Mammography is the process of obtaining x-ray images of the human breast for diagnosis or surgery. It involves positioning a patient's breast in a desired orientation against a cassette holder of a mammography unit, compressing the breast with a compression device, and then exposing the breast to x-rays to create a latent image of the breast on an image receptor.
What is a cassette in radiography?
Cassettes are rigid holders used in conventional and computed radiography (CR) for the screen film system and imaging plate respectively. The back side of the cassette has a rubber or felt for adequate contact between screen film system or with the imaging plate. The front is made of low atomic number material (e.g.
What are imaging plates for mammography?
In the early 21st century, imaging plates were developed for mammography that could be used as cassettes in conventional analog mammography devices.
What is the difference between CR and conventional radiography cassettes?
In case of conventional radiography, two screens are mounted on each side of the cassette, except in mammography, where a single screen is mounted on the back side. These cassettes have to loaded with film in the darkroom unlike the cassettes used in CR which can be loaded with imaging plate in the light.
What is the purpose of a mammogram?
Mammography is a type of medical imaging that uses x-rays to capture images (mammograms) of the internal structures of the breasts. Quality mammography can help detect breast cancer in its earliest, most treatable stages; when it is too small to be felt or detected by any other method. The two types of imaging currently used for mammography are
What is the function of cassette?
Cassettes are used in association with intensifying screens and have related FUNCTIONS: 1. To contain a film 2. to exclude light, 3. to maintain the film in close, uniform contact with both screens during the exposure, 4. to protect the intensifying screens from physical damage.
What is a cassette used for in radiography?
An X-ray cassette is a light-resistant container that protects the film from exposure to daylight, holds the film between two intensifying screens and allows the passage of X-rays through the front cover on to the film.
What are the three types of mammography?
In general, there are two main types of mammograms: Digital mammography in 2D. Digital mammography in 3D (digital breast tomosynthesis).
What is a film cassette?
A film cassette is similar to a film can in that it is a light-tight enclosure containing a spool of film. However a cassette also has a light trap, usually a set of lips covered with velvet, that allow film through without allowing light into the can.
How many types of cassettes are there?
Since then, the four cassette tape types were known as IEC I, IEC II, IEC III and IEC IV.
What are the different sizes of cassettes?
In general, cassettes start at 10, 11 or 12 teeth. Again, there are exceptions, with options available with 9-, 13- or 14-tooth smallest sprockets. You may sometimes see brands refer to their cassettes as having a certain range in the form of a percentage.
Which type of mammogram is best?
The gold standard in breast cancer screening has been 2D digital mammography, which takes two X-ray images of the breast, one from the top and one from the side.
Are there 2 types of mammograms?
There are two main types of mammography: 2D digital mammograms and 3D mammograms — also called digital breast tomosynthesis, digital tomosynthesis, or just tomosynthesis.
What is the latest type of mammogram?
Breast tomosynthesis, also called 3-D mammography, is a new technology. It takes images of the breast from many different angles and creates a three-dimensional picture of the tissue. ... Learn more about breast cancer risk factors.Learn how to perform a self breast exam.
What are film cassettes made of?
Cassette tapes are made of a polyester-type plastic film with a magnetic coating. The original magnetic material was based on gamma ferric oxide (Fe2O3).
How do I know what kind of cassette I have?
Stick with a Type I or Type II tape. The 4 notches found at the top of a metal cassette are the easiest way to identify the tape type. The notches on the outside of the tape tell the cassette deck to use the bias of a Type II tape. The notches on the inside of the cassette tell the player to push the bias even further!
What is cassette with intensifying screen?
The intensifying screen is placed in a cassette in close contact with a film. The visible light from its fluorescent image will add to the latent image on the film. Its function is to reinforce the action of X-rays by subjecting the emulsion to the effect of light as well as ionizing radiation.
What is intensifying screens in radiography?
Intensifying screens are used in the x-ray cassette to intensify the effect of the x-ray photon by producing a larger number of light photons. It decreases the mAs required to produce a particular density and hence decreases the patient dose significantly.
What are film cassettes made of?
Cassette tapes are made of a polyester-type plastic film with a magnetic coating. The original magnetic material was based on gamma ferric oxide (Fe2O3).
What should a radiographer do to prevent radiographic fog?
To increase contrast, the radiologic technologist will increase the grid ratio. An increase in grid ratio absorbs more scatter radiation, reducing image fog, resulting in an increase in image contrast.
What is meant by intensifying screen?
Intensifying screens intensify the effect of the X-ray beam energy on the film by energy conversion. Some X-ray energy is absorbed by the screen and re-emitted as u. v. and visible light energy (Figure 5.1), to which the film has a greater sensitivity, thus producing a greater film response.
How does mammography work?
Mammography systems have automatic exposure control to prevent incorrect exposure. Because breast composition varies greatly between individuals, the radiation dose required can vary by a factor of 4 to 5, even with objects of identical thickness. To calculate the optimum individual dosage in analog mammography, an automatic exposure control is placed below the detector to measure the incident dose. When the desired dosage has been reached, the exposure is terminated. In digital mammography systems, the optimum dosage is calculated from a test exposure at the beginning of the procedure. This pre-scan X-ray dose contributes to the required image acquisition dosage. On the basis of the test exposure the device automatically selects the suitable tube current and the optimum anode–filter combination for the breast being imaged in order to achieve optimal optical density, which should be between 0.6 and 2.2.
What is the purpose of X-ray mammography?
The term “X-ray mammography” (frequently just “mammography”) denotes the radiographic examination of the female (and also the male) breast. An X-ray mammography system consists of a X-ray tube with associated generator that produces the X-rays and a detector that captures the X-rays after they have passed ...
What is the optical density of a mammogram?
The amount of density on a film produced by radiation is referred to as the optical density of the image. It is expressed as the log of the ratio of incident light intensity to transmitted light intensity. The recommended range of optical density ( D) in mammography is from 0.6 to 2.2. Images with an optical density below 0.6 are underexposed (too light), while those with optical density above 2.2 are overexposed (too black). The linearity of the gradation curve in digital mammography allows postprocessing to shift the optical density of an image to a more favorable value. If the image is underexposed, postprocessing results in increased noise. Overexposed images, on the other hand, are well suited for readout after processing, but obtaining them will have exposed the patient to an unnecessary amount of radiation.
How is breast cancer detected by X-rays?
The detection of breast cancer by X-ray mammography is based on the greater X-ray absorption by cancerous tissue than by other intramammary structures. Approximately one-third of all breast cancers are associated with calcifications. Because calcifications absorb X-radiation almost completely, they are depicted clearly in radiographic examinations, making mammography the first-line examination for their visualization. Noncalcifying breast cancer masses also display strong absorption of ionizing radiation due to their very high cell density. Thus they can easily be identified within fatty breast tissue, which shows only moderate X-ray absorption. Because extremely dense glandular tissue structures have X-ray absorption similar to that of both benign and malignant proliferative lesions, these lesions are difficult or impossible to distinguish within such dense parenchyma.
Why is mammography considered a high radiation quality?
Because female breast tissue components have very similar absorption rates, mammography requires very high radiation quality to distinguish these components in varying shades of gray. Radiation quality is affected by generator ripple, anode and filter materials, the applied voltage level, and beam hardening in the breast.
What are the most commonly used filters in mammography?
5.3 ). The most commonly used filter materials in mammography are molybdenum and rhodium. Copper and aluminum may be used in digital spectral mammography (see ▶ Fig. 5.21 b).
What is the purpose of an X-ray tube?
The X-ray tube is a vacuum tube containing electro des that emit, accelerate, and decelerate electrons to produce X-radiation. The voltage applied between the electrodes (cathode and anode) accelerates the electrons ( ▶ Fig. 5.2 ). The anode material determines the characteristics of the radiation. Anodes used today are typically composed of two components: either molybdenum and rhodium, or molybdenum and tungsten. The point at which the electrons strike the anode is called the focal spot. For mammography the focal spot is smaller than that used in other radiographic examination techniques—just 0.3 mm for standard view images and 0.1 mm for magnification mammography.
Does EHR-M3 have better image quality?
EHR-M3 CR Mammography screens will provide overall improved image quality for DirectView CR Mammography applications as compared to EHR-M2 and earlier mammography screens at the same, or lower, dose.
Can EHR M3 and M2 be used in the same reader?
EHR-M3 and EHR-M2 screens are not recommended for use in the same CR reader. CR systems must be calibrated for either EHR-M2 or EHR-M3 screens.
When was mammography considered a reliable clinical tool?
At that time, the significance of breast microcalcifications was also well understood. By the mid-1950s, mammography was considered a reliable clinical tool because of such refinements as low-kilovoltage x-ray tubes with molybdenum targets and high-detail, industrial-grade x-ray film.
What is the goal of mammography?
The primary goal of mammography is to detect breast cancer before it is palpable. The combination of early detection, diagnosis, and treatment has resulted in a steady increase in survival rates. The overall mortality rate for breast cancer has finally decreased for American women.
Why is mammography important?
Mammography is the most important innovation in breast cancer control since the radical mastectomy was introduced by Halstead in 1898. The primary goal of mammography is to detect breast cancer before it is palpable.
How long does it take to get a mammogram?
Mammography is a relatively simple procedure that takes only about 15 minutes to complete. The acceptability of mammography, which is the only radiographic procedure used to screen cancer, has been confirmed in numerous studies. Mammography cannot detect all cancerous lesions, however.
Why is xeromammography used?
23-2). Because many physicians found xerographic images easier to understand and evaluate, xeromammography became widely used for evaluating breast disease.
Why do women refuse mammography?
Although radiation dosage during a mammography examination has decreased dramatically since the 1970s, fear of radiation exposure still causes some women to refuse mammography, and many women who undergo the examination are concerned about exposure levels and the resultant risk of carcino genesis.
How many lobes are there in the breast?
The adult female breast consists of 15 to 20 lobes, which are distributed such that more lobes are superior and lateral than inferior and medial. Each lobe is divided into many lobules, which are the basic structural units of the breast. The lobules contain the glandular elements, or acini. Each lobule consists of several acini, numerous draining ducts, and the interlobular stroma or connective tissue. These elements are part of the breast parenchyma and participate in hormonal changes. By the late teenage years to early 20s, each breast contains several hundred lobules. The lobules tend to decrease in size with increasing age and particularly after pregnancy—a normal process called involution.
What is a cassette in radiography?
Cassette. Cassettes are rigid holders used in conventional and computed radiography (CR) for the screen film system and imaging plate respectively. The back side of the cassette has rubber or felt for adequate contact between the screen film system or with the imaging plate.
How many screens are there in a radiography cassette?
In the case of conventional radiography, two screens are mounted, one on each side of the cassette, except in mammography, where a single screen is mounted on the back side. These cassettes have to be loaded with film in the darkroom unlike the cassettes used in CR which can be loaded with a imaging plate in the light.
What material is the front of a cassette made of?
The front of the cassette is made of a low atomic number material (e.g. plastic or carbon) to enable ease in passage of x-rays and the back is made of a high atomic number material (e.g. lead) to reduce backscatter.
What is the back of a screen film cassette?
The back side of the cassette has rubber or felt for adequate contact between the screen film system or with the imaging plate. The front of the cassette is made of a low atomic number material (e.g. plastic or carbon) to enable ease in passage of x-rays and the back is made of a high atomic number material (e.g. lead) to reduce backscatter.
Can you use a cassette in digital radiography?
No cassette is used in digital radiography.
