106 Z . Tahiri et al .: Radioprotection 2024 , 59 ( 2 ), 104 – 110
Table 2 . c-factors for breasts simulated with PMMA ( based on Dance et al ., 2000 , 2009 , 2011 ).
Thick . PMMA ( mm )
Equivalent breast thickness ( mm )
Breast glandularity (%) c-factors ( mGy / mGy ) HVL ( mm Al ) 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80
20 |
21 |
97 |
0.889 |
0.89 |
0.903 |
0.90 |
0.912 |
0.91 |
0.921 |
0.92 |
0.928 |
0.93 |
0.93 |
30 |
32 |
67 |
0.940 |
0.94 |
0.945 |
0.94 |
0.949 |
0.95 |
0.953 |
0.95 |
0.959 |
0.96 |
0.96 |
40 |
45 |
41 |
1.043 |
1.04 |
1.040 |
1.03 |
1.037 |
1.03 |
1.034 |
1.03 |
1.030 |
1.02 |
1.02 |
45 |
53 |
29 |
1.109 |
1.10 |
1.102 |
1.09 |
1.096 |
1.09 |
1.088 |
1.08 |
1.078 |
1.07 |
1.06 |
50 |
60 |
20 |
1.164 |
1.16 |
1.151 |
1.15 |
1.144 |
1.13 |
1.134 |
1.12 |
1.117 |
1.11 |
1.10 |
60 |
75 |
9 |
1.254 |
1.24 |
1.235 |
1.23 |
1.225 |
1.21 |
1.207 |
1.19 |
1.186 |
1.17 |
1.16 |
70 |
90 |
4 |
1.299 |
1.29 |
1.282 |
1.27 |
1.270 |
1.26 |
1.249 |
1.23 |
1.225 |
1.21 |
1.20 |
80 |
103 |
3 |
1.307 |
1.29 |
1.292 |
1.28 |
1.283 |
1.27 |
1.262 |
1.24 |
1.238 |
1.22 |
1.21 |
Table 3 . Typical HVL measurements for different combinations of tube voltage and anode / filter combination / s-factors for clinically used spectra ( Dance et al ., 2000 ,).
kV
HVL ( mm Al ) for anode / filter combination Mo Mo Mo Rh Rh Rh W Rh W Ag W Al ( 0.5mm ) W Al ( 0.7mm )
25 |
0.32 ±. 02 |
0.38 ±. 02 |
0.37 ±. 02 |
0.50 ±. 03 |
0.51 ±. 03 |
0.34 ±. 03 |
0.42 ±. 03 |
28 |
0.35 ±. 02 |
0.42 ±. 02 |
0.42 ±. 02 |
0.53 ±. 03 |
0.58 ±. 03 |
0.39 ±. 03 |
0.49 ±. 03 |
31 |
0.38 ±. 02 |
0.45 ±. 02 |
0.45 ±. 02 |
0.56 ±. 03 |
0.61 ±. 03 |
0.44 ±. 03 |
0.55 ±. 03 |
34 |
0.40 ±. 02 |
0.47 ±. 02 |
0.47 ±. 02 |
0.59 ±. 03 |
0.64 ±. 03 |
0.49 ±. 03 |
0.61 ±. 03 |
37 |
|
|
|
0.62 ±. 03 |
0.67 ±. 03 |
0.53 ±. 03 |
0.66 ±. 03 |
Target material Filter material Filter thickness ( mm ) S-Factor
Mo |
Mo |
30 |
1.000 |
Mo |
Rh |
25 |
1.017 |
Rh |
Rh |
25 |
1.061 |
W |
Rh |
50-60 |
1.042 |
W |
Ag |
50-75 |
1.042 |
The values of the g , c and s factors , used are shown in Tables 1 – 3 , respectively .
2.2 Procedure
The study included 1100 standard screening mammographic incidences performed on 365 women who underwent mammography in the 5 units listed in Table 4 , located in the Rabat-Salé-Zemmour-Zaër region . The standard screening mammographic examinations encompassed bilateral breast examinations , consisting of both craniocaudal ( CC ) and mediolateral oblique ( MLO ) incidences for each breast .
The mammography units that participated in the study underwent regular quality control and maintenance to ensure proper functioning , with a particular focus on the automatic exposure control ( AEC ) system . The AEC system was carefully monitored and maintained to deliver consistent and appropriate radiation doses while upholding high image quality standards . All images used in the study were validated by both the resident and senior radiologist to ensure they met the necessary quality criteria . The study focused on standard bilateral breast examinations , primarily for breast cancer screening , which involved two radiological incidences : craniocaudal ( CC ) and mediolateral oblique ( MLO ). The use of automatic exposure control ( AEC ) helped ensure that the examinations met the required quality and dose standards for breast cancer screening , and the images were subject to thorough validation by the radiology team .
2.3 Data analysis
The data collected were recorded on Microsoft Excel and classified for each mammography unit , examination and imaging modality . Data processing was performed to analyze the median values , the standard deviation of the means and other measurements of different variables , technical parameters and radiation dose received .
3 Results
Data collected from the 5 mammography units used for breast cancer screening included 365 patients , for a total of 1100 images . The majority ( 99.2 %) of the women were within the standard screening age range recommended in the early