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Computed Tomography Protocol Optimisation for Pediatric Head Trauma: Radiation Dose and Image Quality Assessment

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology 2022年第3期11卷 160-175页

作者： Evelyn Anaafi Mary Boadu Albertina Rusandu Mercy Afadzi kwame anokye amoabeng Department of Medical Physics Graduate School of Nuclear and Allied Sciences University of Ghana Legon Sweden-Ghana Medical Center Accra Ghana Department of Circulation and Medical Imaging Norwegian University of Science and Technology (NTNU) Trondheim Norway Department of Physics Norwegian University of Science and Technology (NTNU) Trondheim Norway National Centre for Radiotherapy and Nuclear Medicine Korlebu Teaching Hospital Accra Ghana

Purpose: Children are sometimes examined with Computed Tomography protocols designed for adults, leading to radiation doses higher than necessary. Lack of optimisation could lead to image quality higher than what is needed for diagnostic purposes with associated high doses to patients. Optimising the protocols for paediatric head trauma CT imaging will reduce radiation dose. Objective: The study aimed to optimise radiation dose and assess the image quality for a set of protocols by evaluating noise, a contrast to noise ratio, modulation transfer function and noise power spectrum. Methods: Somaton Sensation 64 was used to scan the head of an anthropomorphic phantom with a set of protocols. ImageJ software was used to analyse the paediatric head image from the scanner. IMPACTSCAN dosimeter software was used to evaluate the radiation dose to the various organs in the head. MATLAB was used to analyse the Modulation Transfer Function and the Noise Power. Results: The estimated Computed Tomography Dose Index volume (CTDIvol) increased with increasing tube current and tube voltage. The high pitch of 0.9 gave a lower dose than the 0.5 pitch. The eye lens received the highest radiation dose (39.2 mGy) whiles the thyroid received the least radiation dose (13.7 mGy). There was an increase in noise (62.46) when the H60 kernel was used and a lower noise (8.829) was noticed when the H30 kernel was used. Conclusion: The results obtained show that the H30 kernel (smooth kernel) gave higher values for noise and contrast to noise ratio (CNR) than the H60 kernel (sharp kernel). The H60 kernel produced high values for the modulation transfer function (MTF) and noise power spectrum (NPS). The eye lens received the highest radiation dose.

关键词： Image Quality Radiation Dose Modulation Transfer Function Noise Power Spectrum Optimization

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Assessment of Monitor Units and Gamma Pass Rate for 6 MV and Flattening Filter Free (FFF) Beams in Volumetric Modulated Arc Therapy (VMAT)

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International Journal of Medical Physics, Clinical Engineering and Radiation Oncology 2023年第1期12卷 1-8页

作者： kwame anokye amoabeng Anne Beate Langeland Marthinsen Francis Hasford Samuel Nii Adu Tagoe Evelyn Anaafi Mark Pokoo-Aikins Theresa Bebaaku Dery The Cancer Center Nassau Bahamas Department of Radiotherapy St. Olav’s University Hospital Trondheim Norway Department of Medical Physics Graduate School of Nuclear and Allied Sciences University of Ghana Accra Ghana National Centre for Radiotherapy and Nuclear Medicine Korle Bu Teaching Hospital Accra Ghana

Background: In linear accelerators, the treatment field’s uniform intensity is achieved by including a flattening filter in the beam. However, to produce more conformal dose distributions, contemporary radiotherapy practice now frequently uses fluence and aperture modifying techniques, such as volumetric modulated arc therapy. In these circumstances, the flattening filter in the beam manufacturing process is no longer required. It is therefore necessary to compare the monitor units of 6 MV and flattening filter free plans and how it influences the gamma pass rates to determine which is best for treating cervical cancer with pelvic lymph node metastasis. Methods: VMAT plans for fifteen patients with cervical cancer with pathological pelvic lymph node metastasis were included in this study. Each patient had two VMAT plans using conventional 6 MV beam with flattening filter and one with flattening filter free beam (FFF). The VMAT plans were made using two arcs, and then recalculated to give the planned dose distribution to the detectors in a Delta4 phantom. The VMAT plans were irradiated on the Delta4 phantom using an Elekta linear accelerator (6 MV). Results: The mean monitor unit for the 6 MV plans was 506.3 MU and a standard deviation of 48.6 while that of the FFF plans had a mean MU of 701.5 with a standard deviation of 87.6. The total monitor units (MUs) for the FFF plans were significantly greater than the 6 MV plans (p = 6.1 × 10-5). Conclusion: Flattening filter free (FFF) plans require more numbers of monitor units in comparison to conventional 6 MV filtered beams for external radiation of cervical cancer with pelvic lymph nodes involvement.

关键词： Monitor Units Gamma Pass Rate Flattening Filter Free Multileaf Collimator

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Analysis of indoor set-point temperature of split-type ACs on thermal comfort and energy savings for office buildings in hot-humid climates

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Energy and Built Environment 2023年第3期4卷 368-376页

作者： KofiOwura amoabeng Richard Opoku Samuel Boahen George Yaw Obeng Department of Mechanical Engineering Kwame Nkrumah University of Science&Technology(KNUST)KumasiGhana Sustainable Energy Service Centre College of EngineeringKNUSTKumasiGhana Technology Consultancy Centre College of EngineeringKNUSTKumasiGhana

In hot-humid climates,particularly in sub-Saharan Africa(SSA),ambient temperatures and relative humidity are as high as 35°C and 84%,respectively,requiring the use of mechanical cooling systems for indoor thermal ***-type vapor-compression air-conditioners(SVAC)are mainly used for space cooling in SSA and consume 60-80%of total energy consumption in commercial and public *** control strategy of the indoor set-point temperature of SVAC can result in significant energy savings in these *** this study,modeling and dynamic simulation have been conducted using EnergyPlus to predict the energy saving potential and indoor thermal comfort of buildings in hot-humid climates by controlling set-point temperature of the *** a case study,climatic data for Ghana,was used to predict the energy saving potential and indoor thermal *** study results revealed that,to ensure indoor thermal comfort at high outdoor temperature condition of 35°C,the least and optimum set-point temperatures of the SVAC should be 21°C and 25°C,*** the other hand,for low outdoor temperature condition,the least and optimum set-point temperatures were 22°C and 26°C,*** 1-star and 2-star rated SVACs which are dominantly used in Ghana,operating at 21-25°C in the case of high outdoor conditions,and 22-26°C for low outdoor conditions relative to the least temperatures resulted in energy savings of 8-33%and 12-44%,respectively.

关键词： Hot-humid climate Air-conditioners Indoor thermal comfort Set-point temperatures Energy savings

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Surgical Management of Herniated Intrathoracic Gastric Perforation in Traumatic Diaphragmatic Rupture: An Unusual Two Rare Cases

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Open Journal of Thoracic Surgery 2020年第2期10卷 56-68页

作者： Isaac Okyere Sanjeev Singh Perditer Okyere Samuel Gyasi Brenu Samuel Kontor amoabeng Department of Surgery Komfo Anokye Teaching Hospital Kumasi Ghana School of Medicine and Dentistry College of Health Sciences Kwame Nkrumah University of Science and Technology and Komfo Anokye Teaching Hospital Kumasi Ghana Department of Anaesthesia and Intensive Care Komfo Anokye Teaching Hospital Kumasi Ghana Department of Medicine Komfo Anokye Teaching Hospital Kumasi Ghana Department of Pharmacy Komfo Anokye Teaching Hospital Kumasi Ghana

Gastric perforation into the thoracic cavity through a diaphragmatic rupture is rare but, when it occurs, patients present in severe distress, with mortality approaching 50%. We present our experience of two rare and unusual cases of traumatic diaphragmatic rupture from penetrating chest injury associated with herniated intrathoracic gastric perforation over a five-year period from January 2015 to December 2020 at the cardiovascular and thoracic surgery department of the Komfo anokye Teaching Hospital in Kumasi, Ghana. Both patients underwent successful surgical repair through standard posterolateral thoracotomy with one having earlier negative exploratory laparotomy. The essence of the paper is to share and discuss the clinical presentation, diagnostic challenges, surgical management and the postoperative care of this very rare complication of traumatic diaphragmatic rupture.

关键词： Diaphragmatic Rupture Gastric Perforation Penetrating Chest Injury Thoracotomy

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