Aims and objectives
Contrast,
sharpness and noise are the configuration factors of X-ray image quality (Fig.
1).
Mammogram must have excellent contrast to clearly reveal low X-ray contrast structures such as mass densities or spicules on the margin,
which are characteristic of cancer.
Moreover,
the sharpness must be excellent to reveal numbers and shape of micro-calcifications.
Noise (signal fluctuation) is a factor to hinder clear extraction of subtle structures,
therefore must be reduced to be sufficiently low.
It is important to consider the ALARA (as low as reasonably...
Methods and materials
Phantom and setup
TOR MAM Mammography Phantom (Leeds Test Objects) composed of TOR MAM test object combined with 30mm attenuator stack was used as Phantom for image quality evaluation (Fig.
3).This will give a total acrylic thickness of 41mm which is equivalent to a 45mm ‘standard’ breast.
TORMAM test object contains a range of Filaments,
Particles and Circular details to measure Image Quality Indices (IQIs).
These are simulated pathological features often seen in mammography such as spicules,
micro-calcifications and tumorous masses (Fig.
4). The specifications...
Results
The results of multiple comparison are shown in the box plot.
The IQIs values groups were compared by the median value.
Filament (Fig.
9)
Compared to CNR with 100mAs_FSC off,
CNR with 100mAs_FSC on was high for all diameters and significant difference was recognized.
CNR with 71mAs_FSC on showed high tendency for all diameters.
CNR was significantly high for the following diameters 0.25mm,
0.225mm,
while significant differencewas not recognized for others.
Particle (Fig.
10)
Compared to Ratio with 100mAs_FSC off,
Ratio with 100mAs_ FSC on...
Conclusion
A trend for image improvement when FSC is used with same dose was confirmed.
Additionally,
a tendency of significant deterioration of image quality was not seen even by reducing the dose by 28% when using FSC.
This indicates that exposure dose is reducible.
While a phantom simulating a 45mm standard breast was used in this investigation,
further evaluation using phantoms with different breast thickness and mammary gland contain is necessary.
References
1.International Atomic Energy Agency,
IAEA Human Health Series No.
17 - Quality Assurance Programme for Digital Mammography,
IAEA,
Vienna (2011).
2.Excellent-m FUJIFILM Mammography Image Solutions brochure,Xb1046E,
FUJIFILM Corporation,
Tokyo,
Japan (2017).
3.TOR MAM user manual,
Leeds Test Objects LTD,
United Kingdom.
4.CJ Strudley,
JM Oduko,
KC Young.
Technical evaluation of Fujifilm AMULET Innovality digital mammography system.
(NHS Breast Screening Programme Equipment Report 1601).
London: Public Health England,
Screening Programmes (2017).
5.European guidelines for quality assurance in breast cancer screening and diagnosis,
Fourth Edition Supplements.
European...