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Fulltext Determination of the Small-Field Output Factor for 6 MV Photon Beam Using EGSnrc Monte Carlo

Chuah KW, Abdul Aziz MZ, Jayamani J

J Med Phys, 2022;47(3):301-308.
PMID: 36684700 DOI: 10.4103/jmp.jmp_40_22

Accuracy of ionization chamber (IC) to measure the scatter output factor (Scp) of a linear accelerator (linac) is crucial, especially in small field (<4 cm × 4 cm). The common IC volume of 0.6 cc is not adequate for small-field measurement and not all radiotherapy centers can afford to purchase additional IC due to the additional cost. This study aimed to determine the efficiency of the EGSnrc Monte Carlo (MC) to calculate the Scp for various field sizes including small field in Elekta Synergy (Agility multileaf collimator) linac. The BEAMnrc and DOSXYZnrc user codes were used to simulate a 6 MV linac model for various field sizes and calculate the radiation dose output in water phantom. The modeled linac treatment head was validated by comparing the percentage depth dose (PDD), beam profile, and beam quality (Tissue Phantom Ratio (TPR)20,10) with the IC measurement. The validated linac model was simulated to calculate the Scp consisting of collimator scatter factor (Sc) and phantom scatter factor (Sp). The PDD and beam profile of the simulated field sizes were within a good agreement of ±2% compared with the measured data. The TPR20,10 value was 0.675 for field size 10 cm × 10 cm. The Scp, Sc, and Sp simulated values were close to the IC measurement within ±2% difference. The simulation for Sc and Sp in 3 cm × 3 cm field size was calculated to be 0.955 and 0.884, respectively. In conclusion, this study validated the efficiency of the MC simulation as a promising tool for the Scp calculation including small-field size for linac.
Fulltext Monte Carlo dose calculation in dental amalgam phantom

Aziz MZ, Yusoff AL, Osman ND, Abdullah R, Rabaie NA, Salikin MS

J Med Phys, 2015 Jul-Sep;40(3):150-5.
PMID: 26500401 DOI: 10.4103/0971-6203.165080

It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC). On the other hand, computed tomography (CT) images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax) using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation.
Lateral wedge with medial only cardiac shielding (LEMONADE) technique in left chest wall adjuvant radiotherapy

Abdullah R, Appalanaido GK, Shukor SA, Zin HM, Abd Aziz MZ, Ishak N

Rep Pract Oncol Radiother, 2021;26(6):892-898.
PMID: 34992860 DOI: 10.5603/RPOR.a2021.0105

Background: This dosimetric study compared lateral wedge with medial only cardiac shielding (LEMONADE) technique, for left chest wall (LCW) irradiation against three other commonly used techniques.
Materials and methods: Dosimetric parameters of 22 consecutive LBC patients treated using the P1 (LEMONADE technique) were compared with 3 other virtually reconstructed plans : no cardiac shielding with paired wedges; P2 (paired wedges and medial only Y-direction shielding) and P3 (paired wedges and bilateral Y-direction shielding).
Results: P1 showed better target volume (TV) coverage with the mean 90% isodose coverage of 85.59% ± 5.44 compared to 78.90% ± 8.59 and 74.22% ± 9.50 for P2 and P3, respectively. Compared to no cardiac shielding, for a 4.65% drop in TV coverage the V26Gy of heart dropped from 6.68% to a negligible 0.85% for P1. TV receiving < 30Gy is also significantly lesser for P1 compared to P2 and P3 (5.42% vs 10.64% and 15.8%), whilst there is a small difference of 2.75% between no cardiac shielding and P1.
Conclusion: With the improvement in BC survival rate, cardiac toxicity associated with adjuvant irradiation for LBC is a major concern. P1 (LEMONADE) technique has a good compromise between cardiac sparing and target coverage and should suffice for most LCW irradiations. Furthermore, the LEMONADE technique is a simple, reproducible and involves fast planning for cardiac sparing, which is ideal for under-resourced departments with heavy workload.
Photon dose rate distribution inside and outside a brachytherapy room

Aminordin Sabri AH, Mohamad Tajudin S, Abdul Aziz MZ, Furuta T

Radiol Phys Technol, 2023 Mar;16(1):109-117.
PMID: 36729272 DOI: 10.1007/s12194-023-00703-8

In a brachytherapy room irradiated with an Iridium-192 (192Ir) source, the spatial distributions of photon dose rates were measured and calculated for the dose distribution both inside and outside the room. The spatial distributions were measured using a thermoluminescent dosimeter (LiF-100) on the surfaces of the concrete walls and barriers of the irradiation room. The calculations were performed using the particle and heavy ion transport code system (PHITS) by considering the detailed model of the brachytherapy room and the radiation source used in the measurements. The measured and calculated doses exhibited a similar distribution pattern within and outside the brachytherapy room. To reduce the edge effect at the entrance door, the addition of a 3-mm thick lead layer on the surface of the concrete wall on the left doorstop is recommended. For the 60Co source, with the existing walls and lead door thickness, the dose at the control console and in front of the entrance maze increased by a factor of approximately 60.
Fulltext Experiences and Expectations of the Characteristics of Friendly Primary Health Services from the Perspective of Men: A Phenomenological Qualitative Study

Ab Aziz MZ, Tengku Ismail TA, Ibrahim MI, Yaacob NM, Mohd Said Z

Int J Environ Res Public Health, 2022 Sep 29;19(19).
PMID: 36231727 DOI: 10.3390/ijerph191912428

Inadequate men's engagement with health services may be influenced by unmet needs and demands of the local men's community. This study aimed to explore men's experiences with primary health services and their expectations of the characteristics of friendly primary health services, from the perspective of men in Kelantan, Malaysia. A qualitative study using in-depth interviews was conducted with 15 men from six primary health facilities in Kelantan, Malaysia, who were selected based on maximum variation sampling. The data were transcribed and analyzed using the thematic analysis method. The study found that experiences with the existing primary health services were categorized into four subthemes: provision of health services, health promotion delivery, attributes of healthcare providers, and the physical environment of the health facilities. Meanwhile, the expectations of the characteristics of friendly primary health services were categorized into four subthemes: meeting the needs of men in primary health services, approaching men through effective health promotion strategies, standards of a healthcare provider from the viewpoint of men, and a comfortable physical environment for men. Prior experiences hugely influenced men's expectations of friendly primary health services. Men want these health service characteristics customized to meet their needs, allowing them to use health services with confidence and comfort. Thus, to strengthen primary health services for men, it is essential to comprehend their prior experiences with and expectations of the services.
Dose perturbation effects by metal hip prosthesis in gynaecological 192Ir HDR brachytherapy

Ab Shukor NS, Abdullah R, Abdul Aziz MZ, Samson DO, Musarudin M

Appl Radiat Isot, 2023 Jun;196:110751.
PMID: 36871495 DOI: 10.1016/j.apradiso.2023.110751

The present study was conducted to elucidate the effects of hip prostheses in 192Ir HDR brachytherapy and determine dose uncertainties introduced by the treatment planning. A gynaecological phantom irradiated using Nucletron 192Ir microSelectron HDR source was modeled using MCNP5 code. Three hip materials considered in this study were water, bone, and metal prosthesis. According to the obtained results, a dose perturbation was observed within the medium with a higher atomic number, which reduced the dose to the nearby region.
Fulltext Re-irradiation Using Stereotactic Radiotherapy: A Bibliometric Analysis of Research Trends

Mohamed Yoosuf AB, Ajmal Khan M, Abdul Aziz MZ, Mansor S, Appalanaido GK, Alshehri S, et al.

Cureus, 2023 May;15(5):e39600.
PMID: 37384098 DOI: 10.7759/cureus.39600

The objective of this research is to conduct a comprehensive bibliometric analysis using the Web of Science Core Collection (WoSCC) to examine the current research topics and trends pertaining to stereotactic-based re-irradiation. A bibliometric search was conducted for re-irradiation-related literature published in English from the WoSCC database from 1991 to 2022, using VOSviewer to visualize the results. The extracted information comprises the publication year, overall citation count, average citation rate, keywords, and research domains. We conducted a literature review to identify trends in research on re-irradiation. A total of 19,891 citations were found in 924 qualifying papers that came from 48 different nations. The number of publications and citations has grown steadily since 2008 with the highest number of publications in the year 2018. Similarly, a substantial increase in the number of citations has increased since 2004 and the citation growth rate has been positive between 2004 and 2019 with a peak in 2013. The top authorship patterns were six authors (111 publications and 2498 citations), whereas the highest number of citations per publication was attained with an authorship pattern of 17 authors (C/P = 41.1). The collaboration patterns analysis showed that the largest proportion of publications emanated from the United States with 363 publications (30.9%), followed by Germany with 102 publications (8.7%), and France with 92 publications (7.8%). The majority of the analyzed studies were focused on the brain (30%), head and neck (13%), lung (12%), and spine (10%) and there have been emerging studies on the use of re-irradiation for lung, prostate, pelvic and liver utilizing stereotactic radiotherapy. The main areas of interest have changed over time and are now based on a multidisciplinary approach that integrates advanced imaging techniques, stereotactic treatment delivery, the toxicity of organs at risk, quality of life, and treatment outcomes.
Effectiveness of Robotic Stereotactic Radiotherapy in Patients Undergoing Re-irradiation: A Review

Mohamed Yoosuf AB, Alshehri S, Abdul Aziz MZ, Mansor S, Appalanaido GK, Alqathami M

Cureus, 2023 Aug;15(8):e43500.
PMID: 37719625 DOI: 10.7759/cureus.43500

Stereotactic ablative radiotherapy (SABR) is a possible treatment option for patients who develop recurrence within or at the edge of a previously irradiated volume. Robotic stereotactic radiotherapy is the result of technological advances in robotic precision, real-time imaging, non-invasive, highly customizable treatment plan, and delivery with sub-millimeter accuracy. This article reviews the radiobiologic, technical, and clinical aspects of robotic-based SABR re-irradiation for various anatomical sites. An extensive literature search was performed to identify articles on the utilization of robotic stereotactic radiotherapy for patients undergoing re-irradiation. The reported prescription dose and fractionation data along with outcomes such as overall survival, local control rates, and toxicities were qualitatively reviewed. The findings consistently indicate that re-irradiation using robotic SABR provides encouraging survival rates with minimal toxicity in the clinical setting of various anatomical sites delivered using locally non-invasive means where other treatment options are scarce.
Fulltext Performance of natural product-based materials as adhesives in the fabrication of mangrove wood composites

Samson DO, Shukri A, Aziz Hashikin NA, Zuber SH, Addo Buba AD, Abdul Aziz MZ, et al.

Heliyon, 2023 Jan;9(1):e13032.
PMID: 36711293 DOI: 10.1016/j.heliyon.2023.e13032

Biodegradable adhesives prepared using three different forms of soy protein-based products (defatted soy flour/soy protein concentrate/soy protein isolate), sodium hydroxide, and itaconic acid polyamidoamine-epichlorohydrin (IA-PAE) with 0 wt%-20 wt% substitution rates were utilized to enhance the production of mangrove wood composites. 1H nuclear magnetic resonance, differential scanning calorimetry, and ultra-high-resolution field emission scanning electron microscopy were employed to characterize the composite samples. Other measurements involved the determination of viscosity, pH, physical, mechanical, dimensional stability, CT numbers, and relative electron density parameters. The ideal curing conditions for the composite bio-adhesives were found to be 15 wt% IA-PAE, 602.50 ± 172.21-391.11 ± 105.82 mPa s, pH 11.0, 180 °C, and 18 min, respectively. The improved physiochemical characteristics of DSF, SPC, and SPI confirmed that NaOH/IA-PAE was integrated into the adhesive system and ameliorated the overall performance of the resulting composites. The results showed that all composite samples, except for those bonded with 0 wt% and 5 wt% IA-PAE, matched up with the quality specification stated in the JIS A-5908 and ASTM D1037. Samples D1, D2, and D3 exhibited optimum characteristics, demonstrating their uses in the development of low-toxicity and sustainable reference tissue substitute phantom in radiological areas.