Displaying publications 1 - 20 of 69 in total

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  1. Modified recurrent equation-based cubic spline interpolation for missing data recovery in phasor measurement unit (PMU)
    Thangaraj S, Goh VT, Yap TTV
    F1000Res, 2022;11:246.
    PMID: 38152076 DOI: 10.12688/f1000research.73182.3
    BACKGROUND: Smart grid systems require high-quality Phasor Measurement Unit (PMU) data for proper operation, control, and decision-making. Missing PMU data may lead to improper actions or even blackouts. While the conventional cubic interpolation methods based on the solution of a set of linear equations to solve for the cubic spline coefficients have been applied by many researchers for interpolation of missing data, the computational complexity increases non-linearly with increasing data size.

    METHODS: In this work, a modified recurrent equation-based cubic spline interpolation procedure for recovering missing PMU data is proposed. The recurrent equation-based method makes the computations of spline constants simpler. Using PMU data from the State Load Despatch Center (SLDC) in Madhya Pradesh, India, a comparison of the root mean square error (RMSE) values and time of calculation (ToC) is calculated for both methods.

    RESULTS: The modified recurrent relation method could retrieve missing values 10 times faster when compared to the conventional cubic interpolation method based on the solution of a set of linear equations. The RMSE values have shown the proposed method is effective even for special cases of missing values (edges, continuous missing values).

    CONCLUSIONS: The proposed method can retrieve any number of missing values at any location using observed data with a minimal number of calculations.

    Matched MeSH terms: Computer Systems*
  2. Fulltext Minimizing thermal stress for data center servers through thermal-aware relocation
    Chaudhry MT, Ling TC, Hussain SA, Manzoor A
    ScientificWorldJournal, 2014;2014:684501.
    PMID: 24987743 DOI: 10.1155/2014/684501
    A rise in inlet air temperature may lower the rate of heat dissipation from air cooled computing servers. This introduces a thermal stress to these servers. As a result, the poorly cooled active servers will start conducting heat to the neighboring servers and giving rise to hotspot regions of thermal stress, inside the data center. As a result, the physical hardware of these servers may fail, thus causing performance loss, monetary loss, and higher energy consumption for cooling mechanism. In order to minimize these situations, this paper performs the profiling of inlet temperature sensitivity (ITS) and defines the optimum location for each server to minimize the chances of creating a thermal hotspot and thermal stress. Based upon novel ITS analysis, a thermal state monitoring and server relocation algorithm for data centers is being proposed. The contribution of this paper is bringing the peak outlet temperatures of the relocated servers closer to average outlet temperature by over 5 times, lowering the average peak outlet temperature by 3.5% and minimizing the thermal stress.
    Matched MeSH terms: Computer Systems*
  3. Fulltext A Vision-Based Machine Learning Method for Barrier Access Control Using Vehicle License Plate Authentication
    Islam KT, Raj RG, Shamsul Islam SM, Wijewickrema S, Hossain MS, Razmovski T, et al.
    Sensors (Basel), 2020 Jun 24;20(12).
    PMID: 32599883 DOI: 10.3390/s20123578
    Automatic vehicle license plate recognition is an essential part of intelligent vehicle access control and monitoring systems. With the increasing number of vehicles, it is important that an effective real-time system for automated license plate recognition is developed. Computer vision techniques are typically used for this task. However, it remains a challenging problem, as both high accuracy and low processing time are required in such a system. Here, we propose a method for license plate recognition that seeks to find a balance between these two requirements. The proposed method consists of two stages: detection and recognition. In the detection stage, the image is processed so that a region of interest is identified. In the recognition stage, features are extracted from the region of interest using the histogram of oriented gradients method. These features are then used to train an artificial neural network to identify characters in the license plate. Experimental results show that the proposed method achieves a high level of accuracy as well as low processing time when compared to existing methods, indicating that it is suitable for real-time applications.
    Matched MeSH terms: Computer Systems
  4. Fulltext Performance Evaluation of Localization Accuracy for a Log-Normal Shadow Fading Wireless Sensor Network under Physical Barrier Attacks
    Hussein AA, Rahman TA, Leow CY
    Sensors (Basel), 2015;15(12):30545-70.
    PMID: 26690159 DOI: 10.3390/s151229817
    Localization is an apparent aspect of a wireless sensor network, which is the focus of much interesting research. One of the severe conditions that needs to be taken into consideration is localizing a mobile target through a dispersed sensor network in the presence of physical barrier attacks. These attacks confuse the localization process and cause location estimation errors. Range-based methods, like the received signal strength indication (RSSI), face the major influence of this kind of attack. This paper proposes a solution based on a combination of multi-frequency multi-power localization (C-MFMPL) and step function multi-frequency multi-power localization (SF-MFMPL), including the fingerprint matching technique and lateration, to provide a robust and accurate localization technique. In addition, this paper proposes a grid coloring algorithm to detect the signal hole map in the network, which refers to the attack-prone regions, in order to carry out corrective actions. The simulation results show the enhancement and robustness of RSS localization performance in the face of log normal shadow fading effects, besides the presence of physical barrier attacks, through detecting, filtering and eliminating the effect of these attacks.
    Matched MeSH terms: Computer Systems
  5. Fulltext Real-time curvature defect detection on outer surfaces using best-fit polynomial interpolation
    Golkar E, Prabuwono AS, Patel A
    Sensors (Basel), 2012;12(11):14774-91.
    PMID: 23202186 DOI: 10.3390/s121114774
    This paper presents a novel, real-time defect detection system, based on a best-fit polynomial interpolation, that inspects the conditions of outer surfaces. The defect detection system is an enhanced feature extraction method that employs this technique to inspect the flatness, waviness, blob, and curvature faults of these surfaces. The proposed method has been performed, tested, and validated on numerous pipes and ceramic tiles. The results illustrate that the physical defects such as abnormal, popped-up blobs are recognized completely, and that flames, waviness, and curvature faults are detected simultaneously.
    Matched MeSH terms: Computer Systems
  6. Fulltext Synchronisation of output voltage waveforms in phase synchronous inverter with LCL filter for smart grid systems
    Tawfikur Rahman, Ibrahimy, M.I., Motakabber, S.M.A.
    Pertanika Journal of Science & Technology, 2017;25(107):145-156.
    MyJurnal
    A new smart grid system is widely used for energy supply system because it is simple, available, low cost, high efficiency and environmentally friendly. Conventionally, inverter techniques are utilised to convert input DC into output AC with the same frequency and phase. This process suffers the same problem which is a higher harmonic distortion, phase synchronisation, lower quality of waveform and long distance, among others. In this paper, three phase synchronous inverters (PSI) were used to direct synchronous PWM control, LCL filter, three phase RLC load, three phase Yg-Delta transformer, 5 km feeder with 2 MW load. PWM was used to generate the pulse signal for synchronisation. However, LCL filters were used to remove the noise in inverter output and transformer output side of the design. A balanced three phase load (10 kVAR) and also the input DC voltage 500 V were considered in this design. Three phase transformer (100kVA/260V/25kV) was used to increase the inverter output voltage and current with the fundamental frequency (50 Hz). The system conversion efficiency was 99.96% and phase synchronous error for each phase was approximately 4.5 degrees.
    Matched MeSH terms: Computer Systems
  7. Hierarchical control strategy for a three-phase 4-wire microgrid under unbalanced and nonlinear load conditions
    Naderipour A, Abdul-Malek Z, Ramachandaramurthy VK, Kalam A, Miveh MR
    ISA Trans, 2019 Nov;94:352-369.
    PMID: 31078293 DOI: 10.1016/j.isatra.2019.04.025
    This paper proposes an improved hierarchical control strategy consists of a primary and a secondary layer for a three-phase 4-wire microgrid under unbalanced and nonlinear load conditions. The primary layer is comprised of a multi-loop control strategy to provide balanced output voltages, a harmonic compensator to reduce the total harmonic distortion (THD), and a droop-based scheme to achieve an accurate power sharing. At the secondary control layer, a reactive power compensator and a frequency restoration loop are designed to improve the accuracy of reactive power sharing and to restore the frequency deviation, respectively. Simulation studies and practical performance are carried out using the DIgSILENT Power Factory software and laboratory testing, to verify the effectiveness of the control strategy in both islanded and grid-connected mode. Zero reactive power sharing error and zero frequency steady-state error have given this control strategy an edge over the conventional control scheme. Furthermore, the proposed scheme presented outstanding voltage control performance, such as fast transient response and low voltage THD. The superiority of the proposed control strategy over the conventional filter-based control scheme is confirmed by the 2 line cycles decrease in the transient response. Additionally, the voltage THDs in islanded mode are reduced from above 5.1% to lower than 2.7% with the proposed control strategy under nonlinear load conditions. The current THD is also reduced from above 21% to lower than 2.4% in the connection point of the microgrid with the offered control scheme in the grid-connected mode.
    Matched MeSH terms: Computer Systems
  8. A fourth-order compact finite difference scheme for the goursat problem
    Mohd Agos Salim Nasir, Ahmad Izani Md Ismail
    Sains Malaysiana, 2013;42:341-346.
    A high-order uniform Cartesian grid compact finite difference scheme for the Goursat problem is developed. The basic idea of high-order compact schemes is to find the compact approximations to the derivatives terms by differentiating centrally the governing equations. Our compact scheme will approximate the derivative terms by involving the higher terms and reducing the number of grid points. The compact finite difference scheme is given for general form of the Goursat problem in uniform domain and illustrates the performance by applying a linear problem. Numerical experiments have been conducted with the new scheme and encouraging results have been obtained. In this paper we present the compact finite difference scheme for the Goursat problem. With the aid of computational software the scheme was programmed for determining the relative errors of linear Goursat problem.
    Matched MeSH terms: Computer Systems
  9. Fulltext Short term energy consumption forecasting using neural basis expansion analysis for interpretable time series
    Shaikh AK, Nazir A, Khan I, Shah AS
    Sci Rep, 2022 Dec 29;12(1):22562.
    PMID: 36581655 DOI: 10.1038/s41598-022-26499-y
    Smart grids and smart homes are getting people's attention in the modern era of smart cities. The advancements of smart technologies and smart grids have created challenges related to energy efficiency and production according to the future demand of clients. Machine learning, specifically neural network-based methods, remained successful in energy consumption prediction, but still, there are gaps due to uncertainty in the data and limitations of the algorithms. Research published in the literature has used small datasets and profiles of primarily single users; therefore, models have difficulties when applied to large datasets with profiles of different customers. Thus, a smart grid environment requires a model that handles consumption data from thousands of customers. The proposed model enhances the newly introduced method of Neural Basis Expansion Analysis for interpretable Time Series (N-BEATS) with a big dataset of energy consumption of 169 customers. Further, to validate the results of the proposed model, a performance comparison has been carried out with the Long Short Term Memory (LSTM), Blocked LSTM, Gated Recurrent Units (GRU), Blocked GRU and Temporal Convolutional Network (TCN). The proposed interpretable model improves the prediction accuracy on the big dataset containing energy consumption profiles of multiple customers. Incorporating covariates into the model improved accuracy by learning past and future energy consumption patterns. Based on a large dataset, the proposed model performed better for daily, weekly, and monthly energy consumption predictions. The forecasting accuracy of the N-BEATS interpretable model for 1-day-ahead energy consumption with "day as covariates" remained better than the 1, 2, 3, and 4-week scenarios.
    Matched MeSH terms: Computer Systems*
  10. Design and develop a video conferencing framework for real-time telemedicine applications using secure group-based communication architecture
    Mat Kiah ML, Al-Bakri SH, Zaidan AA, Zaidan BB, Hussain M
    J Med Syst, 2014 Oct;38(10):133.
    PMID: 25199651 DOI: 10.1007/s10916-014-0133-y
    One of the applications of modern technology in telemedicine is video conferencing. An alternative to traveling to attend a conference or meeting, video conferencing is becoming increasingly popular among hospitals. By using this technology, doctors can help patients who are unable to physically visit hospitals. Video conferencing particularly benefits patients from rural areas, where good doctors are not always available. Telemedicine has proven to be a blessing to patients who have no access to the best treatment. A telemedicine system consists of customized hardware and software at two locations, namely, at the patient's and the doctor's end. In such cases, the video streams of the conferencing parties may contain highly sensitive information. Thus, real-time data security is one of the most important requirements when designing video conferencing systems. This study proposes a secure framework for video conferencing systems and a complete management solution for secure video conferencing groups. Java Media Framework Application Programming Interface classes are used to design and test the proposed secure framework. Real-time Transport Protocol over User Datagram Protocol is used to transmit the encrypted audio and video streams, and RSA and AES algorithms are used to provide the required security services. Results show that the encryption algorithm insignificantly increases the video conferencing computation time.
    Matched MeSH terms: Computer Systems*
  11. Fulltext A comprehensive review on adaptability of network forensics frameworks for mobile cloud computing
    Khan S, Shiraz M, Wahab AW, Gani A, Han Q, Rahman ZB
    ScientificWorldJournal, 2014;2014:547062.
    PMID: 25097880 DOI: 10.1155/2014/547062
    Network forensics enables investigation and identification of network attacks through the retrieved digital content. The proliferation of smartphones and the cost-effective universal data access through cloud has made Mobile Cloud Computing (MCC) a congenital target for network attacks. However, confines in carrying out forensics in MCC is interrelated with the autonomous cloud hosting companies and their policies for restricted access to the digital content in the back-end cloud platforms. It implies that existing Network Forensic Frameworks (NFFs) have limited impact in the MCC paradigm. To this end, we qualitatively analyze the adaptability of existing NFFs when applied to the MCC. Explicitly, the fundamental mechanisms of NFFs are highlighted and then analyzed using the most relevant parameters. A classification is proposed to help understand the anatomy of existing NFFs. Subsequently, a comparison is given that explores the functional similarities and deviations among NFFs. The paper concludes by discussing research challenges for progressive network forensics in MCC.
    Matched MeSH terms: Computer Systems*
  12. Real-Time Remote Health-Monitoring Systems in a Medical Centre: A Review of the Provision of Healthcare Services-Based Body Sensor Information, Open Challenges and Methodological Aspects
    Albahri OS, Zaidan AA, Zaidan BB, Hashim M, Albahri AS, Alsalem MA
    J Med Syst, 2018 Jul 25;42(9):164.
    PMID: 30043085 DOI: 10.1007/s10916-018-1006-6
    Promoting patient care is a priority for all healthcare providers with the overall purpose of realising a high degree of patient satisfaction. A medical centre server is a remote computer that enables hospitals and physicians to analyse data in real time and offer appropriate services to patients. The server can also manage, organise and support professionals in telemedicine. Therefore, a remote medical centre server plays a crucial role in sustainably delivering quality healthcare services in telemedicine. This article presents a comprehensive review of the provision of healthcare services in telemedicine applications, especially in the medical centre server. Moreover, it highlights the open issues and challenges related to providing healthcare services in the medical centre server within telemedicine. Methodological aspects to control and manage the process of healthcare service provision and three distinct and successive phases are presented. The first phase presents the identification process to propose a decision matrix (DM) on the basis of a crossover of 'multi-healthcare services' and 'hospital list' within intelligent data and service management centre (Tier 4). The second phase discusses the development of a DM for hospital selection on the basis of integrated VIKOR-Analytic Hierarchy Process (AHP) methods. Finally, the last phase examines the validation process for the proposed framework.
    Matched MeSH terms: Computer Systems*
  13. Fulltext Monte Carlo method with heuristic adjustment for irregularly shaped food product volume measurement
    Siswantoro J, Prabuwono AS, Abdullah A, Idrus B
    ScientificWorldJournal, 2014;2014:683048.
    PMID: 24892069 DOI: 10.1155/2014/683048
    Volume measurement plays an important role in the production and processing of food products. Various methods have been proposed to measure the volume of food products with irregular shapes based on 3D reconstruction. However, 3D reconstruction comes with a high-priced computational cost. Furthermore, some of the volume measurement methods based on 3D reconstruction have a low accuracy. Another method for measuring volume of objects uses Monte Carlo method. Monte Carlo method performs volume measurements using random points. Monte Carlo method only requires information regarding whether random points fall inside or outside an object and does not require a 3D reconstruction. This paper proposes volume measurement using a computer vision system for irregularly shaped food products without 3D reconstruction based on Monte Carlo method with heuristic adjustment. Five images of food product were captured using five cameras and processed to produce binary images. Monte Carlo integration with heuristic adjustment was performed to measure the volume based on the information extracted from binary images. The experimental results show that the proposed method provided high accuracy and precision compared to the water displacement method. In addition, the proposed method is more accurate and faster than the space carving method.
    Matched MeSH terms: Computer Systems
  14. Fulltext System interface for an integrated intelligent safety system (ISS) for vehicle applications
    Hannan MA, Hussain A, Samad SA
    Sensors (Basel), 2010;10(2):1141-53.
    PMID: 22205861 DOI: 10.3390/s100201141
    This paper deals with the interface-relevant activity of a vehicle integrated intelligent safety system (ISS) that includes an airbag deployment decision system (ADDS) and a tire pressure monitoring system (TPMS). A program is developed in LabWindows/CVI, using C for prototype implementation. The prototype is primarily concerned with the interconnection between hardware objects such as a load cell, web camera, accelerometer, TPM tire module and receiver module, DAQ card, CPU card and a touch screen. Several safety subsystems, including image processing, weight sensing and crash detection systems, are integrated, and their outputs are combined to yield intelligent decisions regarding airbag deployment. The integrated safety system also monitors tire pressure and temperature. Testing and experimentation with this ISS suggests that the system is unique, robust, intelligent, and appropriate for in-vehicle applications.
    Matched MeSH terms: Computer Systems
  15. Fulltext Photovoltaic Grid-Connected Modeling and Characterization Based on Experimental Results
    Humada AM, Hojabri M, Sulaiman MH, Hamada HM, Ahmed MN
    PLoS One, 2016;11(4):e0152766.
    PMID: 27035575 DOI: 10.1371/journal.pone.0152766
    A grid-connected photovoltaic (PV) system operates under fluctuated weather condition has been modeled and characterized based on specific test bed. A mathematical model of a small-scale PV system has been developed mainly for residential usage, and the potential results have been simulated. The proposed PV model based on three PV parameters, which are the photocurrent, IL, the reverse diode saturation current, Io, the ideality factor of diode, n. Accuracy of the proposed model and its parameters evaluated based on different benchmarks. The results showed that the proposed model fitting the experimental results with high accuracy compare to the other models, as well as the I-V characteristic curve. The results of this study can be considered valuable in terms of the installation of a grid-connected PV system in fluctuated climatic conditions.
    Matched MeSH terms: Computer Systems
  16. Fulltext Android mobile applications in eye care
    Karthikeyan SK, Thangarajan R, Theruvedhi N, Srinivasan K
    Oman J Ophthalmol, 2019 6 15;12(2):73-77.
    PMID: 31198290 DOI: 10.4103/ojo.OJO_226_2018
    Google Play Store was used to search for eye care-related applications the android simulator using various general terms related to eye care to review and categorize various interactive eye care-related applications in android platform from the details available in the application website. Data collected from application description and application developer's webpage include target audience, category of apps, estimated number of downloads, average user rating, involvement of eye care professionals in developing the application, and cost of the app. All these data were collected only from the details provided in the application website considering on online user perspective and the developers were not contacted to collect any other details. In total, 475 applications were identified and grouped into 13 categories depending on the type of service the application provide. Out of which, only 107 (22.53%) applications had mentioned about the eye care professional involvement in their design or development of the application. The applications were also stratified according to the target audience, and many had no user rating with very few downloads. The lack of evidence-based principles and standardization of application development should be taken into consideration to avoid its negative impact on the community, especially in eye care.
    Matched MeSH terms: Computer Systems
  17. Objective assessment of vitiligo with a computerised digital imaging analysis system
    Shamsudin N, Hussein SH, Nugroho H, Fadzil MH
    Australas J Dermatol, 2015 Nov;56(4):285-9.
    PMID: 25367709 DOI: 10.1111/ajd.12247
    An objective tool to quantify treatment response in vitiligo is currently lacking. This study aimed to objectively evaluate the treatment response in vitiligo by using a computerised digital imaging analysis system (C-DIAS) and to compare it with the physician's global assessment (PGA). Tacrolimus ointment 0.1% (Protopic; Astellas Pharma Tech,Toyama, Japan) was applied twice daily on selected lesions which were photographed every 6 weeks for 24 weeks. The primary efficacy end-point was the mean percentage of repigmentation (MPR), as assessed by the digital method (MPR-C-DIAS) or by the PGA. The response was categorised into none (0%), mild (1-25%), moderate (26-50%), good (51-75%) and excellent (76-100%).
    Matched MeSH terms: Computer Systems
  18. Fulltext A Comparative Performance Analysis of Computational Intelligence Techniques to Solve the Asymmetric Travelling Salesman Problem
    Odili JB, Noraziah A, Zarina M
    Comput Intell Neurosci, 2021;2021:6625438.
    PMID: 33986793 DOI: 10.1155/2021/6625438
    This paper presents a comparative performance analysis of some metaheuristics such as the African Buffalo Optimization algorithm (ABO), Improved Extremal Optimization (IEO), Model-Induced Max-Min Ant Colony Optimization (MIMM-ACO), Max-Min Ant System (MMAS), Cooperative Genetic Ant System (CGAS), and the heuristic, Randomized Insertion Algorithm (RAI) to solve the asymmetric Travelling Salesman Problem (ATSP). Quite unlike the symmetric Travelling Salesman Problem, there is a paucity of research studies on the asymmetric counterpart. This is quite disturbing because most real-life applications are actually asymmetric in nature. These six algorithms were chosen for their performance comparison because they have posted some of the best results in literature and they employ different search schemes in attempting solutions to the ATSP. The comparative algorithms in this study employ different techniques in their search for solutions to ATSP: the African Buffalo Optimization employs the modified Karp-Steele mechanism, Model-Induced Max-Min Ant Colony Optimization (MIMM-ACO) employs the path construction with patching technique, Cooperative Genetic Ant System uses natural selection and ordering; Randomized Insertion Algorithm uses the random insertion approach, and the Improved Extremal Optimization uses the grid search strategy. After a number of experiments on the popular but difficult 15 out of the 19 ATSP instances in TSPLIB, the results show that the African Buffalo Optimization algorithm slightly outperformed the other algorithms in obtaining the optimal results and at a much faster speed.
    Matched MeSH terms: Computer Systems
  19. Fulltext Rootkit guard (RG) - an architecture for rootkit resistant file-system implementation based on TPM
    Yew, Teh Jia, Khairulmizam Samsudin, Nur Izura Udzir, Shaiful Jahari Hashim
    Pertanika Journal of Science & Technology, 2013;21(2):507-520.
    MyJurnal
    Recent rootkit-attack mitigation work neglected to address the integrity of the mitigation tool itself. Both detection and prevention arms of current rootkit-attack mitigation solutions can be given credit for the advancement of multiple methodologies for rootkit defense but if the defense system itself is compromised, how is the defense system to be trusted? Another deficiency not addressed is how platform integrity can be preserved without availability of current RIDS or RIPS solutions, which operate only upon the loading of the kernel i.e. without availability of a trusted boot environment. To address these deficiencies, we present our architecture for solving rootkit persistence – Rootkit Guard (RG). RG is a marriage between TrustedGRUB (providing trusted boot), IMA (Integrity Measurement Architecture) (serves as RIDS) and SELinux (serves as RIPS). TPM hardware is utilised to provide total integrity of our platform via storage of the aggregate of the clean snapshot of our platform OS kernel into TPM hardware registers (i.e. the PCR) – of which no software attacks have been demonstrated to date. RG solves rootkit persistence by leveraging on one vital but simple strategy: the mounting of rootkit defense via prevention of the execution of configuration binaries or build initialisation scripts. We adopted the technique of rootkit persistence prevention via thwarting the initialisation of a rootkit’s installation procedure; if the rootkit is successfully installed, proper deployment via thwarting of the rootkit’s
    configuration is prevented. We had subjected the RG to 8 real world Linux 2.6 rootkits and the RG was successful in solving rootkit persistence in all 8 evaluated rootkits. In terms of performance, the RG introduced a maximum of 11% overhead and an average of 4% overhead, hence permitting deployment in production environments.
    Matched MeSH terms: Computer Systems
  20. Fulltext Measurement of dosimetric parameters and dose verifi cation in stereotactic radiosurgery (srs)
    Reduan Abdullah, Ahmad Zakaria, Nur Iziana Mohsin, Nik Ruzman Nik Idris, Ahmad Lutfi Yusof, Mazurawati Mohamed
    Jurnal Sains Kesihatan Malaysia, 2015;13(1):39-49.
    MyJurnal
    The fi rst part of this study was about measurement of dosimetric parameters for small photon beams to be used as input
    data for treatment planning computer system (TPS) and to verify the dose calculated by TPS in Stereotactic Radiosurgery
    (SRS) procedure. The beam data required were percentage depth dose (PDD), off-axis ratio (OAR) and scattering factor.
    Small beams of 5 mm to 45 mm diameter from a circular cone collimator in SRS were used for beam data measurements.
    Measurements were made using pinpoint ionisation chamber (0.016cc). In the second part of this study, we reported
    the important of carrying out quality assurance (QA) procedures before SRS treatment which were found to infl uence the
    accuracy of dose delivery. These QA procedures consisted of measurements on the accuracy in target localization and
    treatment room laser alignment. The calculated TPS dose for treatment was verifi ed using pinpoint ionisation chamber
    and thermoluminescent detector (TLD) 100H. The deviation mean between measured and calculated dose was -3.28%.
    The measured dose obtained from pinpoint ionisation chamber is in good agreement with the calculated dose from TPS
    with deviation mean of 2.17%. In conclusion, pinpoint ionisation chamber gives a better accuracy in dose calculation
    compared to TLD 100H. The results are acceptable as recommended by International Commission on Radiation Units
    and Measurements (ICRU) Report No. 50 (1994) that dose delivered to the target volume must be within ± 5% error.
    Matched MeSH terms: Computer Systems
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