1.1 Introduction
Radiation dose is defined as the amount of ionizing radiation energy absorbed by a specific mass of tissue when exposed during diagnostic or therapeutic procedures. In medical imaging, particularly in radiography, patient radiation dose refers to the measurable quantity of radiation received by a patient during an X-ray examination, which is commonly expressed in units such as milligray (mGy) or dose area product (DAP). The International Commission on Radiological Protection states that ionizing radiation exposure in medical imaging is justified only when it produces more benefit than harm to the patient, and it must be optimized to ensure doses is kept as low as reasonably achievable while still achieving diagnostic image quality (ICRP, 2007).
Chest X-ray examination is one of the most common radiological investigations performed in healthcare facilities worldwide due to its effectiveness in diagnosing a wide range of thoracic conditions such as pneumonia, tuberculosis, heart enlargement, rib fractures, and lung infections. Its wide usage is attributed to its affordability, accessibility, and rapid image acquisition, making it a primary diagnostic tool in both emergency and routine clinical settings (UNSCEAR, 2008).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are significance of the study, scope of work, research hypothesis and questions, limitation of the study and definition of terms.
1.2 Background of Study
Historically, patient radiation dose evaluation in diagnostic radiography is closely linked to the discovery and medical application of X-rays by Wilhelm Conrad Roentgen in 1895, which marked the beginning of medical imaging and revolutionized diagnostic medicine. According to Bushberg et al., the introduction of X-rays led to rapid adoption in clinical practice due to its ability to visualize internal body structures without invasive procedures, although early usage occurred without adequate understanding of radiation risks (Bushberg et al., 2012). As medical imaging expanded globally, concerns about radiation-induced injuries such as skin burns and radiation sickness began to emerge, leading to increased scientific investigation into radiation safety.
ICRP reported that by the mid-20th century, scientific evidence from atomic bomb survivors and occupationally exposed workers contributed significantly to the understanding of the biological effects of ionizing radiation (ICRP, 2007). Long-term epidemiological studies provided strong evidence that exposure to ionizing radiation at diagnostic levels, although low, is not entirely without risk, thereby necessitating continuous monitoring of patient doses in medical imaging (UNSCEAR, 2008).
According to the International Commission on Radiological Protection (ICRP), ionizing radiation is a form of energy that is capable of removing tightly bound electrons from atoms, thereby producing ions, and it is widely used in medicine for both diagnostic and therapeutic purposes (ICRP, 2007). ICRP reported that the use of ionizing radiation in medical imaging must always be justified and optimized to ensure that patient exposure is kept as low as reasonably achievable while still achieving the required diagnostic information. Chest X-ray examination, being one of the most common radiological procedures globally, plays a vital role in the diagnosis and management of thoracic diseases such as pneumonia, tuberculosis, chronic obstructive pulmonary disease, rib fractures, and cardiac enlargement.
According to Bushberg et al., chest radiography remains the most frequently performed imaging procedure because it is fast, cost-effective, and widely available in both developed and developing healthcare systems (Bushberg et al., 2012). ICRP stated that although chest X-ray examinations involve relatively low radiation doses compared to other imaging modalities such as CT scans, repeated exposure or poorly optimized radiographic techniques may still lead to cumulative radiation effects that increase the risk of stochastic health outcomes such as cancer.
UNSCEAR (2008) affirmed that even low doses of ionizing radiation, when accumulated over time, may contribute to an increased probability of radiation-induced biological effects, particularly in sensitive populations such as children and young adults. According to the World Health Organization, diagnostic imaging has become an indispensable component of modern healthcare delivery, but it also contributes significantly to the global population's exposure to man-made radiation sources (WHO, 2016). The organization further asserted that ensuring radiation safety in medical imaging requires strict adherence to quality assurance programs, proper calibration of equipment, and continuous monitoring of exposure parameters. In radiographic practice, exposure factors such as kilovoltage peak (kVp), milliampere-seconds (mAs), focus-to-film distance, and beam collimation significantly influence the amount of radiation dose delivered to patients.
ICRP reported that diagnostic reference levels (DRLs) serve as practical tools for optimization in medical imaging, allowing comparison of typical radiation doses in standard procedures across different healthcare facilities. These reference levels are not dose limits but serve as investigation thresholds that prompt review and optimization when exceeded. According to European Commission guidelines, the establishment and periodic review of DRLs is essential for maintaining dose optimization and ensuring patient safety in radiological practice (European Commission, 2014).
In many developing countries, including Nigeria, studies have shown that there is often limited implementation of standardized dose monitoring systems in diagnostic radiology departments. According to Adejoh et al., many radiology departments operate without regular dose audits, leading to variations in exposure parameters and potential overexposure of patients during routine imaging procedures (Adejoh et al., 2017). The authors further reported that inadequate training of radiographic personnel, lack of updated equipment, and absence of institutional radiation safety protocols contribute significantly to inconsistencies in patient dose management.
Bushberg et al. asserted that optimization of radiation dose in chest X-ray examinations is strongly dependent on the technical competence of radiographers and the availability of properly maintained imaging equipment. They further contended that inappropriate selection of exposure factors is one of the major causes of unnecessary radiation dose to patients, especially in resource-limited healthcare settings. On the other hand, the increasing demand for radiological services due to the rising burden of respiratory and cardiovascular diseases has led to increased workload in radiology departments, thereby increasing the risk of procedural inconsistencies and dose variation.
This study is set against the backdrop of the need to evaluate patient radiation dose in routine chest X-ray examinations at Warri Central Hospital in order to ensure compliance with international radiation protection standards and improve optimization practices in diagnostic radiography.
1.3 Statement of Problems
In routine chest radiography, patient radiation dose is expected to be kept as low as reasonably achievable in line with established radiation protection principles, while still maintaining diagnostic image quality. Studies have shown that variations in radiographic technique, equipment calibration, and operator practices often lead to differences in patient dose levels across healthcare facilities (UNSCEAR, 2008). In many healthcare institutions, particularly in developing regions, there is often limited routine assessment of patient radiation dose during diagnostic imaging procedures.
On the other hand, chest X-ray remains indispensable in emergency and routine clinical diagnosis due to its speed, accessibility, and relatively low cost, which makes its benefits significant despite the associated radiation risks. However, the balance between diagnostic benefit and radiation risk is not always effectively managed, especially where periodic dose audits and standardized exposure protocols is lacking. Variations in exposure parameters such as kilovoltage, milliamperage, and exposure time is often observed, leading to inconsistencies in patient dose and image quality across examinations (Bushberg et al., 2012).
In Warri Central Hospital, there is a need for systematic evaluation of patient radiation dose during routine chest X-ray examinations to ensure compliance with international safety standards and optimization principles. The absence of regular dose assessment and documentation may result in unnecessary radiation exposure, which contradicts the fundamental principle of radiation protection known as ALARA, as outlined by the International Commission on Radiological Protection (ICRP, 2007).
This study therefore seeks to examine the level of patient radiation dose, assess compliance with standard radiographic practices, and identify possible areas of improvement in dose optimization within the facility. It is against this backdrop that this study seeks to evaluate patient radiation dose in routine chest X-ray examinations.
1.4 Aim and Objectives of Study
The aim of the study is to assess patient radiation dose levels in routine chest X-ray examinations at Warri Central Hospital.
The specific objectives of the study are:
- To determine the radiation dose received by patients during routine chest X-ray examinations at Warri Central Hospital.
- To evaluate the exposure parameters used in chest X-ray procedures at Warri Central Hospital.
- To compare the measured radiation dose with established Diagnostic Reference Levels.
- To assess the level of adherence to radiation protection principles among radiographers at Warri Central Hospital.
- To identify factors influencing variation in patient radiation dose during chest X-ray examinations.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- What is the level of patient radiation dose during routine chest X-ray examinations at Warri Central Hospital?
- How are exposure parameters applied during chest X-ray procedures at Warri Central Hospital?
- How do the measured radiation doses compare with established Diagnostic Reference Levels?
- To what extent are radiation protection principles adhered to by radiographers at Warri Central Hospital?
- What factors influence variation in patient radiation dose during chest X-ray examinations?
1.6 Research Hypotheses
In order to pursue the objective of this study, the following generalized statements have been designed to guide and aids in obtaining the result for the experiment to be conducted. For this work, the null hypothesis will be represented with H0 while the alternative hypothesis will be represented with hypothesis H1.
Hypothesis One
- H0: There is no significant difference between patient radiation dose in routine chest X-ray examinations at Warri Central Hospital and established Diagnostic Reference Levels.
- H1: There is a significant difference between patient radiation dose in routine chest X-ray examinations at Warri Central Hospital and established Diagnostic Reference Levels.
Hypothesis Two
- H0: There is no significant relationship between exposure parameters and patient radiation dose during chest X-ray examinations at Warri Central Hospital.
- H1: There is a significant relationship between exposure parameters and patient radiation dose during chest X-ray examinations at Warri Central Hospital.
Hypothesis Three
- H0: There is no significant effect of radiographers' adherence to radiation protection principles on patient radiation dose at Warri Central Hospital.
- H1: There is a significant effect of radiographers' adherence to radiation protection principles on patient radiation dose at Warri Central Hospital.
1.7 Significance of Study
It is believed that at the completion of the study, the findings will provide empirical data on patient radiation dose levels during chest X-ray examinations at Warri Central Hospital. Also, radiologists will benefit from improved understanding of patient dose management in chest X-ray procedures.
Furthermore, radiographers will use the findings to improve exposure parameter selection and reduce unnecessary radiation dose. In addition, patients will experience safer diagnostic imaging with reduced radiation exposure risks.
Lastly, the study will contribute to hospital policy development on quality assurance in radiology. It will serve as a reference for future research in medical imaging and radiation safety.
1.8 Scope and Limitations of the Study
The scope of this study covers patient radiation dose assessment, exposure parameter evaluation, and comparison with Diagnostic Reference Levels in chest X-ray examinations at Warri Central Hospital, Delta State, Nigeria.
The study was limited by restricted access to full radiological equipment data and limited sample size, which was affected by hospital workload and patient flow patterns.
1.9 Definition of Terms
Radiation Dose:
Radiation Dose refers to the amount of energy from ionizing radiation absorbed by human tissue during diagnostic imaging procedures, usually measured in milligray (mGy) (ICRP, 2007).
Chest X-ray Examination:
Chest X-ray Examination is a diagnostic imaging procedure that uses ionizing radiation to produce images of the chest structures including lungs, heart, and bones (Bushberg et al., 2012).
Ionizing Radiation:
Ionizing Radiation is a type of energy that is capable of removing electrons from atoms, thereby producing ions and potentially causing biological effects in living tissues (UNSCEAR, 2008).
Diagnostic Reference Level (DRL):
DRL is a standardized radiation dose level used as a benchmark for medical imaging practices to help optimize patient protection and identify unusually high radiation doses (ICRP, 2007).
Radiation Protection:
Radiation Protection refers to measures and practices used to protect patients and healthcare workers from unnecessary exposure to ionizing radiation during medical procedures (WHO, 2016).
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