Investigation of the image quality of plain abdominal radiographs in three Nigerian hospitals
1 Department of Radiography, College of Medical Sciences, University of Calabar, Nigeria
2 Department of Radiology, University of Calabar Teaching Hospital, Calabar, Nigeria
Purpose: A retrospective study of image quality of
abdominal radiographs to establish a baseline for the development of quality
control programmes in Nigerian hospitals.
Materials and Method: Subjective evaluation of 210
plain abdominal radiographs produced between 2002 and 2004, and drawn from the
film libraries of the hospitals, a teaching hospital (TH), a specialist
hospital (SH) and a private clinic (PC) was carried out by four radiographers
and three radiologists, using basic radiographic criteria such as collimation,
optical film density, positioning, use of and correct placement of gonad
shields, as well as criteria for image quality defined by the Commission for
European Communities. Films were assessed as adequate, not adequate and poor
for the radiographic/technical parameters, and scored 1 to 4 in an ascending order
of performance for image quality. They were then ranked in order of overall
quality. Pooled results were studied by method of analysis of means.
Results: Results generally showed good radiographic
image performance for pooled data.� Respective hospital performance was best
for TH for most of the data assessed. Based on individual parameters, the study
found 6.61% of the total number of films �rejectable�. Of the 210 radiographs
studied, 107 satisfied all the criteria for good quality images.
Conclusion: Findings underscore the need for
implementing quality control programmes using the results of this study as a
baseline. � 2007 Biomedical Imaging and Intervention Journal. All rights
Keywords: Plain abdominal radiographs, image quality, quality
control, films, Calabar
Maximising the benefits of the radiological process is the
objective of efforts at optimisation of technique, reduction of patient doses,
equipment design and research. This has also led to the publication of
guidelines for good radiography practice by the Commission for European
Communities (CEC)  and the International Atomic Energy Agency (IAEA) ,
which list conditions for acceptance of radiographs and recommend appropriate
techniques for obtaining them.
Plain abdominal radiographs commonly form a part of
medical assessments. Although the examination is not ordered or performed
routinely, it forms a significant fraction of radiographic examinations
requested in many X-ray diagnostic centers, particularly in accident and
emergency (A/E) departments. Plain abdominal radiographs have been used in
assessing levels of patient preparation for contrast-based examinations
involving the gastro-intestinal tract (GIT) as well as the urogenital system.
Kidney stones and other forms of calcification are readily demonstrated in
plain films of the abdomen. Some pathology is sometimes demonstrated depending
on age .
Image quality is usually defined for specific tasks 
and could be studied physically or subjectively [4, 5, 6]. The aim of quality
control (QC) is to define levels of acceptability of radiographs in order to
satisfy set clinical targets . This underscores its importance in� defining
safe radiation dose levels for radiologic procedures.
Radiographic practice in most developing countries has
received a boost in recent years with conscious attention to the development of
quality assurance and control programmes. The practice had been lacking in
standardised procedures of technique, image quality and dosimetry. To date, the
level of implementation of the UNSCEAR�s  directive for optimisation of
procedures in many developing countries, particularly in sub-Saharan Africa, is
still at the gestational stage. The situation is not different in Nigeria. Most
diagnostic X-ray centers still operate the manual film processing method, even
though many of these record very high levels of patient through-put.
Following recent establishment of the Nigerian Nuclear
Regulatory Authority (NNRA) to oversee and regulate the use of ionising
radiation in the country, efforts at running quality assessment and control
programmes are being intensified across the country. This has created the need
to define a basis for comparison of results of quality assessment studies. This
work aims at providing information on the radiographic/technical and image
quality of abdominal radiographs obtained in Nigeria. It will serve as a
baseline, as there is no study reported to date, on image quality of abdominal
radiographs or indeed, any other type of radiographic images. The best effort
has been the reports of Ogundare et al [8, 9]. Both reports focus on
radiographic technique and radiation dose to patients, with comparison of doses
to Commission for European Communities (CEC) criteria. This position applies to
countries in the same health care level as Nigeria. It is, therefore, the aim
of this study to provide first time information on the area of study
specifically, and add to the reservoir of information available globally with
respect to studies on image quality. It is hoped that this will serve as a
reference base for future work.
Materials and methods
A subjective evaluation of 210 plain abdominal radiographs
of adult patients, drawn from the film libraries of three hospitals, a teaching
hospital (TH), a specialist hospital (SH) and a private clinic (PC), located
within Calabar Municipality in Southeastern Nigeria, was carried out. The
selected hospitals, though within the same geographical area, present a fair
representation of the spectrum of health care institutions (Federal, State
Government and privately owned) across the country. The radiographs (150 for
TH, 38 for SH and 22 for PC) were taken between 2002 and 2004 in the respective
hospitals. The difference in the number of films from each institution reflects
the level of patronage received. In addition, SH was out of operation for
nearly a year (see footnote). All the centres operated single units for general
purpose radiography over the period* of operation being studied. There was no
record of any QA programmes in operation at any of the institutions including
any information on the reject film analysis. All films used in the study were
taken with the patient in the supine position. Exposure factors could not be
ascertained as there were no records available. Current trend in exposures is
the subject of another study.
Study Plan for radiographic technical criteria
The study was divided into two parts with the first
involving the study of some radiographic parameters defined as follows:
- Collimation of the X-ray beam to the area of interest (this assesses
- Optical density of the film. This was studied with a Sakura PDA � 81
portable densitometer (Konica Corporation, Japan) with a measuring accuracy of
� 0.02 and reproducibility of 0.002. Measurement of density was done on four
arbitrarily selected portions, averaged for each radiograph. Optical densities
between 0.5 and 2.0 were taken as adequate . The same film viewing boxes,
which had been previously tested for uniform light output, as well as
controlled conditions of glare and ambient light levels, were used for
assessment of all films .
- Patient Identification: Correct positioning and printing of
identification was assessed.
- Position of the anatomical marker, correct positioning without
interference with diagnostic information.
- Use of gonad shield: The use of and correct positioning of the gonad
shields were assessed. This also gave indication of attitude to radiation
protection of the patient.
- Assessment of patient positioning for the abdominal radiograph. Patient
rotation was used to check for this.
Radiographs were scored �adequate� or 3 if they satisfied
all the six criteria listed, as well as being free of the characteristics
listed under poor or none. A score of �not adequate� or 2 was given to films
with three or more, but less than the six listed criteria, while �Poor/None� or
a score of 1, was given for films with less than three listed criteria, as well
as evidence of any, or all of artifacts, wrong use of grids, motion blur, poor
film screen contact, fog, and geometric faults. These affect the overall image
quality and therefore the decision making process. It was the opinion of the
assessors that films in this later category would normally have been rejected if
there was a QA programme in place. The films were studied by four experienced
radiographers working independently.
Criteria for image quality
For the assessment of image quality, criteria from the
guidelines recommended by the European Commission (EC)  were adopted for the
study. These were:
- Production of the area of the whole urinary tract from the upper pole of
the kidney to the base of the bladder. This was coded �A�.
- Reproduction of the kidney outlines, coded �B�.
- Visualisation of the Psoas muscle outlines, coded �C�, and
- Visually sharp reproduction of bones, coded �D�.
Three consultant radiologists scored the films from 1 to
4, with each criterion scoring 0 or 1. Thus, a film with all four criteria
scored 4, and those with three, two and one criteria present scored 3, 2 and 1,
respectively. Each assessor worked independent of the others and had no access
to the views of the other assessors. The data from the assessors were pooled
and treated with the method of analysis of means, to reduce the effects of
subjectivity in the results. The coefficient of variation was determined for
both sets of readers to quantify inter-reader differences.
Inter-reader differences determined by the coefficient of variation (COV), was marginal (<1%, averaged for all the readers). COV ranged from 0.5-0.9% (mean 0.7%) for assessors of RTQ, while COV for the IQ assessors was 0.6-1.1% (mean 0.9%). Means of the pooled data were analysed and the percentages determined for the different criteria studied. These are presented under the respective headings.
Radiographic technical quality (RTQ)
Information on equipment and other operating criteria in
the centres at the time of production of the radiographs is shown in Table 1.
Radiographs were ranked according to the criteria satisfied. There was
remarkable variation in the distribution of the parameters studied among the
centres. Pooled data from the assessment of the performance of radiographs for
radiographic technical quality are shown in Table 2. The range of densities
measured was 0.14 to 2.62, with an error of �2%. This was within acceptable
recommendations by the International Standards Organization (ISO) . The TH
films were most consistent in optical density with 76% of them being adequate
and only 24% not being adequate, or having densities above or below accepted
range. Similar results were obtained for the patient identification (81.3%
adequate and 6.7% not adequate). However, 12% of the films were identified
after processing by either �scratching� the identification unto the wet film or
using a marker pen to write on the dry film. The anatomical marker was
positioned correctly in 86% of TH films. However, 10% of them were not
adequately marked while 4% either had no anatomical marker at all or had
something other than the �L� and �R� marker used for marking. Figure 1 (RTQ)
presents the picture of films that would be acceptable purely on radiographic
Radiographic positioning of the patient was adequately
done in 69.3% of TH films, while 22% were not adequate and 8.7% were poorly
positioned. For radiation protection, a very weak effort in the use of gonad
shields was noticed in TH (14.7%), while none of the other hospitals recorded
any abdominal radiographs with gonad shield protection (Table 2). Collimation
fared better but was still sufficiently low as to negatively affect overall
performance of radiographic RTQ. Radiation protection parameters were therefore
omitted in computing the total RTQ.�
Image quality (IQ)
The assessment of image quality with EC  recommended
criteria showed that TH had over 80% of radiographs with a score of 3 and
above, while 62% of SH radiographs and 74.1% of PC radiographs obtained similar
The performance of abdominal radiographs with respect to
image quality assessment using the CEC defined criteria is presented in Figure
1 (IQ). Again TH films performed well above those from the other centres. The
number of radiographs satisfying both radiographic technical and image quality
criteria are shown in Figure 1 (RTQ + IQ).� Films in this category were
considered to be of the appropriate image quality. The percentage of each
hospital�s radiographs in this category is higher for TH, PC and SH in that
The quality of a radiograph is primed on its utility for
the intended diagnostic purpose [4, 12]. The benefits of carrying out quality
control studies in radiodiagnostic departments are well documented . This
practice is however in very short supply among hospitals in the study area.
There is as yet no documentation of any attempt at carrying out this exercise.
Abdominal radiographs studied rate high on individual
study criteria for both technical and image quality parameters. However, since
no radiograph is accepted on the basis of individual parameters, the assessment
of optimum image quality is based on the sum of all the factors under
consideration. In this study, this yields an average score of 50.9% (107 of the
210 films studied). At least 14 radiographs or 6.61% of the total would most
probably have been rejected or repeated, were there a functioning quality
control programme in the hospitals studied. These were those that failed both
the RTQ and IQ tests.�
The performance of the images from each hospital (Figure
1) seems to be a follow up from the caliber and training of the personnel
operating therein. TH has graduate radiographers, SH several technical (X-ray)
assistants and one graduate radiographer, while PC employs a part time graduate
radiographer with a full time technician to cover other hours. The results are
a strong indication of the need for proper pre-employment training and the
development of continuous education programmes for employees in diagnostic
centres. Current efforts by the Radiographers Registration Board of Nigeria
(RRBN) are set to address the need for continuous professional development
This study did not intend to assess the correctness of
diagnosis or to review technical competence, but to review the performance of
the abdominal radiograph within the study area, and confirm areas where the
current efforts at standardisation of technique and quality control could be
improved. It is clear from these results that the lack of QA programmes in the
area has negatively impacted on the quality of radiographs passed. Films are
passed for reasons other than quality. This is in tandem with the report of
Bassey et al  who have attributed this development to economic and
practical reasons. This would explain why �rejectable� films are found in good
numbers in the film library. This situation may also be the case in Ghana,
where a report has attributed the poor quality of radiographic images to poor
techniques and lack of prescribed national standards .�
The dearth of information on image quality of abdominal,
and indeed other types of radiographs, in developing countries makes comparison
difficult and underscores the importance of this study as a baseline for
further investigations, especially of current practices that would lead to
standardisation of technique and procedure, and develop a reservoir of data for
planning and implementation of international regulations guiding image quality
and patients� radiation doses.�
While it is clear that image quality is ultimately �task
specific�, standardisation of major criteria in diagnostic radiology is
essential good practice. It has been shown that abdominal radiographs from
three hospitals in Calabar, Nigeria, reveal generally good individual criteria
image performance, but possess an average or marginal overall quality. A lot of
improvement is needed in the area of study and this will largely be achieved by
the implementation of QA programmes that have been legislated . The results
of this study provide a good starting point.
Figure 1 Summary of fraction of total number of abdominal radiographs satisffying quality criteria in respective hospitals. TH (Teaching hospital), SH (specialist hospital) and PC (Private clinic). RTQ = Radiographic technical quality, IQ = Image quality, and RTQ + IQ inclusive of both RTQ and IQ.
Table 1 Summary of departmental operating criteria for centers at time of production of radiographs.
Table 2 Pooled results of technical assessment of abdominal radiographs for respective hospitals indicating fraction of total films found in each category.
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|Received 12 February 2007; received in revised form 18 July
2007; accepted 20 July 2007
Correspondence: Department of Biomedical Physics and Bioengineering, University of Aberdeen, Foresterhill, AB25 2ZD, Aberdeen, United Kingdom. E-mail: firstname.lastname@example.org (N.O. Egbe).
Please cite as: Egbe NO, Eduwem DU, Ikamaise VC,
Investigation of the image quality of plain abdominal radiographs in three Nigerian hospitals, Biomed Imaging Interv J 2007; 3(4):e39
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