ABSTRACT
The risk of occurrence of cancer in developed and developing nations has become a major concern in the scientific and medical circle. Cancer induction is therefore one of the risk to guard against during medical X-ray exposure. Constant assessment of radiological procedure are thereby crucial in ensuring radiation doses to patients are as low as reasonably achievable. The aim of this study is to determine the patient radiation dose during some X-ray diagnostic procedure in selected centres in North central, Nigeria. These centres include; general hospital Minna (GHM), general hospital Ilorin (GHI) and general hospital Kubwa, FCT (GHK) with a total of 552 patients. The focus to skin distance (FSD), tube potential (kVp) and tube loading (mAs) were measured from the X-ray machine and used to calculate the entrance surface dose, effective dose, absorbed organ dose and the cancer risk index using the Caldose_X 5.0 software. The entrance surface dose (ESD) was also computed using mathematical formula for comparison purpose. Data on sex, age, body mass index (BMI) were recorded for the patients.The obtained results were compared with the documents of international atomic energy agency (IAEA) and other previous studies. The highest and lowest values obtained for ESD were7.10 mGy and 1.00 mGy for GHI and GHM respectively for Caldose_X software while for mathematical estimation, 6.76 mGy and 0.56mGy for GHK and GHM respectively. The effective doses (mSv) for GHI, GHK and GHM ranged from 0.28-0.66, 0.1-0.59 and 0.06-0.37 respectively and the pelvis and breast are with the highest and lowest absorbed organ dose of 2.82 mGy and 0.004 mGy for GHI and GHM respectively. The low dose obtained at GHM is traceable to good radiological practices. The absorbed organ doses when compared with international commission on radiological protection (ICRP) were all within the risk estimates of 35 cancer cases per million cases. The effective dose and ESD shows that for the exception of a few, the patients in selected Nigerian hospitals have their dose within established diagnostic reference levels. For radiation risks and variations in patients dose to be within the recommended limit, quality assurance should be emphasized.
CHAPTER ONE
INTRODUCTION
1.1 Background of Study
Radiation, radioisotopes, and fissionable materials have been of immense benefit to man in medicine, industry, research and power generation. The radionuclides involved include cosmic, which is believed to have originated at the birth of the universe, about 13 to 14 billion years ago, one source is the sun, which emits mainly alpha particles and protons which has increased in subsequent years due to advanced technology (Herman and Thomas, 2009).
According to Turner (2007), the largest proportion of total radiation in the environment comes from natural background (85%) which varies greatly from place to place, followed by medical (diagnostic X-ray, 14%). Environmental radiations, which are due to fallouts from testing of nuclear weapons, and released radionuclides from nuclear accidents, contributes less than 1%.
In November 1895, Roentgen’s discovery of X-ray marks the beginning of ionizing radiation in modern Physics. After this discovery, X-ray rapidly became common in medical usage although it was not immediately obvious that significant or prolonged exposure could be harmful. However, after few years, patients and operator’s record of skin burn became common which gave rise to measures to protect both patients and operators (Turner, 2007). X-rays are made up of X-radiation which is a form of electromagnetic radiation with short wavelength and high frequency. Its interaction with matter results in
the transfer of some of its energy to the atoms and consequently removes electrons from it in a process known as ionization (Akinlade, 2011).
In medicine, diagnosis and therapy are two major uses of ionizing radiation. For diagnostic purposes, X-ray is used to detect; tumors, bone loss, dental issues and also to diagnose infection such as pneumonia, view bones fractures as they contain calcium with high atomic number and thus absorbs this X-ray efficiently. Diagnostic radiation has been a leading cause of man-made radiation exposure to the population (Sherifat and Oyeleke,
2009). Majorly, man-made radiation serves humanity through the use of several medical diagnostic devices, particularly nuclear medicine, X-ray and computed tomography with about 14% of the total radiation burden released from hospitals and medical research institutes (Turner, 2007).
World health organization’s international agency on cancer classified X-rays as carcinogenic because the ionizing radiations involved are responsible for cancerous growth in biological cells. For this reason, cancer induction is one of the risks to guard against during medical X-ray exposure. The risk of cancer induction to an individual during a diagnostic procedure is likely small since radiation doses are typically low (usually <10mGy) as mandated by radiation monitoring and regulatory agencies (Mohamadain et al., 2015). However, a substantial number of cancer cases are caused by the vast number of people exposed annually to these small person threat, combined with growing exposure per examination and repeated procedure. The lifetime risk of developing cancer due to diagnostic X-ray is 0.6-3.2 % (Saeed, 2015) which can surface in an exposed individual’s later years.
Patients’ exposure to radiographic examination and radiation therapy has led to increased background radiation dose and radiation to patients and industrial workers, causing injury and clinical symptoms. Observed radiation injuries include chromosomal transformation, cancer induction, skin burn, cataract, infertility, genetic effect and death but still the health of the population would deteriorate without the use of ionizing radiation techniques to diagnose disease and detect trauma (Ibrahim et al., 2014).
1.2 Statement of the Research Problem
Cancer has been recognized as a significant cause of mortality in developed and developing countries including Nigeria. According to Luntsi et al. (2015) and Adebamowo et al. (2017), the prevalence of cancer in the northern part of Nigeria is at the rate of 12.5% out of 20.7% total incidence. According to the International Atomic Energy Agency (IAEA,
2007), a common factor responsible for high rate of cancer occurrences is exposure to medical ionizing radiation source which provide by far the greatest contribution to artificial population dose (Basmor et al., 2018). About 90% of this contribution comes from diagnostic X-rays Akinlade (2011), revealed that about 70% of Nigerian population undergo X-ray examination either for admission into secondary and tertiary institution, employment or for medical purposes. This continuous exposure has increased the likelihood of cancer occurrence among the Nigerian population. For every X-ray examination a patient undergo, millions of photons (packets of energy) that pass through the body have the potential to damage molecules in the deoxyribonucleic acid (DNA) resulting in the induction of a carcinogenic process (Turner, 2007). Even though the risk to an individual patient may appear not to be significant, it is imperative to understand how much dose the radiation medical imaging delivers in order to establish a balance between the benefits and any likely potential health challenge from X-ray examination processes.
1.3 Justification of the Study
Emphasis placed on justification of diagnostic examination in radiology centers outweighs the optimization of the protection of patient during each examination. Notwithstanding the benefit of radiation in terms of diagnosis and therapy, the aim of achieving quality images have resulted into exposing patients to high radiation dose from repeated procedures. Medical personnel and patients are continually exposed to high radiation burden, therefore, estimating patient dose will provide a means of checking standards of good practice and assist in maintaining dose of exposure to patients to as low as reasonably achievable (ALARA).
This study will also generate organ and tissue doses in some Nigeria diagnostic centres which can be used as basis for future study.
1.4 Aim and Objective of the Study
The Aim of this research is to determine patients’ radiation doses for selected X-ray examinations and centres in North central Nigeria.
The objectives of the study are to;
(i) collate X-ray examinations performed on patients
(ii) estimate the entrance surface dose, effective dose and absorbed organ dose for exposed patients using Caldose-X 5.0 software
(iii) compute the cancer risk index for the patients based on data .
1.6 Scope of Study Adult (male and female) patients are the main sample population in the research. Children are not considered because of their low demand generally for X-ray examination. Quantities for the estimation of patient dose includes the entrance surface dose, effective dose and absorbed organ and tissue dose shall be considered in this study.
This material content is developed to serve as a GUIDE for students to conduct academic research
ESTIMATION OF PATIENT RADIATION DOSES FOR SELECTED X-RAY EXAMINATIONS AND CENTRES IN NORTH-CENTRAL, NIGERIA
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