The rapid development of new optical imaging techniques is dependent on the availability of low-cost and easily reproducible standards for technique validation. This work describes a low-cost fabrication process of an agar gelbased phantom that may accurately simulate the optical properties of different human tissues at 532 and 630nm wavelengths. It was designed to match the optical properties of the brain, bladder wall, and lung tissues. These low-cost phantoms use agar powders dissolved in water as the bulk matrix. The latter is loaded with varying amounts of India ink, and aluminium oxide Al 2 O 3 particles for optical absorption and scattering targets. The optical properties (absorption and scattering coefficients), the primary design factor and critical parameters of these phantoms were deduced from measurements of the total attenuation coefficients ðμ t Þ.It is anticipated that the constructed tissue phantoms have the potential to be used as a reference standard since it's possible to preserve the optical properties in a period exceeding two years, under ideal storage conditions.

The increasing use of the integrated 18F-fluoro-deoxy-glucose (FDG) positron emission tomography/computed tomography (PET/CT) imaging modality in the management of tubercular lesions raises concerns about associated radiation exposure. This work aimed to study the effects of CT model and study protocols on the overall radiation dose from a PET/CT examination. Two PET/CT systems with five representative CT exposure protocols applied for clinical patients in PET/CT imaging following retrospective evaluation were studied. CT doses were calculated using the CT-Expo dosimetry software (version 2.4), while the PET component dose was estimated applying the International Commission on Radiological Protection (ICRP) 106 dose coefficients. The total effective dose ranged from 8.0 to 24.05 mSv for system I and 8.35 to 26.85 mSv for system II, resulting in differences of 4.3 to 15% for the low-dose scan and 4.1 to 11% for standard dose scans. The CT component contribution to the total dose was between 32 and 77% for system I, and 35 and 79% for system II. However, the contributions were not significantly different (p > 0.05) for all protocols. The observed variation in CT contribution represents a requisite pedestal on the need for a nation-wide dose assessment for further optimization of the imaging procedure to maximize benefit to patients.

The impact of climate temperature on the counts (number of positive COVID-19 cases reported), recovery, and death rates of COVID-19 cases in all of South Africa's 9 provinces was investigated. The data for confirmed cases of COVID-19 were collected for March 25 and June 30, 2020 (14 weeks) from South Africa's Government COVID-19 online resource, while the daily provincial climate temperatures were collected from the website of the South African Weather Service. Our result indicates that a higher or lower climate temperature does not prevent or delay the spread and death rates but shows significant positive impacts on the recovery rates of COVID-19 patients. Thus, it indicates that the climate temperature is unlikely to impose a strict limit on the spread of COVID-19. There is no correlation between the cases and death rates, an indicator that no particular temperature range is closely associated with a faster or slower death rate of COVID-19 patients. As evidence from our study, a warm climate temperature can only increase the recovery rate of COVID-19 patients, ultimately impacting the death and active case rates and freeing up resources quicker to enable health facilities to deal with the climbing rates of those patients who need treatment.

No abstract