S. Semghouli et al.: Radioprotection 2025, 60( 3), 256 – 261 257
justification and optimisation as two essential principles of radiological protection in medical imaging. The principle of justification means that the individual or societal benefit resulting from medical exposure to ionising radiation must be sufficient to compensate for the harm caused. The principle of optimisation means that individual doses of exposure must be kept as low as reasonably achievable, considering economic and societal factors( ICRP, 2007).
Diagnostic reference levels( DRLs) have proven effective in optimizing patient protection during medical imaging procedures. In this context, in the UK, where data have been collected approximately every five years since the mid-1980s, the DRL values determined from the 2005 survey results were 16 % lower than the corresponding values from the 2000 survey and approximately half the corresponding values from the mid- 1980s survey( ICRP, 2017). In addition, the DRL concept represents a tool that will be used primarily by equipment operators to effectively identify X-ray diagnostic and interventional procedures that may require optimization. However, the DRL concept is currently insufficiently known and implemented in many facilities( Schegerer et al., 2019).
In the Souss Massa Region in Morocco, a particular attention has been paid to patient radiation protection in hospital settings in terms of( 1) the perception of professionals( Amaoui et al., 2023; EL Fahssi et al., 2024a),( 2) dose optimization( Amaoui et al., 2019; Semghouli et al., 2022a; El Fahssi et al., 2023) and( 3) radiological risks estimation( Semghouli et al., 2022b, 2024a). Furthermore, the equipment’ s for the most prescribed modality are not equipped with a system for displaying the dose-area product( DAP) values for each X-ray examination. To the best of our knowledge, no study relating to the establishment of LDRLs in terms of DAP has been conducted in this region. The aim of this study was to assess the DRLs for four types of X-ray examination in terms of DAP at the Regional Hospital of Agadir. The establishment of DRLs in terms DAP is motivated by the need to have dosimetric measurements, especially in the absence of a national or local approach to optimizing doses delivered to patients. The results of the present study will be used to compare the values obtained with those established by previous studies and as a basis for future local or national studies.
2 Materials and methods
2.1 Populations studied
This was a retrospective study conducted at the regional hospital of Souss Massa between January and March 2023, and included adult patients( age ≥ 18 years) receiving a radiographic examination in the radiology department of the hospital. In total, data from 120 adult patients, 30 per location( thorax( PA), pelvis( AP), lumbar spine( AP) and abdomen( AP)) were collected.
Patient parameters such as gender, age, BMI, clinical indications, and examination acquisition parameters such as kV, mAs, patient source distance( PSD), and exposure field dimensions were recorded for each patient.
The X-ray equipment used in this study was type IAE X50H, serial number B8383, manufactured in KOREA. It has a permanent filtration of 1.5 mm A1 and a maximum voltage of 150 kV.
2.2 Dose estimation |
2.2.1 Estimation of dose-area product( DAP) |
The DAP is the product of the average dose absorbed in the |
air in a straight section of the X-ray beam in the absence of |
the scattering medium and the surface area of this section. |
The DAP was |
calculated |
using the following |
formula |
( ICRU, 2005): |
|
|
|
|
DAP ¼ ESDxA
BSF; ð1Þ
|
|
where DAP: is the dose-area product, A: is the surface area of the exposed section, BSF: is the backscatter factor.
The backscatter factor FRD depends on the constants, particularly the kilo voltage. It ranges from 1.2 to 1.5. We used a value of 1.35 between 60 and 80 kV( this is the case for three examinations in this study: lumbar spine, abdomen and pelvis) and 1.5 at high kV( 120 – 140 kV, in the case of the thorax). The DAP is expressed in cGy cm 2.
The ESD was calculated by the following empirical formula( Adambounou et al., 2022):
ESDðmGyÞ ¼ 0:15x
U 2 xQx 100
1 2
; ð2Þ
SFD
where U: Tube voltage in kV; Q: electrical charge in mAs; FSD: The focus-to-skin distance in m.
2.2.2 Estimation of DRLs
The calculation of DRLs is based on a statistical method known as the 75th percentile of the DAP distribution according to the formalism of the International Commission on Radiological Protection( ICRP, 135).
2.3 Data analysis method
The data were statistically analysed by SPSS software V 21.0. After checking the normality of the variables, Pearson’ s parametric test was used to explore the relationship between the different quantitative variables.
3 Results
Of the 120 patients examined, 48 % were male and 52 % were female, with a male / female ratio of 0.92. All patients are adults over the age of 18.
According to Table 1, the average voltage for the four radiographic examinations ranged from 69.23 to 87 kV, with a maximum value of 109 kV for the thorax( PA) and a minimum value of 60 kV for the pelvis( AP) and abdomen( AP). The average charge for the four X-ray examinations ranged from 3.35 to 34.9 mAs, with a maximum value of 51 mAs for the abdomen( AP) and a minimum value of 2.5 mAs for the thorax( PA).