1.1 Introduction
Diagnostic radiology is one of the most common fields to use the benefits of X-rays. Minimizing the disadvantages of ionizing radiation is the driving force of radiation protection. A basic principle in radiation protection is the ALARA principle, which is an acronym for as low as reasonably achievable (ICRP 2007). It summarizes the approach to ionizing radiation according to the current knowledge; in the region of low doses, the probability of radiation detriment increases as a function of increasing radiation dose (ICRP 2007). In X-ray imaging, the patient receives a certain amount of radiation energy through absorption processes.
The radiation that passes through the patient is attenuated according to the properties of the organs and tissues. The radiation sensitivities of different organs and tissues vary. The radiation energy absorbed in a tissue or an organ divided by the tissue or organ mass is the organ dose. Organ dose determination is most fundamental part of estimating the radiation risk of an individual. Organ doses cannot be measured directly and the selected method for organ dose determination has a marked impact on the uncertainty related to the organ doses.
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, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
Nowadays human organ imaging is performed by different systems and methods. As the new diagnostic methods including conventional radiography, fluoroscopy, and computed tomography (CT) procedures will continue to provide tremendous benefit to modern health care, radiography is expected to be in progress as well, because it is still a powerful tool with enough benefit for the patients undoubtedly. Therefore, patients’ exposure to radiation has been increased all over the world due to this radiography (The 2007 Recommendations of the International Commission on Radiological Protection, ICRP publication 103, 2007; European Commission, European Guidance on Estimating Population Doses from Medical X-Ray Procedures. Radiation Protection N.154, 2008; Fazel et al., 2009; Hart et al, 2010; United Nations Scientific Committee Effects Atomic Radiation, 2010).
A wide range of radiation absorbed doses is delivered to patients by the various diagnostic imaging modalities that use ionizing radiation. Even though these procedures are assumed to produce a net benefit, the potential for radiation-induced injuries to the patient exists (The AAPM/RSNA Physics Tutorial for Residents Typical Patient Radiation Doses in Diagnostic Radiology 1, 1999). Since using ionising x-rays is associated with some risk of developing cancer, the basic radiation protection concept or philosophy ALARA states that all exposures must always be kept ‘As Low As Reasonably Achievable’ (National Council on Radiation Protection and Measurements, 1990). So, the knowledge of the radiation dose received by the patient during the radiological examination is essential to prevent risks of exposures that involve a great number of people. Various indicators are used to estimate detriment from cancer and genetic effects of radiation.
According to ICRP 60, the basic quantity associated with the risk of deleterious effects on health is the effective dose that is the valuable and central quantity for dose limitation in the field of radiological protection of the patient (International Commission on Radiological Protection, 1991). This dose descriptor is being increasingly used to determine the quantity of radiation dose received by patient undergoing diagnostic x-ray examinations (Brenner and Huda, 2008; Kharita et al., 2010; Mettler et al, 2008; Osei and Darko, 2013; Shahbazi-Gahrouei and Baradaran-Ghahfarokhi, 2013; Teles et al., 2013). Whereas effective dose (ED) is affected by patient structure and radiological method, as such, the calculation of this quantity is of utmost importance. Because it is almost impossible to directly measure effective dose during clinical procedures, it must be determined indirectly.
In general, indirect estimate of effective dose starts from incident air kerma (Ka,i) measurement as input parameters and uses dedicated conversion coefficients (European Commission, European Guidance on Estimating Population Doses from Medical X-ray Procedures, Radiation Protection N.154, 2008; International Atomic Energy Agency, 2007; International Commission Radiation Units, 2005). Entrance skin dose (ESD) is also an important parameter in accessing the dose received by a patient in a single radiographic exposure. The European Union has identified this physical quantity as one to be monitored as a diagnostic reference level in the hopes of optimizing patient dose (Bushong, 2001 and ICRP, 1991).
The radiation detriment effects can be either deterministic or stochastic. Deterministic effects of radiation are related to high dose levels and cause injury and loss in populations of cells. Deterministic effects have a threshold dose below which no clinically visible effects are observed. The severity of the effect increases as a function of dose. Stochastic effects consist of cancer risk and hereditary effects, and the probability of an effect, but not its severity, increases as a function of dose without a threshold (ICRP 2007). The radiation effect classification, dose limitation concepts, and the definition of detriment and threshold have undergone several changes in the past decades (Hamada & Fujimichi 2014).
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to know the Estimation of Organ Equivalent and Effective Doses From Diagnostic X-Ray.
1.3 Statement of Problems
Investigation revealed that the problems associated with this work were mainly financial constraints encountered during the execution of this project, limited sources of materials and difficulties in acquiring data for analysis.
1.4 Aim and Objectives of Study
The aim of the study is to establish the trend of dose received by patient during x-ray examination in Federal Medical Centre, Keffi in Nasarawa state, Nigeria. In achieving this aim, the following specific objectives were laid out as follows:
- To examine the organ diagnostic x-ray from absorbed dose against weight; and
- To evaluate the chest thickness against dose absorbed using diagnostic x-ray.
1.5 Significance of Study
This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.6 Scope of Study
The scope of the research is focused on the Estimation of Organ Equivalent and Effective Doses From Diagnostic X-Ray.
1.7 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
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