Displaying publications 1 - 20 of 189 in total

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  1. Said MA, Musarudin M, Zulkaffli NF
    Ann Nucl Med, 2020 Dec;34(12):884-891.
    PMID: 33141408 DOI: 10.1007/s12149-020-01543-x
    OBJECTIVE: 18F is the most extensively used radioisotope in current clinical practices of PET imaging. This selection is based on the several criteria of pure PET radioisotopes with an optimum half-life, and low positron energy that contributes to a smaller positron range. In addition to 18F, other radioisotopes such as 68Ga and 124I are currently gained much attention with the increase in interest in new PET tracers entering the clinical trials. This study aims to determine the minimal scan time per bed position (Tmin) for the 124I and 68Ga based on the quantitative differences in PET imaging of 68Ga and 124I relative to 18F.

    METHODS: The European Association of Nuclear Medicine (EANM) procedure guidelines version 2.0 for FDG-PET tumor imaging has adhered for this purpose. A NEMA2012/IEC2008 phantom was filled with tumor to background ratio of 10:1 with the activity concentration of 30 kBq/ml ± 10 and 3 kBq/ml ± 10% for each radioisotope. The phantom was scanned using different acquisition times per bed position (1, 5, 7, 10 and 15 min) to determine the Tmin. The definition of Tmin was performed using an image coefficient of variations (COV) of 15%.

    RESULTS: Tmin obtained for 18F, 68Ga and 124I were 3.08, 3.24 and 32.93 min, respectively. Quantitative analyses among 18F, 68Ga and 124I images were performed. Signal-to-noise ratio (SNR), contrast recovery coefficients (CRC), and visibility (VH) are the image quality parameters analysed in this study. Generally, 68Ga and 18F gave better image quality as compared to 124I for all the parameters studied.

    CONCLUSION: We have defined Tmin for 18F, 68Ga and 124I SPECT CT imaging based on NEMA2012/IEC2008 phantom imaging. Despite the long scanning time suggested by Tmin, improvement in the image quality is acquired especially for 124I. In clinical practice, the long acquisition time, nevertheless, may cause patient discomfort and motion artifact.

    Matched MeSH terms: Signal-To-Noise Ratio
  2. Maman Hermana, Hammad Hazim Mohd Azhar, Zuhar Zahir Tuan Harith
    Sains Malaysiana, 2012;41:953-959.
    This paper presents the improvement of quality factor (Q) estimation using shift frequency method. A new method was developed based on two previous methods; peak frequency shift (PFS) method and centroid frequency shift (CFS) method. The proposed algorithm has been tested to gauge its performance using three different scenarios; Q variation, travel
    time variation, and signal to noise ratio (SNR) variation. The test was performed using the Ricker wavelet with random noise included. Based on the results obtained, it can be concluded that the new proposed method was able to improve Q estimation using shift frequency method. This method can also be implemented in the low and high Q condition, shallow and deep wavelet targets and in the low and high SNR conditions of seismic data. The limitations in the PFS and CFS methods can be reduced by this method.
    Matched MeSH terms: Noise; Signal-To-Noise Ratio
  3. Islam MA, Jassim WA, Cheok NS, Zilany MS
    PLoS One, 2016;11(7):e0158520.
    PMID: 27392046 DOI: 10.1371/journal.pone.0158520
    Speaker identification under noisy conditions is one of the challenging topics in the field of speech processing applications. Motivated by the fact that the neural responses are robust against noise, this paper proposes a new speaker identification system using 2-D neurograms constructed from the responses of a physiologically-based computational model of the auditory periphery. The responses of auditory-nerve fibers for a wide range of characteristic frequency were simulated to speech signals to construct neurograms. The neurogram coefficients were trained using the well-known Gaussian mixture model-universal background model classification technique to generate an identity model for each speaker. In this study, three text-independent and one text-dependent speaker databases were employed to test the identification performance of the proposed method. Also, the robustness of the proposed method was investigated using speech signals distorted by three types of noise such as the white Gaussian, pink, and street noises with different signal-to-noise ratios. The identification results of the proposed neural-response-based method were compared to the performances of the traditional speaker identification methods using features such as the Mel-frequency cepstral coefficients, Gamma-tone frequency cepstral coefficients and frequency domain linear prediction. Although the classification accuracy achieved by the proposed method was comparable to the performance of those traditional techniques in quiet, the new feature was found to provide lower error rates of classification under noisy environments.
    Matched MeSH terms: Noise; Signal-To-Noise Ratio
  4. Siti Nadia Mohd Bakhori, Mohamad Zaki Hassan, Feiruz Ab’lah, Aadil Nausherwan, Mohd Azlan Suhot, Mohd Yusof Daud, et al.
    MyJurnal
    The construction industry is one of the major sectors in Malaysia. Apart from providing
    facilities, services and goods it also offers employment opportunities to local and
    foreign workers. In fact, the construction workers are exposed to high risk of noises
    being generated from various sources including excavators, bulldozers, concrete mixer
    and piling machines. Previous studies indicated that the piling and concrete work were
    recorded as the main source that contributed to the highest level of noise among
    others. Therefore, the aim of this study is to obtain the level of noise exposure during
    piling process and to determine the awareness of workers against noise pollution at
    the construction site. Initially, the reading of noise level was obtained at construction
    site by using a digital sound level meter (SLM) and noise exposure to the workers was
    mapped. Readings were taken from four different distances; 5, 10, 15 and 20 meters
    from the piling machine. Furthermore, a set of questionnaire was also distributed to
    assess the knowledge of regarding noise pollution at the construction site. The result
    showed that the mean noise level at 5 meters distance was more than 90 dB, which
    exceeded the recommended level. Although the level of awareness of regarding the
    effect of noise pollution is satisfactory but majority of workers (90%) still did not wear
    ear muffs during working periods. Therefore, the safety module guidelines related to
    noise pollution controls should be implemented to provide a safe working environment
    and prevent initial occupational hearing loss.
    Matched MeSH terms: Hearing Loss, Noise-Induced; Noise
  5. Ismail, N., Bashah, F. A. A., Zakaria, F.
    MyJurnal
    Many recent studies focused on the patient’s safety from the administration of gadolinium-based contrast agents (GBCAs), their concentration, the dose of administration and their effects on the image quality. The present study was aimed at evaluating the effects of reduced GBCAs (gadobutrol and gadoterate meglumine) volume on the image quality by using phantoms. Eight (8) human brain mimicking phantom made of nickel chloride (NiCl2) doped agarose gel were added with 0.00500 ml (100% volume), 0.00350 ml (75% volume), 0.00250 ml (50% volume) and 0.00125 ml (25% volume) of gadobutrol, 0.0100 ml (100% volume), 0.0075 ml (75% volume), 0.0050 ml (50% volume) and 0.0025 ml (25% volume) of gadoterate meglumine. The phantoms were scanned using a 1.5-T and a 3 T-MRI system. Signal-to-noise ratio (SNR) and the contrast agents enhancement were evaluated quantitatively and qualitatively. The 50% volume of gadobutrol and gadoterate meglumine at 3 T showed greater enhancement when compared with 50% and 100% volumes of gadobutrol and gadoterate meglumine at 1.5 T. It can be concluded that the volume of gadobutrol and gadoterate meglumine contrast agents can be reduced when using a higher field system
    Matched MeSH terms: Signal-To-Noise Ratio
  6. Daud MK, Noh NF, Sidek DS, Abd Rahman N, Abd Rani N, Zakaria MN
    B-ENT, 2011;7(4):245-9.
    PMID: 22338236
    The effect of noise on employees of dental clinics is debatable. The purposes of this study were to determine the intensity and frequency components of dental instruments used by dental staff nurses and the prevalence of noise induced hearing loss.
    Matched MeSH terms: Hearing Loss, Noise-Induced/diagnosis; Hearing Loss, Noise-Induced/epidemiology*
  7. Liew SC, Liew SW, Zain JM
    J Digit Imaging, 2013 Apr;26(2):316-25.
    PMID: 22555905 DOI: 10.1007/s10278-012-9484-4
    Tamper localization and recovery watermarking scheme can be used to detect manipulation and recover tampered images. In this paper, a tamper localization and lossless recovery scheme that used region of interest (ROI) segmentation and multilevel authentication was proposed. The watermarked images had a high average peak signal-to-noise ratio of 48.7 dB and the results showed that tampering was successfully localized and tampered area was exactly recovered. The usage of ROI segmentation and multilevel authentication had significantly reduced the time taken by approximately 50 % for the tamper localization and recovery processing.
    Matched MeSH terms: Signal-To-Noise Ratio
  8. Khor HL, Liew SC, Zain JM
    J Digit Imaging, 2017 Jun;30(3):328-349.
    PMID: 28050716 DOI: 10.1007/s10278-016-9930-9
    Tampering on medical image will lead to wrong diagnosis and treatment, which is life-threatening; therefore, digital watermarking on medical image was introduced to protect medical image from tampering. Medical images are divided into region of interest (ROI) and region of non-interest (RONI). ROI is an area that has a significant impact on diagnosis, whereas RONI has less or no significance in diagnosis. This paper has proposed ROI-based tamper detection and recovery watermarking scheme (ROI-DR) that embeds ROI bit information into RONI least significant bits, which will be extracted later for authentication and recovery process. The experiment result has shown that the ROI-DR has achieved a good result in imperceptibility with peak signal-to-noise ratio (PSNR) values approximately 48 dB, it is robust against various kinds of tampering, and the tampered ROI was able to recover to its original form. Lastly, a comparative table with the previous research (TALLOR and TALLOR-RS watermarking schemes) has been derived, where these three watermarking schemes were tested under the same testing conditions and environment. The experiment result has shown that ROI-DR has achieved speed-up factors of 22.55 and 26.65 in relative to TALLOR and TALLOR-RS watermarking schemes, respectively.
    Matched MeSH terms: Signal-To-Noise Ratio
  9. Azhar, N. A. A., Tee, H. S., Yee, Y. Y., Awang, M. N. A., Abdul Manan, H., Yusoff, A. N.
    MyJurnal
    Many studies have been carried out to produce magnetic resonance imaging (MRI) phantoms as alternative to water phantom. Among the important properties of a phantom are the T1 and T2 relaxation times. The objective of this study is to investigate the T1 and T2 characteristics of the agarose gel phantoms with different relaxation modifier (gadolinium (III) oxide, Gd2O3) concentrations or [Gd2O3]. Six agarose gel phantoms were prepared with different [Gd2O3]. The T1 (fixed echo time (TE) and different repetition time (TR)) and T2 (fixed TR and different TE) measurements on all phantoms were conducted using the 3-T MRI system via spin echo (SE) and turbo spin echo (TSE) sequences, respectively. The signal-to-noise ratio (SNR) of all phantoms was calculated using Image-J software by implementing the region of interest (ROI) analysis. The SNR against TR and SNR against TE curves were fitted to the exponential equations for saturation, T1 and T2 determination. For every phantom, T1 curve demonstrated that the SNR increased exponentially with increasing TR, while T2 curves showed that the SNR decreased exponentially with increasing TE. Gd2O3 was found to successfully act as the relaxation modifier for the T1 but not the T2 curves. The T1 curve started to show saturated SNR (SNRo) and increasing SNRo for TR > 1000 ms and [Gd2O3] = 0.005 g/ml or higher. These behaviours are explained based on the dipole-dipole interaction that increases in phantoms with higher [Gd2O3], thus shortening the T1 relaxation. However, a systematic change in the T2 parameters with increasing [Gd2O3] was not observed. While Gd2O3 has significant effects on T1 relaxation parameters, the T2 relaxation parameters were minimally affected. With a shorter T1, the Gd2O3 added agarose gel can potentially be used as test phantom in fast imaging sequence, e.g. gradient echo pulse sequences.
    Matched MeSH terms: Signal-To-Noise Ratio
  10. Suhaila Abdul Halim, Arsmah Ibrahim, Yupiter Harangan Prasada Manurung
    Scientific Research Journal, 2012;9(1):15-27.
    MyJurnal
    Accurate inspection of welded materials is important in relation to achieve acceptable standards. Radiography, a non-destructive test method, is commonly used to evaluate the internal condition of a material with respect to defect detection. The presence of noise in low resolution of radiographic images significantly complicates analysis; therefore attaining higher quality radiographic images makes defect detection more readily achievable. This paper presents a study pertaining to the quality enhancement of radiographic images with respect to different types of defects. A series of digital radiographic weld flaw images were smoothed using multiple smoothing techniques to remove inherent noise followed by top and bottom hat morphological transformations. Image quality was evaluated quantitatively with respect to SNR, PSNR and MAE. The results indicate that smoothing enhances the quality of radiographic images, thereby promoting defect detection with the respect to original radiographic images.
    Matched MeSH terms: Noise
  11. Salleh SH, Hussain HS, Swee TT, Ting CM, Noor AM, Pipatsart S, et al.
    Int J Nanomedicine, 2012;7:2873-81.
    PMID: 22745550 DOI: 10.2147/IJN.S32315
    Auscultation of the heart is accompanied by both electrical activity and sound. Heart auscultation provides clues to diagnose many cardiac abnormalities. Unfortunately, detection of relevant symptoms and diagnosis based on heart sound through a stethoscope is difficult. The reason GPs find this difficult is that the heart sounds are of short duration and separated from one another by less than 30 ms. In addition, the cost of false positives constitutes wasted time and emotional anxiety for both patient and GP. Many heart diseases cause changes in heart sound, waveform, and additional murmurs before other signs and symptoms appear. Heart-sound auscultation is the primary test conducted by GPs. These sounds are generated primarily by turbulent flow of blood in the heart. Analysis of heart sounds requires a quiet environment with minimum ambient noise. In order to address such issues, the technique of denoising and estimating the biomedical heart signal is proposed in this investigation. Normally, the performance of the filter naturally depends on prior information related to the statistical properties of the signal and the background noise. This paper proposes Kalman filtering for denoising statistical heart sound. The cycles of heart sounds are certain to follow first-order Gauss-Markov process. These cycles are observed with additional noise for the given measurement. The model is formulated into state-space form to enable use of a Kalman filter to estimate the clean cycles of heart sounds. The estimates obtained by Kalman filtering are optimal in mean squared sense.
    Matched MeSH terms: Signal-To-Noise Ratio
  12. Yuen FK
    Noise Health, 2014 Nov-Dec;16(73):427-36.
    PMID: 25387540 DOI: 10.4103/1463-1741.144429
    Environmental noise remains a complex and fragmented interplay between industrialization, population growth, technological developments, and the living environment. Next to the circulatory diseases and cancer, noise pollution has been cited as the third epidemic cause of psychological and physiological disorders internationally. A reliable and firm relationship between the cumulative health implications with the traffic annoyance and occupational noise has been established. This agenda has called for an integrated, coordinated, and participatory approach to the reliable protection of noise interference. Despite several fragmented policies, legislation and global efforts have been addressed; the noise pollution complaints have been traditionally neglected in developing countries, especially in Malaysia. This paper was undertaken to postulate an initial platform to address the dynamic pressures, gigantic challenges, and tremendous impacts of noise pollution scenario in Malaysia. The emphasis is speculated on the traffic interference and assessment of industrial and occupational noise. The fundamental importance of noise monitoring and modeling is proposed. Additionally, the confronting conservation program and control measure for noise pollution control are laconically elucidated.
    Matched MeSH terms: Noise/adverse effects; Noise/legislation & jurisprudence; Noise/prevention & control; Noise, Occupational/adverse effects; Noise, Occupational/legislation & jurisprudence; Noise, Occupational/prevention & control*; Noise, Transportation/adverse effects; Noise, Transportation/legislation & jurisprudence; Noise, Transportation/prevention & control*
  13. Huang C, Lou C, Chuang Y, Lin J, Liu C, Yu Z
    Sains Malaysiana, 2015;44:1757-1763.
    Following rapid technological and industrial development, factories have been equipped with a great deal of machines.
    The blend of industrial and residential areas in turn resulted in many environmental problems. In particular, machine
    operation causes noise pollution that easily causes physiological and psychological discomfort for the human body thus
    makes noise abatement a crucial and urgent issue. In this study, vermiculite functional fillers were added to polyurethane
    (PU) foam mixtures in order to form sound absorbent PU foams. The correlations between the contents of functional fillers
    and the sound absorption of flexible and rigid PU foams were then examined. The optimal PU foams were combined with
    PET/carbon fiber matrices in order to yield the electromagnetic shielding effectiveness. The sound absorption, noise
    reduction coefficient (NRC), electromagnetic shielding effectiveness and resilience rate of the composite boards were
    finally evaluated. The test results indicated that rigid PU foam composites can reach a sound absorption coefficient of
    0.8 while the flexible PU foam composites have higher mechanical properties.
    Matched MeSH terms: Noise
  14. Lombigit, Lojius, Maslina Ibrahim, Nolida Yusup, Nur Aira Abdul Rahman, Yong, Chong Fong
    MyJurnal
    Pulse Shaping Amplifier (PSA) is an essential component in nuclear spectroscopy system. This
    amplifier has two functions; to shape the output pulse and performs noise filtering. In this paper,
    we describe the procedure for the design and development of a pulse shaping amplifier which can
    be used in a nuclear spectroscopy system. This prototype was developed using high performance
    electronics devices and assembled on a FR4 type printed circuit board. Performance of this
    prototype was tested by comparing it with an equivalent commercial spectroscopy amplifier (Model
    Silena 7611). The test results showed that the performance of this prototype was comparable
    to the commercial spectroscopic amplifier.
    Matched MeSH terms: Noise
  15. Ahmad H, Albaqawi HS, Yusoff N, Yi CW
    Sci Rep, 2020 Jun 17;10(1):9860.
    PMID: 32555280 DOI: 10.1038/s41598-020-66664-9
    A wide-band and tunable Q-switched erbium-doped fiber (EDF) laser operating at 1560.5 nm with a tungsten ditelluride (WTe2) saturable absorber (SA) is demonstrated. The semi-metallic nature of WTe2 as well as its small band gap and excellent nonlinear optical properties make it an excellent SA material. The laser cavity uses an 89.5 cm long EDF, pumped by a 980 nm laser diode as the linear gain while the WTe2 based SA generates the pulsed output. The WTe2 based SA has a modulation depth, non-saturable loss and saturation intensity of about 21.4%, 78.6%, and 0.35 kW/cm2 respectively. Stable pulses with a maximum repetition rate of 55.56 kHz, narrowest pulse width of 1.77 µs and highest pulse energy of 18.09 nJ are obtained at the maximum pump power of 244.5 mW. A 56 nm tuning range is obtained in the laser cavity, and the output is observed having a signal to noise ratio (SNR) of 48.5 dB. The demonstrated laser has potential for use in a large number of photonics applications.
    Matched MeSH terms: Signal-To-Noise Ratio
  16. Bin WS, Richardson S, Yeow PH
    Int J Occup Saf Ergon, 2010;16(3):345-56.
    PMID: 20828490
    The study aimed to conduct an ergonomic intervention on a conventional line (CL) in a semiconductor factory in Malaysia, an industrially developing country (IDC), to improve workers' occupational health and safety (OHS). Low-cost and simple (LCS) ergonomics methods were used (suitable for IDCs), e.g., subjective assessment, direct observation, use of archival data and assessment of noise. It was found that workers were facing noise irritation, neck and back pains and headache in the various processes in the CL. LCS ergonomic interventions to rectify the problems included installing noise insulating covers, providing earplugs, installing elevated platforms, slanting visual display terminals and installing extra exhaust fans. The interventions cost less than 3 000 USD but they significantly improved workers' OHS, which directly correlated with an improvement in working conditions and job satisfaction. The findings are useful in solving OHS problems in electronics industries in IDCs as they share similar manufacturing processes, problems and limitations.
    Matched MeSH terms: Noise, Occupational/prevention & control
  17. Sen RN, Yeow PH
    Int J Occup Saf Ergon, 2003;9(1):57-74.
    PMID: 12636892
    The study aimed at reducing the occupational health and safety problems faced by the manual component insertion operators. Subjective and objective assessments, and direct observations were made in the printed circuit assembly factory. Simple and low-cost ergonomic interventions were implemented, that is, repairing chairs, reducing high workloads, assigning operators to a maximum of 2 workstations, confining machines that emitted bad smell and much noise, and providing finger work aids. The results of the interventions were reductions in operators' work discomforts, that is, chair discomfort (by 90%), high work stress, and discomfort due to profound change in their workstations. Their health hazards were also eliminated, that is, inhalation of toxic fumes, exposure to too much noise, and pain due to pressing sharp components.
    Matched MeSH terms: Noise, Occupational
  18. Hu S, Anschuetz L, Hall DA, Caversaccio M, Wimmer W
    Trends Hear, 2021 3 6;25:2331216520986303.
    PMID: 33663298 DOI: 10.1177/2331216520986303
    Residual inhibition, that is, the temporary suppression of tinnitus loudness after acoustic stimulation, is a frequently observed phenomenon that may have prognostic value for clinical applications. However, it is unclear in which subjects residual inhibition is more likely and how stable the effect of inhibition is over multiple repetitions. The primary aim of this work was to evaluate the effect of hearing loss and tinnitus chronicity on residual inhibition susceptibility. The secondary aim was to investigate the short-term repeatability of residual inhibition. Residual inhibition was assessed in 74 tinnitus subjects with 60-second narrow-band noise stimuli in 10 consecutive trials. The subjects were assigned to groups according to their depth of suppression (substantial residual inhibition vs. comparator group). In addition, a categorization in normal hearing and hearing loss groups, related to the degree of hearing loss at the frequency corresponding to the tinnitus pitch, was made. Logistic regression was used to identify factors associated with susceptibility to residual inhibition. Repeatability of residual inhibition was assessed using mixed-effects ordinal regression including poststimulus time and repetitions as factors. Tinnitus chronicity was not associated with residual inhibition for subjects with hearing loss, while a statistically significant negative association between tinnitus chronicity and residual inhibition susceptibility was observed in normal hearing subjects (odds ratio: 0.63; p = .0076). Moreover, repeated states of suppression can be stably induced, reinforcing the use of residual inhibition for within-subject comparison studies.
    Matched MeSH terms: Noise
  19. Li M, Mathai A, Lau SLH, Yam JW, Xu X, Wang X
    Sensors (Basel), 2021 Jan 05;21(1).
    PMID: 33466530 DOI: 10.3390/s21010313
    Due to medium scattering, absorption, and complex light interactions, capturing objects from the underwater environment has always been a difficult task. Single-pixel imaging (SPI) is an efficient imaging approach that can obtain spatial object information under low-light conditions. In this paper, we propose a single-pixel object inspection system for the underwater environment based on compressive sensing super-resolution convolutional neural network (CS-SRCNN). With the CS-SRCNN algorithm, image reconstruction can be achieved with 30% of the total pixels in the image. We also investigate the impact of compression ratios on underwater object SPI reconstruction performance. In addition, we analyzed the effect of peak signal to noise ratio (PSNR) and structural similarity index (SSIM) to determine the image quality of the reconstructed image. Our work is compared to the SPI system and SRCNN method to demonstrate its efficiency in capturing object results from an underwater environment. The PSNR and SSIM of the proposed method have increased to 35.44% and 73.07%, respectively. This work provides new insight into SPI applications and creates a better alternative for underwater optical object imaging to achieve good quality.
    Matched MeSH terms: Signal-To-Noise Ratio
  20. Khairur Rijal Jamaludin, Nolia Harudin, Faizir Ramlie, Mohd Nabil Muhtazaruddin, Che Munira Che Razali, Wan Zuki Azman Wan Muhamad
    MATEMATIKA, 2020;36(1):69-84.
    MyJurnal
    Prediction analysis has drawn significant interest in numerous field. Taguchi’s T-Method is a prediction tool that developed practically but not limited to small sample analysis. It was developed explicitly for multidimensional system prediction by relying on historical data as the baseline model and adapting the signal to noise ratio (SNR) as well as zero proportional concepts in strengthening its robustness. Orthogonal array (OA) in T-Method is a variable selection optimization technique in improving the prediction accuracy as well as help in eliminating variables that may deteriorate the overall performance. However, the limitation of OA in dealing with higher multidimensionality restraint the optimization accuracy. Binary particle swarm optimization used in this study helps to cater to the limitation of OA as well as optimizing the variable selection process to better prediction accuracy. The results show that if the historical data consist of samples with higher correlation of determination (R2) value for the model creation, the optimization process in reducing the number of variables would be much reliable and accurate. Comparing between T-Method+OA and T-Method+BPSO in four different case study, it shows that T-Method+BPSO performing better with greater R2 and means relative error (MRE) value compared to T-Method+OA.
    Matched MeSH terms: Signal-To-Noise Ratio
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