This experimental study investigated the significant different in image quality and dose between different automatic exposure of exposure parameter (AOP) mode in full field digital mammography (FFDM) system. CIRS012A and PMMA breast phantom (4cm, 5cm and 6 cm thickness) were used as subject using Senographe Essential FFDM system. TLD chip was used as dose measurement tool. Exposures were taken in cranio-caudal projection. 2 radiographers with more than 10 years of working experience in performing mammography scored the image independently. Kappa finds a good agreement between raters (kappa value=0.9, p0.05). DOSE mode is the preferred selection in optimizing between dose and image quality

Sharip, Hairenanorashikin

Supar, Rafidah

English

Universiti Teknologi MARA Institutional Repository

Journal of Academia Vol.8, Issue 1 (2020) 18-23 
18 
OPTIMIZATION OF EXPOSURE PARAMETERS IN AUTOMATIC 
OPTIMIZATION OF EXPOSURE PARAMETERS (AOP) MODE OF FULL 
FIELD DIGITAL MAMMOGRAPHY (FFDM) SYSTEM: BREAST 
PHANTOM STUDY 
Hairenanorashikin Sharip, Rafidah Supar 
Faculty of Health Sciences, Universiti Teknologi MARA Selangor, 42300, Bandar Puncak Alam, Selangor, Malaysia 
Email: hairena@uitm.edu.my 
Abstract 
This experimental study investigated the significant different in image quality and dose between different 
automatic exposure of exposure parameter (AOP) mode in full field digital mammography (FFDM) system. 
CIRS012A and PMMA breast phantom (4cm, 5cm and 6 cm thickness) were used as subject using 
Senographe Essential FFDM system. TLD chip was used as dose measurement tool. Exposures were taken 
in cranio-caudal projection. 2 radiographers with more than 10 years of working experience in performing 
mammography scored the image independently. Kappa finds a good agreement between raters (kappa 
value=0.9, p<0.01). One-way ANOVA shows a significant different in dose between CNT and DOSE mode 
(p=0.013). However, there is no significant different in image quality between CNT, DOSE and STD 
(p>0.05). DOSE mode is the preferred selection in optimizing between dose and image quality.  
Keywords: AOP mode, CNT, DOSE, STD, FFDM, image quality, dose, breast phantom. 
Article history:- Received: 10 October 2019; Accepted: 12 December 2019; Published: 14 March 2020 
© by Universiti Teknologi Mara, Cawangan Negeri Sembilan, 2019. e-ISSN: 2289-6368 
Introduction 
This paper aims to investigate the significance different in image quality and average glandular 
dose (AGD) between different mode of Automatic Optimization Parameters (AOP) selection. Full Field 
Digital Mammography (FFDM) system has incorporated the automatic beam quality selection mode which 
is known as AOP (Bsrisse et al., 2007). In AOP mode, the kilovoltage peak (kVp), mAs, target material 
and filter are automatically selected based on the thickness and composition of the breast (Ozdemir, 2007). 
The AOP mode has three selections which are the standard (STD), dose (DOSE) and contrast (CNT).  
However, Ko et al. (2013) found that radiographers are not familiar on the selection of DOSE and 
CNT mode in AOP selection. The common selected mode is STD. By understanding more on the 
characteristics of each mode selected, optimization could be highly appreciated. 
Literature Review 
Breast cancer is a major concern for women in most parts of the world. In 2006, breast cancer was 
reported to be the most common cancer among female in Peninsular Malaysia (Omar et al., 2006). It is also 
reported as the most frequent cause of cancer death among female in economically developing and 
developed countries (Ferlay et al., 2008). In diagnosing the disease, mammography is the most effective 
Journal of Academia Vol.8, Issue 1 (2020) 18-23 
 
19 
 
tool for early detection before it becomes clinically palpable (Sree at al., 2011). Consequently, regular 
mammography screening may significantly reduce the mortality of breast cancer (Krishnaiah et al., 2012).  
The conventional image capturing system in mammography was successfully obtained by using 
film-screen mechanism. Unlike other conventional imaging procedures which use double emulsion film, 
mammography uses single emulsion film with single radiographic intensifying screen to record the image.  
The full field digital mammography (FFDM) system which is totally cassette-less system has been 
rapidly replacing the screen-film mammography. The advantage of digital mammography system is the 
ability to do the post-processing and manipulation of the images due to its wider dynamic range if compared 
to film screen system (Faridah, 2008). This will consequently increase the diagnostic value of the images, 
reduce repeat exposure and reduce extra radiation dose delivered to patient. 
Most FFDM system has incorporated the automatic beam quality selection mode which is known 
as automatic optimization of exposure parameters (AOP). In AOP mode, the kilovoltage peak (kVp), 
milliamperage-seconds (mAs), target material and filter are automatically selected based on the thickness 
and composition of the breast (Ozdemir, 2007). The AOP mode has three selections which are the standard 
(STD), dose (DOSE) and contrast (CNT).  These three selections of AOP mode are designed to give a 
balance between high image quality and low dose during mammographic procedure (Ozdemir, 2007). The 
STD mode gives balance between dose reduction and good contrast while the DOSE mode emphasizes on 
the dose reduction with optimum image quality (Ko et al., 2013). The CNT mode is preferable when higher 
image quality with higher contrast is the point of focus (Ko et al., 2013).  
However, the selection of DOSE and CNT modes were not familiar among radiographers (Ko et 
al., 2013). The common selected mode is STD. Suitable selection of exposure parameters is a main concern 
in mammography as it may reduce radiation dose to the glandular breast tissue, as glandular breast dose is 
closely related to carcinogenesis (Kanaga et al., 2010). Thus, by understanding more on the characteristic 
of each mode selected, optimization between image quality and radiation dose could be highly appreciated. 
Methods 
         This study was conducted based on experimental design and involved the qualitative evaluation of 
image quality. FFDM Senographe Essential system, which was manufactured by General Electric 
Healthcare (GE) was used. The AOP mode has three selections which are the standard (STD), dose (DOSE) 
and contrast (CNT).   
          Thermo luminescence dosimeter (TLD-100H) was used in this study to capture the dose received. 3 
sets of mammography phantom model CIRS012A (Computerized Imaging Reference System Inc.) which 
have the shape of a real breast and different thickness of compressed breast (4cm, 5 cm and 6 cm) were 
used to assess image quality. For assessment of average glandular dose (AGD), polymethylmethacrylate 
(PMMA) breast phantom with different thickness of compressed breast (4cm, 5 cm and 6 cm) were used.  
Each phantom was positioned on the surface of FFDM image receptor in cranio-caudal (CC) 
position and compression was applied until the compression plate touched the surface of breast phantom. 
The first exposure made was using the STD mode. For dose measurement, PMMA was used. TLD chip was 
positioned at the surface of FFDM image receptor in cranio-caudal (CC) position and compression was 
Journal of Academia Vol.8, Issue 1 (2020) 18-23 
 
20 
 
applied until the compression plate touched the surface of breast phantom. These steps were repeated using 
the CNT mode and DOSE mode. TLD chips were read using TLD reader. 
Image quality was evaluated through qualitative assessment by using weighted scoring protocol 
adapted from American College of Radiology (ACR) Mammography Quality Control Manual (Papp, 2018). 
Evaluation was done based on the visibility of speck, fibers and masses on the image of CIRS012A 
phantom. The grading score used with respect to the visibility of fibers, speck and masses were 1, 0.5 and 
0. 
Total image score was obtained by summing up the visualization score of mass, fiber and speck. 
Two independent radiographers with minimum experience of 10 years in mammographic procedure have 
scored the images independently with blinded exposure parameters. Edge enhancement application and 
magnification tool was not allowed. 
Statistical analysis: Data was analyzed by using statistical software for social science (SPSS) version 21.0. 
Statistical test used was One-way ANOVA. 
Ethical approval: Ethical approval was obtained from the ethical committee of Faculty of Health Sciences, 
Universiti Teknologi MARA (UiTM). 
Results 
Figure 1 shows the pattern of mean AGD versus AOP mode for all breast thickness. CNT shows 
the highest value of AGD for all breast thickness, followed by STD. The lowest value of AGD is given by 
the DOSE. To find the significant difference in AGD between three selections of AOP mode, one-way 
ANOVA test was performed. All assumptions for using this test are met. According to the test conducted, 
there is a significant different in AGD value between CNT and DOSE mode (p=0.013). Mean AGD in CNT 
selection is significantly higher than mean AGD in DOSE selection.  
Figure 2 shows the pattern of relationship between image quality score and AOP mode for all breast 
thickness. CNT selection gives the highest score in all thickness of breast. CNT also gives the highest score 
for the visualization of mass, speck and fiber for all breast thickness, except in 4cm thickness whereby 
highest score for the visualization of fiber is given by the DOSE mode. The DOSE mode gives the lowest 
score for the total image score, visualization of mass and visualization of speck. While the STD mode gives 
moderate score between CNT and DOSE, except for visualization score of fiber, the STD shows the lowest 
score. 
Kappa test shows a good agreement between the two raters (kappa value = 0.90, p value of <0.01).  
One-way ANOVA was used to test the significance difference in image quality score between different 
modes of AOP. All assumptions of using one-way ANOVA are met in this test. The result shows that there 
is no significant different in image quality between different selections of AOP mode. 
 
 
 
 
Journal of Academia Vol.8, Issue 1 (2020) 18-23 
 
21 
 
Figures, Diagrams and Pictures 
 
 
 
 
Figure 1: Pattern of image quality score versus AOP mode. 
Discussion 
Dose received by patient in CNT mode is significantly higher than the dose received in DOSE mode. This 
is due to the nature of the mode itself. CNT mode uses high mAs selection to get the best quality of images 
0
5
10
15
20
25
STD DOSE CNT STD DOSE CNT STD DOSE CNT STD DOSE CNT
mass fiber specks total score
Im
a
g
e 
Q
u
a
li
ty
 S
co
re
AOP Mode
4cm 5cm 6cm
Fig 1: The pattern of mean AGD versus AOP mode for all beast thickness. 
Journal of Academia Vol.8, Issue 1 (2020) 18-23 
 
22 
 
while the DOSE mode uses optimum mAs selection to get optimum dose with acceptable image (Ko et al., 
2013). During data collection process, the FFDM system selected the same kVp value for the same breast 
thickness for each mode but different value of mAs (Chen et al., 2012). Among the three selections, mAs 
selected for CNT was the highest, followed by STD and DOSE. Thus, different in AGD value between 
CNT and DOSE is due to the amount of mAs (Chen et al, 2012). Although STD mode gives higher value 
of AGD compared to DOSE mode, but there is no significant different between these two modes in term of 
dose. Thus, to compromise for optimization purpose, DOSE mode may be selected rather than STD mode 
due to its lower value of dose reading. 
For image quality assessment, CNT mode gives the highest total score compared to STD and DOSE mode, 
but there is no significant different between those three selections. This is slightly different with the result 
of previous study conducted, which found that there is a significant different in image quality score between 
CNT and DOSE mode (Ko et al., 2013). This could be due to the background of evaluator. The previous 
study used radiologists as evaluator while for this study, experienced radiographers were used.  
Although this study found no significant different in image quality between CNT, DOSE and STD mode, 
but it is found that in evaluating abnormality in fibrous tissue of a 4cm compressed breast, DOSE mode is 
more preferred to be used.  Previous study has highlighted the importance of choosing CNT mode to be 
used for characterization of microcalcifications and masses in diagnostic mammography procedure and 
should not compromise to the dose reduction (Ko et al., 2013). To optimize and balance the requirement 
between dose and image quality, this study found that the selection of either STD and DOSE mode could 
be used. Between the two modes, the selection of DOSE mode is the most preferred as it provides acceptable 
image quality similar to STD, with the lowest radiation dose.  
Conclusion 
In conclusion, DOSE is the optimum selection in AOP mode which gives balance between dose and image 
quality for all breast thickness. The result of this research will give a clear direction to radiographer on the 
dose reduction initiative in mammography procedure. Dose reduction will give an impact on reducing the 
risk of radiation induced cancer. To improve the accuracy of this research, the method of image quality 
assessment can be improved by using both qualitative and quantitative measurement. 
References 
Brisse, H. J., Madec, L., Gaboriaud, G., Lemoine, T., Savignoni, A., Neuenschwander, S. & Rosenwald, J. C. (2007). 
Automatic exposure control in multichannel CT with tube current modulation to achieve a constant level of 
image noise: experimental assessment on pediatric phantoms. Medical physics, 34, 3018. 
Chen, B., Wang, Y., Sun, X., Guo, W., Zhao, M., Cui, G., ... & Yu, J. (2012). Analysis of patient dose in full field 
digital mammography. European journal of radiology, 81(5), 868-872. 
Faridah, Y. (2008). Digital versus screen film mammography: a clinical comparison. Biomedical imaging and 
intervention journal, 4(4). 
Ferlay, J., Shin, H. R., Bray, F., Forman, D., Mathers, C., & Parkin, D. M. (2010). Estimates of worldwide burden of 
cancer in 2008: GLOBOCAN 2008. International journal of cancer, 127(12), 2893-2917. 
Journal of Academia Vol.8, Issue 1 (2020) 18-23 
 
23 
 
Kanaga, K. C., Yap, H. H., Laila, S. E., Sulaiman, T., Zaharah, M., & Shantini, A. A. (2010). A critical comparison 
of three full field digital mammography systems using figure of merit. Med J Malaysia, 65(2), 119-122. 
Ko, M. S., Kim, H. H., Cha, J. H., Shin, H. J., Kim, J. H., & Kim, M. J. (2013). Dose reduction in automatic 
optimization parameter of full field digital mammography: Breast phantom study. Journal of breast 
cancer, 16(1), 90-96. 
Krishnaiah, P. B., Nunes, N. L., & Safranek, S. (2012). Screening Mammography for Reducing Breast Cancer 
Mortality. Clinical Inquiries, 2012 (MU). 
Omar, Z. A., Ali, Z. M., & Tamin, N. S. I. (2006). Malaysian cancer statistics–Data and figure Peninsular Malaysia 
2006. National cancer registry, ministry of health Malaysia. 
Ozdemir, A. (2007). Clinical evaluation of breast dose and the factors affecting breast dose in screen-film 
mammography. Diagnostic and Interventional Radiology, 13(3), 134. 
Papp, J. (2018). LIC-Quality Management in the Imaging Sciences. Elsevier Health Sciences. 
Shramchenko, N., Blin, P., Mathey, C., & Klausz, R. (2004, May). Optimized exposure control in digital 
mammography. In Medical Imaging 2004 (pp. 445-456). International Society for Optics and Photonics. 
Sree, S. V., Ng, E. Y. K., Acharya, R. U., & Faust, O. (2011). Breast imaging: a survey. World journal of clinical 
oncology, 2(4), 171. 


Optimization of exposure parameters in automatic optimization of exposure parameters (Aop) mode of full field digital mammography (FFDM) system: breast phantom study / Hairenanorashikin Sharip and Rafidah Supar

http://ir.uitm.edu.my/id/eprint/31987/1/31987.pdf

Optimization of exposure parameters in automatic optimization of exposure parameters (Aop) mode of full field digital mammography (FFDM) system: breast phantom study / Hairenanorashikin Sharip and Rafidah Supar

Abstract

Similar works

Full text

Available Versions

Universiti Teknologi MARA Institutional Repository