58178 research outputs found
Sort by
Evaluating interfraction motion thresholds in image-guided radiotherapy (IGRT) for lung and spine stereotactic body radiotherapy (SBRT)
No full textStereotactic body radiotherapy (SBRT) is an advanced technique for small tumour volumes that requires precise dose delivery due to its hypofractionated nature and steep dose gradients. However, tumour motion, particularly respiratory-induced displacement, poses a challenge to treatment accuracy. This study aimed to evaluate interfraction motion thresholds using kilovoltage cone-beam computed tomography (kV-CBCT) in image-guided radiotherapy (IGRT) for lung and spine SBRT at Hospital Pakar Universiti Sains Malaysia (HPUSM). Methods: For seven lung SBRT cases, tumour motion was measured in Eclipse treatment planning system (TPS) by measuring the distance between contours of average gross tumour volume (GTV) and GTV from maximum and minimum respiratory phases using 4D-gated slow CT simulation images. Interfraction motion was quantified using kV-CBCT across 18 lung and spine SBRT patients, evaluating translational and rotational displacements over 3 to 5 treatment fractions. The mean interfraction displacements were evaluated against the AAPM TG-142 recommended thresholds (≤ 1 mm/°). Results: Tumour motion was highest in the superior-inferior (Y) direction during both maximum (mean = 0.3371 ± 0.4043 cm) and minimum (mean = 0.1205 ± 0.1677 cm) phases. A strong correlation (ρ ≥ 0.7) was observed between tumour motion and average GTV volume in most axes but the relationships were not statistically significant (p > 0.05). Interfraction displacement was highest in the lateral axis for lung SBRT (mean = 22.89 ± 33.75 mm) while spine SBRT showed more stable displacements, with the highest in vertical axis (mean = 22.38 ± 27.36 mm). No significant differences in displacement were observed across fractions and between simulation techniques (p > 0.05). The ratio of AAPM TG-142 threshold to actual displacement was approximately 1:20 for translational displacement and nearly 1:1 for rotational displacement. Conclusion: Interfraction motion displacements exceeded AAPM TG-142 translational threshold, highlighting the need of further study for motion management to optimise SBRT delivery
Verification of the rule of thumb to determine electron range parameter using egsnrc Monte Carlo
No full textThis study successfully models and validates the Varian Clinac iX linear accelerator for 9 MeV and 12 MeV electron beams using the EGSnrc Monte Carlo simulation framework, specifically BEAMnrc and DOSXYZnrc. The LINAC head was accurately reconstructed using nine component modules (CMs), representing key structures such as the primary collimator, scattering foils, and applicator, with material properties defined through the 700icru.pegsdat file for precise particle interaction modelling. A phase space file generated at 100 cm SSD was used to simulate dose distribution in a voxelised water phantom that replicates clinical setups. Experimental data, collected with a Markus plane-parallel ionisation chamber following IAEA TRS-398 protocol, served to validate the MC-generated PDD and beam profiles. The simulation showed strong agreement with measured values, with percentage differences for R₁₀₀, R₉₀, R₅₀, and Rp within clinically acceptable limits. Beam flatness and symmetry also aligned closely with measurements, aside from slight discrepancies at 12 MeV due to potential geometric modelling issues. Additionally, comparison with rule-of-thumb estimates for electron range parameters confirmed the accuracy of the simulation. Overall, the study demonstrates that EGSnrc, when combined with precise input data and geometric modelling, can produce high-fidelity dose predictions suitable for clinical treatment planning, quality assurance, and benchmarking in electron beam therapy
The persistence study of gasoline residue in palm oil soil using gas chromatography mass spectrometry
No full textGasoline is often used as an accelerant in arson cases due to its highly volatile
and flammable nature. However, detecting gasoline residues after a fire is challenging,
as the residues may evaporate or degrade depending on environmental conditions and
soil characteristics. This study examines the detection of gasoline residues in oil palm
soil over five days by analyzing how soil type, depth, and environmental factors
influence residue retention. In this study, 100 mL of gasoline was poured into a 60 cm
PVC pipe containing oil palm soil. Residue sampling was conducted at different
depths. An Agilent Gas Chromatography-Mass Spectrometry (GC-MS) system was
used to identify gasoline compounds in the soil samples. The results revealed that
gasoline residues were significantly reduced within the first three days. These findings
enhance forensic soil sampling techniques, improve residue recovery strategies, and
contribute to a more accurate interpretation of fire investigations by demonstrating the
rapid degradation of gasoline in certain soil conditions
Removal of lead, cadmium, and nickel ions from aqueous solution using okra and chilli seeds as adsorbent
No full textHeavy metal contamination in water sources, especially lead (Pb), cadmium (Cd), and nickel (Ni), poses a significant threat to human health, due to their toxicity, persistence in the environment, and bioaccumulative nature. This study examined the effectiveness of okra (Abelmoschus esculentus), and chilli (Capsicum annuum L) seeds as adsorbents for these metals removal from aqueous solution. Several parameters, including initial concentration, adsorbent dosage, contact time, and temperature, were conducted for this adsorption experiment. Flame Atomic Absorption Spectroscopy (FAAS) was used to measure Pb, Cd, and Ni ion concentrations. Fourier Transform Infrared Spectroscopy (FTIR) was used to characterise biosorbents before and after treatment to discover functional groups involved in the adsorption process. The optimal parameters for Pb, Cd, and Ni removal using okra seeds were 1 ppm of initial concentration, 0.5 g adsorbent dosage, 20 minutes of contact time, and 30°C temperature, resulting in removal efficiencies of 84.9%, 87.3%, and 28%, respectively. For chili seeds, the same conditions with a 1.0 g adsorbent dosage resulted in 92% removal efficiency for Pb, 82.4% for Cd, and 37.4% for Ni. Based on the observations, Pb yielded the highest percentage removal efficiency compared to Cd and Ni, whereas Ni had the lowest for both adsorbent types. However, the findings indicated that both okra and chilli seeds have the potential to remove Pb, Cd, and Ni heavy metals from aqueous solution
Study on knowledge, attitudes, and experiences related to sexual harassment in malaysian workplaces
No full textThis study examines knowledge, attitudes, and experiences (KAE) related to sexual harassment (SH) in Malaysian workplaces. A quantitative research approach was employed using an online survey to collect data from employees across various sectors. The survey instrument was adapted from established scales and validated sources to assess participants' understanding of SH, their attitudes toward it, and their personal or observed experiences in the workplace. The survey consisted of five parts: sociodemographic characteristics, knowledge of SH, attitudes toward SH, experiences of SH, and reporting behaviours. A total of 394 Malaysian employees participated in the study, with 271 respondents included in the final analysis after applying exclusion and withdrawal criteria. Statistical analyses, including Kruskal-Wallis test, Mann- Whitney U test, and Binary Logistic Regression; were conducted to identify significant relationships between KAE with SH reporting behaviour. Findings revealed that knowledge is relatively uniform between genders, employment sectors, and job levels. Attitudes toward SH were influenced by personal attributes, workplace culture and awareness campaigns. Meanwhile reporting behaviours were hindered by fear of retaliation, lack of trust in reporting mechanisms, and organisational inaction. The study highlights the need for transparent policies and improved workplace-specific- sector training. Future research should explore sector-specific awareness and training programmes, and enhance reporting mechanism as well as support system
Three-dimensional superimposition analysis of occlusal surface of upper first premolar for human identification
No full textForensic dental identification using the comparative method relies on the unique features of dental structures to establish an individual’s identity. This study aimed to determine the reliability and uniqueness of the occlusal surface of the maxillary first premolar for human identification. A cross-sectional study was conducted using retrospective archived dental casts of Kelantanese Malays obtained from the Orthodontic Clinic of Hospital USM. A total of 90 dental casts were scanned into digital models using the Medit i500 intraoral scanner (Medit Corp, South Korea). The occlusal surfaces were isolated using 3-Matic software (Materialise NV, Belgium), and superimposition analysis was performed using CloudCompare software (CloudCompare, Paris, France). The intra-examiner and inter-examiner analyses on matched 18 pairs achieved a perfect agreement with a Cohen's Kappa value of 1.00, thus confirming 100% reliability for both tests. Under blind study conditions, only the Root Mean Square (RMS) values were used to distinguish between 45 matched and 45 unmatched pairs. The mean RMS for matched pairs was 0.011 ± 0.005 mm, while for unmatched pairs it was 0.219 ± 0.059 mm. The established RMS threshold of 0.1 mm correctly identified 100% of matched and unmatched pairs, with no overlap between the two groups (p < 0.05), hence confirming the uniqueness of the occlusal surface of the maxillary first premola
Next generation sequencing based targeted gene mutational profiles of formalin-fixed paraffin embedded specimens from colorectal carcinoma cases in Hospital Pakar Universiti Sains Malaysia
No full textColorectal carcinoma (CRC) is the third most prevailing cancer and the third most common cause of cancer-related deaths worldwide. It is a multistep process involving the accumulation of multiple genetic alterations. Through comprehensive molecular profiling and analysis of CRC using NGS, genetic mutations in colorectal cancer can be accurately identified for potential CRC screening. The present study carried out molecular analysis of formalin-fixed, paraffin-embedded (FFPE) specimens from 30 CRC cases in Hospital Pakar Universiti Sains Malaysia using NGS. Extracted gDNA from FFPE samples using a QIAgen FFPE extraction kit was used for library preparation, then sequenced in an Illumina MiniSeq machine. From a total of 30 FFPE samples [60% male and 40% female] sequenced, 22 completed the sequencing run, representing 73.3% of the samples: 20 CRC samples and 2 normal tissues. From demographics results, the highest data was recorded for “less than 65 years old” at 66.7%, “Retired group” at 70%, “Stage-3” at 53.3%, “Moderately differentiated grade” at 76.7%, and lastly, patients with “More than 2 comorbid” at 36.7%. Overall, 552 mutations involving 29 genes and 11 chromosomes were detected. The most upregulated were KIT:68(12.3%), FGFR4:61(11.1%), EGFR:60(10.9%), ALK:53(9.6%), DCUN1D1:41(7.4%), PDGFR:40(7.2%), KRAS:33(6.0%), CDK4:27(4.9%), and FGFR3:26(4.7%). Most downregulated gene mutations were ESR1, FGFR1, CCND1, HRAS, AR. The five most involved chromosome were chr4:(24.3%), chr7:(15.2%), chr12:(12.2%), chr5:(11.6%), and chr2:(11.1%) respectively. After applying filter criteria, 105 mutations involving 15 genes passed the filter. In-Silico Prediction model of clinical consequences of filtered mutations identified 21 pathogenic mutations (from 9 genes), 57 tolerated benign mutations (from 5 genes), and 17 variants unspecified (from 4 genes). Identified pathogenic gene mutations are APC, NRAS, ALK, PIK3CA, KRAS, IDH1, FGFR1, ERBB2, and ESR1. Validation of the pathogenic mutations on dbSNP, Ensembl, and Franklin by Genoox online databases also identified them as pathogenic genes. This is the first comprehensive NGS genetic profiling of CRC cases in Malaysia and HPUSM. The study’s novelty is based on the successful identification of pathogenic gene mutations in colorectal cancer cases in Malaysia and HPUSM. These findings will serve as a leadway for potential targeted therapy for CRC case
The characterisation of mdm2 and cdk4 gene amplification and their association with recurrence in lipomatous tumours
No full textMDM2 and CDK4 are frequently amplified genes in liposarcoma, particularly in atypical lipomatous tumour/well-differentiated liposarcoma (ALT/WDLS) and dedifferentiated liposarcoma (DDLS). Although the individual oncogenic role of MDM2 and CDK4 genes are well established, the prevalence and ratio of their concurrent amplification, as well as their prognostic significance in liposarcoma, remain unclear. The aim of this study was to evaluate MDM2 and CDK4 amplification ratios across lipomatous tumour subtypes, determine their concurrent amplification statuses, and assess associations with patients’ prognosis. Clinicopathological data of cases histologically diagnosed as liposarcoma of any size or benign lipomatous tumours measuring at least 10 cm (≥10 cm), at Hospital Pakar Universiti Sains Malaysia (HPUSM) between January 2014 and May 2021, were retrospectively retrieved from Laboratory Information System of Pathology Department, HPUSM. Formalin-fixed paraffin-embedded tissue samples of eligible cases were subjected to fluorescence in situ hybridisation (FISH) for MDM2 and CDK4 gene amplification detection. Amplification ratio was determined by comparing MDM2 or CDK4 mean copy number with centromere 12 signals, where ratios more than 2.0 indicated amplification, and ratio less than 2.0 indicated no amplification. Recurrence-free and metastasis-free survival across amplification groups were evaluated using Kaplan-Meier survival analysis and compared with log-rank statistics. Prognostic factors of recurrence were analysed using Cox proportional hazard regression. Among 86 cases 23 (27%) were liposarcoma and 63 (73%) were benign lipomatous tumours (≥10 cm) following reclassification by FISH. MDM2 and CDK4 co-amplification (MDM2+/CDK4+; 13%) was observed in all (6/6) DDLS and half (5/10) of ALT/WDLS cases. Five MDM2-amplified cases lacked CDK4 amplification (MDM2+/CDK4-; 6%), all detected in ALT. No amplification of either gene (MDM2-/CDK4-; 81%) was detected in myxoid liposarcoma, pleomorphic liposarcoma, or benign tumours. DDLS showed higher MDM2 and CDK4 amplification ratios (4.4 and 2.8, respectively) than ALT/WDLS (2.9 and 2.6, respectively). In both subtypes, MDM2 amplification ratio exceeded CDK4. MDM2+/CDK4+ group had the shortest recurrence-free (p=0.002; median 34 months) and metastasis-free survival (p=0.003; median 83 months) compared to other groups. Multivariate analysis showed recurrence was significantly associated with surgery combined with chemotherapy (p=0.021), but MDM2 and CDK4 amplification was not an independent prognostic factor. In conclusion, MDM2 amplification was more consistent and quantitatively higher than CDK4, supporting its central role in tumourigenesis. While MDM2/CDK4 co-amplification was associated with poorer outcomes, it lacked independent prognostic value, reflecting the potential influence of other clinical variables. Nevertheless, co-amplification may hold clinical relevance in identifying high-risk liposarcoma subgroup
Development and characterization of flowable composite derived from rice husk using urethane dimethacrylate
No full textThe study aimed to develop and characterize flowable composites (FCs) using silica derived from rice husk as the primary filler, urethane dimethacrylate (UDMA) as the base monomer, and zirconia as the radiopacifying agent. The resin matrix combined UDMA with triethylene glycol dimethacrylate (UDMA:TEGDMA) at ratios of 20:80, 30:70, 50:50, 60:40, 80:20, and 90:10. Commercial FCs, including Revolution Formula 2, G-aenial Universal Flo, and Filtek Supreme Flowable Composite, were used for comparison. The newly developed FCs were categorized into high (20:80, 30:70), medium (50:50, 60:40), and low-flow (80:20, 90:10), based on the flowability evaluation. These newly developed FCs were subsequently characterized for their chemical, physical, and mechanical properties, as well as polymerization shrinkage. Data were statistically analyzed using one-way ANOVA, followed by posthoc Tukey or Games-Howell tests for comparison, except for the depth of cure, which was analyzed using the Kruskal-Wallis. The chemical properties, assessed through Fourier transform infrared (FTIR) and degree of conversion analyses, confirmed the presence of silica and zirconia in the newly developed FCs and showed an increase in the degree of conversion with higher UDMA ratios (55.38 – 68.58%). The physical properties evaluated included radiopacity, viscosity, depth of cure, surface roughness, water sorption and solubility, and wettability. The newly developed FCs at all ratios were radiopaque (2.87 – 3.06 mmAl) and passed the International Organization for Standardization 4049 (ISO 4049) requirement. As the UDMA ratio in the newly developed FCs increased, both viscosity and depth of cure increased Improved surface roughness and reduced water sorption were also observed with higher UDMA ratios. For solubility, the values were independent of the UDMA ratios. Wettability, assessed through contact angle measurements, revealed a significant increase in contact angle after polymerization, indicating a shift from hydrophilic (24.218 – 50.617º) to more hydrophobic behaviour (85.901 – 88.669º). The mechanical properties evaluated included Vickers hardness, flexural strength and modulus, and compressive strength and modulus. Most properties improved with increasing UDMA ratios, with some flexural strength values (79.61 – 102.1 MPa) meeting the requirement of ISO 4049. Polymerization shrinkage was also reduced as the UDMA ratio increased. Overall, higher UDMA ratios (80:20, 90:10) exhibited superior chemical, physical, and mechanical properties, along with reduced polymerization shrinkage. Moderate (50:50, 60:40) and lower UDMA ratios (20:80, 30:70) demonstrated intermediate and inferior performance, respectively. These findings suggest that the newly developed FCs, particularly at higher UDMA ratios, could serve as viable alternatives to commercially available FCs, supporting a green-based industry that reduces waste and promotes sustainabilit
Investigating the validation, reliability and usability of automated method for testing auditory sensitivity (AMTAS) with malay instructional video in clinical and non-clinical settings
No full textThe Automated Method for Testing Auditory Sensitivity (AMTAS) is a self-administered hearing assessment tool that utilizes a tablet, headphones, and AMTAS software to determine hearing thresholds. While AMTAS has been validated internationally for over two decades and has shown strong potential, such research has never been conducted in Malaysia. This study aimed to assess the validity, reliability, and usability of AMTAS with a Malay instructional video among Malaysian adults through three phases. Phase I involved the verbatim translation of AMTAS instructional video and face validation of the Malay version of the mHealth App Usability Questionnaire (M-MAUQ). Based on responses from 30 participants (mean age = 45.62 ± 14.13 years), the face validity index (FVI) was 0.98 for both Item-FVI and Scale-FVI, indicating excellent clarity and comprehensibility. Phase II, conducted in clinical settings at Hospital Tuanku Ja’afar Seremban (HTJS) and Hospital Rembau (HR), assessed validity by comparing AMTAS and pure-tone audiometry (PTA) thresholds, reliability through AMTAS test-retest measurements, and usability using M-MAUQ. A total of 100 participants (mean age 44.72 ± 14.13) underwent validation testing, while 30 participants (mean age 44.43 ± 14.63) participated in reliability testing. All 130 participants were included in the usability testing. For validity, the mean difference between AMTAS and PTA thresholds ranged from 0.30 dB HL to 3.40 dB HL, with over 95% of results within an acceptable ±10 dB difference. Agreement in hearing loss severity between AMTAS and PTA was high (Kappa = 0.95-0.96). Reliability demonstrated good consistency across all frequencies with intraclass correlation coefficient (ICC) ranged from 0.64 to 0.99. Phase III replicated Phase II in a non-clinical setting at a community centre, involving 22 participants for validation (mean age = 27.41 ± 7.92) and 15 for reliability (mean age = 26.82 ± 8.29). The mean difference between AMTAS and PTA thresholds ranged from 3.18 dB HL to 7.50 dB HL, with strong reliability (ICC > 0.80). Usability showed high ratings in both Phase II and III, with mean scores exceeding 6.0 (out of 7.0) across all domains, reflecting high user satisfaction and feasibility. AMTAS testing was also significantly faster than PTA, reducing test time by an average of 3.03 minutes per person in clinical settings and 2.68 minutes in non-clinical settings. In conclusion, AMTAS meets the standards of conventional PTA in terms of validity, reliability, and usability, supporting its potential for wider use in clinical and non-clinical settings among the Malaysian populatio