The document provides a comprehensive overview of mammography, detailing its purpose, principles, and advanced techniques such as tomosynthesis, which produces 2D and 3D breast images using low-energy x-rays. It outlines essential equipment features, imaging needs, and various components of mammography systems, emphasizing the importance of resolution, dose management, and the use of grids for improved image quality. Additionally, the document compares indirect and direct conversion methods for image detectors, highlighting their efficiency and resolution capabilities.

1. Mammography
BY HEENA PARVEEN
RADIOLOGY FACULTY

2. CONTENTS
1.Introduction to Mammography
2.Principle of Mammography
3.Mammography imaging needs
4.Equipment Features
5.Magnification Mode
6.Image Receptors

3. What is Mammography?
Mammography is the process to examine the human breast for
diagnosis and screening by using low-energy X-rays .
PRINCIPLE OF MAMMOGRAPHY-
Nowadays Mammography is based on the
principle of TOMOSYNTHESIS.
Tomosynthesis or “3D” mammography is a
new type of digital x-ray mammogram which
creates 2D and 3D-like pictures of the breasts.
During a “3D” exam, an X-ray arm sweeps in a
slight arc over your breast, taking multiple
low dose x-ray images.
Then, a computer produces synthetic 2D and
“3D” images of your breast tissue.
The images include thin one millimeter slices,
enabling the radiologist to scroll through
images of the entire breast.
NOTE- Only difference between conventional digital mammogram & tomosynthesis is that
the X-ray arm sweeps in a slight arc over your breasts.

6. Excellent Spatial Resolution-
•Shape and spatial configuration of calcification (0.15mm)
•Achieved with-
-Dedicated Digital detector
-X-ray tube with small focal spot
Excellent Contrast Resolution
•Required to see minimal attenuation difference
between normal glandular tissue & breast tissue
•Achieved with-Low Kvp technique
•Compression
•Grid
Mammography imaging needs

7. Noise should be low
•Required for accurate detector of subtle contrast difference & tiny structure
•Achieved with- Appropriate mAs (balance between noise & dose)
-Compression (Reduces breast thickness)
Dose should be low
•As breast is radiosensitive organ
•Must balance with resolution,contrast & noise
•Achieved with- Appropriate exposure factors
-Appropriate target & filter material
-AEC
-Collimation
-Shielding

8. Mammography system comprises-
• Generator
•X-ray Tube
•Tube Filtration
•Compression Device
•Anti-scatter Grid
•Image Recording System (Detectors)
•Technologist Workstation
•Radiologist viewing console
EQUIPMENT FEATURES

10. •Stationery
•Anode Angle-6 degree
•Tube angle- 23 degree
•Focal Spot size- small (0.1mm – 0.3mm)
•Target Material- Tungsten(W)
-Molybdenum (Mo)
-Rhodium (Rh)
When tungsten target is used- Only Bremstrahlung xrays
predominate.
L-shell xrays are of no value (too low to penetrate)
Contribute only to patient radiation dose.
•Exposure factors- Low Kvp & High mAs
•X-ray most useful for enhancing differential absorption in
breast tissue & maximising
radio-contrast are in the range of 25-28 Kvp.
Source to Image Receptor Distance (SID)- 60-70 cm
X-ray Tube

11. The conic shape of the breast requires that the radiation intensity near the chest wall
must be higher than that to the nipple side to ensure near uniform exposure of the image
Receptor.
Accomplished by positioning the cathode to the chest wall.
However its not absolutely necessary because compression ensures imaging of a uniform
thickness of tissue
HEEL EFFECT APPLICATION

12. In dedicated mammography x-ray tubes have either beryllium(Z=4) window or a very thin
borosilicate glass window.
Most mammography x-ray tubes have inherent filtration in the window of approximately
0.1mm Al equivalent.
FILTRATION
Anode Target or Beam filter for
Producing mammographic x-ray beam.
Those physical properties highly
Favourable for mammographic
Imaging are highlighted in bold; these
Include the energies of the characteristic
X-rays from Mo & Rh and the high
Melting point of W.

14. COMPRESSION DEVICE

16. Routinely used in Mammography.
Most system now have a moving grid with a ratio of 4:1 to 5:1.
Grid frequency- 40lines /cm
Use of such grid increases patient dose compared with nongrid contact mammography.
Dose is still acceptably low, & improvement in contrast is signifant.
Unique grid that has been developed especially for mammography is HTC
(High Transmission Cellular Grid)
•Cross-Hatched grid
•Cleanup characteristics of crossed grid
•Grid strip material- Copper
•Air- Interspace material
Anti-Scatter Grid

17. Air gap between breast and detector
not only increases magnification but also
reduces amount of scatter radiation.
NO grid used.
MAGNIFICATION MODE

18. Phototimers- measure not only image intensity but also x-ray quality.
Position of AEC- after Image Receptor to minimize OID & improve spatial resolution.
AUTOMATIC EXPOSURE CONTROL

19. Indirect Conversion
•Xrays are converted in two step process,
•Xray energy is collected by CsI & converted into light.
•Light photons are then converted into electric signals by photodiode array.
•Some earlier models, such as GE 2000D or Fisher SenoScan use this type of detector s with CsI.
•This process is less efficient & results in some light scatter during conversion.
Direct Conversion
•Xrays are converted in a one step process.
•The layer of a-Se in the detector absorbs the xray energy & converts it into electronic
signal directly.
•Based on efficiency of direct conversion & its elimination of light scatter, a-Se offer
high resolution.
•Later system like Hologic Dimensions uses direct flat panel detectors with a-Selenium.
Image Receptors/Detectors