Mammography What is Mammography? Mammography is a specific type of imaging that uses a low-dose x-ray system to examine breasts and is used to aid in the early detection and diagnosis of breast diseases in women. Screening Mammography Mammography plays a central part in early detection of breast cancers because it can show changes in the breast up to two years before a patient or physician can feel them.
CT is an accurate technique for diagnosis of abdominal diseases. Its uses include diagnosis and staging of cancer, as well as follow up after cancer treatment to assess response. It is commonly used to investigate acute abdominal pain.
Extremities[ edit ] CT is often used to image complex fracturesespecially ones around joints, because of its ability to reconstruct the area of interest in multiple planes. Fractures, ligamentous injuries and dislocations can easily be recognised with a 0. First, CT completely eliminates the superimposition of images of structures outside the area of interest.
Finally, data from a single CT imaging procedure consisting of either multiple contiguous or one helical scan can be viewed as images in the axialcoronalor sagittal planes, depending on the diagnostic task. This is referred to as multiplanar reformatted imaging. CT is regarded as a moderate- to high- radiation diagnostic technique.
The improved resolution of CT has permitted the development of new investigations, which may have advantages; compared to conventional radiography, for example, CT angiography avoids the invasive insertion of a catheter. CT colonography also known as virtual colonoscopy or VC for short is far more accurate than a barium enema for detection of tumors, and uses a lower radiation dose.
CT VC is increasingly being used in the UK and US as a screening test for colon polyps and colon cancer and can negate the need for a colonoscopy in some cases.
The radiation dose for a particular study depends on multiple factors: Computed tomography CT scan has been shown to be more accurate than radiographs in evaluating anterior interbody fusion but may still over-read the extent of fusion.
The radiation doses received from CT scans is variable. Compared to the lowest dose x-ray techniques, CT scans can have to 1, times higher dose than conventional X-rays.
In general, the radiation dose associated with a routine abdominal CT has a radiation dose similar to 3 years average background radiation from cosmic radiation.
Some experts project that in the future, between three and five percent of all cancers would result from medical imaging. In this group one in every CT scans was followed by an excess cancer. People with mild kidney impairment are usually advised to ensure full hydration for several hours before and after the injection.
For moderate kidney failure, the use of iodinated contrast should be avoided; this may mean using an alternative technique instead of CT. Those with severe renal failure requiring dialysis require less strict precautions, as their kidneys have so little function remaining that any further damage would not be noticeable and the dialysis will remove the contrast agent; it is normally recommended, however, to arrange dialysis as soon as possible following contrast administration to minimize any adverse effects of the contrast.
In addition to the use of intravenous contrast, orally administered contrast agents are frequently used when examining the abdomen. However, oral alternatives to iodinated contrast exist, such as very dilute 0.
Dilute barium sulfate has the advantage that it does not cause allergic-type reactions or kidney failure, but cannot be used in patients with suspected bowel perforation or suspected bowel injury, as leakage of barium sulfate from damaged bowel can cause fatal peritonitis.
CT scanner with cover removed to show internal components. Gantry rotation Left image is a sinogram which is a graphic representation of the raw data obtained from a CT scan. At right is an image sample derived from the raw data. Operation of computed tomography Computed tomography operates by using an X-ray generator that rotates around the object; X-ray detectors are positioned on the opposite side of the circle from the X-ray source.
A visual representation of the raw data obtained is called a sinogram, yet it is not sufficient for interpretation. Once the scan data has been acquired, the data must be processed using a form of tomographic reconstructionwhich produces a series of cross-sectional images.
Pixels in an image obtained by CT scanning are displayed in terms of relative radiodensity. Pixel is a two dimensional unit based on the matrix size and the field of view. When the CT slice thickness is also factored in, the unit is known as a Voxelwhich is a three-dimensional unit.
The phenomenon that one part of the detector cannot differentiate between different tissues is called the "Partial Volume Effect". That means that a big amount of cartilage and a thin layer of compact bone can cause the same attenuation in a voxel as hyperdense cartilage alone.
The attenuation of metallic implants depends on atomic number of the element used:View and Download Hologic Selenia dimensions user manual online. Selenia dimensions Medical Equipment pdf manual download.
ABSTRACT: OBJECTIVE. The purpose of this study was to quantify the amount of scatter radiation received at the skin surface overlying the thyroid gland, salivary gland, lens of the eye, sternum, and uterus during a routine screening digital mammographic examination measured in a representative patient population.
The American Association of Physicists in Medicine is a member society concerned with the topics of medical physics, radiation oncology, imaging physics, health physics, hospital physics, medical radiation, physics careers, ionizing radiation, brachytherapy and diagnostic imaging.
9. Total-variation Joint Planar Imaging for Parathyroid Scintigraphy Medical Imaging Program, Department of Radiology, Faculty of Medicine, Chulalongkorn University Thunyaluk Sawatnatee. Mar 27, · This document supersedes “Class II Special Controls Guidance Document: Full-Field Digital Mammography System,” issued November 5, On .
Mammography (also called mastography) is the process of using low-energy X-rays (usually around 30 kVp) to examine the human breast for diagnosis and screening. The goal of mammography is the early detection of breast cancer, typically through detection of characteristic masses or microcalcifications..
As with all X-rays, mammograms use doses of ionizing radiation .