Validating Dose Uncertainty Estimates Produced by AUTODIRECT: An Automated Program to Evaluate Deformable Image Registration Accuracy.

Deformable image registration is a powerful tool for mapping information, such as radiation therapy dose calculations, from one computed tomography image to another. However, deformable image registration is susceptible to mapping errors. Recently, an automated deformable image registration evaluation of confidence tool was proposed to predict voxel-specific deformable image registration dose mapping errors on a patient-by-patient basis. The purpose of this work is to conduct an extensive analysis of automated deformable image registration evaluation of confidence tool to show its effectiveness in estimating dose mapping errors. The proposed format of automated deformable image registration evaluation of confidence tool utilizes 4 simulated patient deformations (3 B-spline-based deformations and 1 rigid transformation) to predict the uncertainty in a deformable image registration algorithm's performance. This workflow is validated for 2 DIR algorithms (B-spline multipass from Velocity and Plastimatch) with 1 physical and 11 virtual phantoms, which have known ground-truth deformations, and with 3 pairs of real patient lung images, which have several hundred identified landmarks. The true dose mapping error distributions closely followed the Student t distributions predicted by automated deformable image registration evaluation of confidence tool for the validation tests: on average, the automated deformable image registration evaluation of confidence tool-produced confidence levels of 50%, 68%, and 95% contained 48.8%, 66.3%, and 93.8% and 50.1%, 67.6%, and 93.8% of the actual errors from Velocity and Plastimatch, respectively. Despite the sparsity of landmark points, the observed error distribution from the 3 lung patient data sets also followed the expected error distribution. The dose error distributions from automated deformable image registration evaluation of confidence tool also demonstrate good resemblance to the true dose error distributions. Automated deformable image registration evaluation of confidence tool was also found to produce accurate confidence intervals for the dose-volume histograms of the deformed dose

Multi-scale Optics for Enhanced Light Collection from a Point Source

High efficiency collection of photons emitted by a point source over a wide field-of-view (FoV) is crucial for many applications. Multi-scale optics over improved light collection by utilizing small optical components placed close to the optical source, while maintaining a wide FoV provided by conventional imaging optics. In this work, we demonstrate collection efficiency of 26% of photons emitted by a point-like source using a micromirror fabricated in silicon with no significant decrease in collection efficiency over a 10 mm object space.Comment: 4 pages, 4 figure

Level Set Topology Optimization of Load Carrying Heat Dissipation Devices

In this paper, we introduce a level set method topology optimization method of structures subjected to coupled mechanical and thermal loads. Different examples considering compliance minimization and stress minimization under temperature and volume constraints, and mass minimization under stress and temperature constraints, are presented. The p-norm of the stress field and temperature field is used to approximate the maximum stress and temperature, respectively. The developed method is applied in the design of an L-bracket and a battery package. The results show that designs obtained by ignoring the thermal or structural constraints can result in high values of temperature or stress, respectively

The O(N) Nonlinear Sigma Model in the Functional Schr\"{o}dinger Picture

We present a functional Schr\"{o}dinger picture formalism of the (1+1)-dimensional $O(N)$ nonlinear sigma model. The energy density has been calculated to two-loop order using the wave functional of a gaussian form, and from which the nonperturbative mass gap of the boson fields has been obtained. The functional Schr\"{o}dinger picture approach combined with the variational technique is shownto describe the characteristics of the ground state of the nonlinear sigma model in a transparent way.Comment: 13 pages, no figures, Latex fil

Outcomes of Fusions From the Cervical Spine to the Pelvis.

Study designRetrospective cohort study.ObjectiveDetermine the indications, complications, and clinical outcomes in patients requiring fusions from the cervical spine to the pelvis. Several investigators have examined fusions from the thoracic spine to the sacrum, but no similar study has been performed for cervical-to-pelvis fusions.MethodsPatients from 2003 to 2014 with an upper instrumented vertebrae (UIV) in the cervical spine (any level) and a lower instrumented vertebrae (LIV) in the sacrum or pelvis were included in the study. Those with infectious or acute trauma-related deformities were excluded. Patient demographics, medical history, diagnosis, operative procedure, and health-related quality of life measures were analyzed. Student's t test, Kruskal-Wallis test, and χ2 test were used as appropriate; significance was set at P < .05 for all tests.ResultsFifty-five patients met inclusion criteria for the study. Average follow-up was 2.8 years. Proximal junctional kyphosis was the most common indication for cervical-to-pelvis fusions (36%). The most common UIV was C2 (29%) followed by C7 (24%). There was an average 31° correction in maximum kyphosis and a 3.3 cm improvement in sagittal vertical axis. In adults, the rate of complication was 71.4%, with a major complication rate of 39.3% and reoperation rate of 53.6%. There was significant improvement in the Scoliosis Research Society (SRS-22r) score (3.0 to 3.5; P < .01).ConclusionProximal junctional kyphosis is the most common indication for patients requiring fusion to the cervical spine. Adult patients incur a significant risk of major complications and reoperations. However, significant improvement in SRS-22r outcomes are noted in these patients

Obesity-Induced Colorectal Cancer Is Driven by Caloric Silencing of the Guanylin-GUCY2C Paracrine Signaling Axis.

Obesity is a well-known risk factor for colorectal cancer but precisely how it influences risks of malignancy remains unclear. During colon cancer development in humans or animals, attenuation of the colonic cell surface receptor guanylyl cyclase C (GUCY2C) that occurs due to loss of its paracrine hormone ligand guanylin contributes universally to malignant progression. In this study, we explored a link between obesity and GUCY2C silencing in colorectal cancer. Using genetically engineered mice on different diets, we found that diet-induced obesity caused a loss of guanylin expression in the colon with subsequent GUCY2C silencing, epithelial dysfunction, and tumorigenesis. Mechanistic investigations revealed that obesity reversibly silenced guanylin expression through calorie-dependent induction of endoplasmic reticulum stress and the unfolded protein response in intestinal epithelial cells. In transgenic mice, enforcing specific expression of guanylin in intestinal epithelial cells restored GUCY2C signaling, eliminating intestinal tumors associated with a high calorie diet. Our findings show how caloric suppression of the guanylin-GUCY2C signaling axis links obesity to negation of a universal tumor suppressor pathway in colorectal cancer, suggesting an opportunity to prevent colorectal cancer in obese patients through hormone replacement with the FDA-approved oral GUCY2C ligand linaclotide

Cervical Deformity Patients Have Baseline Swallowing Dysfunction but Surgery Does Not Increase Dysphagia at 3 Months: Results From a Prospective Cohort Study.

Study designProspective cohort study.ObjectivesMost studies of dysphagia in the cervical spine have focused on a degenerative patient population; the rate of dysphagia following surgery for cervical deformity (CD) is unknown. This study aims to investigate if surgery for cervical deformity results in postoperative dysphagia.MethodsPatients with CD undergoing surgery from 2013 to 2015 were prospectively enrolled to evaluate dysphagia. Demographic, operative, and radiographic variables were analyzed. The Quality of Life in Swallowing Disorders (SWAL-QoL) was used to measure dysphagia. Paired t test, independent t tests, and bivariate Pearson correlations were performed.ResultsA total of 88 CD patients, aged 61.52 ± 10.52 years, were enrolled. All patients (100%) had 3-month SWAL-QoL for analysis. The baseline preoperative SWAL-QoL was 78.35. This is roughly the same level of dysphagia as an anterior cervical discectomy patient that is 3 weeks removed from surgery. Increasing body mass index (BMI) was correlated with decreased SWAL-QoL score (r = -0.30, P = .001). Age, gender, smoking, and Charlson Comorbidity Index (CCI) showed no significant correlations with preoperative SWAL-QoL. Patients with prior cervical surgery had a lower preoperative SWAL-QoL (P = .04). While 11 patients had acute postoperative dysphagia, CD surgery did not result in lower SWAL-QoL at 3 months (77.26 vs 78.35, P = .53). Surgical variables, including estimated blood loss (EBL), anterior or posterior fusion levels, steroid use, preoperative traction, staged surgery, surgical approach, anterior corpectomy, posterior osteotomy, and UIV (upper instrumented vertebrae) location, showed no impact on postoperative SWAL-QoL. Correction of cervical kyphosis was not correlated to 3-month SWAL-QoL scores or the change in SWAL-QoL scores.ConclusionsWhile patients undergoing surgery for cervical deformity had swallowing dysfunction at baseline, we did not observe a significant decline in SWAL-QoL scores at 3 months. Patients with prior cervical surgery and higher BMI had a lower baseline SWAL-QoL. There were no surgical or radiographic variables correlated to a change in SWAL-QOL score