Objective To evaluate the variations of effective doges with the preset scanning parameters from linac-integrated kV cone beam CT( CBCT). Methods Weighted CT dose index(CTDIW) were measured with PTW TM30009 CT ion chamber in head phantom and body phantom, respectively, for different combinations of tube voltage, mAs, collimator and gantry rotation range. Dose length products(DLP) were derived from CTDIW and effective doses(E) were calculated by the DLP and EDLP. Results CTDIW and effective dose had the quadratical relationship with tube voltage, depending linearly on product of tube current and exposure time. Effective dose had close relationship with the collimator and the gantry rotation range. Both the DLP and ED for CBCT were lower than the reference dose level recommended for conventional CT. Conclusions Effective dose from CBCT has a close relationship with the scanning parameters. Optimal imaging parameters should be chosen according to the patient's anatomy to reduce patient dose.

Objective To the value of ultrasonic imaging in diagnosis of appendiceal mucinous neoplasms in patients.Methods A retrospective review was performed for the 26 cases undergoing pre-operative ultrasonography and finally diagnosed as appendiceal mucinous neoplasms by pathology.The 26 patients were included in the study,11 elderly patients aged ≥60 years as group A,and 15 younger patients aged ＜ 60 years as group B.The characteristics of the ultrasonic imaging were analyzed.Results Features of ultrasound images leading to diagnosis were summarized as following.The lesion transverse diameter was over 2 cm,with anechoic or hypoechoic area of lesion or onion skin sign inside the lesions.There were distinct borderlines between lesions and surrounding tissues,with no or little blood in the color doppler flow imaging.Conclusions There are same u1trasonography characteristics of appendiceal mucinous neoplasms in two age groups.Improving the knowledge of this disease and grasping the clinical and sonography characteristics are stringent to enhance the accuracy rate of diagnosis.

ObjectiveTo investigate the features of normal and psoriasis skin on ultrasound biomicroscopy (UBM) and explore the method of thickness measurement.MethodsUsing 50 MHz ultrasound probe of biological microscope, ultrasonographic observation and ultrasonic thickness measurement were conducted in 90 normal adults and 40 psoriasis patients. Innormal patients, ultrasound evaluations were performed at 10 different parts of the body skin.ResultsOn sonogram, the normal skin showed a “sandwich” structure with two parallel hyperechoic bands and the middle isoechoic dots and short liens. The sonograms of the psoriasis skin showed obviously thickened epidermis and dermis, disordered internal structure and clear boundary from adjacent normal skin. The range of the epidermis’ thickness measurement was between the medial forearm (0.12±0.03) mm and the palm (0.29±0.15) mm. The range of dermal thickness measurement was between the back hand (1.18±0.32) mm and parasternal (1.55±0.21) mm. Psoriasis skin was thicker than the uninvolved skin (P<0.001). And the dermis’ thickness of uninvolved skin in psoriasis patients was thicker than that of the normal adults (P<0.001).ConclusionNormal adult’s epidermis, dermis and skin appendages can be shown clearly using 50 MHz ultrasound biomicroscopy. And ultrasound biomicroscopy canaccurately measure the thickness of dermis and epidermis, which provides the basis for the diagnosis and treatment of psoriasis.

To investigate the dose effect of isocenter difference during IMRT dose verification with the 2D chamber array. The samples collected from 10 patients were respectively designed for IMRT plans, the isocenter of which was independently defined as P(o), P(x) and P(y). P(o) was fixed on the target center and the other points shifted 8cm from the target center in the orientation of x/y. The PTW729 was used for 2D dose verification in the 3 groups which beams of plans were set to 0 degrees. The γ-analysis passing rates for the whole plan and each beam were gotten using the different standards in the 3 groups, The results showed the mean passing rate of γ-analysis was highest in the P(o) group, and the mean passing rate of the whole plan was better than that of each beam. In addition, it became worse with the increase of dose leakage between the leaves in P(y) group. Therefore, the determination of isocenter has a visible effect for IMRT dose verification of the 2D chamber array, The isocenter of the planning design should be close to the geometric center of target.
Gamma Rays ; Humans ; Radiotherapy Dosage ; Radiotherapy, Intensity-Modulated ; instrumentation ; methods

Objective To compare the difference between color Doppler flow imaging (CDFI) and superb microvascular imaging (SMI) in the evaluation of vascular grading and the display rate of vascular in papillary thyroid carcinoma (PTC).Methods Between June 2015 and December 2015 in Beijing Chaoyang Hosptial,50 patients with 61 thyroid nodules were detected by ultrasonography,and pathologic types were confirmed as PTC.CDFI and SMI were used to evaluation the same nodule respectively according to Adler's grading criteria.The different flow characteristics were analyzed by the x2 test.Results In CDFI,the vascular grading of 33 patients were 0 ～ Ⅰ and these of 28 patients were Ⅱ ～Ⅲ by CDFI.In SMI,the vascular grading of 6 patients were 0 ～ Ⅰ and these of 55 patients were Ⅱ ～Ⅲ by SMI.There was a significant difference between CDFI and SMI for vascular grading (x2=27.475,P ＜ 0.01).In CDFI,50 patients with PTC showed punctiform and rod-like flow signals,and 5 patients showed more detail internal small branches by CDFI.In SMI,42 patients with PTC showed punctiform and rod-like flow signals,and 17 patients showed more detail internal small branches.There was a significant difference between CDFI and SMI about the display rate of vascular (x2=7.011,P ＜ 0.01).Conclusions Compared with CDFI,SMI is highly improved blood flow sensitivity.It can provide more detail internal small branches in PTC.The characteristics of vascular distribution are similar to strengthening mode of contrast-enhanced ultrasound in PTC,therefore,SMI is worth to further research.

This study aims to propose a multifrequency time-difference algorithm using spectral constraints. Based on the knowledge of tissue spectrum in the imaging domain, the fraction model was used in conjunction with the finite element method (FEM) to approximate a conductivity distribution. Then a frequency independent parameter (volume or area fraction change) was reconstructed which made it possible to simultaneously employ multifrequency time-difference boundary voltage data and then reduce the degrees of freedom of the reconstruction problem. Furthermore, this will alleviate the illness of the EIT inverse problem and lead to a better reconstruction result. The numerical validation results suggested that the proposed time-difference fraction reconstruction algorithm behaved better than traditional damped least squares algorithm (DLS) especially in the noise suppression capability. Moreover, under the condition of low signal-to-noise ratio, the proposed algorithm had a more obvious advantage in reconstructions of targets shape and position. This algorithm provides an efficient way to simultaneously utilize multifrequency measurement data for time-difference EIT, and leads to a more accurate reconstruction result. It may show us a new direction for the development of time-difference EIT algorithms in the case that the tissue spectrums are known.