Breast cancer is the second most common cause of death among women ages 40 to 55, and this is where the mammography machine comes into the picture.
It is advisable for women to have mammograms after the age of 40 on a regular basis because there are high chances of breast cancer during this period.
Due to family history, body changes, reproductive or menstrual history, obesity, breast density, less physical activity after menopause, unbalanced diet, previous biopsy are the few common reasons.
Regular screening helps detect any type of malignancy at its early stage to start treatment, thus improving the chances of curing breast cancer.
What is a mammogram?
It is a process of achieving good quality internal imaging (mammography) of the breast using X-rays to increase the radiologist’s ability to see abnormal masses.
Although in some cases instead of X-ray ultrasound is used for the study of the breasts but the most common practice is the mammography machine.
Exposes the breasts to a relatively small amount of radiation, usually less than 20% of the annual average
Background radiation. Mammography is of two types, screening and diagnostic.
A screening mammogram is the standard screening test for breast cancer today. A “breast screening” exam is a test used for routine checkups, to make sure that supposedly healthy women do not have a specific disease.
Once a mass is found on a screening mammogram, the patient will often return for diagnosis.
mammography, which consists of specialized close-up views of the mass with added compression.
This will help the radiologist to better characterize the mass as benign or malignant.
Mammography Machine Technology
The team evolved over at least the last 40 years to the present. While there are some differences from manufacturer to manufacturer, there are also many features and characteristics that are common to all.
It is basically a C-arm with a fixed source at the detector distance with some additional modifications and movements. That is what we will introduce and cover here.
X-ray tube anode
While most X-ray tubes use tungsten as the anode material, mammography equipment uses molybdenum anodes or, in some designs, a dual material anode with an additional track of rhodium.
These materials are used because they produce a characteristic radiation spectrum that is close to optimal for breast imaging.
X-ray machines use aluminum or “aluminum equivalent” to filter the X-ray beam (soft X-rays) to reduce unnecessary patient exposure.
Mammography uses filters that work on a different principle and are used to improve contrast sensitivity. Molybdenum (same as in the anode) is the standard filter material.
Some systems allow the operator (or the automatic control function) to select the molybdenum or rhodium filter to optimize the spectrum for specific mammary conditions.
The typical X-ray tube for mammography has two selectable focal points. The spots are generally smaller than for other X-ray procedures.
Due to the requirements of minimal blur and good detail visibility to see small calcifications. The smaller of the two points is generally used for the enlargement technique.
Good breast compression is one of the essential elements of an effective mammogram (and a common source of patient discomfort and concern). Potential benefits from compression include:
A more uniform chest thickness resulting in a better fit of exposure to the latitude or dynamic range of the film.
1 Reduced blur due to patient movement.
2 Reduced scattered radiation and improved contrast sensitivity.
3 Reduced radiation dose.
4 Better visualization of tissues near the chest wall.
A grating is used as in other X-ray procedures to absorb scattered radiation and improve contrast sensitivity.
Compared with general X-ray imaging grids, mammography grids have a lower ratio, and the material between the strips is selected for low X-ray absorption.
The grid is contained in a Bucky device that moves it during X-ray exposure to blur and reduce the visibility of the grid lines.
Detector/Sensor / Receiver
Both film/screen and digital detectors are used for mammography. Each has special features to improve image quality.
To complete the study on the fundamentals of X-rays and its application, follow X-Ray.
Digital mammography has several advantages over film in optimizing the transfer of contrast from the breast to image viewing and maximizing overall contrast sensitivity.
The main advantages are here.
Digital Receiver Dynamic Range
A valuable feature of most digital receivers is consistent sensitivity over a wide range of exposures. This is very different from the relatively narrow latitude or dynamic range of film.
The full exposure histogram will be easily covered by the wide dynamic range and considerable variation in exposure to the receiver (exposure error) can be tolerated without loss of contrast.
The transfer from exposure contrast to digital image contrast is represented by a linear characteristic curve (straight line) rather than the steep characteristic of film with its limited latitude.
The digital image recorded by the typical digital receiver will have relatively low contrast, but will be uniform throughout the exposure range.
The next step is to select the exposure range that represents the actual image, i.e. the histogram, and enhance the contrast using digital processing and windowing.
digital image processing
One of the great advantages of digital images is the ability to apply a variety of processing procedures to change image characteristics to improve quality and visibility.
Contrast processing is common to most forms of digital radiography and is used to render digitally acquired radiographs like more conventional film radiographs with respect to contrast.
The advantage is that the user can select from many different “film features” to meet the needs of specific clinical procedures.
For example, in general radiography, one type of “characteristic curve” would be appropriate for imaging the chest, while another would be used for imaging the extremities.
In digital mammography, the various contrast processing procedures are usually built into the system and can vary somewhat from manufacturer to manufacturer.
Windowing used in viewing and displaying most digital images (including CT, MRI, etc.) is the last step in optimizing contrast and visibility of specific objects and structures within an image.
The various contrast characteristics of digital images (wide dynamic range, processing, and windowing) can be combined to produce the maximum contrast sensitivity required in mammography.
Reviewing breast tissue slice by slice allows the radiologist to view breast tissue in a way that has never been possible before.
Digital Breast Tomosynthesis (DBT) is a 3D imaging technology that acquires a series of low-dose projection images of the compressed breast at different angles.
The system produces thin slices of the breast, allowing radiologists to pass through slices one millimeter at a time.
Unlike a traditional mammogram, the slices separate objects at different heights in the breast, producing a three-dimensional image.
The x-ray tube is moved in an arc through the breast. A series of low-dose images are acquired from different angles. Total dose approximately equal to a 2D digital mammogram.
Projection images are reconstructed in 1mm slices using low-level X-rays to produce multiple images of the breast, layer by layer, using an oscillating camera.
This image overlay simplifies the detection of normal breast structures (mammary ducts, lobules, fatty tissues, etc.) from cancerous ones.
X-rays are converted into limited three-dimensional digital images for examination by radiologists. Computer-aided detection (CAD) helps detect regions where cancer appears to be present.
Dense tissue is more easily examined through CT than traditional mammography, increasing detection of invasive breast cancers by 40% compared to 2D mammography.
To find out how CT scan works or reconstruct images of internal body organs using X-rays, follow CT scan.
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