Objective To evaluate the impact of simultaneous integrated boost ( SIB) with different radiotherapy plans on the dosimetry of the target volume and organs at risk ( OAR) in patients with multiple brain metastases ( MBM ) , and to provide a basis for the selection of an optimal clinical radiotherapy. Methods Ten patients with MBM who were treated with whole-brain SIB radiotherapy were randomly selected in this analysis. The local imaging data from the enrolled patients were re-planned with dynamic intensity-modulated radiotherapy ( dynamic IMRT ) , dual-arc volumetric modulated arc therapy ( dual-arc VMAT) , and hybrid-IMRT ( h-IMRT) . h-IMRT plan was created by inversely optimizing 3 and 4 fixed fields of IMRT based on conformal radiotherapy. Two-tailed Wilcoxon matched pairs signed rank sum test was performed to analyze the differences between the three radiotherapy plans in the conformity index ( CI) and homogeneity index (HI) of the planning target volumes (PTV), Dmean and Dmax of OAR, monitor units ( MU) , and delivery time. Results CI of PTVs with VMAT plan was better than that with IMRT and h-IMRT plans (P=004,000), and no significant difference in HI was observed between the three plans( P>005) . There were no significant differences in CI and HI between 3 and 4 fields in dynamic IMRT ( P>005 ) . h-IMRT 3-and 4-field plans had significantly reduced doses to the eye lens and eyeballs than dynamic IMRT and VMAT plans (all P=000), and the three plans had similar doses to the brainstem and optic nerve ( P>005) . As for the MHs and delivery time, dynamic IMRT and VMAT plans showed the highest and lowest value, respectively ( all P= 000 ) . Conclusions All the three plans meet the clinical requirements. VMAT shows the highest treatment efficiency. H-IMRT protects the eye lens and eyeballs more effectively while maintaining the doses to the PTV, with reduced MU compared with IMRT. These offer a reference for designing the radiotherapy plan in MBM patients.

Objective To investigate dose escalation by metabolic sub-volume based on standard uptake values ( SUV) gradient of pre-treatment positron emission tomography/computed tomography ( PET/CT) for locally advanced non-small cell lung cancer ( NSCLC) radiotherapy. Methods The pre-treatment 18 F-FDG PET/CT images of 29 patients with locally advanced NSCLC were analyzed retrospectively. Gross tumor volume ( GTV) was delineated on the PET/CT fusion images. Tumor metabolic sub-volume was segmented according to the threshold of 50% and 75% maximum standard uptake values ( SUVmax ) . The region that under 50% SUVmax was defined as GTV1. From 50% to 75% SUVmax was defined as GTV2,and over 75% SUVmax was defined as GTV3. PTV (planning target volume), PTV1, PTV2 and PTV3 were extended from GTV, GTV1, GTV2 and GTV3, and different plans were designed subsequently. Plan 1 was designed for PTV with prescription dose 60 Gy, and Plan 2 was designed for PTV1, PTV2 and PTV3 with prescription dose 60-66 Gy, 66-72 Gy and≥72 Gy, respectively. The dosimetric parameters between tumor target and organs at risk (OARs) were compared. Results Compared to Plan 1, the absorbed dose in Plan 2 that covers 2% volume of the PTV ( D2 ) was increased from 66. 5 Gy to 78. 5 Gy and the dose was escalated by about 23. 2%. The average dose of PTV1, PTV2 and PTV3 increased by 2. 8% (62. 7-64. 4 Gy), 10. 3% (63. 5 -70. 0 Gy), 18. 7% (63. 8 -75. 8 Gy), and the average dose of PTV increased by 8. 9% (63. 2-68. 8 Gy). The sub-regional dose had been effectively improved. There was no significant difference in target coverage between Plan 1 and Plan 2 ( P >0. 05 ) . Homogeneity index (HI) was decreased with the escalation of maximum dose for Plan 2(t=23. 3, P<0. 05). There was no statistically significant difference in radiation dose of OARs between two plans ( P>0. 05 ) . Conclusions Dose escalation based on metabolic sub-volume from 18 F-FDG PET/CT was feasible, and radiation dose escalation of sub-volume with high metabolic activity can be achieved without increasing the OARs dose.

Objective To study the dose volume histogram ( DVH ) difference of target and organs at risk in intensity-modulated radiation therapy ( IMRT ) planning of cervical cancer based on the interquartile range. Methods A total of 22 cervical cancer patients′ IMRT plans were retrospectively analyzed. Five groups of DVH curves of PTV and OARs ( bladder, rectum, left and right femoral heads) were derived from the Pinnacle3 planning system. The mean DVH curves and interquartile range of volume ( IQRvol ) as a function of dose were calculated from each group′s DVH curve. Results The maximum volume variation for PTV reached at IQRvol(54. 03 Gy) =6. 95%, the volume of the target reached by the prescription dose was ( 96. 43 ± 1. 63 )%. The maximum volume variation for bladder reached at IQRvol (17. 24 Gy) = 14. 62%. V40 and V30 for bladder were ( 32. 79 ± 7. 06 )% and ( 56. 47 ± 9. 94 )%, respectively. Rectal DVH showed the largest difference at 35. 92 Gy, with the quartile of 19. 94%, the V40 and V30 for rectum were (30. 17 ± 10. 80)% and (58. 16 ± 11. 99)%, respectively. The difference in the bladder and the rectum was statistically significant (z = -6. 59, P < 0. 05). The maximum volume variation of left femoral head reached at IQRvol(16. 06 Gy) =31. 47%. The maximum volume variation of right femoral head was reached at IQRvol (17. 47 Gy) =32. 82%. There was no significant difference in IQRvol between right and left femoral head (P>0. 05). Conclusions Quartile range curve of DVHs can be used to analyze the deviations of DVH curves of PTV and OARs, and provide guidance for automatic planning optimization parameter setting.

Objective To investigate the impact of multi-b-value on texture features of DWI in liver cirrhosis.Methods DWI manifestations of liver cirrhosis in 37 patients were analyzed retrospectively,and DWI of 27 healthy volunteers (control group) were enrolled as controls.The b values were set as 0,20,50,100,200,400,800,1 000,1 200 and 1500 s/mm2,respectively.Three ROIs at different levels of every set image were selected,and 37 texture features within these ROIs were extracted.Unstable texture features affected by different b-values were screened with the percent coefficient of variation (％COV),and the fitting degree between the unstable texture features and b values were analyzed with exponential fitting.Results Among 37 texture features,20 (20/37,54.05 ％) were unstable.With the increase of b values,exponential upward trend was found in 10 texture features,exponential downward trend was found in 4 texture features,and the relative trends could not be defined in other 6 unstable texture features.Conclusion The b values of DWI impact the texture features in liver cirrhosis.Correlations exist among some texture features and b values.

Objective To compare the size of the internal target volume (ITV),biological target volume (BTV) and internal biological target volume (IBTV) based on PET-CT and 4DCT for primary nonsmall cell lung cancer (NSCLC),as well as try to apply IBTV in radiotherapy planning.Methods A total of 15 patients with NSCLC were sequentially scanned by an axial enhanced 3DCT,4DCT and 18F-FDG PET-CT in the thoracic region.The gross target volumes (GTVs) of ten phases of 4DCT images were contoured,and ITV was obtained by fusion of ten GTVs.BTV based on PET-CT images was determined by the SUV 2.0.The IBTV was defined by fusion of ITV and BTV.Planning target volumes (PTVs) based on ITV,BTV,and IBTV (PITV,PBTV,PIBTV) were obtained by ITV,BTV and IBTV with a 10-mm expansion respectively.The metrics of PIBTV,PITV and PBTV were compared,and the planning parameters of target volumes and risk organs were evaluated.Results There was no significant difference between ITV and BTV,but there was significant difference between IBTV and ITV and BTV (F=22.533,P ＜ 0.05).To include more than 95％ volume of IBTV,it is necessary to expand the margin of 9.0(6.0,12.0)mm based on BTV or 10.00(7.0,12.0)mm based on ITV.There was no significant difference between the two groups (P ＞ 0.05).Dice's similarity coefficient of BTV and ITV was 0.72(0.54,0.79).The intensity modulated radiotherapy plan based on PBTV can guarantee 85.6％ (80.5％,91.2％) of PITV to reach the prescription dose,compared with 80.2％ (74.4％,87.6％) of PBTV by the plan from PITV.Additionally,the conformity index and homogeneity index were not ideal.The dosimetric parameters of PITV and PBTV in the PIBTV plan were much better than those in PBTV-and PITV plan.Conclusions The radiotherapy plan based on PET-CT or 4DCT could not guarantee a reasonable dose distribution of PTV expanded from ITV or BTV.Thus,using IBTV for radiotherapy is advised.

Radiomics has played an irreplaceable role along with the development of precision medicine. In the field of radiomics researches,the stability of imaging features is of vital significance,which is directly linked to the modeling analysis. In this review,we summarized the recent research progress on the reproducibility problems in four crucial steps of the standard workflow of radiomics including imaging acquisition and reconstruction, region of interest(ROI)segmentation, imaging feature extraction and modeling establishment. In addition,the commonly used software related to radiomics was briefly introduced.

Objective:To measure the displacement of the solitary pulmonary lesion (SPL) located in different pulmonary segments based on 4D-CT technology (4DCT) and to establish and verify a relevant mathematical model of tumor displacement.Methods:The modeling samples of 290 SPLs were subject to both 4DCT and active breath control (ABC) spiral CT scans. The tumor displacement in different pulmonary segments was measured based on 4DCT images. The tumor volume was obtained by contouring the gross tumor volume (GTV) on ABC spiral CT images. The diaphragm movement was measured by X-ray simulator. The vital capacity and tidal volume were gained by pneumatometer. The baseline data, such as gender, age, height, weight, respiratory rate, and tumor lobe and segment where tumors were located, were collected. Multivariate linear regression was used to analyze the correlation between the 3D-tumor displacement and gender, age, height, weight, respiratory rate, tumor location, volume and diaphragm movement. The displacement model was established based on the modeling sample of 290 cases. Then, it was verified by comparing the tumor displacement derived from the model with that of 4DCT technology based on the randomly selected 17 SPLs.Results:The displacement model for tumors located in the upper lobe was established as Xup=-0.267+0.002TV+0.446DM, Yup=-1.704+0.004TV+0.725DM+2.250SII+1.349SIII and Zup=0.043+0.626DM+0.599SII+0.519SIII. The displacement model of the middle lobe tumors was Xmid=0.539+0.758DM, Ymid=-2.316+2.707DM+0.009TV and Zmid=0.717+1.112DM. The displacement model for tumors located in the lower lobe was Xlow=-0.425+0.004TV+0.857DM, Ylow=4.691+4.817DM+0.005TV-0.307RR+3.148SIX+2.655SX and Zlow=0.177+0.003TV+0.908DM.(DM: diaphragm movement, TV: tidal volume, RR: respiratory rate, SII: posterior segment, SIII: anterior segment, SIX: lateral basal segment, SX: posterior basal segment). There was no significant difference between two results derived from the displacement model and 4DCT technology.( P>0.05). Conclusions:The diaphragm movement and tidal volume are the main influencing factors of 3D lung tumor displacement. The tumor displacement in the superior-inferior direction is correlated with different pulmonary segments of the upper and lower lobes. The displacement of tumors located in different segments of middle lobes is similar. The displacement model can predict the displacement of SPLs located in different lobes, providing reference for individualized delineation of PTV.

As the development of radiotherapy, the plan making that depends on CT image information and staff skills limits its further development. Whereas virtual reality (VR) based on computer technology is a simulation system for human-machine interaction in 3D environment. VR can provide 3D information on the radiotherapy environment, patient anatomy, isodose distribution, etc. VR has been used to guide patient positioning, automatic collision detection of non-coplanar treatment plans, holographic imaging system to optimize radiotherapy plans, teaching and training, and patient publicity and education. The purpose is to improve the quality of radiotherapy on a safe and effective basis, and provide practical tools for radiotherapy technical training, teaching and publicity education.

Objective:To analyze the symmetry of different reference planes in the surgical simulation design of patients with protrusive jaw deformity with high and low eyes.Methods:Fifteen patients with partial jaw deformity were selected from January 2019 to June 2020, including 3 males and 12 females, aged 18-26 years, with average 23.78 years. Inclusion criteria were that the patients, aged more than 18 years, were diagnosed as protrusive jaw deformity with maxillary occlusal plane tilt and high and low eyes by clinical and imaging analysis. Three different 3D reference plane systems were established by different modeling methods. The distance between the landmarks of soft and hard tissues and the median sagittal plane was measured. The symmetry of skull was qualitatively analyzed by mirror image technique. The difference of three reference planes in surgical simulation symmetry of patients with protrusion jaw and high and low eyes was evaluated by one-way ANOVA.Results:Qualitative analysis showed that in the three measurement planes, the symmetry of the third reference plane was the best, and the symmetry of the second and the first was poor. Quantitative analysis showed that in measurement index of hard tissue, there was statistical difference between the distance of each landmark in the reference plane established by Method 3 and Method 1, Method 2 [(1.65±1.19) mm; (3.37±1.58) mm; (3.26±2.36) mm, P<0.05], but there was no statistical difference between Method 1 and Method 2 (P > 0.05). The measurement result of soft tissue was consistent with that of hard tissue, and the distance of each landmark in Method 3 from the median sagittal plane was very small, and the mean error was less than 0.5 mm, which was consistent with the clinical results. Conclusions:Digital model surgery technology can assist orthognathic surgeons in the design and prediction of surgical scheme, especially for patients with special partial jaw deformity.