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Assessment of the Local Exposure Level during Adult Chest X-Rays at the Ngaoundere Regional Hospital, Cameroon

Assessment of the Local Exposure Level during Adult Chest X-Rays at the Ngaoundere Regional... Hindawi Radiology Research and Practice Volume 2019, Article ID 3619498, 5 pages https://doi.org/10.1155/2019/3619498 Research Article Assessment of the Local Exposure Level during Adult Chest X-Rays at the Ngaoundere Regional Hospital, Cameroon 1 2 3 4 Guiswe Gnowe , Henri Paul Ekobena Fouda, Mbo Amvene Je´remie, Takmou Pascal, and Bonaventure Babinne Graobe Higher Institute of Sciences, Health Technics and Management of Garoua, Garoua, Cameroon University Technological of Institute, University of Ngaoundere, Ngaoundere, Cameroon Faculty of Medicine and Biomedical Sciences of Garoua, Garoua, Cameroon General Hospital of Douala, Douala, Cameroon Correspondence should be addressed to Guiswe Gnowe; gnoweguiswe@gmail.com Received 7 May 2019; Revised 24 July 2019; Accepted 23 August 2019; Published 19 September 2019 Academic Editor: Paul Sijens Copyright © 2019 Guiswe Gnowe et al. +is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. +e purpose of this study was to estimate the doses delivered to adult patients during chest examination for comparison with those elsewhere and to establish a local diagnostic reference level for the chest. +e doses delivered in the standard X-ray examinations are not sufficiently optimized and controlled. +e working protocols for the same exam given differ for similar morphotypes within the same hospital structure. Materials and Methods. +e entrance skin dose (mGy) of the chest was th evaluated on 105 adult patients with a mass of 70± 10 kg in accordance with the 75 percentile of the irradiation parameters. +e analysis and processing of the data was carried out by Excel 2010. +e entrance skin dose of the chest obtained in mGy was 0.18± 0.21 for the PA incidence. Conclusion. +e present study allowed us to observe large variations at the entrance skin doses of the chest. +ese variations have made it possible to understand that the entrance skin doses to the chest are optimized and do not exceed the proportions of those estimated by others and standards internationally. +is aspect demonstrates that the diagnostic reference levels as enumerated are dependent on the doses delivered and include not only the notions of quality of the ra- diographic image and the quality assurance of the radiological equipments but also the level of the manipulators trained. observed elsewhere, there are also wide variations in the dose 1. Introduction for the same type of examination and the same morphotype +e medical applications of ionizing radiation have, for of X-ray patients [3]. +e health effects of doses delivered in many years now, contributed to an improvement of medical radiodiagnostics are not only low but zero below an im- practicals and bring a real benefit in terms of health. In precise threshold [4] since the linear relationship without radiology, dosimetry and diagnostic quality of images are threshold not based on 0.6% to 3% of cancers would be inseparable. Diagnosis is a function dependent on the quality attributable to radiodiagnostics. of the radiological image. Dosimetry could be defined as the When one is in a world structured by the important measurement of ionizing radiation received or deposited in a uncertainty of ionizing radiation, uncertainties remain and it medium [1]. Diagnostic medical examinations using ion- is impossible as for the risks created by the ionizing radi- izing radiation such as radiology, CT, and nuclear medicine ations. Some think that the risk exists even at low doses, lead to variable exposure of patients according to the pro- others think that it does not exist, and others finally think cedure implemented, the facility of the technology, and the that it can be even more complicated; it is normal that patient’s morphotype [2]. In view of this, the reality of these knowledge from all horizons can be taken into account in the risks, however, comes up against the general problem definition of protective devices. In the case of ionizing ra- commonly referred to as the problem of low doses. As diation, the difficulty experienced passes from the 2 Radiology Research and Practice process of justification and optimization of radiological prevention of proven risks to precautionary approaches aimed at hypothetical risks. +is difficulty is evident in the practices [9]. +e knowledge of these doses necessarily involves in the handling of limit values or threshold values considered useful. +e radioprotection of patients in imaging appears as determination of doses according to the disymmetric an emergency and a particular attention related to the quantities. +e determination of these values must be based th practices because zero risk is hardly possible. Without on the statistical method known as the 75 percentile of the compromising the effectiveness of the diagnosis or their measured dose distribution [10, 11] since 75% of individuals therapeutic value, the overall goal is to reduce exposure to receive doses below these values [7, 11], or the reference what is absolutely necessary. +at is why any examination levels. Diagnostics are of practical interest only if they are must be justified by its diagnostic contribution in relation assigned to dosimetric quantities accessible by the mea- with the irradiation, its realization must be optimal, that is to surement. In conventional radiology, the entrance skin dose say, in conformity with the ALARA (as low as reasonably (ESD in mGy) and the dose area product (DAP in Gy·cm ) achievable) principle, and the doses delivered must be were retained. +e entrance skin dose (ESD) can be de- regularly evaluated for comparison with diagnostic reference termined by two approaches: the indirect method, also called levels, which should not be exceeded without justification semiempirical method, using the exposure parameters [5]. Regulatory actions, if necessary, must be considered to linked to examinations and the direct method using the correct any differences between dose and these irradiation dosimeter thermoluminescent (TLD) for measurement. parameters [6]. Moreover, the diagnosis being subordinated +ese two methods have relatively small differences. +e by the informative quality of the images may not be ap- calculation or mathematical method appears reliable and is plicable but may substitute the DRLs which are indicators of an effective alternative for measuring the entrance skin dose the quality of the practices, allowing each one to situate his [12]. practice by the whole of the profession and overexposure of +e problem of dosimetry usually stems from the in- patients. correct use of radiological equipment and the higher patient +e use of ionizing radiation for diagnostic or thera- exposure required [13]. +e optimization and dose de- peutic purposes is indeed incompatible with a regulatory termination approach must take into account the specific- limitation of doses: the level of irradiation is necessarily ities associated with the standardization of procedures [14]. subordinate to the medical objective and imposing “a priori” +e factors influencing the dose delivered to patients in impassable thresholds would be the contradiction detri- conventional radiology can be classified as follows [10]. mental to patients. Radiation protection for people exposed Several calculation models are proposed for the evaluation of for medical reasons is therefore based exclusively on the the dose at the entrance of the skin. But in our approach, we principles of justification and optimization [7]. Diagnostic used the estimation of the output [15]. According to the reference levels (DRLs) are defined as “dose levels in medical manufacturers, the value of the DAP is also displayed radiodiagnostic practices, or in the case of radiopharma- permanently at the control room monitor or actually ceuticals, activity levels, for standard examinations on measured by a device installed at the output of the X-ray tube typical patient groups or on typical ghosts, for broad cat- (ionization chamber) or calculated from the parameters of egories of types of installations” [8]. +e Respect for the the exposure and the size of the irradiation field. Because of reference levels is not, by itself, a criterion of good practice. the two physical laws (inverse of the square of the distance) +e priority objective, inseparable from dosimetry, is the and geometry (+ales theorem), the value of the DAP is diagnostic quality of images [9]. +is aspect means that the independent of the distance where it is measured [16]. other 25% corresponding to the highest doses were made under nonoptimized conditions. For this purpose, it is 2. Materials and Methods necessary to initiate control and correction actions, in case of unjustified overrun of the doses delivered. Our study was monocentric and prospective and was carried Diagnostic reference levels are tools for improving out at the Radiology and Medical Imaging Department of practices and optimizing doses. +e Respect for the reference the Regional Medical Imaging Center of Ngaoundere during levels is not, by itself, a criterion of good practice. +e the period from April to July 2016. A total of 105 adult primary and inseparable goal of dosimetry is to combine the patients weighing 70± 10 kg who had standard examinations diagnostic quality of images with the reasonably feasible during the study period were involved. +e examinations low-dose processes. Recognizing that a diagnostic reference were carried out on a General Electric-branded appliance, level is a level established for a standard procedure and for model 5192454, whose maximum voltage at the terminals is typical patient groups and not for individual exposures, 150 kV. +e studied parameters concerned the patient (age, compliance with this level does not automatically corre- sex, and anatomical region explored), parameters related to spond to the use of good practice, as the quality of the image the procedure (focus-film-distance or FFD; focus-skin-dis- may be poor and this will not make a good diagnosis. Di- tance or FSD; incidence), irradiation (kilovoltage or kV; agnostic reference levels are of diagnostic interest only if milliAmperesecond or mAs), and dosimetric constants that they are assigned to dosimetric quantities accessible by were otherwise absent on the manipulative console (en- measurement or calculation. Characterizing the level of trance skin dose or ESD; the dose area product or DAP). irradiation of an examination by a different size in con- +e first step in calculating the entrance skin dose in ventional radiology and CT may appear as a limitation in a standard radiography using the theoretical models is to Radiology Research and Practice 3 Table 1: Sociodemographic data. calculate the power (output) of the ray tube. +e power of the tube was estimated in our model study [16] using ir- Age Weight Radiography Sex radiation parameters directly involved in the achievement of (years) (kg) the examinations. M 55 29–53 (40.92± 7.42) 64–80 (70.84± 4.7) O mR − 1 Chest 23–56 60–78 − 4 2 2 (mR) � A × 6.53 × 10 􏼒 􏼓􏼐kV 􏼑 × kV × mAs, F 50 (35.58± 10.19) (66.66± 4.71) P mAs Total 105 (1) M: male. F: female. where (O/P)mR is the power (output) of the X-ray tube; A � 0, 8, kV is the voltage applied to the tube, for performing − 1 Table 2: Tube yield in mR and mGy · (mAs) . the examination; mAs is the charge passing through the tube; A was an equal constant of 0.5, 0.8, and 1 for single- Output Output Incidence − 1 phase, three-phase, and high-frequency generator tubes. In Radiography (mR) mGy · (mAs) our study, the X-ray tube was three-phase. +e yields ob- Min-max Min-max − 1 tained were converted from (mR) to mGy · (mAs) by Chest PA 75.22–81.75 0.65–0.71 multiplication at a factor of 0.00877/mAs [17]. PA: posteroanterior. Min: minimum. Max: maximum. +e entrance skin dose for each patient was calculated using the irradiation parameters of each radiographic ex- amination following this model. average age of men was 40.93, the standard deviation was mR − 1 − 4 2 2 7.42 years, and the age range was 29–53 years. In contrast, ESD(mGy) � A × 6.53 × 10 􏼒 􏼓􏼐kV 􏼑 × kV mAs the mean age of women was 35.58 years, the standard de- viation was 10.19 years, and the age range was 23–56 years. 100 mGy Men were more represented than women at 52% or a sex × mAs × × BSF × 0.00877 , 􏼒 􏼓 􏼒 􏼓 FSD mR ratio (M/F � 1.1). (2) Table 2 shows the efficiency of the X-ray tube. +ese values are essential parameters in the process of optimizing where ESD(mGy) is the entrance skin dose, FSD(cm) is the the dose delivered and the quality of the images. +ey are focus-skin-distance, and BSF is the radiation backscatter directly a function of the high voltage (kV) and the load factor. In the context of this work, it is equal to 1.35 for (mAs). adults according to the IAEA [1]. Table 3 summarizes the minimum, maximum, and mean +e anthropometric data and the technical parameters values of the main patient exposure parameters (kV, mAs, used (kV, mAs, FFD, and FSD) were collected at the time of FFD, and FSD) used during the course of this exploration in examinations. Only images of good qualities having been the study. used for diagnosis were considered. +e analysis and th Table 4 presents a comparative state of entrance skin treatment of the data according to the 75 percentile of the dose of the thorax, the DRLs, and those obtained elsewhere. irradiation parameters as well as the calculation of the en- trance skin dose (ESD) of the patients were carried out by Excel 2010. 4. Discussion We are very clearly aware of the difficulties of an evaluation 3. Results without having access to the actual measurement of the dose. +e data relating to this examination were collected by It is however necessary to have access to the measured dose means of a questionnaire whose items concerned the to indicate to the user the direction towards which the equipment, the patient, the radiological technique, the image technical progress is going. Indeed, if these results are closer criteria, and the dose received by the patient. +ese data were to the reality of the actual dose, then they can contribute processed and the results obtained are presented in tabular for the more appropriate determination of the “reference” form. Table 1 presents the distribution of sociodemographic values. From these results, we observe wide variations in the characteristics. Table 2 shows the performance of the X-ray use of pulmonary chest exposure parameters (PA) for pa- tube on the chest X-ray. Table 3 presents the values of the tients with similar morphotypes. +is diversity of the main patient exposure parameters (kV, mAs, FFD, and FSD) technical protocols is at the origin of the large variations of used during the course of this review in the study. Table 4 the irradiation parameters for the same morphotype. On the compares the entrance dose of the chest, the DRLs, and the contrary, despite the differences observed, our results are less values found elsewhere. than those estimated in [20], but these are similar to the Table 1 presents the statistical distribution of the soci- DRL’s for chest radiography. +is aspect proves the em- odemographic characteristics of the patients who partici- bryonic state of radioprotection of patients in the radiology pated in this study. Patient anthropometric data (sex, age, departments. +ese discrepancies with those obtained and weight) are essential for interpreting the results of ra- elsewhere and with international standards can be explained diological examination and dosimetry. Only complete data apart by the absence of dosimetric values and working on 105 adult male and female patients were selected. +e protocols in the examination room. 4 Radiology Research and Practice Table 3: Technical parameters used to conduct this exam. rd ESD Radiography Incidence kV mAs FFD FSD SD quartile Min-max Max/min 120–125 2.5–4 140–180 160–200 Chest PA 0.08–0.09 1.04 0.18 0.21 (122.8± 1.72) (3.17± 0.46) (180± 0.09) (128± 0.20) kV: kilovolt. mAs: milliampere second. FFD: focus-film-distance. FSD: focus-skin-distance. ESD: entrance skin dose. SD: standard deviation. Table 4: Comparison of the entrance skin dose (mGy) with those obtained elsewhere and at DRLs. Radiography Incidence Our study IRSN (DRL) Sudan [18] Iran [19] Mali [20] Chest PA 0.18± 0.21 0.3 0.53± 0.24 0.70± 0.38 3.84 On the contrary, international standards and DRLs must ionizing radiation, it is important to note that the risk of be used to control and optimize radiological practices. In irradiation increases with the nonobservance of the basic practice, by displaying and applying these, it is possible to principles of radiation protection of patients. +e results avoid unnecessary irradiation and the periodic evaluation of obtained show that the doses delivered to patients are not the delivered doses should become a routine activity. optimal. However, an improvement in practices, especially Consequently, the doses delivered for the realization of the in relation to the technical parameters and protocols as- thorax are not sufficiently mastered. +ese differences lead sociated with strengthening the permanent radiation pro- us to think like [5] that unlike developed countries, in sub- tection skills of radiological manipulators, could contribute Saharan African countries, particularly Cameroon and Mali, to better radiological protection of patients in this radiology legislative and regulatory frameworks are either nonexistent department. Moreover, note that the indirect method used or implemented in a rough way. Moreover, the practice of here is a reliable alternative for measuring the entrance skin radioprotection of patients is poorly documented in a dose of the patient. +is method could also serve as a means context of constant expansion of medical imaging for a of measurement for the control and dosimetric assessment decade.. in case of dosimeter deficiency in developing countries As imaging spreads to the most remote areas of the whose scarcity of resources constrains the implementation country, there is an urgent need to optimize work protocols. of approximate international conventions and legislation. In +is optimization of doses delivered to the patients could radiation protection, however, corrective measures should well be effective by the setting up of a regulatory framework be evaluated and undertaken, if there are excessive dis- with the obligation of designation and training of humans crepancies between the doses delivered and those observed competent in radioprotection which would allow not only to elsewhere. For this, the radioprotection of patients is an improve the radioprotection of the patients but also of emergency quality in a context where quality is a global the personnel, for the establishment of regular dosimetric aspiration. control and dosimetric standards. +e lack of ongoing training of personnel on radiation protection measures Data Availability could be noted as potential factors of patient exposure. +is finding is still very worrying, when the professional profile Our data may be available upon request. (nurse and caregivers) of some radiology manipulators does not correspond to their “background” because they are Conflicts of Interest rather converted into radiological manipulators and a large rotation of radiology trainees who find work protocols not +e authors declare that they have no conflicts of interest. available and also who are often forced to produce images capable of being exploited. In view of this, they have either no idea or a rough idea of the good practice in radio- References diagnostics or even radiation protection of patients. From [1] Agence Internationale de l’Energie Atomique (AIEA), these observations, we can affirm with [5] the low level of “Normes fondamentales internationales de protection contre knowledge in radioprotection in African countries, espe- les rayonnements ionisants et de suret´e des sources de cially those of sub-Saharan Africa, despite the existence of rayonnements,” Collection S´ecurit´e, vol. 115, pp. 309–332, the laws governing radiation protection and the lack of resources forced to approximate, DRLs. [2] P. Roch, D. Celier, C. Etard, and A. Noel, BilanDu Recueil 2011- 2012 Des Nrd Par L’irsn Et Recommandations D’evolution Du Syst`eme Par Le GPMED-ASN, pp. 1–3, Socie´te´ Française de 5. Conclusion Radioprotection, Congre`s National de Radioprotection, Tours, At the end of this work, it should be noted that dosimetry is a France, 2005. [3] J. Gray, “Reference, values-what are they?,” American Asso- good match between the image quality and low-dose pro- ciation of Physicist in Medicine, vol. 24, pp. 9-10, 1999. cess. Far from trivializing the exposure of patients to Radiology Research and Practice 5 [4] A. B. de Gonzalez ´ and S. Darby, “Risk of cancer from di- examinations in Sudan,” Sudan Journal of Medical Sciences, agnostic X-rays: estimates for the UK and 14 other countries,” vol. 11, no. 1, pp. 7–16, 2016. [19] D. Khoshdel-Navi, A. Shabestani-Monfared, M. R. Deevband, 2e Lancet, vol. 363, no. 9406, pp. 345–351, 2004. [5] P. Ongolo-Zogo, C. Mpeke Mokubangele, B. Moifo, and R. Abdi, and M. Nabahati, “Local-reference patient dose evaluation in conventional radiography examinations in J. Gonsu fotsin, “Evaluation de la dose patient en scanogra- mazandaran, Iran,” Journal of Biomedical Physics and Engi- phie pediatrique ´ dans deux hopitaux ˆ universitaires a` yaounde´ neering, vol. 6, no. 2, pp. 61–70, 2016. cameroun,” Radioprotection, vol. 47, no. 4, pp. 533–542, 2012. [20] S. Traore, ´ “Etude comparative de la dose patient a la dose de [6] R. Azzoz, K. M. ElShahat, R. A. MonemRezk, and R. Monem, ref ´ erence ´ dans le service de radiologie et d’imagerie medicale ´ “Evaluation of quality control systems for X-ray machines at de l’hopital ˆ gabriel tour´e (HGT) a` propos de 70 cas,” Uni- different hospitals using patient’s radiological dose assessment versite´ de Bamako, Faculte´ de Medecine, ´ de Pharmacie et technology,” IOSR Journal of Applied Physics, vol. 6, no. 5, d’Odontostomatologie (FMPOS), Bamako, Mali, +ese ` de pp. 29–34, 2014. Doctorat Medecine, 2006. [7] H. Beauvais-March, M. Valero, A. Biau, N. Hocine, J.-L. Rehel, and M. Bourguignon, “L’exposition des patients en radiodiagnostic: bilan de l’etude ´ dosimetrique ´ realis ´ ee ´ en 2001–2003 dans 24 services français de radiologie,” Radio- protection, vol. 39, no. 4, pp. 493–511, 2004. [8] G. A. Monnehan, K. J. Anouan, D. P. Onoma et al., “Determination ´ des niveaux de ref ´ erence ´ diagnostiques en cote ˆ d’ivoire: cas de la radiographie Standard du thorax de face et de l’abdomen sans preparation ´ (ASP) de face chez l’adulte dans le district d’abidjan et dans la region ´ du sud comoe,” ´ Revue Internationale des Sciences et Technologies, vol. 14, pp. 45–53, 2009. [9] Y. S. Cordoliani, P. Grenier, H. Beauvais, J. Grellet, E. Marshall-Depommier, and M. Bourguignon, “Le point sur les proc´edures en radiologie conventionnelle et en tomo- densitometrie,” ´ M´edecine Nucl´eaire Imagerie Fonctionnelle et M´etabolique, vol. 26, no. 5, pp. 241–246, 2002. [10] H. Beauvais-March, A. Biau, M. Bourguignon et al., “Les Proc´edures radiologiques: crit`eres de qualit´e et optimisation des doses,” Office de Protection Contre les Rayonnements Ionisants-Soci´et´e Française de Radiologie, pp. 17–46, 2000. [11] C. J. Olowookere, I. A. Babalola, N. N. Jibiri, R. I. Obed, L. Bamidele, and E. O. Ajetumobi, “A preliminary radiation dose audit in some nigerian hospitals: need for determination of national diagnostic reference levels (NDRLs),” 2e Pacific Journal of Science and Technology, vol. 13, no. 1, pp. 87–495, [12] V. Tsapaki, I. A. Tsalafoutas, I. Chinofoti et al., “Radiation doses to patients undergoing standard radiographic exami- nations: a comparison between two methods,” 2e British Journal of Radiology, vol. 80, no. 950, pp. 107–112, 2007. [13] M. Gholami, N. Fataneh, and V. Karami, “+e evaluation of conventional x-ray exposure parameters including tube voltage and exposure time in private and governmental hospitals of lorestan province, Iran,” Iranian Journal of Medical Physics, vol. 12, no. 2, pp. 85–92, 2015. [14] M. H. Beauvais, A. Biau, M. Bourguignon, C. Challeton De Vathaire, J. F. Lacronique, and M. Valero, “Optimisation des doses delivr ´ ees ´ aux patients en radiologie medicale,” ´ Rapport Scientifique et Technique, vol. 4, no. 5, pp. 143–151, 2002. [15] S. Kothan and M. Tungjai, “An estimation of X-radiation output using mathematic model,” American Journal of Ap- plied Sciences, vol. 8, no. 9, pp. 923–926, 2011. [16] M. Carlo and O. Bar, “Guide des bonnes pratiques de ra- dioprotection du patient en cardiologie interventionnelle,” Soci´et´e Française de Cardiologie, pp. 1–54, 2015. [17] K. Faulkner, D. A. Broadhead, and R. M. Harrison, “Patient dosimetry measurement methods,” Applied Radiation and Isotopes, vol. 50, no. 1, pp. 113–123, 1999. [18] A. A. Abu Khiar, A. O. Hamza, and N. A. 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Assessment of the Local Exposure Level during Adult Chest X-Rays at the Ngaoundere Regional Hospital, Cameroon

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Abstract

Hindawi Radiology Research and Practice Volume 2019, Article ID 3619498, 5 pages https://doi.org/10.1155/2019/3619498 Research Article Assessment of the Local Exposure Level during Adult Chest X-Rays at the Ngaoundere Regional Hospital, Cameroon 1 2 3 4 Guiswe Gnowe , Henri Paul Ekobena Fouda, Mbo Amvene Je´remie, Takmou Pascal, and Bonaventure Babinne Graobe Higher Institute of Sciences, Health Technics and Management of Garoua, Garoua, Cameroon University Technological of Institute, University of Ngaoundere, Ngaoundere, Cameroon Faculty of Medicine and Biomedical Sciences of Garoua, Garoua, Cameroon General Hospital of Douala, Douala, Cameroon Correspondence should be addressed to Guiswe Gnowe; gnoweguiswe@gmail.com Received 7 May 2019; Revised 24 July 2019; Accepted 23 August 2019; Published 19 September 2019 Academic Editor: Paul Sijens Copyright © 2019 Guiswe Gnowe et al. +is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. +e purpose of this study was to estimate the doses delivered to adult patients during chest examination for comparison with those elsewhere and to establish a local diagnostic reference level for the chest. +e doses delivered in the standard X-ray examinations are not sufficiently optimized and controlled. +e working protocols for the same exam given differ for similar morphotypes within the same hospital structure. Materials and Methods. +e entrance skin dose (mGy) of the chest was th evaluated on 105 adult patients with a mass of 70± 10 kg in accordance with the 75 percentile of the irradiation parameters. +e analysis and processing of the data was carried out by Excel 2010. +e entrance skin dose of the chest obtained in mGy was 0.18± 0.21 for the PA incidence. Conclusion. +e present study allowed us to observe large variations at the entrance skin doses of the chest. +ese variations have made it possible to understand that the entrance skin doses to the chest are optimized and do not exceed the proportions of those estimated by others and standards internationally. +is aspect demonstrates that the diagnostic reference levels as enumerated are dependent on the doses delivered and include not only the notions of quality of the ra- diographic image and the quality assurance of the radiological equipments but also the level of the manipulators trained. observed elsewhere, there are also wide variations in the dose 1. Introduction for the same type of examination and the same morphotype +e medical applications of ionizing radiation have, for of X-ray patients [3]. +e health effects of doses delivered in many years now, contributed to an improvement of medical radiodiagnostics are not only low but zero below an im- practicals and bring a real benefit in terms of health. In precise threshold [4] since the linear relationship without radiology, dosimetry and diagnostic quality of images are threshold not based on 0.6% to 3% of cancers would be inseparable. Diagnosis is a function dependent on the quality attributable to radiodiagnostics. of the radiological image. Dosimetry could be defined as the When one is in a world structured by the important measurement of ionizing radiation received or deposited in a uncertainty of ionizing radiation, uncertainties remain and it medium [1]. Diagnostic medical examinations using ion- is impossible as for the risks created by the ionizing radi- izing radiation such as radiology, CT, and nuclear medicine ations. Some think that the risk exists even at low doses, lead to variable exposure of patients according to the pro- others think that it does not exist, and others finally think cedure implemented, the facility of the technology, and the that it can be even more complicated; it is normal that patient’s morphotype [2]. In view of this, the reality of these knowledge from all horizons can be taken into account in the risks, however, comes up against the general problem definition of protective devices. In the case of ionizing ra- commonly referred to as the problem of low doses. As diation, the difficulty experienced passes from the 2 Radiology Research and Practice process of justification and optimization of radiological prevention of proven risks to precautionary approaches aimed at hypothetical risks. +is difficulty is evident in the practices [9]. +e knowledge of these doses necessarily involves in the handling of limit values or threshold values considered useful. +e radioprotection of patients in imaging appears as determination of doses according to the disymmetric an emergency and a particular attention related to the quantities. +e determination of these values must be based th practices because zero risk is hardly possible. Without on the statistical method known as the 75 percentile of the compromising the effectiveness of the diagnosis or their measured dose distribution [10, 11] since 75% of individuals therapeutic value, the overall goal is to reduce exposure to receive doses below these values [7, 11], or the reference what is absolutely necessary. +at is why any examination levels. Diagnostics are of practical interest only if they are must be justified by its diagnostic contribution in relation assigned to dosimetric quantities accessible by the mea- with the irradiation, its realization must be optimal, that is to surement. In conventional radiology, the entrance skin dose say, in conformity with the ALARA (as low as reasonably (ESD in mGy) and the dose area product (DAP in Gy·cm ) achievable) principle, and the doses delivered must be were retained. +e entrance skin dose (ESD) can be de- regularly evaluated for comparison with diagnostic reference termined by two approaches: the indirect method, also called levels, which should not be exceeded without justification semiempirical method, using the exposure parameters [5]. Regulatory actions, if necessary, must be considered to linked to examinations and the direct method using the correct any differences between dose and these irradiation dosimeter thermoluminescent (TLD) for measurement. parameters [6]. Moreover, the diagnosis being subordinated +ese two methods have relatively small differences. +e by the informative quality of the images may not be ap- calculation or mathematical method appears reliable and is plicable but may substitute the DRLs which are indicators of an effective alternative for measuring the entrance skin dose the quality of the practices, allowing each one to situate his [12]. practice by the whole of the profession and overexposure of +e problem of dosimetry usually stems from the in- patients. correct use of radiological equipment and the higher patient +e use of ionizing radiation for diagnostic or thera- exposure required [13]. +e optimization and dose de- peutic purposes is indeed incompatible with a regulatory termination approach must take into account the specific- limitation of doses: the level of irradiation is necessarily ities associated with the standardization of procedures [14]. subordinate to the medical objective and imposing “a priori” +e factors influencing the dose delivered to patients in impassable thresholds would be the contradiction detri- conventional radiology can be classified as follows [10]. mental to patients. Radiation protection for people exposed Several calculation models are proposed for the evaluation of for medical reasons is therefore based exclusively on the the dose at the entrance of the skin. But in our approach, we principles of justification and optimization [7]. Diagnostic used the estimation of the output [15]. According to the reference levels (DRLs) are defined as “dose levels in medical manufacturers, the value of the DAP is also displayed radiodiagnostic practices, or in the case of radiopharma- permanently at the control room monitor or actually ceuticals, activity levels, for standard examinations on measured by a device installed at the output of the X-ray tube typical patient groups or on typical ghosts, for broad cat- (ionization chamber) or calculated from the parameters of egories of types of installations” [8]. +e Respect for the the exposure and the size of the irradiation field. Because of reference levels is not, by itself, a criterion of good practice. the two physical laws (inverse of the square of the distance) +e priority objective, inseparable from dosimetry, is the and geometry (+ales theorem), the value of the DAP is diagnostic quality of images [9]. +is aspect means that the independent of the distance where it is measured [16]. other 25% corresponding to the highest doses were made under nonoptimized conditions. For this purpose, it is 2. Materials and Methods necessary to initiate control and correction actions, in case of unjustified overrun of the doses delivered. Our study was monocentric and prospective and was carried Diagnostic reference levels are tools for improving out at the Radiology and Medical Imaging Department of practices and optimizing doses. +e Respect for the reference the Regional Medical Imaging Center of Ngaoundere during levels is not, by itself, a criterion of good practice. +e the period from April to July 2016. A total of 105 adult primary and inseparable goal of dosimetry is to combine the patients weighing 70± 10 kg who had standard examinations diagnostic quality of images with the reasonably feasible during the study period were involved. +e examinations low-dose processes. Recognizing that a diagnostic reference were carried out on a General Electric-branded appliance, level is a level established for a standard procedure and for model 5192454, whose maximum voltage at the terminals is typical patient groups and not for individual exposures, 150 kV. +e studied parameters concerned the patient (age, compliance with this level does not automatically corre- sex, and anatomical region explored), parameters related to spond to the use of good practice, as the quality of the image the procedure (focus-film-distance or FFD; focus-skin-dis- may be poor and this will not make a good diagnosis. Di- tance or FSD; incidence), irradiation (kilovoltage or kV; agnostic reference levels are of diagnostic interest only if milliAmperesecond or mAs), and dosimetric constants that they are assigned to dosimetric quantities accessible by were otherwise absent on the manipulative console (en- measurement or calculation. Characterizing the level of trance skin dose or ESD; the dose area product or DAP). irradiation of an examination by a different size in con- +e first step in calculating the entrance skin dose in ventional radiology and CT may appear as a limitation in a standard radiography using the theoretical models is to Radiology Research and Practice 3 Table 1: Sociodemographic data. calculate the power (output) of the ray tube. +e power of the tube was estimated in our model study [16] using ir- Age Weight Radiography Sex radiation parameters directly involved in the achievement of (years) (kg) the examinations. M 55 29–53 (40.92± 7.42) 64–80 (70.84± 4.7) O mR − 1 Chest 23–56 60–78 − 4 2 2 (mR) � A × 6.53 × 10 􏼒 􏼓􏼐kV 􏼑 × kV × mAs, F 50 (35.58± 10.19) (66.66± 4.71) P mAs Total 105 (1) M: male. F: female. where (O/P)mR is the power (output) of the X-ray tube; A � 0, 8, kV is the voltage applied to the tube, for performing − 1 Table 2: Tube yield in mR and mGy · (mAs) . the examination; mAs is the charge passing through the tube; A was an equal constant of 0.5, 0.8, and 1 for single- Output Output Incidence − 1 phase, three-phase, and high-frequency generator tubes. In Radiography (mR) mGy · (mAs) our study, the X-ray tube was three-phase. +e yields ob- Min-max Min-max − 1 tained were converted from (mR) to mGy · (mAs) by Chest PA 75.22–81.75 0.65–0.71 multiplication at a factor of 0.00877/mAs [17]. PA: posteroanterior. Min: minimum. Max: maximum. +e entrance skin dose for each patient was calculated using the irradiation parameters of each radiographic ex- amination following this model. average age of men was 40.93, the standard deviation was mR − 1 − 4 2 2 7.42 years, and the age range was 29–53 years. In contrast, ESD(mGy) � A × 6.53 × 10 􏼒 􏼓􏼐kV 􏼑 × kV mAs the mean age of women was 35.58 years, the standard de- viation was 10.19 years, and the age range was 23–56 years. 100 mGy Men were more represented than women at 52% or a sex × mAs × × BSF × 0.00877 , 􏼒 􏼓 􏼒 􏼓 FSD mR ratio (M/F � 1.1). (2) Table 2 shows the efficiency of the X-ray tube. +ese values are essential parameters in the process of optimizing where ESD(mGy) is the entrance skin dose, FSD(cm) is the the dose delivered and the quality of the images. +ey are focus-skin-distance, and BSF is the radiation backscatter directly a function of the high voltage (kV) and the load factor. In the context of this work, it is equal to 1.35 for (mAs). adults according to the IAEA [1]. Table 3 summarizes the minimum, maximum, and mean +e anthropometric data and the technical parameters values of the main patient exposure parameters (kV, mAs, used (kV, mAs, FFD, and FSD) were collected at the time of FFD, and FSD) used during the course of this exploration in examinations. Only images of good qualities having been the study. used for diagnosis were considered. +e analysis and th Table 4 presents a comparative state of entrance skin treatment of the data according to the 75 percentile of the dose of the thorax, the DRLs, and those obtained elsewhere. irradiation parameters as well as the calculation of the en- trance skin dose (ESD) of the patients were carried out by Excel 2010. 4. Discussion We are very clearly aware of the difficulties of an evaluation 3. Results without having access to the actual measurement of the dose. +e data relating to this examination were collected by It is however necessary to have access to the measured dose means of a questionnaire whose items concerned the to indicate to the user the direction towards which the equipment, the patient, the radiological technique, the image technical progress is going. Indeed, if these results are closer criteria, and the dose received by the patient. +ese data were to the reality of the actual dose, then they can contribute processed and the results obtained are presented in tabular for the more appropriate determination of the “reference” form. Table 1 presents the distribution of sociodemographic values. From these results, we observe wide variations in the characteristics. Table 2 shows the performance of the X-ray use of pulmonary chest exposure parameters (PA) for pa- tube on the chest X-ray. Table 3 presents the values of the tients with similar morphotypes. +is diversity of the main patient exposure parameters (kV, mAs, FFD, and FSD) technical protocols is at the origin of the large variations of used during the course of this review in the study. Table 4 the irradiation parameters for the same morphotype. On the compares the entrance dose of the chest, the DRLs, and the contrary, despite the differences observed, our results are less values found elsewhere. than those estimated in [20], but these are similar to the Table 1 presents the statistical distribution of the soci- DRL’s for chest radiography. +is aspect proves the em- odemographic characteristics of the patients who partici- bryonic state of radioprotection of patients in the radiology pated in this study. Patient anthropometric data (sex, age, departments. +ese discrepancies with those obtained and weight) are essential for interpreting the results of ra- elsewhere and with international standards can be explained diological examination and dosimetry. Only complete data apart by the absence of dosimetric values and working on 105 adult male and female patients were selected. +e protocols in the examination room. 4 Radiology Research and Practice Table 3: Technical parameters used to conduct this exam. rd ESD Radiography Incidence kV mAs FFD FSD SD quartile Min-max Max/min 120–125 2.5–4 140–180 160–200 Chest PA 0.08–0.09 1.04 0.18 0.21 (122.8± 1.72) (3.17± 0.46) (180± 0.09) (128± 0.20) kV: kilovolt. mAs: milliampere second. FFD: focus-film-distance. FSD: focus-skin-distance. ESD: entrance skin dose. SD: standard deviation. Table 4: Comparison of the entrance skin dose (mGy) with those obtained elsewhere and at DRLs. Radiography Incidence Our study IRSN (DRL) Sudan [18] Iran [19] Mali [20] Chest PA 0.18± 0.21 0.3 0.53± 0.24 0.70± 0.38 3.84 On the contrary, international standards and DRLs must ionizing radiation, it is important to note that the risk of be used to control and optimize radiological practices. In irradiation increases with the nonobservance of the basic practice, by displaying and applying these, it is possible to principles of radiation protection of patients. +e results avoid unnecessary irradiation and the periodic evaluation of obtained show that the doses delivered to patients are not the delivered doses should become a routine activity. optimal. However, an improvement in practices, especially Consequently, the doses delivered for the realization of the in relation to the technical parameters and protocols as- thorax are not sufficiently mastered. +ese differences lead sociated with strengthening the permanent radiation pro- us to think like [5] that unlike developed countries, in sub- tection skills of radiological manipulators, could contribute Saharan African countries, particularly Cameroon and Mali, to better radiological protection of patients in this radiology legislative and regulatory frameworks are either nonexistent department. Moreover, note that the indirect method used or implemented in a rough way. Moreover, the practice of here is a reliable alternative for measuring the entrance skin radioprotection of patients is poorly documented in a dose of the patient. +is method could also serve as a means context of constant expansion of medical imaging for a of measurement for the control and dosimetric assessment decade.. in case of dosimeter deficiency in developing countries As imaging spreads to the most remote areas of the whose scarcity of resources constrains the implementation country, there is an urgent need to optimize work protocols. of approximate international conventions and legislation. In +is optimization of doses delivered to the patients could radiation protection, however, corrective measures should well be effective by the setting up of a regulatory framework be evaluated and undertaken, if there are excessive dis- with the obligation of designation and training of humans crepancies between the doses delivered and those observed competent in radioprotection which would allow not only to elsewhere. For this, the radioprotection of patients is an improve the radioprotection of the patients but also of emergency quality in a context where quality is a global the personnel, for the establishment of regular dosimetric aspiration. control and dosimetric standards. +e lack of ongoing training of personnel on radiation protection measures Data Availability could be noted as potential factors of patient exposure. +is finding is still very worrying, when the professional profile Our data may be available upon request. (nurse and caregivers) of some radiology manipulators does not correspond to their “background” because they are Conflicts of Interest rather converted into radiological manipulators and a large rotation of radiology trainees who find work protocols not +e authors declare that they have no conflicts of interest. available and also who are often forced to produce images capable of being exploited. In view of this, they have either no idea or a rough idea of the good practice in radio- References diagnostics or even radiation protection of patients. 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[18] A. A. Abu Khiar, A. O. Hamza, and N. A. 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