Determination of Ambient Dose Equivalent Using a Microprocessor-Controlled Universal Reference-Class Dosemeter

Collins Kafui Azah; Daniel  Adjei; Philip Deatanyah; Samuel Osei; Prince Marcus  Appiah; Joseph Kwabena  Amoako; Frederick Sam; Christiana Subaar; Anthony  Amable

doi:10.4314/just.v43i1.1765

Collins Kafui Azah Ghana Atomic Energy Commission https://orcid.org/0000-0002-1346-3624
Daniel Nii Adjei Ghana Atomic Energy Commission https://orcid.org/0009-0006-3085-0219
Philip Deatanyah Ghana Atomic Energy Commission https://orcid.org/0000-0003-4670-3329
Samuel Osei Ghana Atomic Energy Commission https://orcid.org/0000-0003-4322-8489
Prince Marcus Appiah https://orcid.org/0009-0000-4778-8470
Joseph Kwabena Amoako University of Ghana, Legon https://orcid.org/0000-0003-0797-0045
Frederick Sam University of Cape Coast, Ghana https://orcid.org/0000-0002-6778-1978
Christiana Subaar Kwame Nkrumah University of Science and Technology https://orcid.org/0000-0003-1158-5780
Anthony Selorm Kwesi Amable University of Health and Allied Sciences https://orcid.org/0000-0002-2587-0534

DOI: https://doi.org/10.4314/just.v43i1.1765

Keywords: Air kerma, ambient dose equivalent, ionisation chamber, offset current

Abstract

Ambient dose equivalent is determined at nine source-to-detector distances in a Secondary Standard Dosimetry Laboratory in a Cs-137 beam using a Physikalisch-Technische-Werkstaetten (PTW) ionisation chamber and Unidos electrometer as a measuring assembly. This work aims to estimate the gamma ambient dose equivalent resulting from air kerma rate distributions and subject the data generated to counting statistics to determine whether these data reflect proper instrument operation. The method of varying the source-to-detector distances was used. From the results, the total kinetic energy of all charged particles liberated by uncharged incident radiation per unit mass of material of the ionisation chamber ranged from 0.3168 ± 0.0146 μGy/s at an SSD of 1.0 m to 0.0151 ± 0.0007 μGy/s at 5.0 m within two standard deviations. The coefficient of variation among the various datasets ranged from 0.05% to 0.31%. Counting statistics of the generated data reflects proper measuring system operation and reliability. It is proposed that, in between calibrations, dosimetrists should consider relying upon counting statistics to check the output of their ionisation chambers for conformance to statistical laws.

Author Biographies

Collins Kafui Azah, Ghana Atomic Energy Commission

Collins Kafui Azah is a practicing Health Physicist and Research scientist with the Radiation Protection Institute of the Ghana Atomic Energy Commission. He is the head of Ghana Secondary Standard Dosimetry Laboratory (SSDL); a member of the WHO/IAEA global Network of SSDLs providing traceability of radiation detecting and measuring devices to the international system of units. He is a member of Ghana Association for Radiation Protection (GARP), International Radiation Protection Association (IRPA), and Ghana Nuclear Society (GNS). Research objectives: Radiation protection of people and the environment, Radiation metrology; Radiofrequency safety assessment; and Radiation dosimetry.

Daniel Nii Adjei, Ghana Atomic Energy Commission

Daniel N. Adjei is a scientist at the Radiation Protection Institute (RPI) of the Ghana Atomic Energy Commission (GAEC). He has professional experience in the field of radiation protection, nuclear safety and security; particularly in research and development, education and training and advisory services. He is a member of the Ghana Nuclear Society (GNS) and the Ghana Association for Radiation Protection (GARP). His research interests include radiation s, radiation dosimetry, radiation detector calibration and studies of physical protection systems and security culture at nuclear installations.

Philip Deatanyah, Ghana Atomic Energy Commission

Philip Deatanyah is a Lecturer and a radiation protection physicist at the Department of Nuclear Safety and Security at the graduate school of nuclear and Allied Sciences (SNAS), Atomic, Ghana. His area of expertise is in Radiation Shielding and Non-Ionizing radiation Safety. He is a member of the Ghana Nuclear Society (GNS) and Internation Association of Radiation Protection (IRPA). He collaborates with scientists in universities and sister institutions.

Samuel Osei, Ghana Atomic Energy Commission

Samuel Osei is a research scientist and EMF expert at the Radiation Protection Institute (RPI) of the Ghana Atomic Energy Commission. His research areas include ionizing and non- ionizing radiation, radiation physics, and health physics. His expertise incorporates electromagnetic fields, radiation protection and safety, calibration of radiation measuring instruments, radiation dosimetry, radiation safety education and training, and radiation measurement. He is a member of the Technical Industry Working Group of the National Communications Authority (NCA) and a principal representative on the Telecommunications Infrastructure and Network Systems subcommittee of the Ghana Standards Authority (GSA). Samuel is a member of the Ghana Association for Radiation Protection (GARP) and the Ghana Nuclear Society (GNA).

Prince Marcus Appiah

Prince Appiah is a Senior Technologist in Ghana Secondary Standard Dosimetry Laboratory (SSDL) with expertise in radiation protection and measurement. He has calibrated thousands of survey meters and nuclear density gauges in his course of work at the SSDL.

Joseph Kwabena Amoako, University of Ghana, Legon

Joseph .K. Amoako holds a BSc (Hons) degree in Physics and a Diploma in Education from the University of Cape Coast; an M.Phil. in Physics from the University of Ghana, Legon, and a Ph.D. in Physics from the University of Cape Coast. He also holds a Post Graduate Diploma in Radiation Protection from the University of Witwatersrand Johannesburg, South Africa. He undertook fellowship training in Occupational Radiation Protection at the Greek Atomic Energy Commission. He is currently, an Associate Professor in Health Physics at the School of Nuclear and Allied Sciences, University of Ghana. He is the President of the Ghana Association for Radiation Protection and an Executive Council member of the International Radiation Protection Association

Frederick Sam, University of Cape Coast, Ghana

Frederick Sam is an Associate Professor in the Department of Physics, University of Cape Coast, Ghana and also serves as the Vice Dean of the School of Physical Sciences, a position he has held since August 2022. Prof. Sam holds a PhD in Solid Earth Physics from the University of Birmingham, UK, an MPhil in Geophysics from the University of Bergen, Norway, B.Sc. (Hons) in Physics and Dip Ed. from the University of Cape Coast, Ghana. His academic excellence has been recognized with awards such as the Commonwealth Scholarship and the Norwegian Government Scholarship. He is an active member of several professional bodies, including the International Association of Hydrogeologists (IAH), Ghana Institute of Physics (GIOP) and Ghana Science Association (GSA).

Christiana Subaar, Kwame Nkrumah University of Science and Technology

Christiana Subaar is a Lecturer and a Medical Physicist at the Department of Physics at the Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana. Her research focuses on radiation safety and pathophysiology. Expertise includes MRI, Radiation Dosimetry, and Radiation Therapy. She is a member of the Ghana Science Association (GSA) and the Ghana Society for Medical Physics (GSMP), and continues to establish cooperative relationships with scientists at the Ghana Atomic Energy Commission (GAEC).

Anthony Selorm Kwesi Amable, University of Health and Allied Sciences

Anthony S.K. Amable is a Lecturer and a Physicist at the Department of Basic Sciences at the University of Health and Sciences, Ho-Volta Region, Ghana. His research focuses on non- ionizing and ionizing, stopping power and range computations. Expertise includes radon, natural radioactivity and Radiation Dosimetry. He is a member of the Ghana Science Association (GSA), and MathTech Thinking Foundation (MTTF), and has continuous research cooperation with scientists at the Ghana Atomic Energy Commission (GAEC).