Pusat Pengajian Sains Kesihatan - Tesis

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Quantitative comparison between low energy high resolution (LEHR) and medium energy general purpose (MEGP) collimator on nema spect imaging
(2024-06)
Paramesivam, Divya
Nuclear medicine leverages radioactive materials, known as radiopharmaceuticals or radiotracers, for diagnosing and treating diseases. This field uses radionuclide biomarkers to visualize physiological functions and detect abnormalities, such as cancer cells. Imaging tools such as gamma cameras, which record emissions from radiotracers inside the body, are essential to this process. The gamma camera is a crucial imaging device in Nuclear Medicine, enabling two-dimensional imaging of body processes using radiotracers. It aids in disease diagnosis, monitoring heart function, and detecting radioactive energy. The camera's components include a collimator, large-area NaI(Tl) scintillation crystal, light guide, and photomultiplier tubes. Nuclear medicine imaging systems' quality is influenced by factors such as detector and collimator physical characteristics, image reconstruction algorithms, photon attenuation, scattering, and patient motion. The right collimator is crucial for high-quality images, as it limits photon acceptance angle and allows precise information about the photons' initial emission position. The collimator response to gamma rays is determined by hole diameter, septa width, and septa thickness. Nuclear medicine imaging uses four primary collimator types: parallel-hole, diverging-hole, converging-hole, and pinhole. The type of collimator is influenced by hole diameter and septa length. This research aims to compare the image quality obtained using Low Energy High Resolution (LEHR) and Medium Energy General Purpose (MEGP) collimators in nuclear medicine imaging. The study focuses on assessing differences in sensitivity, contrast, resolution, and signal-to-noise ratio (SNR). A phantom study was conducted using a NEMA 2012/IEC 2008 phantom and Tc-99m point source, by using SPECT technique. The GE Discovery NM/CT 670 Pro Gamma Camera was employed, and both LEHR and MEGP collimators were tested. The experiment involved preparing Tc-99m, acquiring images, and analyzing them for image sensitivity, image contrast, resolution, and SNR. The study measured and compared the performance of LEHR and MEGP collimators. The analysis of image sensitivity, image contrast, resolution, and SNR in both LEHR and MEGP collimator revealed significant variations. MEGP collimator showed better image sensitivity and image contrast but also resulted in degraded resolution and higher image noise. Conversely, the LEHR collimator with their smaller and deeper holes, resulted image with profound resolution and reduced image noise. Image acquired from MEGP collimator exhibited average image sensitivity value of 4.716 𝑥 104 cps/Ci, while image acquired from LEHR collimator exhibited an average image sensitivity of 3.965 𝑥 104 cps/Ci. Image acquired from MEGP collimator had an average image contrast value of 0.982, while the average image contrast of image acquired from LEHR collimator is 0.976. The average spatial resolution measured by FWHM for image acquired from LEHR collimator is 5.64 mm, while the FWHM value of image acquired from MEGP collimator is 5.71 mm. The collimator resolution of LEHR collimator is 3.69 mm, while the collimator resolution of MEGP collimator is 4.91 mm. For SNR, the value exhibited by image acquired from LEHR collimator is 83.997 while image acquired from MEGP collimator exhibited a value of 77.064. The research highlights the trade-offs between image sensitivity and resolution in nuclear medicine imaging. LEHR collimator offers superior resolution, while MEGP collimator provide higher image sensitivity. In order to optimize imaging methods based on clinical requirements, this comparison is essential in determining the quality of image required.
Evaluation of the image quality by using MEGP and HEGP collimators for Iodine-131 in planar imaging
(2024-06)
Jianan, Ding
Purpose: High-energy general-purpose (HEGP) collimators are mostly used for iodine- 131 in SPECT and planar imaging, while medium-energy general-purpose (MEGP) collimators are seldom used due to the high radiation of iodine-131. In this study, we evaluated the image quality by using MEGP and HEGP collimators with different activities of iodine-131 in planar imaging. Aspects of image quality evaluated include sensitivity, contrast, signal-to-noise ratio, and resolution. Materials and methods: To scan the iodine-131 in several activities, three petri dishes were used to contain iodine-131. Each petri dish contained 0.2 mCi, 0.4 mCi, and 0.6 mCi of iodine-131, and saline was also added to the petri dish. The planar technique produces static images of petri dishes with iodine-131 from two detectors, and then the information about the petri dishes and background were measured in Xeleris workstation. Based on the specific formulas, sensitivity, contrast, SNR, and resolution were calculated. Results: Sensitivity in the MEGP collimator is higher than that in the HEGP collimator, while SNR for the HEGP collimator is higher than that in the MEGP collimator. As for resolution and contrast, the MEGP and HEGP collimators show almost similar but still slightly different results in the generated images. Conclusion: All in all, MEGP and HEGP collimators have their own strengths in image quality using low-activity of iodine-131. Sensitivity in the MEGP collimator is better, and SNR in the HEGP collimator is better.
Incidence and spatial distribution of lymphatic filariasis in Sarawak, 2018-2022
(2023-06)
Ariffin, Mohd Aslam
Introduction: Lymphatic filariasis is a neglected tropical disease caused by Wuchereria bancrofti, Brugia malayi, or Brugia timori. It leads to severe morbidity and have a significant impact on health. Spatial analysis helps identify hotspot areas in Sarawak, enabling better targeting and focusing of prevention and control activities. Objective: To investigate the incidence and geographic dispersion of lymphatic filariasis in the region of Sarawak during the period ranging from 2018 to 2022, identify spatial distribution and hotspot area with present of any autocorrelation between cases. Methodology: This study utilized secondary data from Vekpro online system, Sarawak State Health Department for all cases registered from period of 2018 till 2022. The data pertaining to the population of Sarawak were acquired from the Department of Statistics Malaysia. The coordinates were transformed into the format of Kertau Rectified Skewed Orthomorphic (RSO) Malaya (EPSG:3168). The incidence of filariasis was calculated at the district level, and point pattern analysis was conducted using Kernel Density Estimates and Nearest Neighboring Index (NNI). The study additionally examines the existence of hot spots in order to differentiate spatial risk at the district level. Analyses were done using the gtsummary, tmap, spdep, spatialeco, and spastat packages in R Software Version 4.2.3. Result: There were varying incidence rates, with the highest in 2018 at 4.7 cases per 100,000 population followed by fluctuation trend, which 0.4 cases per 100,000, 2.3 cases per 100,000, 0.9 cases per 100,000 and 2.7 cases per 100,000 population in 2019, 2020, 2021 and 2022 respectively. The kernel density estimator (KDE) showed the potential hotspot area in the northern region of Sarawak, mainly Limbang district. The nearest neighbouring index (NNI) showed there was statistically significant clustering of filariasis cases, but using Global Moran’s I analysis, it showed there was no spatial autocorrelation between adjacent districts where confirmed filariasis was registered in Vekpro online system. Conclusion: The implementation of mass drug administration (MDA) has resulted in a reduction in filariasis infections in Sarawak. However, it is important to note that the risk of filariasis remains significantly high, particularly in the northern region. The application of spatial statistics and cluster detection techniques assists health planners in accurately evaluating and detecting spatial inequalities in risk among populations. Cluster analysis aids in the identification and prioritisation of regions with persistent transmission, preventing the spread of infection and subsequent resurgence on a larger scale.
Proportion and factors associated with covid-19 reinfection among Universiti Sains Malaysia health campus residents
(2023-06)
Background: COVID-19 will remain an endemic disease worldwide, and reinfection is possible. This phenomenon can be attributed to the highly mutable nature of COVID-19, which gives rise to new variants that exhibit increased transmission and immune evasion. Universiti Sains Malaysia (USM) Health Campus is a unique population as the campus has a higher-risk population due to the presence of a health center where the risk of COVID-19 exposure is the highest among the clinical staff. The risk is also shared among clinical health students who reside in student residences and risk exposing other residences. Identifying people at risk will help us in better prevention and control of the disease. Objective: This study aimed to describe the proportion of COVID-19 reinfection among USM Health Campus residents and to determine the factors associated with COVID-19 reinfection among USM Health Campus residents for the years 2021 and 2022. Methodology: This was a retrospective record review using secondary data year 2021 and 2022 from COVID-19 diseases outbreak and management data in USM Health Campus. The study was conducted from November 2022 till April 2023. Relevant data were extracted from the secured EXCEL sheet. The data were collected using proforma and were analyzed using SPSS version 26. The data were analyzed using descriptive analysis, as well as simple and multiple logistic regression. Result: A total of 137 cases out of 3469 COVID-19 positive cases were included in this study in which the proportion of COVID-19 reinfection cases were 3.95%. The associated factors for COVID-19 reinfection that were found to be significant were age group >40 years old, adjOR = 0.265 (95% CI: 0.15,0.47, p-value <0.001), vaccination status, adjOR = 0.254 (95% CI: 0.15,0.43, p-value <0.001), and workplace transmission adjOR = 1.815 (95% CI: 1.06,3.10, p-value = 0.003). Conclusions: COVID-19 reinfections were uncommon on USM Health Campus. Age group >40 years old, vaccination status and workplace transmission were the factors associated with COVID-19 reinfection among USM Health Campus residents. Screening targeted young age group should be enhanced and greater emphasis on health promotion and awareness in workplace for prevention and control of COVID-19 reinfection.
Satisfaction towards virtual consultation services and its associated factors among health care providers in government health clinics in Selangor
(2023-06)
Razak, Ihsan Abdul
Background: Virtual consultation services have been implemented by the Ministry of Health since 2019 to complement current healthcare service delivery in government health clinics in Malaysia. While the services have been proven to benefit the patients, little is known about the satisfaction of healthcare providers who run the services. This study utilizes the extended Technology Acceptance Model to evaluate the satisfaction of health care providers and identify the associated factors to further improve the services. Objectives: To determine the proportion of health care providers (HCP) who were satisfied with the virtual consultation services and identify the associated factors that contribute to HCP’s satisfaction towards virtual consultation services. Methodology: A cross sectional study was conducted in 42 government health in Selangor using a questionnaire adopted from the extended Technology Acceptance Model. A total of 137 health care providers from various categories responded to the online survey. Data were analysed using descriptive statistic, simple and multiple logistic regression. Result: Majority of respondents (72.3%) were satisfied with the virtual consultation services with mean score of 14.47 (3.391). Two factors were found to have significant association with health care providers’ satisfaction which were perceived usefulness (AdjOR 9.396, 95% CI: 3.196 to 27.625) and behavioural intention (AdjOR 8.311, 95% CI: 2.494 to 27.694). Conclusion: Perceived usefulness and behavioural intention of health care providers strongly predict satisfaction towards virtual consultation services in government health clinics in Selangor. Therefore efforts should be directed towards improving satisfaction level of health care providers by addressing these factors to ensure sustainability of the services in the future and to continue benefit the patients.

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