Computationally effective solution of the inverse problem in time-of-flight spectroscopy.

Photon time-of-flight (PTOF) spectroscopy enables the estimation of absorption and reduced scattering coefficients of turbid media by measuring the propagation time of short light pulses through turbid medium. The present investigation provides a comparison of the assessed absorption and reduced scattering coefficients from PTOF measurements of intralipid 20% and India ink-based optical phantoms covering a wide range of optical properties relevant for biological tissues and dairy products. Three different models are used to obtain the optical properties by fitting to measured temporal profiles: the Liemert-Kienle model (LKM), the diffusion model (DM) and a white Monte-Carlo (WMC) simulation-based algorithm. For the infinite space geometry, a very good agreement is found between the LKM and WMC, while the results obtained by the DM differ, indicating that the LKM can provide accurate estimation of the optical parameters beyond the limits of the diffusion approximation in a computational effective and accurate manner. This result increases the potential range of applications for PTOF spectroscopy within industrial and biomedical applications.

Sensitivity analysis for oblique incidence reflectometry using Monte Carlo simulations.

Oblique incidence reflectometry has developed into an effective, noncontact, and noninvasive measurement technology for the quantification of both the reduced scattering and absorption coefficients of a sample. The optical properties are deduced by analyzing only the shape of the reflectance profiles. This article presents a sensitivity analysis of the technique in turbid media. Monte Carlo simulations are used to investigate the technique and its potential to distinguish the small changes between different levels of scattering. We present various regions of the dynamic range of optical properties in which system demands vary to be able to detect subtle changes in the structure of the medium, translated as measured optical properties. Effects of variation in anisotropy are discussed and results presented. Finally, experimental data of milk products with different fat content are considered as examples for comparison.

Triage of urology service to cope with COVID-19 pandemic: A single institution study.

Almost a year ago, no one has ever heard of COVID-19 but now, every individual in the world is familiar with this term. It is far from over and yet, it has affected every aspect of human life. The Department of Urology at King's College Hospital London provides all types of urology care ranging from benign to cancer treatments to the community. However, this service was badly affected by COVID-19. Policies were made by the experts in the field to reduce patient traffic in the hospital and at the same time, attempting to ensure appropriate and timely treatment was provided to patients suffering from urological conditions requiring urgent attention. In this article, we discuss the triage guidelines set up at our centre. Treatments for benign conditions such as kidney stones were delayed for 3-6 months. For the first time, telephone and video clinics were setup to follow-up patients with benign conditions. Urological emergencies such as acute urinary retention and priapism were discharged from accidental and emergency department after treatment. Small T1 renal cancers were put on surveillance, whereas T2 and T3 renal cancers were offered nephrectomy at a COVID-free specialized center. Transurethral removal of bladder tumor was offered only for solid or actively bleeding tumor. High risk prostate cancer patients were started on hormonal therapy and radiotherapy was only offered for spinal cord compression secondary to metastasis. Low and intermediate non-metastatic prostate cancers were placed on active surveillance. Patients with testicular tumor continued to have immediate inguinal orchidectomy. The multi-disciplinary meetings were done remotely using blue jeans software®. These steps not only strive to provide adequate and timely urology care to patients but also protect health care workers and prevent the spread of COVID-19.

Association of Pulmonary Hypertension With End-Stage Renal Disease Among the Obese Population.

Introduction Pulmonary hypertension (PH) is a known complication that occurs in patients of end-stage renal disease (ESRD) that have an arteriovenous fistula (AVF) for hemodialysis (HD). It is defined as pulmonary artery pressure (PAP) of greater than 30 mmHg on echocardiography. The presence of PH in ESRD is an independent risk factor and decreases the survival likelihood among HD patients. Unexplained PH is frequently seen in ESRD following AVF. Obesity can lead to various complications, such as sleep apnea, cardiac complications, pulmonary hypertension, and mortality. Data on the prevalence of coexisting PH and obesity are scarce. Obese patients often have increased albumin excretion rates (AER) that can lead to early renal impairment and an increase in intraglomerular pressure, which may increase the risk of cardiovascular (CV) morbidity and mortality. Therefore, the study aimed to evaluate and compare the associated PH and obesity separately and collectively among ESRD patients. Methods This comparative cross-sectional study was conducted in a tertiary care public sector hospital with the approval of the medical ethics review board committee. The study enrolled all consecutive patients with ESRD as defined by having an estimated glomerular filtration rate (GFR) of <15 mL/min/1.7 3 m2 from April 2017 till March 2019, who presented to our facility. These patients underwent dialysis twice or thrice a week, each session lasting three to four hours approximately. On initial encounter, trans-thoracic echocardiography (TTE) was done by the cardiologist to diagnose pulmonary hypertension. In addition, body mass index (BMI) was calculated for all patients, and the patients were categorized into underweight, normal, overweight, or obese. All patients underwent post-dialysis TTE at one hour or when patients were at the optimal dry weight. Systolic PAP and ejection fraction were measured, and pulmonary hypertension was defined as a PAP of 30 mmHg or greater on TTE. ESRD patients that were diagnosed with PH prior to hemodialysis or had primary PH were excluded from the study. Only ESRD patients developing secondary PH after hemodialysis were included in the study. The chi-square test was used to see the correlation of gender, ambulation status, smoking status, obesity, pulmonary hypertension, body mass index (BMI), and pulmonary hypertension and obesity combined on the final outcome. A p-value of 0.05 was considered significant. Odds ratio (OR) and relative risk (RR) were calculated for pulmonary hypertension and obesity combined, obesity, and pulmonary hypertension in the final outcome. Results The study enrolled 204 patients with a mean age of 46.23 (±20.45 SD) having higher female participation of 108 (52.9%), whereas 96 (47.1%) were males. The average weight of the cohort was 66.78 kg (±22.98 SD) with a mean BMI of 29.91 kg/m2 (±13.29SD), 52 (25.5%) patients were underweight, 40 (19.6%) had a normal BMI, 29 (14.2%) were overweight, and 83 (40.7%) patients were obese. Pulmonary hypertension and obesity combined were observed in 48 (23.5%) of the cases and there was a 4.60 relative risk of death among these individuals, with an odds ratio of 13.35 and a p-value of 0.00. Conclusion The study shows a strong synergistic effect of pulmonary hypertension and obesity towards the final survival outcome in ESRD patients who are on hemodialysis.

Mean Tip-Apex Distance In Lag Screw Cut-Out After Dynamic Hip Screw Fixation Of Hip Fracture.

BACKGROUND: To determine mean tip-apex distance after Dynamic Hip Screw fixation of intertrochanteric fracture. METHODS: This descriptive cross-sectional study was conducted in the Department of Orthopaedics, Hayatabad Medical Complex, Peshawar from October 2015 to September 2016 on a total 285 patients. RESULTS: A total of 285 patients were observed. Status of TAD among 285 patients was analysed as 171 (60%) patients had TAD ranged 15 mm to 20 mm, 91(32%) patients had TAD ranged 21 mm to 25 mm, 23 (8%) patients had TAD ranged >25mm. Mean TAD was 18 mm with SD±7.45. Eight percent patients had screw cut out while 92% patients didn't had screw cut out. CONCLUSIONS: To avoid lag screw cut out in dynamic hip screw for intertrochanteric fracture of hip the Tip apex distance must be accurate otherwise there will be cut out of lag screw.

Transmission near-infrared (NIR) and photon time-of-flight (PTOF) spectroscopy in a comparative analysis of pharmaceuticals.

We present a comprehensive study of the application of photon time-of-flight spectroscopy (PTOFS) in the wavelength range 1050-1350 nm as a spectroscopic technique for the evaluation of the chemical composition and structural properties of pharmaceutical tablets. PTOFS is compared to transmission near-infrared spectroscopy (NIRS). In contrast to transmission NIRS, PTOFS is capable of directly and independently determining the absorption and reduced scattering coefficients of the medium. Chemometric models were built on the evaluated absorption spectra for predicting tablet drug concentration. Results are compared to corresponding predictions built on transmission NIRS measurements. The predictive ability of PTOFS and transmission NIRS is comparable when models are based on uniformly distributed tablet sets. For non-uniform distribution of tablets based on particle sizes, the prediction ability of PTOFS is better than that of transmission NIRS. Analysis of reduced scattering spectra shows that PTOFS is able to characterize tablet microstructure and manufacturing process parameters. In contrast to the chemometric pseudo-variables provided by transmission NIRS, PTOFS provides physically meaningful quantities such as scattering strength and slope of particle size. The ability of PTOFS to quantify the reduced scattering spectra, together with its robustness in predicting drug content, makes it suitable for such evaluations in the pharmaceutical industry.

Non-invasive assessment of dairy products using spatially resolved diffuse reflectance spectroscopy.

The quality of a dairy product is largely determined by its microstructure which also affects its optical properties. Consequently, an assessment of the optical properties during production may be part of a feedback system for ensuring the quality of the production process. This paper presents a novel camera-based measurement technique that enables robust quantification of a wide range of reduced scattering coefficients and absorption coefficients. Measurements are based on hyperspectral images of diffuse reflectance in the wavelength range of 470 to 1020 nm. The optical properties of commercially available milk and yogurt products with three different levels of fat content are measured. These constitute a relevant range of products at a dairy plant. The measured reduced scattering properties of the samples are presented and show a clear discrimination between levels of fat contents as well as fermentation. The presented measurement technique and method of analysis is thus suitable for a rapid, non-contact, and non-invasive inspection that can deduce physically interpretable properties.