in K562. CONCLUSION: SeO_2 induces apoptosis in three leukemia cells. The declines of intracellular ROS and Ca~(2+) levels are involved in apoptosis induced by SeO_2.