ABSTRACT
Objective:To assess the shielding requirements of low energy X-ray intraoperative radiotherapy room under the domestic and foreign standards and guidelines, to measure the sured transmission factors for a range of shielding materials, the ambient dose equivalent rate around concerned positions and the shielding effect of protective devices, so as to provide references for shielding design of such radiotherapy units and applications of radiological protection devices.Methods:The required shielding thicknesses for a treatment room with INTRABEAM intraoperative radiotherapy system were calculated under the Chinese national standard GBZ 121, IPEM report No. 75 and NCRP report No. 151, respectively. The transmission factors for a range of shielding materials including solid water slab, shielding sheet and shielding apron were measured. Moreover, the ambient dose equivalent rates were measured under the simulated working conditions and the shielding effectiveness of a lead screen was evaluated.Results:The required lead thicknesses calculated under different standards and guidelines were less than 0.6 mm for all the concerned points, with the differences at sub-millimeter level. The low energy X-rays generated by this equipment attenuated rapidly in the shielding materials. The measured transmission factors of 0.05 mm lead equivalent shielding sheet and 0.25 mm lead equivalent shielding apron were 0.068 and 0.003 8, respectively. When the radiation was delivered using spherical applicator without any attenuation, the ambient dose equivalent rates at 1 m and 2 m from the X-ray source were 10.7 and 2.6 mSv/h, respectively. The corresponding measurement values decreased to 3.8 and 0.9 μSv/h, respectively, when the spherical applicator was inserted into a small water tank. Meanwhile, the ambient dose equivalent rate at 2 m was reduced to the background level when using protective screen.Conclusions:The shielding requirements for a low energy X-ray intraoperative radiotherapy facility are minimal, with low effective energy of X-rays generated by this equipment, but the dose rate close to the unshielded radiation source is high. The shielding scheme of treatment room should be optimized in design and the protective device should be used in a reasonable way.
ABSTRACT
Objective:To investigate the application of equivalent uniform dose (EUD) in the combination of intracavitary and interstitial brachytherapy (combined-BT) for cervical cancer.Methods:Twenty cervical cancer patients treated with combined-BT in Tianjin Medical University Cancer Institute and Hospital were recruited in this study. For each patient, treatment plans were optimized based on EUD and hybrid EUD (h-EUD). The results were statistically compared with predefined plans generated by Oncentra Brachy v4.3 using hybrid inverse planning optimization (HIPO). Furthermore, virtual uniform interstitial experiments were applied to evaluate the advantage of EUD.Results:All three plans showed consistent conformity index. Compared with the HIPO plans, the average D 2cm 3 of bladder, rectum and intestine in the EUD plans were decreased by 0.22 Gy, 0.23 Gy and 0.28 Gy, and those in the h-EUD plans were declined by 0.16 Gy, 0.22 Gy and 0.24 Gy, respectively. The average EUD of bladder, rectum and intestine in the EUD plans were decreased by 0.14 Gy, 0.20 Gy and 0.15 Gy, and those in the h-EUD plans were declined by 0.20 Gy, 0.13 Gy and 0.16 Gy, respectively (all P<0.05). The virtual interstitial experiment showed EUD could significantly improve the dose sparing for organs at risk (OARs). Conclusion:The application of EUD can significantly improve the dose sparing for normal tissues without compromising dose homogeneity and conformity during combined-BT for cervical cancer.
ABSTRACT
Objective:To identify the radiomics features related to the occurrence of radiation pneumonitis based on localized CT images of the chest in lung cancer patients, establish a machine learning model and investigate the value of radiomics technology in predicting the incidence of radiation pneumonitis.Methods:Clinical data of 86 patients with stage Ⅲ non-small cell lung cancer who received radical intensity-modulated radiation therapy (IMRT) were retrospectively analyzed. The radiation pneumonitis was graded by follow-up imaging data and clinical information. The planning CT images were collected. The lung was used as the volume of interest for extraction of radiomics features. The radiomics features, clinical and dosimetric parameters associated with the incidence of radiation pneumonitis were analyzed. Using the support vector machine to construct the model, the prediction performance of the model was evaluated by the five-fold verification method.Results:A total of 1029 radiomics features were extracted from CT images and 5 features were selected by ANOVA and LASSO. Two validation sets showed differences between adopting radiomics features alone and incorporating clinical and dosimetric parameters and radiomics features (AUC=0.67 and 0.71, respectively).Conclusions:The radiomics model constructed by planning CT images of lung cancer patients has the potential to predict the occurrence of radiation pneumonitis. Addition of clinical and dosimetric parameters can further improve the prediction performance of the model.
ABSTRACT
Objective To propose a novel preoperative planning method for laparoscopic ultrasound-guided implantation of I125 seeds in treating pancreatic cancer based on CT images,and to evaluate the feasibility of this treatment.Methods CT images of a pancreatic cancer patient were transmitted into the treatment planning system (TPS) developed by our laboratory,to obtain three-dimensional representations of the tumor and surrounding organs.All the positions of puncture were selected with the aid of virtual template,then possible needle paths and the number of necessary I125 seeds were planned,and the radiation dose was evaluated.Results A total of 21 needle paths with 45 seeds implantation into the tumor were planned.In the preoperative planning,the dosage parameters D90 and V100 of the tumor were 12 481 cGy and 92.83％,which was relatively eligible for the clinic requirement,whereas of suurounding non-tumor pancreatic tissue was 0 and 0.40％,respecyively.Conclusion Laparoscopic ultrasound-guided implantation of I125 seeds can be considered as a useful method for treating pancreatic cancer with accurate implantation of 125I seeds and satisfying effect of local control for the tumor in theory.
ABSTRACT
Objective To evaluate the performance of progressive optimization algorithm-based Auto-Planning module in automated volumetric-modulated arc therapy(VMAT)planning for nasopharyngeal carcinoma. Methods Thirteen treated VMAT plans of nasopharyngeal carcinoma were re-planed with Auto-Planning module. Only one cycle of automated optimization of the Auto-Planning module was performed for each plan without any manual intervention. The dosimetric parameters of the automated treatment plans were compared with those of the manual plans. Paired t-test was used for statistical analysis. The time required for automated planning using the Auto-Planning module was also measured. Results All plans generated with the Auto-Planning module met the routine dosimetric requirements and were acceptable for clinical use. The homogeneity index of targets was superior in the automated plans than in manual plans(P= 0.000).In addition,the automated plans had significantly improved protection for some organs at risk than the manual plans. The mean dose to the left and right parotids were reduced by 7.75 Gy(P=0.000)and 5.79 Gy(P=0.000)in the automated plans,respectively. Furthermore,the V60(0.58% vs. 3.12%,P=0.000)and Dmean(34.11 Gy vs. 40.78 Gy,P= 0.000)of the mandible were also significantly lower with Auto-Planning than with manual planning. Conclusions Auto-Planning module can improve the overall quality and consistency of treatment plans,and reduce the workload and time of treatment planning,resulting in substantially enhanced treatment planning efficiency.
ABSTRACT
Purpose Sustained attention dysfunction is a common symptom of patient with attention-deficit/hyperactivity disorder (ADHD).To reveal the neural mechanism of the abnormality of sustained attention of patients with ADHD,the cerebral blood flow (CBF) abnormalities in patients were studied by perfusion imaging.Materials and Methods Sixteen children with ADHD and twenty normal controls treated at the 401st Hospital of PLA from June 2013 to September 2015 underwent 3D arterial spin labeling (3D-ASL)scanning with GE 3.0T MRI scanner.The participants were performed four continuous sections of sustained attention to response task (SART) for 20 minutes in the scanner.Using SPM 8 toolkit,the local CBF values of both groups were compared in a voxel-wise manner,and their correlations with response time and target accuracy of SART were analyzed.Results When performing the SART,the patients with ADHD showed significantly inhibited trend of increasing CBF in the anterior cortex like dorsal cortex,medial prefrontal cortex,and motor area;however,they presented enhanced trend of increasing CBF in the posterior cortex such as posterior cingulate cortex and parietooccipital sulcus (P＜0.01);the change of CBF in the dorsal prefrontal cortex and that in the precentral and postcentral gyrus had significant correlation with response time of SART task and targeting ratio (dorsal prefrontal cortex:r=0.745,P＜0.001;r=0.591,P＜0.001;r=-0.521,P＜0.001.Precentral and postcentral gyrus:r=0.579,P＜0.001).Conclusion Patients with ADHD show different CBF redistribution between anterior and posterior cerebral cortex in performing SART,and the abnormal CBF shows significant correlations with behavioral metrics,which reflects the mechanism of sustained attention dysfunction of patients with ADHD.
ABSTRACT
Objective To analyze the impact of dose calculation resolution on Gamma pass rate for planar dose distribution verification of intensity-modulated radiotherapy (IMRT),and to find out the appropriate calculation resolution value with specific applied criteria.Methods 25 IMRT plans were selected for the planar dose verification.The Gamma pass rates with 3 mm/3％,2 mm/2％ and 1 mm/1％ criteria were compared and analyzed.The planar dose distributions were calculatedand exported from TPS with different resolutions of 0.5,1,2,3,4 and 5 mm.The pass rates of Gamma analysis between the computed dose distributions with different resolutions and the dose distributions measured by Mapcheck device were compared and analyzed.Results The average Gamma pass rates of all the 225 fields decreased with the increment of calculation resolution.When the pass rates of Gamma analysis were calculated using 3 mm/3％ criteria,the gamma pass rate with 1 mm and 0.5 mm calculation resolution were (98.3±1.3)％ and (98.3±1.2)％,respectively.The results were almost the same and the difference wasn't statistically significant (P＞0.05).The gamma pass rates with greater than or equal to3 mm calculation resolution were significantly less than the pass rate with 0.5 mm calculation resolution (P＜0.05).When the pass rates of Gamma analysis were calculated using 2 mm/2％ criteria,all the pass rates with greater than 0.5 mm calculation resolution were significantly less than the pass rate with 0.5 mm calculation resolution (P＜0.05).Conclusions The Gamma pass rates of planar dose verification reduce significantly with the increment of calculation resolution.In order to reduce the effect of calculation resolution on Gamma pass rate,the lower calculation resolution should be used.When using the 3 mm/3％ criteria for the Gamma analysis,1 mm calculation resolution is recommended.When using the 2 mn/2％ criteria for the Gamma analysis,0.5 mm calculation resolution is recommended.The appropriate calculation resolution will ensure the reliability of planar dose verification.
ABSTRACT
Objective To discuss the mid?to long?term results and possible prognostic factors of Bernese periacetabu?lar osteotomy for adolescents and young adults with developmental dysplasia of the hip. Methods Bernese periacetabular os?teotomy was performed on 162 patients (171 hips) with hip dysplasia from August 1997 to July 2009. Follow?up data was ac?quirable completely in 123 cases (137 hips), including 30 males (33 hips) and 93 females (104 hips). Age of surgery was 12-48 years (average 27.1 years). The X?ray radiographs and Harris scores were recorded preoperatively and at the last follow?up. The lateral center?edge angle (LCE), acetabular incline angle (AI), continuity of Shenton's line were also recorded. The grades of the hip osteoarthritis were classified by T?nnis classification. Insufficient corrections of osteotomy, excessive corrections of osteotomy, nonunion of the pubis, nerve injuries, and vascular injuries were recorded as complications. Results All the con?tactable cases was followed up again in June and July in 2014. Follow?up duration was 5-17 years (mean, 8.1 years). The LCE angle improved from 7.13° ± 8.86° preoperatively to 30.17° ± 14.98° at the final follow?up. The T?nnis acetabular incline angle decreased from 27.84° ± 12.85° preoperatively to 7.06° ± 10.58° at the final follow?up. The continuity of Shenton's line was in?tact in 106 cases postoperatively, compared with 87 cases preoperatively. Harris score improved from 83.34±9.82 preoperative?ly to 92.79±7.05 at the last follow?up. There was significant correlation between preoperative Harris score and Harris score at the last follow?up. Early complications were observed in 15 cases (15 hips), along with 17 cases (17 hips) of progressions of hip osteoarthritis. Survival rate of the hip at the last follow?up was 97.8%. Conclusion Bernese periacetabular osteotomies can significantly improve bone coverage and joint function of hip dysplasia patients with low rate of short?term complications. Further?more, there was little osteoarthritis progression observed, with good survival rate of the joint in mid?to long?term follow?up. Lower pre?operative Harris scores and higher pre?operative T?nnis classifications are important prognostic factors for post?operative pain.
ABSTRACT
Objective To investigate the radiological characteristics and the relationships between the parameters by X?ray and direct magnetic resonance arthrography (dMRA) in non?completely dislocated dysplasia hips. Methods We retro?spectively reviewed patients (above 13 years old) with dysplasia hips from August 2009 to August 2012. These patients were classi?fied as Hartofilakidis typeⅠand typeⅡ. 188 patients (274 hips) involved 28 males (30 hips) and 160 females (244 hips), average aged 27.3 years (range 13-47 years). Standard pelvic A?P, bilateral 65° oblique X?rays, and dMRA were conducted in each pa?tient. Lateral central?edge angle (LCE), anterior central?edge angle (ACE), femoral neck?shaft angle (FNSA), and tonnis acetabu?lar index (AI) angle were measured based on the X?ray. The dysplasia hips were classified into 4 grades (GradeⅠ:CE 11°-20° , GradeⅡ:CE 1°-10°, GradeⅢ:CE-9°-0°, and GradeⅣ:CE≤-10°). Femoral neck anteversion angle (FNA), labral tear, labral inversion, and labral cyst was observed on dMRA films. Variance analysis and rank correlation were applied to find the relation?ship between CE grades and the relevant parameters by using SPSS 19.0. Results LCE has negative correlation with AI and grade of osteoarthritis, and has positive correlation with age, ACE. However, there was no relationship between FNSA and FNA. There was significantly different in Shenton's line, labral tear, labral inversion, cartilage lesion, among different grade of LCE. Conclusion LCE is an important parameter used in evaluating for dysplasia hips without complete dislocation. LCE can reflect age of onset, ACE, AI angle and degree of joint damages. Evaluation for the severity of non?completely dislocated dysplasia hips can be conducted according to grades of CE.
ABSTRACT
Objective To analyze the anatomic changes and dosimetric variations of patients with head-and-neck cancer during intensity-modulated radiotherapy and to assess the necessity of re-planning the treatment course.Methods Twenty-one nasopharyngeal carcinoma patients were selected to receive the second CT scan in the course of intensity-modulated radiotherapy,targets and organs at risk were re-contoured on the new CT images with the help of deformable registration software.Actual dose distribution delivered by the original treatment plan was calculated on the second CT image,and then the volume and doses of targets and organs at risk were compared between the planning CT and second CT.Results The volume of patient's head-and-neck outlines and GTVnd decreased significantly,the volume of cord and brainstem didn't change much,while the volume of left and right parotids decreased significantly by (24.23 ± 12.15)％ and (25.82± 10.46)％,respectively.The parameters D95％ and Dmean of PGTVnx kept stable,but the parameters D1cc of spinal cord PRV and brainstem PRV increased by (8.12± 10.32)％ and (14.60±18.85)％ respectively.The mean dose of the left and right parotids increased significantly by (27.43±17.67)％ and (26.76±12.46)％,respectively.Conclusion The anatomical changes of patients undergoing intensity-modulated radiotherapy will cause significant dosimetric variations of the cord,brainstem and parotids,so it's meaningful and necessary to re-design the treatment plan in the course of radiotherapy.Repeat CT imaging and replanning during the course of IMRT is essential to ensure adequate doses to target volumes and safe doses to normal tissue.
ABSTRACT
@#Objective To survey the situation and related factors of maintenance medication treatment in schizophrenic patients re-hospitalized for relapse. Methods 362 patients re-admitted with schizophrenia and their relatives were interviewed with questionnaire which included 16 factors that might affect maintenance medication treatment. Results 63.8% patients stopped medication and 21.1% patients were on low-dose maintenance medication treatment by themselves, while 7.7% patients were on reasonable dose anti-psychotics in 2 years. The time of maintenance medication treatment related with insight (OR=2.2144, P=0.001), family care (OR=4.8842, P=0.025), outcomes of treatment (OR=2.2056, P=0.007) and negative life events (OR=0.4529, P=0.003). Conclusion Schizophrenic patients re-admitted with relapse often withdraw or reduce their medication by themselves, which risked with poor insight, poor therapeutic effect, poor care from their family, and more negative life events