SU-E-I-16: Automated Liver Segmentation Method for CBCT Dataset by Probabilistic Atlas Construction

PURPOSE

The aiming is getting accurate liver contour structures automatically for following adaptive radiation therapy in daily CBCT images which is very low-contrast comparing the planning CT.

METHODS

Probabilistic atlas is constructed by 50 intravenous contrast planning CT images by iterative affine registration process. The incoming CBCT images are registered with the atlas using deformable registration algorithm which is based on edge preserving scale space, and the liver contour structures are generated automatically by using the deformation map. Incorporating the intensity distribution of candidate liver region into the segmentation processing, we can further remove the irrelative tissue from the original liver region. Our algorithm is capable of segmenting the liver from low-contrast cone beam CT images. In our probabilistic atlas construction process, firstly one training data is arbitrarily chosen as reference image while the rest of training datasets are registered to this reference using the affine transformation. For improving the efficiency of our method, iterative construction method is employed. The resulting atlas which is gained before is used as the reference image for the following atlas construction. This process can be iterated by many loops. However, we used two iterations for efficiency. This iterative atlas construction process can avoid bias toward the specific patient.

RESULTS

The experiments are tested on 10 newly incoming patient data. The volumetric overlap is on an average 87%-94% comparing with manually segmented tumors by oncologists. After evaluation by clinical oncologists, they concluded that the segmentation results are close to the manual results and the liver contours on CBCT which is produced by the deformation field automatically can be used for following adaptive radiation therapy.

CONCLUSIONS

We can conclude that the proposed segmentation method is very effective with low contrast CBCT for adaptive radiation therapy in daily using.

SU-E-T-107: Uncertainty Estimate of a Practical EBT-2 Film Dosimetry Approach: Transpose-And-Scan Technique

PURPOSE

To estimate the uncertainty of a practical EBT2 film dosimetry approach that has been established at our institution and used for routine patient-specific plan verifications, particularly for SBRT and RapidArc, as well as planning system commissioning. Our technique is unique from other common dosimetry protocols with respect to calibration, irradiation and scanning.

METHODS

Film dosimetry for patient-specific quality assurance of 29 patient plans were retrospectively reviewed. For each case, four films were irradiated; two for calibration and two for treatment plan. Each pair of two films were irradiated together in a phantom with one film transposed (rotated 180 degrees relative to the other) to compensate for asymmetric film response. After a minimum of 12 hrs post-irradiation, each film was scanned in four different orientations to mitigate non-uniform response of the scanner light and detector elements. The scanned 8 calibration and 8 plan images were averaged into one calibration and one plan film image, respectively. Each color channel of the calibration film was correlated to the reference dose matrix to produce a 3rd order polynomial calibration curve. Finally, each color channel of the plan film was converted to a dose map using the corresponding calibration curve. Average dose maps of the red and green channels were correlated to the treatment planning dose matrix, and the mean dose differences at the center of dose distributions (5×5mm̂2 area) as well as a gamma analysis were evaluated.

RESULTS

The absolute dose differences were -0.8±1.7% (range=-4.5-3.0%). The gamma pass-rates (3%/3mm) were 94±7% (min.=74%). The pass rate increased to 99±3%(min.=87%) with the film scaled relatively to the plan doses.

CONCLUSIONS

Based on a large number of cases, our approach appears to be robust to non-uniform film and scanner responses, and is shown to have an uncertainty (1SD) of less than 2% for absolute film dosimetry.

Controlled growth of ZnO/Zn₁-xPbxSe core-shell nanowires and their interfacial electronic energy alignment

ZnO/Zn(1-x)Pb(x)Se core-shell nanowires (NWs) have been synthesized by a solution based surface ion transfer method at various temperatures. The energy dispersive spectroscopic (EDS) mapping of single NWs suggests that the Zn, Pb and Se atoms are uniformly distributed in their shell layers. The ternary Zn(1-x)Pb(x)Se layers with tunable bandgaps extend the band-edge of optical absorption from 450 nm to 700 nm contrasting with the binary ZnSe layers. The ultraviolet photoelectron spectroscopic (UPS) analysis reveals a transition from the type I to type II band alignment when the x fraction decreases from 0.66 to the value of 0.36 in the nanoshell layers. This quantitative investigation of electronic energy levels at ZnO and Zn(1-x)Pb(x)Se interfaces indicates that the proper type II band alignment is well suited for photovoltaic energy conversion. The photovoltaic cells comprising a ZnO/Zn(1-x)Pb(x)Se nano-heterojunction with the optimized Pb content are expected to be more efficient than the devices sensitized by binary ZnSe or PbSe.

In vitro and in vivo evaluation of Triptolide-loaded pluronic P105 polymeric micelles

Thin film method was applied successfully to prepare Triptolide (TP)-loaded micelles system. With a dynamic light scattering sizer and a transmission electron microscopy, it was shown that the TP-loaded micelles had a mean size of 84.3±6.4 nm with a spherical shape. The in vitro release profiles indicated that the release of TP from the micelles exhibited a sustained release behavior. A similar phenomenon was also observed in a pharmacokinetic study in rats, in which AUC of the micelles formulation were 4.7-fold higher than that of TP injection. The biodistribution study in rats showed that the TP-loaded micelles not only decreased drug uptake by liver, but also increased distribution of drug in ovary. The present work demonstrated the feasibility of controlled delivery of TP utilizing micelles system.

Perceived parenting and risk for major depression in Chinese women

BACKGROUND

In Western countries, a history of major depression (MD) is associated with reports of received parenting that is low in warmth and caring and high in control and authoritarianism. Does a similar pattern exist in women in China?

METHOD

Received parenting was assessed by a shortened version of the Parental Bonding Instrument (PBI) in two groups of Han Chinese women: 1970 clinically ascertained cases with recurrent MD and 2597 matched controls. MD was assessed at personal interview.

RESULTS

Factor analysis of the PBI revealed three factors for both mothers and fathers: warmth, protectiveness, and authoritarianism. Lower warmth and protectiveness and higher authoritarianism from both mother and father were significantly associated with risk for recurrent MD. Parental warmth was positively correlated with parental protectiveness and negatively correlated with parental authoritarianism. When examined together, paternal warmth was more strongly associated with lowered risk for MD than maternal warmth. Furthermore, paternal protectiveness was negatively and maternal protectiveness positively associated with risk for MD.

CONCLUSIONS

Although the structure of received parenting is very similar in China and Western countries, the association with MD is not. High parental protectiveness is generally pathogenic in Western countries but protective in China, especially when received from the father. Our results suggest that cultural factors impact on patterns of parenting and their association with MD.

Ectopic expression of glucagon receptor in skeletal muscles improves glucose homeostasis in a mouse model of diabetes

AIMS/HYPOTHESIS

Excessive secretion of glucagon partially contributes to the development of diabetic hyperglycaemia. However, complete blocking of glucagon action will lead to adverse effects, since glucagon exerts certain beneficial effects via its receptor in many organs. We aimed to study the effects of a 'decoy receptor' for circulating glucagon on modulating beta cell function and glucose homeostasis in mice by over-producing the glucagon receptor (GCGR) in skeletal muscles.

METHODS

We generated transgenic mice in which the expression of Gcgr is driven by the muscle specific creatine kinase (Mck) promoter, and assessed the effects of glucagon on the modulation of glucose homeostasis under conditions of extremes of glucose influx or efflux.

RESULTS

Mck/Gcgr mice showed increased circulating levels of glucagon and insulin, resulting in an unchanged ratio of glucagon-to-insulin. The levels of hepatic glucose-6-phosphatase (G6PC) and fructose-1,6-bisphosphatase (F1,6P2ase) were significantly decreased, whereas the phosphorylation level of pancreatic cAMP-response-element-binding-protein (CREB) was significantly increased in these transgenic mice. Under basal conditions, the mice displayed normal blood glucose levels and unchanged glucose tolerance and insulin sensitivity when compared with their age-matched wild-type (WT) littermates. However, following multiple low-dose streptozotocin injections, Mck/Gcgr mice exhibited a delay in the onset of hyperglycaemia compared with the WT controls. This was associated with preserved beta cell mass and beta cell secretory capacity in response to glucose challenge.

CONCLUSIONS/INTERPRETATION

We suggest that mild and chronic hyperglucagonaemia, through a strategy involving neutralising peripheral glucagon action, provides beneficial effects on beta cell function and glucose homeostasis. Mck/Gcgr mice thus represent a novel mouse model for studying the physiological effects of glucagon.

A randomised trial comparing the CEL-100 videolaryngoscope(TM) with the Macintosh laryngoscope blade for insertion of double-lumen tubes

We performed a randomised trial comparing the CEL-100 videolaryngoscope(TM) with the Macintosh laryngoscope blade in 170 patients undergoing double-lumen tube placement for thoracic surgery. Compared with the Macintosh laryngoscope blade, use of the CEL-100 resulted in significantly more patients with a Cormack and Lehane Grade-1 laryngeal view (90.4% vs 61.0%, p < 0.001), a higher rate of successful intubation on the first attempt (92.8% vs 79.3%, p = 0.012), a lower median (IQR [range]) intubation difficulty score (0 (0-0 [0-60]) vs 15 (0-30 [0-80]), p < 0.001), a higher incidence of correct positioning of the tube (90.3% vs 79.2%, p = 0.041) and significantly fewer patients requiring external laryngeal pressure (19.3% vs 32.9%, p = 0.046). Median (IQR [range]) time to successful intubation was 45 (38-55 [22-132]) s with the CEL-100 compared with 51 (40-61 [30-160] s using the Macintosh laryngoscope blade. We conclude that the CEL-100 videolaryngoscope is superior to the Macintosh laryngoscope blade for double-lumen tube insertion.