10 results on '"Alkhorayef, Mohammed"'
Search Results
2. Committed effective dose to the Kuwaiti population via the dietary intake of red meat
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Alrefae, Tareq, Nageswaran, Tiruvachi N., Demir, Nasser S., Khandaker, Mayeen Uddin, Bradley, David A., Alkhorayef, Mohammed, and Alzimami, Khalid S.
- Published
- 2018
- Full Text
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3. The potential use of three photon positron annihilation in positron emission tomography for tumour hypoxia imaging
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Alkhorayef, Mohammed A.
- Subjects
615.84 - Abstract
Identifying and localising tumor hypoxia in cancer patients is a challenge in oncology imaging. There are many ongoing clinical trials using conventional positron emission tomography (PET) scans and PET agents as cellular markers for detection of tumour hypoxia depending on the concept of the basic physics of 2gamma annihilation. However, Kacperski and Spyrou (2004) proposed, for the first time, to use 3gamma annihilation as a new PET molecular imaging modality, where the positronium and its annihilation, could serve as an oxygen-sensitive marker. The effective yield of 3gamma annihilation depends on the rates of formation and quenching. The formation of positronium is not only sensitive to the physics parameters, but also behaves as an active chemical particle. A hypoxic cell is a microenviromnent which has an inadequate amount of oxygen. Oxygen is known to be a strong positronium quencher where 2gamma annihilation replaces the 3gamma process. It is thus possible for hypoxic cells to be characterised by higher 3gamma rates than those cells which are well oxygenated. The measurement of 3gamma annihilation to differentiate between oxygenated and non-oxygenated biological samples in order to extract useful information in PET for oncology is a challenging project. It opens up very interesting applications in nuclear medicine imaging as the 3gamma yield has not been measured before in biological tissue and in particular hypoxic tumour cells. The project is multidisciplinary involving physics, biology and chemistry. There are many factors which affect the dissolved oxygen in mineral water, defibrinated horse blood and serum samples. These factors and the challenges to prepare in-vitro hypoxic samples have been experimentally measured using polarography with different chemical reactions e.g. carbon dioxide, nitrogen and AnaeroGen(TM). Results have shown that polarography was more suitable than colorimetery in the measurement of dissolved oxygen in blood due to the high absorption characteristic of blood. AnaeroGen(TM) is the method of choice, unlike carbon dioxide or nitrogen treatment, for preparing hypoxic samples due to the good agreement of the behaviour of the oxygen reduction as in the oxyhaemoglobin dissociation curve which is caused by a decrease in pH, an increase in partial pressure of carbon dioxide and an increase in temperature. The 3gamma yield was measured in normoxic and hypoxic environments using the triple coincidence measurement of three high-energy resolution detectors (HPGe). The AnaeroGen(TM) was used to generate a hypoxic environment. The percentage of the coincidence events qualified as 3gamma was 26.5% higher in the hypoxic environment. This reseach work is a step towards the application of the novel modality of 3gamma PET which in conjunction with conventional 2gamma PET could serve as a non-invasive oxygen sensitive marker. The combination of 3gamma and 2gamma coincidences in nuclear medicine imaging systems may contribute important information for the development and validation of appropriate hypoxia markers. The relative 3gamma/2gamma yield was measured for a positron emitter 22Na with the new generation of scintillator LaC13:Ce and LaBr3:Ce detectors, which had been characterised together with NaI(Tl) and HPGe detectors. The experimental focus was on measuring the relative 3gamma/2gamma yield in different samples by applying the peak-to-peak and the peak-to-valley methods. The value of the ratio 3gamma/2gamma depends on the specimen and is of the order of 10-2. The relative 3gamma/2gamma yields obtained for the peak to peak method in the silica sample were, for example, (3.41+/-0.18)x10 -2, (2.98+/-0.13)x10-2, (4.01+/-0.16)x10 -2 and (2.12+/-0.14)x10-2 for LaBr3:Ce, LaCl3:Ce, NaI(Tl) and HPGe detectors, respectively. The results show that the lanthanum based crystals, LaBr3:Ce and LaCl3:Ce, have the potential to replace NaI(Tl) and HPGe due to both good energy resolution and good detection efficiency and can be the scintillator of choice for determining the yield of 3gamma. The peak-to-valley method was applied to measure the relative yield of 3gamma/2gamma positron annihilation using 18F in 11 haematological samples of different oxygenation levels. The relative 3gamma/2gamma yield was found to vary as much as 11% between the components investigated.
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- 2010
4. Safety Survey on Lone Working Magnetic Resonance Imaging Technologists in Saudi Arabia
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Alghamdi, Sami A., primary, Alshamrani, Saad A., additional, Alomair, Othman I., additional, Alashban, Yazeed I., additional, Abujamea, Abdullah H., additional, Mattar, Essam H., additional, Almalki, Mohammed, additional, and Alkhorayef, Mohammed, additional
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- 2023
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5. Monte Carlo Simulation of 6MV Varian Clinac Photon Beam Using GEANT4-GATE
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Gonias Panagiotis, Kappas Constantin, Theodorou Kiki, Sulieman Abdelmoneim, Alkhorayef Mohammed, and Zaverdinos Panagiotis
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Physics ,Monte Carlo method ,Photon beam ,Computational physics - Published
- 2020
6. Favorable therapeutic response of osteoporosis patients to treatment with intravenous zoledronate compared with oral alendronate
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Al-Bogami, Mohammed M., primary, Alkhorayef, Mohammed A., additional, Bystrom, Jonas, additional, Akanle, Olufunso A., additional, Al-Adhoubi, Nasra K., additional, Jawad, Ali S., additional, and Mageed, Rizgar A., additional
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- 2015
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7. Medical Imaging and Image-Guided Interventions
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Sulieman, Abdelmoneim and Alkhorayef, Mohammed
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Medical / Diagnostic Imaging - Abstract
The discovery of X-rays at the end of the nineteenth century is one of the most important discoveries that changed the human being life in all fields and applications. Since that date, X-ray systems are developed rapidly, and still new applications are emerging in medical, agricultural, and industrial fields. This chapter provides sufficient historical background for X-ray production and image acquisition techniques. It covers also fluoroscopic equipment and radiation dosimetry and protection techniques in detail. Image-guided intervention is here to stay. Thus, suitable radiation protection measures are required to minimize the risk to patients and staff to its minimal level without affecting the outcome of the procedures.
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- 2020
8. "To-and-fro" waveform in the diagnosis of arterial pseudoaneurysms.
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Mahmoud MZ, Al-Saadi M, Abuderman A, Alzimami KS, Alkhorayef M, Almagli B, and Sulieman A
- Abstract
Medical ultrasound imaging with Doppler plays an essential role in the diagnosis of vascular disease. This study intended to review the clinical use of "to-and-fro" waveform at duplex Doppler ultrasonography (DDU) in the diagnosis of pseudoaneurysms in the arterial vessels of upper and lower extremities, abdominal aorta, carotid and vertebral arteries as well as to review our personal experiences of "to-and-fro" waveform at DDU also. After receiving institutional review board approval, an inclusive literature review was carried out in order to review the scientific foundation of "to-and-fro" waveform at DDU and its clinical use in the diagnosis of pseudoaneurysms in various arterial vessels. Articles published in the English language between 2000 and 2013 were evaluated in this review study. Pseudoaneurysms in arterial vessels of the upper and lower extremities, abdominal aorta, carotid and vertebral arteries characterized by an extraluminal pattern of blood flow, which shows variable echogenicity, interval complexity, and "to-and-fro" flow pattern on color Doppler ultrasonography. In these arterial vessels, Duplex ultrasonography can demonstrate the degree of clotting, pseudoaneurysm communication, the blood flow patterns and velocities. Spectral Doppler applied to pseudoaneurysms lumen revealed systolic and diastolic turbulent blood flow with traditional "to-and-fro" waveform in the communicating channel. Accurate diagnosis of pseudoaneurysm by spectral Doppler is based on the documentation of the "to-and-fro" waveform. The size of pseudoaneurysm determines the appropriate treatment approach as surgical or conservative.
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- 2015
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9. High-Intensity Focused Ultrasound (HIFU) in Localized Prostate Cancer Treatment.
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Alkhorayef M, Mahmoud MZ, Alzimami KS, Sulieman A, and Fagiri MA
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Background: High-intensity focused ultrasound (HIFU) applies high-intensity focused ultrasound energy to locally heat and destroy diseased or damaged tissue through ablation. This study intended to review HIFU to explain the fundamentals of HIFU, evaluate the evidence concerning the role of HIFU in the treatment of prostate cancer (PC), review the technologies used to perform HIFU and the published clinical literature regarding the procedure as a primary treatment for PC., Material/methods: Studies addressing HIFU in localized PC were identified in a search of internet scientific databases. The analysis of outcomes was limited to journal articles written in English and published between 2000 and 2013., Results: HIFU is a non-invasive approach that uses a precisely delivered ultrasound energy to achieve tumor cell necrosis without radiation or surgical excision. In current urological oncology, HIFU is used clinically in the treatment of PC. Clinical research on HIFU therapy for localized PC began in the 1990s, and the majority of PC patients were treated with the Ablatherm device., Conclusions: HIFU treatment for localized PC can be considered as an alternative minimally invasive therapeutic modality for patients who are not candidates for radical prostatectomy. Patients with lower pre-HIFU PSA level and favourable pathologic Gleason score seem to present better oncologic outcomes. Future advances in technology and safety will undoubtedly expand the HIFU role in this indication as more of patient series are published, with a longer follow-up period.
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- 2015
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10. High-Intensity Focused Ultrasound (HIFU) in Uterine Fibroid Treatment: Review Study.
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Mahmoud MZ, Alkhorayef M, Alzimami KS, Aljuhani MS, and Sulieman A
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Background: High-intensity focused ultrasound (HIFU) is a highly precise medical procedure used locally to heat and destroy diseased tissue through ablation. This study intended to review HIFU in uterine fibroid therapy, to evaluate the role of HIFU in the therapy of leiomyomas as well as to review the actual clinical activities in this field including efficacy and safety measures beside the published clinical literature., Material/methods: An inclusive literature review was carried out in order to review the scientific foundation, and how it resulted in the development of extracorporeal distinct devices. Studies addressing HIFU in leiomyomas were identified from a search of the Internet scientific databases. The analysis of literature was limited to journal articles written in English and published between 2000 and 2013., Results: In current gynecologic oncology, HIFU is used clinically in the treatment of leiomyomas. Clinical research on HIFU therapy for leiomyomas began in the 1990s, and the majority of patients with leiomyomas were treated predominantly with HIFUNIT 9000 and prototype single focus ultrasound devices. HIFU is a non-invasive and highly effective standard treatment with a large indication range for all sizes of leiomyomas, associated with high efficacy, low operative morbidity and no systemic side effects., Conclusions: Uterine fibroid treatment using HIFU was effective and safe in treating symptomatic uterine fibroids. Few studies are available in the literature regarding uterine artery embolization (UAE). HIFU provides an excellent option to treat uterine fibroids.
- Published
- 2014
- Full Text
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