EVALUATION OF COMPLIANCE WITH STANDARD POSTERO–ANTERIOR (PA) CHEST TECHNIQUES

This study was carried out to evaluate the compliance with standard postero-anterior (PA) chest Techniques in University of Nigeria Teaching Hospital Ituku Ozalla.  A total of 375 assessment sheets were used in this study.  The age  range of  patients whose  their  chest radiographs participated  in this study  ranged  from (1-10) years to (70-80) years with the female radiographs being much in number tan that  of  male  patients. Form hundred assessment sheet were used but only three hundred and seventy five assessment sheets were properly filled and used for analysis. From the result s obtained  the age group of (31-40) years was the highest in female category with 44 chest radiographs while (21-30) years age  group  appeared  to  be  highest in  male  category  with 39 chest  radiographs.  The study showed that the major cause of film repeats and rejections were one to much of artifacts. From my finding, I observed that lots of radiographs about 115 (30.7)% chest radiographs had rotations. This was detected from misalignments of medical ends of clavicles from spinous process.  The study detailed that 60 (16)% chest radiographs were without  identification markers especially anatomical markers while 298 (79.5)% chest  radiographs  had the ,marker properly and clearly placed  at the right  borders. Also, the write up revealed that 340 (90.7) % chest radiographs were without objective lung field while 320 (85.3) % chest radiographs had good inspirational demonstrations. Moreover, a good scapulars thrown off were witnessed in the study with 300 (80) % chest radiographs while 360 (96) % chest radiographs with symmetric density of the lungs denotes a fairly alignment of grid in relation to the image receptors.  Also, the contrast of lung periphery was not adequate throughout the study, causing 180 (48)% chest radiographs  to the in fair range a sin fig 1. Also the histogram in fig 1.  Shown that the cardiac shadow had the greatest contrast in 260 (69.3)% chest radiographs. The fig 11 left us with the knowledge that 181(172.8) chest radiographs had a greatest sharpness of radiographs qualities. 

                                              

CHAPTER ONE 

Introduction

Background of study

CHAPTER TWO

Literature review

Review of related literature …………………………………………………….14

Theoretical Background ………………………………………………………...19

2.2 Anatomy of the respiratory system ……………………………….19

2.2.1 The pharynx ……………………………………………………...19

2.2.2 The larynx ………………………………………………………..20

2.2.3 The trachea ……………………………………………………….21

2.2.4 The Bronchi ……………………………………………………....22

2.2.5 The Lungs ………………………………………………………...23

2.2.6 The pleura ………………………………………………………..24

2.3 The Anatomy of  the Heart ………………………………………..26

2.4 Radiographic procedure …………………………………………...29

2.4.1 Projection …………………………………………………….…..29

2.4.2 Posterior – anterior care of the patient …………………….……29

2.4.3 Positioning ………………………………………………….…….29

2.4.4 Centering Point …………………………………………….……..30

2.5 Radiographic description of chest ………………………………..,.30

CHAPTER THREE

Research Methodology

3.1 Research designs …………………………………………………...33

3.2 Area of study …………………………………………………….....33

3.3 Population Sampling Method and sampling size ………………….33

3.4 Method of Data collection ………………………………………….34

3.5 Description of the Assessment Sheet ………………………………34

3.6 Explanation of standard Chest Criteria …………………………....35

CHAPTER FOUR

Data Analysis and Presentation ……………………………………………41

CHAPTER FIVE

5.1 Discussion ……………………………………………………….…….46

5.2 Summary of findings …………………………………………………..48

5.3 Recommendation ………………………………………………………49

5.4 Area of further studies …………………………………………………50 

5.5 Limitation of study ……………………………………………………50

5.6 Conclusion …………………………………………………………….51

     Reference ………………………………………………………………52

     Bibliography …………………………………………………………...55 

LIST OF TABLES    

      

Table I: Age and sex distribution of patients.

Table II: A distribution of patients’ identification markers.

Table III: A distribution of patients positioning criteria.

Fig I: Distribution of subjective contrast of radiographs with number of radiographs.

Fig II: Distribution of the radiographs according to their degree of sharpness.

The clinical application of r-ray began almost immediately following the discovery of x-rays by Wilhelm Conrad Roentgen in 1895. Since then, diagnostic x-ray equipment has developed considerably and the imaging quality of x- ray examination has been greatly improved and the method has been widely disseminated1. In particular chest radiography is the most  common  examination  to be  used  as one of the initial steps to diagnose pulmonary disease including  respiratory  infection with  tuberculosis (TB)2 .The role of  chest radiography  has  gained  increasing  importance in  trauma cases, routine check  ups,  disease  conditions and  metastatic  problems.    The rational  behind this study is that many faulty  diagnoses by chest radiography may be associated with  inappropriate  radiological  techniques and  application  and that improvement of imaging quality of chest  radiography benefits not only the patients infected  by  disease but also those suffering from various  pulmonary disease. In terms of detection and treatment of  pulmonary disease, poor  imaging  quality  may  be more  harmful  to patients than  having  the patients  not diagnosed through  x- ray study is to provide a simple way to assess the quality of chest radiograph as well as  fundamental  of chest  radiography, and  to lead  to  conducting  quality  assurance for chest  radiography even  in resource constrained  settings, chest  radiograph with poor image  quality can  cause misdiagnoses or  require repeated examinations, wasting  economic  resources and  exposing  patients to unnecessary radiation. Consequently, providing high quality imaging of chest radiograph befits anyone who will be examined by x-ray, and the precise control of these x-ray images is an important task for the radiographers; radiological technologists or radiological technicians. 

Quality assessment is the measurement against a gold standard.  Quality  improvement  is the  process of using  the information  gained through assessment to improve  quality, with the key component of data  collection data  analysis, and  creative  problem  solving. It includes continuous monitoring and evaluation, identifying defects and retaining of staff for prevention of recurrent problems.  In other words, we can only achieve quality assurance through quality control, quality assessment, and quality improvement. Pointing out the assessment result of a chest radiograph to staff is not the end but the means. 

What is important in the assessment procedure is to seek the source of the problem and to take the steps to improve, so that in the end the quality of the chest radiograph will be improved4.  In medicine, a chest radiograph, commonly called a chest x-ray (CXR), is a projection radiographs are among the most common films taken, being diagnostic of many conditions. 

Like all methods of radiography, chest radiographs employs ionizing radiation in the form of x-rays to generate images of the chest. The typical radiation dose to an adult form a chest radiograph is around 0.06mSv5. Chest radiographs are used to diagnose many conditions involving the chest wall, bones of the thorax, and structures contained within the thoracic cavity including the lungs, heart, and great vessels. 

There are various approaches to quality assurance, some being better than others. Concurrent monitoring  off  classification  levels  can be  accompanied  by adding  quality  assurance (calibration) radiographs to the set  for which classifications are being sought  without  the reader being  aware  of which  are the calibration  radiographs. For example, a national Institute of health sponsored workshop suggested including chest films of unexposed workers in epidemiological studies for purpose of quality control6. Optimally, quality assurance radiographs should included a range of abnormality levels and types previously classified by expert readers. There are many benefits to this approach; 

First, because the reader is unaware of which are the quality control radiographs, yet knows that they exist within the study, the reader is under pressure to conform to standard classification  practices7. 

Knowledge of the functions of x-ray equipment is essential to assess the quality of chest x-rays. With respect to regular maintenance of x –ray equipment, at least one radiographer must bee in charge. On the other hand, it is recommended to have a maintenance contract with a local agent for fault detection, calibration and repair work by a qualified x-ray enginner9.

With regard to chest x-ray, the recommended distance between the tube focus and x-ray film (FFD) is in range of 140-200cm. longer distanced is more desirable for radiological chest examination. The main reason for this longer distance is that it improves the image sharpness through geometric means.  The x- ray beam must be aligned straight with the x-ray film10.  

The penetrating power of the x-ray beam is controlled by the adjustment of x-ray tube voltage12.  The higher the voltage setting, the more energetic and penetrative the x-ray that is produced and the different tissues are visualized at different density levels according to the penetrating power of the x-ray beam. The difference of density levels according to the penetrating power of the x-ray beam. The difference of density levels between the light and dark areas of x-ray films is defined as contrast.  

In general, the higher the voltage setting, the different organs in the human body are visualized with less contrast in a radiograph9. With regard to the chest radiograph, higher voltage in the range of 100-120kV is recommended; in order words low contrast imaging between lungs and bones is desirable. The advantage of high x-ray tube voltage is that it produces a more energetic x-ray which penetrates bones so that the pulmonary vessels can be visualized under the bone structure. 

The dosage of the x-ray beam is controlled by 2 functions: x-ray tube current and exposure time adjustment. The higher the current setting and / or the longer the exposure time setting, the more x-ray photons are produced and this affects the higher density of x-ray film11. The units of x-ray tube current and exposure time are mA (milliampere) and seconds respectively. In a general ways, the dosage of the x-ray beam control is referred to as ‘mAs, which refers to the multiplication of mA and seconds. The suitable mAs depends on the x-ray unit used, but the recommended exposure time is less than 0.05 second in order to minimize motion artifact caused by the beating of  the heart. 

With respect to the chest radiograph, the recommended effective focal size of the x-ray tube is smaller than 1.2mm.  The main advantage of selecting in smaller focal size is that it reduces the blur of the edge pulmonary vessels in the chest radiography through geometric means13. The degree of appearance of the edge between two density areas in the imaging subject is defined as sharpness. Consequently, a smaller focal size can improve a factor of imaging sharpness, smaller effective focal size example 0.6mm, is more desirable for radiological chest examination, however the smaller  the  focal size, the harder it is to use  a higher mAs setting.13

The x-ray grid looks like a flat metallic plate which is the same size as the x-ray film cassette and it contains very narrow lead strips. The function of the grid is to reduce the scattered radiation from regard to the chest radiography with higher voltage techniques (for example, in the range of 80-120KV), the x ray grid is essential. The minimum required specification of fixed grid for chest radiography is 34 lead strip lines per cm and an 8:1 grid ratio. 

Most stationary x-ray equipment needs to be connected to the main electricity in the range of 100 -150A (ampere) with small electrical impedance ie. 0.3 (ohm) or less. The special type of x-ray equipment with high frequency inverter generator requires only 10 -20A electric supply14. Most mobile type of x-ray equipment requires a 10-20A electrical supply. In order to produce a good quality x-ray beam, specifications of the current capacity and its impedance are indicated in the instruction manual specific to that unit of x-ray equipment. The higher the impedance of the electrical supply, the bigger drop of x-ray tub voltage. 

      Viewing chest radiographs under good conditions is important in order to detect the maximum amount of information. The x-ray film viewer requires a minimum of 2 vertically mounted 15W (watts) fluorescent tubes and the light intensity of x –ray film should be sufficient and even across the entire surface of it.15 

A mobile x-ray unit is defined as an x-ray unit on wheels, capable of being moved from one location to another. The capacity and stability of x –ray generation by a mobile x – ray unit is limited. Accordingly, mobile x-ray units should be used only for restricted applications. With regard to chest radiography, basically mobile x-ray is not recommended. However, in a place where only a mobile x-ray units is available, the radiographer can utilize it, paying careful attention to x-ray exposure factors and beam alignment.14

The intensifying screen is a device made of fluorescent materials that emits light when exposed to x –ray. 

Two types are available. One emits blue light and the other one emits green light. The emitted blue or  green light contributes to  a blackening  effect on the  x-ray  film,  in terms  of its blackening function, green light is more effective than blue light so that  the  rare earth material (example, gadolinium) which emits green light is widely  used in recent  years. The intensifying screen may be divided into 3 sensitivity categories such as fast, medium, and slow speed. In general, the lower the sensitivity, the more x-ray exposure needed and the better imaging quality produced.  With regard to chest radiography, the intensifying screen emits green light and medium speed sensitivity is recommend. The combination of intensifying screen and film must be matched according to the type of x-ray film; otherwise the imaging quality will be worsened. With regard to the chest radiography, general or regular of either the blue or green variety is recommended.16

Poor darkroom management causes fogging (unwanted density in the areas that are not exposed to the x- ray beam) and artifact (unwanted imaging). With regard to the regular type of x-ray film, the color of safelight is red for both blue and green emission light sensitivity. The recommended electrical power is 15W and should  be no  more  than 25W.17 The  distance be more than 150cm, each x-ray  film  has its own expiration date marked on the outside of the film box and the film have to be use before it  expiration date.  The temperature and humidity in the darkroom should be controlled through air conditioning and /or a verification fan depending on the local circumstances. Temperatures of 10- 24oC and humidity of 30-50% are recommended.17 The leakage of light from  outside into the  darkroom must be absolutely  avoided by  renovation  of the  darkroom and/or  by using  some  type  of  light proof materials. The light from a mobile phone will be another source of light that damages x-ray film in a darkroom x –ray film must be handled with care so that its  not bent or touched with dirty fingers in a careless manner. Careless handling of x-ray films causes unwanted types of artifacts on the x-ray films. 

X-ray film processing will be divided into 5 processes: developing, rinsing, fixing, washing, and drying. The implication of these 5 processes for imaging quality is crucial. This x-ray film processing can be manual procedure or with an automatic processor. 

The temperature of the developing solution and the developing time are regulated to maintain a consistent density of x-ray film constantly. The higher the temperature and / or the longer the developing time, the darker the density of x –ray film. Exhausted developing solution has less blackening effect and requires a longer developing time which causes excessive tagging at the same time.18 

Rinsing is the process of rinsing of the developing solution with water. Fixing is a process that requires at least 5 minutes and fixes the image on x-ray film semi permanently. Exhausted fixing solution and / or shorter fixing time will cause unwanted strains later on. The condition of developing and fixing solutions can be checked by observation of the color of the solutions.  Washing is a process that requires at least 30 minutes to wash out the fixing solution from the x-ray films. Insufficient washing time will cause unwanted yellow color stains later on. Drying is the process that dries out water in a dust free area.  The drying temperature must not exceed 350C to avoid damage from overheating. 

An automatic x-ray film processor follows the 4 basic procedures as those of manual processing (except rinsing), but under automated and controlled conductions. Consequently, the imaging quality of x-ray film is constant and better and the processing duration is shorter than with manual processing.18

On the other hand, the operation  of an  automatic  x –ray film processor requires appropriate and  regular maintenance of a stable power supply, an  adequate  water  supply for washing  the film and the regular purchase of developing  and fixing  solutions.  The temperature setting of the developing and  the drying procedure must be done following  the instructions, for protection against an unreliable  supply  of electricity, the equipment  should be  plugged into  a voltage  stabilizer and also  wired to the electric generator so that  it will have a power supply in the event of  frequent black outs. 

All the entire above write –up have to be, into practice to maintain optimum output in chest radiography production, processing and reading skills.