Patient dosimetry during chest, abdomen, skull and neck radiography in SW Nigeria

Article Outline

• Abstract
• Introduction
• Materials and methods
• Results
• Discussion
• Conclusion
• Acknowledgements
• References
• Copyright

Abstract 

The technique factors and X-ray output from the X-ray units of three Nigerian hospitals were obtained and used to calculate doses delivered to patients during chest, abdomen, skull and neck examinations. DoseCal software was used to calculate the entrance skin dose (ESD) and effective dose (E) based on the values of technique factors employed. The result obtained for inter-hospital comparison showed wide variation of mean hospital ESD, from a factor of 1.3 for chest posteroanterior (PA) in hospital 2 (H2) to a factor of 63 for the same chest X-ray projection in hospital 1 (H1). A comparison of ESD obtained in this work with established reference doses in the United Kingdom (UK 2005 review), International Atomic Energy Agency (IAEA), Community of European Commission (CEC), Ghana and Sudan shows that the values of ESD obtained in H1 for five examinations; namely: chest (PA) and lateral (LAT), abdomen anteroposterior (AP) and skull (PA and LAT) are higher. In H2, the dose value for chest PA is about 50% higher than that of UK but comparable with CEC and less than IAEA and Ghanaian values. The dose values obtained in H3 chest PA are higher than UK, IAEA and CEC values but comparable with that of Ghana. For abdomen AP, the dose is a factor of 1.2 less than IAEA and CEC values but greater than the UK, Ghanaian and Sudanese values by a factor of 2.1, 1.2 and 4.5, respectively. Reference data for abdomen LAT and neck AP were not available for comparison. Higher effective doses are being delivered to patients in chest PA (H1 and H3) and abdomen AP (H1) when compared with the range of values reported in the literature. This trend is an indication that patients examined are at higher health risks.

Keywords: Entrance surface dose, Chest, Abdomen, Skull, Radiological, Neck

Back to Article Outline

Introduction 

Due to the continual leading role of X-rays as an important diagnostic tool in modern healthcare, it serves as a significant source of radiation exposure to both patient and medical personnel.¹ It is estimated that diagnostic radiology and nuclear medicine contributed 88% to the collective effective dose from man-made source in the US,² while in the UK similar contribution was 96%.³ The need for determination or at least a realistic estimation of radiation dose to patients during X-ray examinations in every hospital as well as compared with reference doses established by competent regulatory authorities has been emphasized in the literature.⁴, ⁵

Based on the important knowledge of the dose absorbed and the consequences of the absorbed dose, National Occupation Health and Safety Commission (NOHSC, 1995)⁶ indicated that dose assessment of employees and members of the public is required and appropriate to ensure compliance with recommendation. Although diagnostic imaging using X-rays produces a net benefit, the potential for radiation induced injury to the patient exists. Therefore, understanding absorbed doses and the factors that affect them is very important.⁷, ⁸, ⁹, ¹⁰, ¹¹ Earlier publications have indicated that radiation doses are affected by technique factors, patient characteristics, filtration, projection type and age of the machine.¹⁰ Therefore, through proper choice of technique factors, dose reduction is possible while maintaining the image quality during radiographic examinations.

The classification of United Nations Scientific Committee on the Effects of Atomic Radiation¹² shows that, Nigeria is in healthcare level IV category. This is an indication that the physician–patient ratio is higher than in healthcare level II countries with 1000–3000 persons per physician; consequently, there is no adequate information on patient doses in healthcare level IV countries as required by the international regulatory bodies. Earlier dose measurements in Nigeria have been carried out by few researchers¹³, ¹⁴, ¹⁵ using direct method of dose assessment. However, only Ogundare et al. documented the technique factors, patient characteristics and attempted calculating the effective doses while others dwelt on entrance skin doses. As far as we know all these researchers obtained part of their data from University College Hospital, Ibadan and few hospitals within and outside Ibadan. More recent studies on dose measurements have been carried out in southeastern Nigeria using thermoluminescent dosimeters (TLDs)¹⁶ and a mathematical method.¹⁷

The aim of this study is to evaluate the radiation doses to patients undergoing some common diagnostic X-ray examinations in three large hospitals in SW Nigeria. Part of the aim is to assess the radiographic techniques used during the different examinations. It was anticipated that the study will help in the optimization of radiation protection of the patient. Information from this dose evaluation will serve as a useful baseline against which assessment at an individual X-ray department may be compared. The doses and technique factors reported in this work will be useful for the Nigerian Nuclear Regulatory Authority (NNRA) and other regulatory bodies when exploring the possibility of dose reduction and the assessment of radiographic practices in Nigerian hospitals. The patient dose was estimated in the present study in terms of entrance skin dose (ESD) and effective dose (E). Estimated ESDs and Es were compared with the reference doses found in Africa and Europe. Analysis of dose distributions among different radiological departments under study was also performed.

Back to Article Outline

Materials and methods 

In this study, technique factors, that is, kVp, mAs, FSD and patient characteristics such as weight, height, age, and thickness of the irradiated regions were obtained for chest, abdomen, skull and neck radiographic examinations. These data were recorded for each patient undergoing the specified diagnostic examinations. The data were collected in three different hospitals which include one teaching hospital (H1), one private hospital (H2) and one state hospital (H3), all located in three large cities of southwestern Nigeria namely Osogbo (Osun state), Ibadan (Oyo state) and Ijebu Ode (Ogun state). A total of 209 adult (above 16 years) patients undergoing routine X-ray examinations were considered in this study.

Three different X-ray units were included in this study. They were all analogue systems installed at different times as presented in Table 1. The films were examined and considered acceptable to the radiologists/radiographers after exposure and film processing. This ensured that all dose levels used were representative of diagnostic image.

Table 1. Specific data of machines used at selected hospitals

Hospital code	Name of machine	Year of installation	X-ray output (mGy/mAs)×10−2	Effective kVp	Filtration (mm Al)
H1	Neo Diagnomax	1982	7.9	89.8	3.0
H2	Aicoma	2005	5.6	97.1	1.0
H3	GEC Apollo	1984	2.7	94.5	2.0

The output of the X-ray machines (in mGy/mAs) at 80kVp at a distance of 1m normalized to 10mAs¹⁰ was measured using a calibrated KV meter (Victoreen invasive X-ray test device model 4000 m+).

Indirect measurement of entrance skin dose (ESD) and effective dose (E) was carried out in this study. This involved the use of technique factors, output of the X-ray machine and the backscatter factors for adult. The DoseCal software¹⁸ was used to calculate ESD and E based on the values of technique factors employed, that is, the X-ray tube output and the projections. This method of dose calculation is a realistic alternative to dosimetry methods such as thermoluminescence dosimetry (TLD).¹⁰ The DoseCal software was developed in the Radiological Protection Centre of Saint George’s Hospital (London) and plays an essential role in the evaluation of radiation doses for a great number of patients. For the operation of the software, X-ray outputs in mGy/mAs at 80kV at a distance of 100cm normalized to 10mAs were entered and when kVp (in kilovolts), mAs (product of tube current and exposure time), FSD (focus to skin distance in cm), BSF (backscatter factor) are known, Eq. (1) demonstrates the ESD.¹⁹

(1)

Back to Article Outline

Results 

The data were collected in three major hospitals in SW Nigeria, comprising three X-ray facilities. Table 1 shows the specific data of the three X-ray units used for this study. The filtration of the X-ray units in H2 and H3 was found to be lower than 2.5mm Al prescribed by the National Radiological Protection Board (NRPB). Patient information and technique factors for chest posteroanterior (PA) and lateral (LAT), abdomen anteroposterior (AP) and LAT, skull PA and LAT and neck AP examinations in the three hospitals (H1, H2 and H3) investigated are shown in Table 2. All the three X-ray units under study undertook the chest PA examination but only hospital H1 undertook chest LAT examination. Two hospitals undertook the abdomen AP examination while again only hospital H1 undertook abdomen LAT examination. Two hospitals (H1 and H3) undertook skull (PA and LAT) examination and only hospital H1 undertook neck AP examination.

Table 2. Patient information and technique factors for different X-ray examinations (range in parentheses)

Radiograph (hospital)	Projection	Thickness (cm)	Height (cm)	Weight (kg)	Body mass index (kgm−2)	Tube potential (kVp)	Mean (mAs)	FSD (cm)
Chest (H1)	PA	20 (12–30)	166 (133–192)	62 (35–91)	23 (14–36)	66 (16–80)	20 (8–100)	105 (55–100)
Chest (H2)	PA	21 (17–25)	167 (148–182)	61 (46–77)	22 (17–28)	80 (constant value used)	15 (constant value used)	129 (125–133)
Chest (H3)	PA	23 (20–26)	164 (116–181)	68 (48–170)	26 (19–48)	85 (75–90)	9 (constant value used)	125 (66–157)
Chest (H1)	LAT	26 (15–33)	165 (149–176)	61 (37–91)	23 (14–41)	71 (63–90)	23 (15–40)	96 (63–114)
Abdomen (H1)	AP	23 (16–34)	169 (157–176)	68 (55–97)	24 (18–39)	76 (70–90)	131 (100–250)	85 (60–110)
Abdomen (H3)	AP	24 (20–28)	163 (151–173)	65 (52–82)	25 (19–27)	106 (100–120)	27 (16–45)	91 (47–178)
Abdomen (H1)	LAT	34 (19–48)	167 (157–176)	73 (55–95)	27 (18–39)	83 (67–100)	150 (80–200)	69 (49–111)
Skull (H1)	PA	21 (16–27)	165 (152–182)	71 (48–109)	26 (18–43)	76 (60–85)	106 (82–160)	95 (67–132)
Skull (H1)	LAT	16 (11–23)	162 (152–182)	71 (48–100)	28 (18–43)	74 (60–100)	69 (10–100)	98 (66–118)
Neck (H1)	AP	12 (10–14)	160 (154–170)	72 (59–91)	28 (18–43)	70 (67–72)	28 (16–40)	91 (74–104)

The median patient weight measured was found to be 67kg. This median patient size was within the range of a standard sized person of 60–80kg recommended by the Community of European Commission (CEC).²¹ It can be seen from Table 2 that a constant value of tube potential of 80kVp was used for chest PA examination in H2. Hospital H1 was using low kVp, ranging between 16 and 80kVp, with a median of 66kVp for chest PA examination. Both high-kVp and low-kVp radiological techniques were reported to be commonly used in chest radiography examinations in Europe and USA.²² However, CEC recommends that kVp in the range 100–150kVp be used for chest PA examinations which results in low doses.

In H1, the mean FSD as low as 105cm was used for chest PA examination. As a result, higher ESDs were encountered in this hospital. The use of optimum FSD is considered very important, since there is a direct relationship between shorter FSD, higher patients’ dose and decreased geometric sharpness.²³, ²⁴ It is also evident from the table that a constant value of 15mAs and 9mAs were used in H2 and H3, respectively, for patients of various sizes during chest examination.

Table 3 is a comparison of patient information and technique factors with Ghana, UK, CEC and the combination of European and Asian values. The mean value of thickness of the chest of the patient was comparable to Ghanaian value of 20cm while the mean thickness of the abdomen of the patient of 23cm in H1 is higher than that of Ghana. It is clear from the procedural data shown that where guidelines are available, the three hospitals are not complying with international guidelines for some parameters.

Table 3. Comparison of patient information and technique factors (adult) with Ghanaian, UK, EC and European–Asian values

Patient information and technical parameters	Radiograph	This work	Ghanaa	UK (NRPB)a	CECa	European–Asianb
Patient thickness (cm)	Chest PA	20 (12–30) H1	20 (13–33)	–	–	–
		21 (17–25) H2
		23 (16–34) H3
	Abdomen AP	23 (16–34) H1	19.6 (15–28)	–	–	–
		24 (20–28) H3
Applied tube potential (kVp)	Chest PA	66 (16–81) H1	70.1 (50–90)	76 (44–150)	100–150	70–125
		80 (constant) H2
		85 (75–90) H3
	Chest LAT	71 (63–90) H1	–	–	–	101–125
	Abdomen AP	76 (70–90) H1	78.1 (65–90)	73 (55–120)	70–90	66–84
		106 (100–120) H3
	Skull PA	76 (60–85) H1	–	–	65–85	–
Focus to skin distance (FSD) (cm)	Chest PA	105 (55–100) H1	152 (41–201)	–	–	150–180
		129 (125–33) H2
		125 (66–157) H3
	Chest LAT	96 (63–114) H1	–	–	–	180
	Abdomen AP	85 (60–110) H1	84.1 (60–107)	–	–	100–115
		91 (47–178) H3
	Skull PA	95 (67–132) H1	–	–	100–150	–
Product of tube current and exposure time (mAs)	Chest PA	20 (80–100) H1	32.7 (8–90)	8 (1–200)	–	1.4–4.7
		15 (constant) H2
		9 (constant) H3
	Chest LAT	23 (15–40) H1	–	–	–	4.4–20.7
	Abdomen AP	131 (100–250) H1	83.1 (40–26)	53 (3–400)	–	12–63
		27 (16–45) H3

The distribution and mean values of ESD for different examinations and hospitals are presented in Table 4. Wide variations are demonstrated between hospitals. Minimum/maximum ratio of ESD for mean hospital dose ranged from 1.3 for chest PA in H2 to 63 for the same projection in H1. For abdomen AP, the range of mean hospital dose varies from a factor of 6.4 in H3 to a factor of 11.8 in H1.

Table 4. Distribution of individual entrance skin dose (ESD)

Back to Article Outline

Discussion 

Variation in FSD, mAs and kVp used among the three hospitals is a reflection of non standardization of procedures.¹⁰ Variations of exposure factors were also found within the same hospital. The kVp for chest PA projection ranged from 16 to 80kVp in H1, while the mAs varied from 8 to 100mAs for the same projection. The radiologists in this hospital prefer higher contrast chest radiographs which result from low kVp.²⁵ The low kVp here indicates poor practice and shows that the focus of radiographers is just the image quality at the expense of patient dose. The FSD varied from 55 to 100cm in H1, 125–133cm in H2 and 66–157cm in H3.

It is worthy of note that the constant value of mAs used in both H2 and H3 for patients of various sizes is far from good practice since it is necessary to account specifically for patient weight when setting the technique factors. Failure to account specifically for patient weight (especially when there is no automatic exposure control – AEC)²⁸ during radiographic examinations could lead to patients of small weight being unnecessarily exposed and patients of large weight being under exposed.²⁹ This could produce suboptimal image quality.³⁰ It is interesting to observe that the mAs values used in H3 (for abdomen AP) were lower than the mean value used in both Ghana and the UK.

The tube filtrations found in the three hospitals (as seen in Table 1) show that only H1 with filtration of 3.0mm Al exceeded the minimum standard of 2.5mm Al prescribed in the UK standard.⁷, ¹¹ Due to the low filtration found in H2, the effective dose could not be calculated since the NRPB report did not provide data for filtration of 1mm Al. The facility with this lowest filtration in this study is in a private hospital. There was probably a lack of adequate information about the required minimum filtration.

As regards the FSD for all the examinations, the three hospitals did not comply with international guidelines. The values were found to be lower in all cases. Also, the mean value of mAs used for chest PA in hospital H1 was found to be within the range of UK values. For abdomen AP and chest LAT, the hospitals did not comply with international guidelines. Reference values for skull LAT, abdomen LAT and neck AP were not available for comparison.

The range of mean hospital dose varies from a factor of 1.3 to a factor of 63 for the anteroposterior chest (Table 4). An Irish study showed a hospital dose variation from a factor of 3 for the lumbar spine AP to a factor of 23 for the chest PA.³² An inter-hospital comparison shows that the mean ESD calculated for chest PA (H1) is higher than the value found in H2 and H3 by a factor of 4.7 and 2.3, respectively. Also in abdomen AP, the ESD calculated in H1 is higher than that of H3 by a factor of 2.8. The mean values obtained for skull (PA), skull (LAT) and neck (AP) were 12.1, 8.5 and 2.7mGy, respectively. The highest value of 46.5mGy is recorded in abdomen LAT in H1. This high value could be attributed to the large tube current–time product of 150mAs used. Apparently, the quality of the image produced is primed above patient safety. Because of this, education of the radiologist and radiographer about the specific factors that affect radiation doses to patients as well as the steps that could be taken to minimize such doses is essential.¹¹ This would help to optimize the dose–image quality relationship. The trend found in H2 and H3 in the choice of technique factors shows that the technique factors are not matched with patients’ weights. This could be due in part to the absence of a chart that suggests radiographic technique factors for various examinations and patients’ thicknesses.

Table 5 is a comparison of ESD obtained in this work with established reference doses in the UK (2005 review), IAEA, EC, Ghana and Sudan. In this comparison, the values of ESD obtained in H1 for five examinations namely chest (PA and LAT), abdomen (AP) and skull (PA and LAT) are higher than those of UK, IAEA, EC, Ghana and Sudan. The ESD for chest PA was found to be higher than UK values by a factor of 9.3; skull (PA and LAT) were higher than UK and Sudanese values by factors 6.1 and 6.5, respectively while abdomen AP was a factor of 5.6 and 12.3 higher than UK and Sudanese values, respectively. The chest (LAT) projection had the lowest variation with the UK, varying with a factor of 3.3. In H2, the ESD value for chest PA is about 50% higher than that of UK, comparable with EC but less than IAEA and Ghanaian values. The ESD values obtained in H3 for chest PA are higher than UK, IAEA and EC values but comparable with that of Ghana. For abdomen AP, it is a factor of 1.2 less than IAEA and EC values but greater than the UK, Ghanaian and Sudanese values by a factor of 2.1, 1.2 and 4.5, respectively. Reference data for abdomen LAT and neck AP were not available for comparison.

Table 5. Comparison of ESD (mGy) with international reference doses and those obtained in Ghana and Sudan for adults

Table 6 presents the minimum, maximum, mean and standard deviation of effective dose obtained in this study. The mean effective doses and ranges for chest PA, chest LAT, abdomen AP, skull PA and skull LAT projections were found to be 0.2 (0.0–0.6), 0.1 (0.1–0.2), 3.2 (0.8–11.8), 0.1 (0.1–0.3) and 0.1 (0.0–0.3) mSv, respectively. Table 7 shows the comparison of this work’s mean effective dose with the ranges of effective doses reported in the literature for the different examinations and procedures.

Table 6. Summary of effective dose (E) for different examinations

Examination	Effective dose (×10−1mSv)
	Min.	Mean	Max.	Standard deviation (SD)
Chest PA (H1)	0.1	1.5	6.1	0.8
Chest PA (H3)	0.4	0.7	1.6	0.4
Chest LAT (H1)	0.6	1.4	2.3	0.5
Abdomen AP (H1)	8.4	31.7	117.8	34.4
Abdomen AP (H3)	2.1	10.3	15.2	0.5
Skull PA (H1)	0.5	1.0	2.5	0.6
Skull LAT (H1)	0.4	0.9	2.7	0.8

Table 7. Comparison of effective dose (mSv) with doses reported in the literature

Comparing the mean effective dose obtained in H1 with that of H3 shows that the mean effective dose in H1 is greater than the doses obtained in H3 by a factor of 2 and 1.4 for chest PA and abdomen AP, respectively. The comparison of mean effective dose obtained in H1, for chest PA and abdomen AP with the reference doses reported in the literature indicates that the effective dose calculated in this study is greater than the established reference doses by 33% in both projections. For skull (PA and LAT) examinations, the mean effective doses obtained in this study are within the range of values reported in the literature. Reference data for abdomen LAT and neck AP were not available. Comparison in H3 shows about 14% increase in the effective dose values for chest PA but the mean value for abdomen AP was found to be within the range of the values reported in the literature. The results of this study showed that higher effective doses are being delivered to patients in chest PA (H1 and H3) and abdomen AP (H1) when compared with the range of values reported in literature. Radiologists and radiographers in these hospitals have an obligation to balance the risks and benefits of these medical procedures.

Back to Article Outline

Conclusion 

The findings of this study clearly showed that both the ESD and E calculated in H1 and H3 were higher than UK (2005 review), IAEA and EC established reference doses elsewhere. However, the practices in H2 in most part agreed with the established reference doses but the filtration of 1mm Al used is unacceptable. The trend found in H1 and H3 is an indication that there is a need to improve the quality of radiodiagnostic procedures in the hospitals.

In addition, radiation staff need awareness concerning the levels of dose and distribution of doses being delivered to patients undergoing various diagnostic procedures and the attendant risk to the population being exposed. Meanwhile, these results would be useful to the Nigerian Nuclear Regulatory Authority (NNRA) as baseline upon which future dose measurements may be compared and in the formulation of both local and national diagnostic reference levels. The findings of this work indicate the need for serious monitoring, quality assurance programme (QAP) in Nigeria and re-training of the personnel responsible for the exposure of patients.

Back to Article Outline

Acknowledgements 

The authors would like to thank the hospitals that participated in this study and their staff for their cooperation. They are also grateful to a staff of Fundacao Oswaldo Cruz (Fiocruz), Brazil for kindly providing the DoseCal software used for the present study. One of the authors who is an associate undertook part of this work with the support of “ICTP, Trieste, Italy”.

Back to Article Outline

References 

1. Merric N, Bor D, Buget N, Ozkirli M. The use of Monte Carlo technique for the determination of tissue–air ratios (TAR) in diagnostic energy range. Phys Med. 1998;14:
   • View In Article
2. National Council on Radiation Protection and Measurements (NCRP). Ionizing radiation exposure of the population of the United States. NCRP report 93; 1987.
   • View In Article
3. National Radiological Protection Board (NRPB). A national survey of doses to patients undergoing a selection of routine X-ray examinations in English hospitals. NRPB report 261; 1993.
   • View In Article
4. National Radiological Protection Board (NRPB) . Patient dose reduction in diagnostic radiology. NRPB. 1990;1(3):
   • View In Article
5. Commission of European Communities (CEC). European Commission. European guidelines on quality criteria for diagnostic radiographic images in paediatrics. EUR 16261 EN; 1996.
   • View In Article
6. National Occupational Health and Safety Commission (NOHSC). Recommendations for limiting exposure to ionizing radiation. NOHSC: 3022 (Radiation health series 39); 1995.
   • View In Article
7. Parry RA, Sharon A, Glaze MS, Benjamin RA. The AAPM/RSNA physics tutorial for residents: typical patient radiation doses in diagnostic radiology. Radiographics. 1999;19:1289–1302
   • View In Article
   • MEDLINE
8. Ng KH, Rassiah P, Wang HB, Hambali AS, Muthuvellu P, Lee MP. Doses to patients in routine X-ray examinations in Malaysia. Br J Radiol. 1998;71:654–660
   • View In Article
   • MEDLINE
9. Muhogora WE, Nyanda AM. The potential for reduction of radiation doses to patients undergoing some common X-ray examinations in Tanzania. Radiat Prot Dosimetry. 2001;94:381–384
   • View In Article
   • MEDLINE
   • CrossRef
10. Mohammadain KEM, da Rosa LAR, Azevedo ACP, Guebel MRN, Boechat MCB, Habani F. Dose evaluation for paediatric chest X-ray examinations in Brazil and Sudan: low doses and reliable examinations can be achieved in developing countries. Phys Med Biol. 2004;49:1017–1031
    • View In Article
    • MEDLINE
    • CrossRef
11. Ware DE, Huda W, Mergo PI, Litwiller AL. Radiation effective doses to patients undergoing abdominal CT examinations. Radiology. 1999;210(3):645–650
    • View In Article
    • MEDLINE
12. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Sources, effects and risks of ionizing radiation. Vol. 2. Report to the General Assembly, with scientific annexes; 2000.
    • View In Article
13. Ogunseyinde AO, Adeniran SAM, Obed RI, Akinlade BI, Ogundare FO. Comparison of entrance surface doses of some X-ray examinations with CEC reference doses. Radiat Prot Dosimetry. 2002;98(2):231–234
    • View In Article
    • MEDLINE
    • CrossRef
14. Ajayi IR, Akinwumiju A. Measurement of entrance skin doses to patients in four common diagnostic examinations by thermoluminescence dosimetry in Nigeria. Radiat Prot Dosimetry. 2000;87:217–220
    • View In Article
15. Ogundare FO, Uche CZ, Balogun FA. Radiological parameters and radiation doses of patients undergoing abdomen, pelvis and lumbar spine X-ray examinations in three Nigerian hospitals. Br J Radiol. 2004;77:934–940
    • View In Article
    • MEDLINE
    • CrossRef
16. Egbe NO, Chiaghanam NO, Azogor WE, Inyang SO. A baseline study of entrance dose and image quality for lumbar spine radiography in Calabar, Nigeria. Radiography. 2008;15:306–312
    • View In Article
17. Egbe NO, Inyang SO, Eduwem DU, Ama I. Doses and image quality for chest radiographs in three Nigerian hospitals. Eur J Radiogr. 2009;1:30–36
    • View In Article
18. Kyriou JC, Newey V, Fitzgerald MC. Patient doses in diagnostic radiology at the touch of a button. London, UK: The Radiological Protection Centre, St George’s Hospital; 2000;
    • View In Article
19. Davies M, McCallum H, White G, Brown J, Hlem M. Patient dose audit in diagnostic radiography using custom designed software. Radiography. 1997;3:17–25
    • View In Article
20. Hart D, Jones DG, Wall BF. Normalised organ doses for medical X-ray examinations calculated using Monte Carlo techniques. NRPB-SR262; 1994.
    • View In Article
21. Commission of European Communities (CEC). European Commission. European guidelines on quality criteria for diagnostic radiographic images. EUR 16260 EN; 1996.
    • View In Article
22. Fung KKL, Gilboy WB. The effect of beam tube potential variation on gonad dose to patients during chest radiography investigated using high sensitivity LiF:Mg, Cu, P thermoluminescent dosemeters. Br J Radiol. 2001;74:358–367
    • View In Article
    • MEDLINE
23. Vano E, Olite S, Gonzalez L, Guibelade E, Velasco A, Fernandez JM. Image quality and dose in lumbar spine examinations: results of a 5 year quality control programme following the European quality criteria trial. Br J Radiol. 1995;68:1332–1335
    • View In Article
    • MEDLINE
    • CrossRef
24. Brennan PC, Nash M. Increasing FFD: an effective dose-reducing tool for lateral lumbar spine investigations. Radiography. 1998;4:251–259
    • View In Article
25. Martin CJ, Darragh CL, McKenzie GA, Bayliss AP. Implementation of a programme for reduction of radiographic doses and results achieved through increases in tube potential. Br J Radiol. 1993;66:228–233
    • View In Article
    • MEDLINE
    • CrossRef
26. Schandorf C, Tetteh GK. Analysis of dose and dose distribution for patients undergoing selected X-ray diagnostic procedures in Ghana. Radiat Prot Dosimetry. 1998;76:249–255
    • View In Article
27. Rainford LA, Al-Qattan E, McFadden S, Brennan PC. CEC analysis of radiological images produced in Europe and Asia. Radiography. 2007;13:202–209
    • View In Article
28. International Commission on Radiological Protection (ICRP). Protection of the patient in diagnostic radiology. ICRP publication 34; 1982.
    • View In Article
29. Huda W, Slone RM, Belden CJ, Williams JL, Cumming WA, Palmer KC. Mottle on computed radiographs of the chest in pediatric patients. Radiology. 1996;199:249–252
    • View In Article
    • MEDLINE
30. Huda W, Scalzetti EM, Galina GBS. Technique factors and image quality as functions of patient weight at abdominal CT. Radiology. 2000;217:430–435
    • View In Article
    • MEDLINE
31. Hart D, Hillier MC, Wall BF. Doses to patients from radiographic and fluoroscopic X-ray imaging procedures in the UK – 2005 review. Chilton, UK. HPA-RPD-029; 2007.
    • View In Article
32. Johnston DA, Brennan PC. Reference dose levels for patients undergoing common diagnostic X-ray examinations in Irish hospitals. Br J Radiol. 2000;73:396–402
    • View In Article
    • MEDLINE
33. Mettler FA, Huda W, Yoshizumi TT, Mahesh M. Effective doses in radiology and diagnostic nuclear medicine: a catalog. Radiology. 2008;248:254–263
    • View In Article
    • CrossRef