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Submitted: 05 Mar 2023
Revised: 15 May 2023
Accepted: 27 May 2023
First published online: 17 Jul 2023
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Avicenna J Care Health Oper Room. 1(1):11-15. doi: 10.34172/ajchor.2

Original Article

Estimation of Entrance Surface Dose and Dose Area Product in Most Frequently Used Radiography Examinations in Hamadan

Faeze Heidari 1 ORCID logo, Maedeh Saiedi 1, Salman Jafari 2, * ORCID logo
1Student Research Committee, Hamadan University of Medical Sciences, Hamadan, Iran
2Department of Radiology Technology, School of Paramedicine, Hamadan University of Medical Sciences, Hamadan, Iran
*Corresponding author: Salman Jafari, Email: sa.jafari@umsha.ac.ir

Abstract

Background: Radiation dose in C-arm procedure and radiography may lead to late complications such as cancer. Entrance surface dose (ESD) and dose area product (DAP) are two practical indicators for patient dose estimation. This study aimed to calculate ESD and DAP based on exposure parameters for the most common radiographic examinations in educational hospitals of Hamadan.

Methods: This work was conducted in three radiography centers in Hamadan in 2020. ESD was determined using a standard equation. Radiation parameters, including maximum kilovolt and milliampere-seconds (mAs), were obtained from the device console, and the output factor was obtained from the calibration certificate. Eventually, ESD and DAP were computed for the head, chest, abdomen, and pelvic radiography examinations.

Results: Means of ESD and DAP were 0.68±0.44 mGy and 274.03±179.84 mGy.cm2 for head, as well as 0.13±0.07 mGy and 117.64±70.07 mGy.cm2 for chest. In addition, the corresponding valures were 1.31±0.82 mGy and 1187.17±738.3 mGy.cm2 for the abdomen, as well as 0.84±0.83 mGy and 764.84±753.59 mGy.cm2 for the pelvic. The difference in ESD and DAP for all examinations between centers was significant (P<0.05).

Conclusion: Several factors affect radiation exposure and patient dose in radiography. Some of these factors are subjective and depend on technician knowledge. It is possible to reduce the patients’ dose while maintaining image quality by regular training of technicians.

Keywords: Digital radiography, Radiation dosages, Radiation protection

Copyright

© 2023 The Author(s); Published by Hamadan University of Medical Sciences.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Please cite this article as follows: Heidari F, Saiedi M, Jafari S. Estimation of entrance surface dose and dose area product in most frequently used radiography examinations in Hamadan. Avicenna Journal of Care and Health in Operating Room. 2023; 1(1):11-15. doi:10.34172/ajchor.2


Introduction

Today, medical imaging plays an important role in diagnosing many diseases (1-3). Exposure of patients to X-ray irradiation may lead to late complications such as cancer. Several studies have shown that low doses of radiation in the diagnostic range can cause an increased risk of cancer, the possibility of chromosomal damage, and genetic mutations due to DNA damage (4-9). Applying radiation protection principles is mandatory for patients and staff. Keeping a suitable distance and shielding are used for personnel during imaging, but patients are directly exposed to X-rays. In recent years, extensive studies have been conducted to reduce patient exposure. Adjustment of exposure parameters such as maximum kilovolt (kVp) and milliampere-seconds (mAs) to a low level while considering image quality, precise collimation, and accuracy in performing radiography is highly important for patients. In 1996, the diagnostic reference dose level was introduced by the International Commission on Radiation Protection for the purpose of dose optimization in medical imaging (10). Extensive patient dose variations for a specific radiography test have been reported in various centers. The diagnostic reference level takes into account both the patient’s dose and image quality (11,12). The advent of digital radiography in the 1980s created a major transformation in radiology (13). Despite the advantages, the wide dynamic range of digital systems in response to radiation allows for more errors in exposure parameters, causing a higher radiation dose to patients. Therefore, applying dose optimization methods seems to be of higher importance than conventional radiography (13). Exposure information is displayed on the console immediately after irradiation. If the devices are properly calibrated, this information can be used to calculate the values of entrance surface dose (ESD) and dose area product (DAP). Thus, the patient dose can be observed subsequently. This study sought to estimate ESD and DAP for most common radiographic tests in educational hospitals of Hamadan in 2020.


Materials and Methods

This work was conducted as a descriptive cross-sectional study in three educational centers of Hamadan with the ethics code of IR.UMSHA.REC.1398.393. Three digital radiography units, including one Shimadzu (0.6/1.2P324DK-85) and two Toshiba (E7252X), underwent investigation. All radiography units had a calibration certificate attached to them. Four commonly used radiographies, including the head, chest, abdomen, and pelvis, were chosen after refereeing to the registry of radiographic examinations. The head and chest examinations were performed in posterior-anterior projection, and the abdomen and pelvic radiographs were obtained in anterior-posterior projection. The ESD was calculated using the standard equation as follows (14):

(1) ESDmGy=OP.kV802.mAs.100FSD2.BSF

The parameters of kV and mAs were obtained from the device console. OP is the output of the device in order of mGy/mAs and is obtained from the calibration certificate. Since the output has been determined in specific kilovolts, to obtain the output in kilovolts used in radiographic examinations, the relationship was created in Excel software. The focal spot-to-surface distance (FSD) is equal to the adjusted distance for each radiograph in centimeters. The backscattered factor (BSF) has been obtained from the study of Vijayam et al (15). The data of 100 patients were collected for each examination.

Next, the entrance surface area exposed to X-rays was determined using collimation. The ESDs multiplied by the area of the field size were considered as DAP. The Kruskal-Wallis test was performed to compare the ESD and DAP for each examination separately between centers.


Results

Radiography exposure parameters (i.e., kVp and mAs), as well as the characteristics of patients, including number, gender, and age, in order of examination type and center, are provided in Table 1. Centers’ names are defined as A, B, and C.

Table 1. Radiography Exposure Parameters, Including kVp and mAs, as Well as the Characteristics of Patients in Order of Examination Type and Centers
Center Examination Type Patients’ Gender, Age, and Number Exposure Parameters
Male Female kVp
Mean±SD
mAs
Mean±SD
Number Age (y) Mean±SD Number Age (y) Mean±SD
AHead1528 ± 141138 ± 2165.4 ± 2.3520.3 ± 3.57
Chest1240 ± 261537 ± 2568.4 ± 7.912.6 ± 8.12
Abdomen1744 ± 14829 ± 1270.3 ± 5.7333.5 ± 9.57
Pelvic2048 ± 17760 ± 2065.4 ± 3.2825.3 ± 5.13
BHead1341 ± 161344 ± 1974.9 ± 4.4522.8 ± 3.83
Chest1257 ± 171457 ± 2269 ± 2.1314.1 ± 4.09
Abdomen1956 ± 14849 ± 770.1 ± 2.0528.6 ± 10.42
Pelvic1358 ± 171245 ± 1466.5 ± 1.3220.3 ± 2.94
CHead1341 ± 161239 ± 2260.4 ± 7.4417.44 ± 10.53
Chest1453 ± 191154 ± 2283.16 ± 7.718.01 ± 2.14
Abdomen1150 ± 121558 ± 1978.4 ± 6.0730.2 ± 7.38
Pelvic1452 ± 171156 ± 2278.4 ± 6.4430.62 ± 4.1

Note. SD, Standard deviation; kVp, Maximum kilovolt; mAs, milliampere-seconds.

The output factor (the output in terms of mGy/mAs) for each device was obtained from the calibration certificate. Output values were specified only in certain kilovolts. By plotting output versus kVp curves (Figures 1-3), the output values at desired kilovolts for each examination were obtained in centers A, B, and C.

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Figure 1.

Output Factor Curve in Order of kVp for the Radiography Device in Center A. Note. kVp: Maximum kilovolt.


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Figure 2.

Output Factor Curve in Order of kVp for the Radiography Device in Center B. Note. kVp: Maximum kilovolt.


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Figure 3.

Output Factor Curve in Order of kVp for the Radiography Device in Center C. Note. kVp: Maximum kilovolt.


The BSF values for the small field of the head and large field of other examinations were obtained from the study of Vijayam et al (15). Considering that the BSF values in the mentioned study are defined at specific kilovolts, curves in Figures 4 and 5 were used to obtain BSF values in the desired kilovolts.

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Figure 4.

Backscattered Factor Curve for Head Field Size in Order of Different kVp. Note. kVp: Maximum kilovolt; BSF: Backscattered factor.


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Figure 5.

Backscattered Factor Curve for Large Field Sizes in Order of Different kVp. Note. kVp: Maximum kilovolt; BSF: Backscattered factor.


Table 2 presents the calculated values of ESD (mGy) and DAP (mGy.cm2) for each examination in different centers. Means of EDD and DAP for head and chest were 0.68 ± 0.44 mGy and 274.03 ± 179.84 mGy.cm2, as well as 0.13 ± 0.07 mGy and 117.64 ± 70.07 mGy.cm2, respectively. Moreover, they were 1.31 ± 0.82 mGy and 1187.17 ± 738.3 mGy.cm2, as well as 0.84 ± 0.83 mGy and 764.84 ± 753.59 mGy.cm2 for abdomen and pelvic, respectively. The differences of ESD and DAP for all examinations between centers were significant (P < 0.05).

Table 2. Values of Entrance Surface Dose (mGy) and Dose Area Product (mGy.cm2) for Each Examination in Different Centers
Center Examination Type ESD (mGy) DAP (mGy.cm2) P Value
Mean±SD Minimum Maximum Mean±SD Minimum Maximum
AHead0.395 ± 0.080.190.57158 ± 34.7377230.23 < 0.05
Chest0.09 ± 0.060.010.2484.63 ± 55.8113.69216.27 < 0.05
Abdomen0.86 ± 0.290.141.43774.74 ± 264.19130.531294.93 < 0.05
Pelvic0.37 ± 0.1160.130.769333.62 ± 104.84117.40 692.41 < 0.05
BHead1.2 ± 0.290.541.46483.93 ± 118.93218.78584.8 < 0.05
Chest0.09 ± 0.060.010.2484.63 ± 55.8113.69216.27 < 0.05
Abdomen1.16 ± 0.550.672.951046.39 ± 499.19608.322657.34 < 0.05
Pelvic0.37 ± 0.110.130.76333.62 ± 104.84117.40692.41 < 0.05
CHead0.450 ± 0.3090.047 0.81 180.17 ± 123.6219.15327 < 0.05
Chest0.204 ± 0.050.120.33183.64 ± 45.76112.73302.94 < 0.05
Abdomen1.93 ± 1.020.425.581740.38 ± 918.23383.145023.26 < 0.05
Pelvic1.80 ± 0.830.513.451627.27 ± 752.88462.463105.9 < 0.05

Note. SD, standard deviation; ESD, entrance surface dose; DAP, dose area product.


Discussion

Given that there is no safe dose limit for ionizing radiation, three principles of radiation protection, including justification, optimization, and dose limit, should be employed in radiography practice to reduce the risk of radiation effects (16). In this study, the ESD and DAP were calculated for head, abdomen, chest, and pelvic radiography examinations. These quantities depend on a number of factors that influence the patient’s exposure. kVp has an effect on both the quantity and quality of the radiation beam. For all radiography devices, the output increased with increasing kVp, resulting in a higher dose to the patients. The exposure is directly proportional to the mAs parameter. The scattered radiation will increase with a larger field size and impose more surface doses. These mentioned parameters are selected by the operator. Therefore, the level of knowledge and commitment of the operator in applying the appropriate parameters is effective on the absorbed dose.

The ESD and DAP for abdomen radiography are higher than the other protocols. This is due to higher exposure parameters (i.e., kVp and mAs) than the other tests. Field size is another factor influencing the diagnostic reference level, which is larger for the abdomen than the other tests. The lowest ESD and DAP values are related to chest radiography for which exposure is less than the other examinations.

Table 3 compares the results of other studies with those of this study. ESD for all examinations in this study was less than others. In all studies, abdominal radiography had the maximum ESD, and the minimum ESD was related to chest radiography. This demonstrates that higher exposure parameters are used for abdomen radiography because of more thickness in this part of the body.

Table 3. Means of Entrance Surface Dose (mGy) and Local Diagnostic Reference Levels of This Study in Order of Third Quartile of ESDs (mGy) Compared With Other Studies
ESD (mGy)
Examination Head Chest Abdomen Pelvic
This study0.68 ± 0.440.13 ± 0.071.31 ± 0.820.84 ± 0.83
Mohsenzadeh et al (17)0.97 ± 0.410.6 ± 0.311.65 ± 0.791.43 ± 0.69
Gholami et al (18)2.98 ± 2.870.56 ± 0.465.58 ± 4.563.34 ± 3.31
Bahreyni Toosi (19)Not reported0.672.562.93
Gyan et al (20)1.77 ± 0.30.93 ± 0.73.152.31 ± 0.4

Note. ESD, entrance surface dose.

Based on the results of this study and those of other studies, variations in patient’s dose for a specific radiography procedure between different centers are to some extent inevitable. However, it is important to prevent abnormal variations which in turn lead to extra doses to patients. In this study, the difference between centers was significant for all radiography procedures. The issue of dose variation with digital radiography units becomes more important due to more dynamic range responses to radiation, giving more maneuverability to technicians. Therefore, using an appropriate dose reference and regular training courses can help optimize radiation dose when performing radiography with mentioned equipment.


Conclusion

According to the obtained results, several factors could affect radiation exposure to patients. Some of these factors such as kVp, mAs, FSD, and field size are subjective depending on the technician’s opinion and knowledge. Other parameters are objective, including radiography device model, regular calibration of the device, and detector type. By regular training of technicians, it is possible to prevent patients from irradiating unnecessary dose.


Acknowledgements

The authors would like to thank all those who have helped us during this research, especially radiography centers, because of their friendly cooperation.


Authors’ Contribution

Conceptualization: Faeze Heidari.

Data curation: Salman Jafari.

Formal analysis: Salman Jafari.

Funding acquisition: Salman Jafari.

Investigation: Faeze Heidari, Maedeh Saiedi.

Methodology: Salman Jafari.

Project administration: Salman Jafari.

Resources: Faeze Heidari, Maedeh Saiedi.

Software: Faeze Heidari, Maedeh Saiedi.

Supervision: Salman Jafari.

Validation: Salman Jafari.

Visualization: Salman Jafari.

Writing–original draft: Salman Jafari.

Writing–review & editing: Salman Jafari.


Competing Interests

There is no conflict of interests.


Ethical Approval

This study has been approved by the Research Ethics Committee of Hamadan University of Medical Sciences (IR.UMSHA.REC.1398.393).


Funding

This study was funded by the Vice-chancellor for Research and Technology, Hamadan University of Medical Sciences (No. 9805083634). We thank all those who supported and helped us during this research.


References

  1. Tavakoli HM, Jabari K, Salman J. SU-E-I-51: investigation of absorbed dose to the skin, eyes and thyroid of patients during CT angiography and comparison with conventional angiography. Med Phys 2012; 39(6Part4):3636. doi: 10.1118/1.4734767 [Crossref] [ Google Scholar]
  2. Giardino A, Gupta S, Olson E, Sepulveda K, Lenchik L, Ivanidze J, et al. Role of imaging in the era of precision medicine. Acad Radiol 2017; 24(5):639-49. doi: 10.1016/j.acra.2016.11.021 [Crossref] [ Google Scholar]
  3. Rawal K, Sethi G, Ghai D. Medical imaging in healthcare applications. In: Artificial Intelligence and Machine Learning in 2D/3D Medical Image Processing. CRC Press; 2020. p. 97-106.
  4. Brenner DJ, Doll R, Goodhead DT, Hall EJ, Land CE, Little JB, et al. Cancer risks attributable to low doses of ionizing radiation: assessing what we really know. Proc Natl Acad Sci U S A 2003; 100(24):13761-6. doi: 10.1073/pnas.2235592100 [Crossref] [ Google Scholar]
  5. Cardis E, Vrijheid M, Blettner M, Gilbert E, Hakama M, Hill C, et al. Risk of cancer after low doses of ionising radiation: retrospective cohort study in 15 countries. BMJ 2005; 331(7508):77. doi: 10.1136/bmj.38499.599861.E0 [Crossref] [ Google Scholar]
  6. Hall EJ, Brenner DJ. Cancer risks from diagnostic radiology. Br J Radiol 2008; 81(965):362-78. doi: 10.1259/bjr/01948454 [Crossref] [ Google Scholar]
  7. Tavakoli MB, Jabbari K, Jafari S, Hashemi SM, Akbari M. Comparing the absorbed doses by skin, thyroid, and eyes in CT coronary angiography and conventional angiography. J Isfahan Med Sch 2011;29(159):1703-12. [Persian].
  8. Shah DJ, Sachs RK, Wilson DJ. Radiation-induced cancer: a modern view. Br J Radiol 2012; 85(1020):e1166-73. doi: 10.1259/bjr/25026140 [Crossref] [ Google Scholar]
  9. Tavakoli MB, Faraji R, Sajjadieh A, Jafari S. Determination of the weighted computed tomography dose index in coronary multidetector computed tomography angiography. J Isfahan Med Sch 2016;34(398):1060-5. [Persian].
  10. Vañó E, Miller DL, Martin CJ, Rehani MM, Kang K, Rosenstein M, et al. ICRP Publication 135: diagnostic reference levels in medical imaging. Ann ICRP 2017; 46(1):1-144. doi: 10.1177/0146645317717209 [Crossref] [ Google Scholar]
  11. Afzalipour R, Abdollahi H, Hajializadeh MS, Jafari S, Mahdavi SR. Estimation of diagnostic reference levels for children computed tomography: a study in Tehran, Iran. Int J Radiat Res 2019; 17(3):407-13. doi: 10.18869/acadpub.ijrr.17.3.407 [Crossref] [ Google Scholar]
  12. Jafari S, Ghazikhanlu Sani K, Karimi M, Khosravi H, Goodarzi R, Pourkaveh M. Establishment of diagnostic reference levels for computed tomography scanning in Hamadan. J Biomed Phys Eng 2020; 10(6):792-800. doi: 10.31661/jbpe.v0i0.2004-1099 [Crossref] [ Google Scholar]
  13. Busch HP, Faulkner K. Image quality and dose management in digital radiography: a new paradigm for optimisation. Radiat Prot Dosimetry 2005; 117(1-3):143-7. doi: 10.1093/rpd/nci728 [Crossref] [ Google Scholar]
  14. Tamboul JY, Yousef M, Mokhtar K, Alfaki A, Sulieman A. Assessment of entrance surface dose for the patients from common radiology examinations in Sudan. Life Sci J 2014; 11(2):164-8. [ Google Scholar]
  15. Vijayam M, Shigwan JB, Dixit BS, Shaha VV, Misra SC. Determination of backscatter factors for diagnostic X-ray beams by experimental and Monte Carlo methods and determination of air kerma to dose equivalent conversion factors for the calibration of personal monitors. In: 10th International Congress of the International Radiation Protection Association (IRPA); 2000.
  16. Kase KR. Radiation protection principles of NCRP. Health Phys 2004; 87(3):251-7. doi: 10.1097/00004032-200409000-00005 [Crossref] [ Google Scholar]
  17. Mohsenzadeh B, Deevband MR, Paydar R, Ghorbani M. Assessment of patient dose in routine digital radiography in Iran. Int J Radiat Res 2020; 18(3):449-60. [ Google Scholar]
  18. Gholami M, Maziar A, Khosravi HR, Ebrahimzadeh F, Mayahi S. Diagnostic reference levels (DRLs) for routine X-ray examinations in Lorestan province, Iran. Int J Radiat Res 2015; 13(1):85-90. [ Google Scholar]
  19. Bahreyni Toosi MT, Nazery M, Zare H. Application of dose-area product compared with three other dosimetric quantities used to estimate patient effective dose in diagnostic radiology. Iran J Radiat Res 2006; 4(1):21-7. [ Google Scholar]
  20. Gyan E, Inkoom S, Amoako G. Entrance skin dose assessment of selected computed radiography facilities in Ghana. Iran J Radiat Res 2020; 18(4):817-23. doi: 10.18869/acadpub.ijrr.18.4.817 [Crossref] [ Google Scholar]