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Radiology is the science that uses medical imaging to diagnose and sometimes also treat diseases within the body.

A variety of imaging techniques such as X-ray radiography, ultrasound, computed tomography (CT), nuclear medicine including positron emission tomography (PET), and magnetic resonance imaging (MRI) are used to diagnose and/or treat diseases. Interventional radiology is the performance of (usually minimally invasive) medical procedures with the guidance of imaging technologies.

Plain radiography was the only imaging modality available during the first 50 years of radiology. Due to its availability, speed, and lower costs compared to other modalities, radiography is often the first-line test of choice in radiologic diagnosis. Also despite the large amount of data in CT scans, MR scans and other digital-based imaging, there are many disease entities in which the classic diagnosis is obtained by plain radiographs. Examples include various types of arthritis and pneumonia, bone tumors (especially benign bone tumors), fractures, congenital skeletal anomalies, etc.

CT or CAT scan

CT scanners first began to be installed in 1974. CT scanners have vastly improved patient comfort because a scan can be done quickly. Improvements have led to higher-resolution images, which assist the doctor in making a diagnosis. For example, the CT scan can help doctors to visualize small nodules or tumors, which they cannot see with a plain film X-ray.CT scan images allow the doctor to look at the inside of the body just as one would look at the inside of a loaf of bread by slicing it. This type of special X-ray, in a sense, takes "pictures" of slices of the body so doctors can look right at the area of interest. CT scans are frequently used to evaluate the brain, neck, spine, chest, abdomen, pelvis, and sinuses

If one looks at a standard X-ray image or radiograph (such as a chest X-ray), it appears as if they are looking through the body. CT and MRI are similar to each other, but provide a much different view of the body than an X-ray does. CT and MRI produce cross-sectional images that appear to open the body up, allowing the doctor to look at it from the inside. MRI uses a magnetic field and radio waves to produce images, while CT uses X-rays to produce images. Plain X-rays are an inexpensive, quick test and are accurate at diagnosing things such as pneumonia, arthritis, and fractures.

Urine Specific Gravity

Urine specific gravity Medical diagnostics Urine specific gravity.JPG Reading of a urine specific gravity of ~1.024 via a handheld refractometer. SG measurement is taken by reading the boundary between the dark and light fields against the graduations on the left column. Purpose evaluation of kidney function Specific gravity, in the context of clinical pathology, is a urinalysis parameter commonly used in the evaluation of kidney function and can aid in the diagnosis of various renal diseases.

Adults generally have a specific gravity in the range of 1.010 to 1.030 Increases in specific gravity (hypersthenuria, i.e. increased concentration of solutes in the urine) may be associated with dehydration, diarrhea, emesis, excessive sweating, urinary tract/bladder infection, glucosuria, renal artery stenosis, hepatorenal syndrome, decreased blood flow to the kidney (especially as a result of heart failure), and excess of antidiuretic hormone caused by Syndrome of inappropriate antidiuretic hormone. A specific gravity greater than 1.035 is consistent with frank dehydration. In neonates, normal urine specific gravity is 1.003. Hypovolemic patients usually have a specific gravity >1.015. Decreased specific gravity (hyposthenuria, i.e. decreased concentration of solutes in urine) may be associated with renal failure, pyelonephritis, diabetes insipidus, acute tubular necrosis, interstitial nephritis, and excessive fluid intake (e.g., psychogenic polydipsia). Osmolality is normally used for more detailed analysis but USG remains popular for its convenience

Mammography

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 to create images. These images are then analyzed for abnormal findings. It is usual to employ lower-energy X-rays, typically Mo (K-shell x-ray energies of 17.5 and 19.6 keV) and Rh (20.2 and 22.7 keV) than those used for radiography of bones. Ultrasound, ductography, positron emission mammography (PEM), and magnetic resonance imaging (MRI) are adjuncts to mammography. Ultrasound is typically used for further evaluation of masses found on mammography or palpable masses not seen on mammograms. Ductograms are still used in some institutions for evaluation of bloody nipple discharge when the mammogram is non-diagnostic. MRI can be useful for further evaluation of questionable findings, as well as for screening pre-surgical evaluation in patients with known breast cancer, in order to detect additional lesions that might change the surgical approach, for example, from breast-conserving lumpectomy to mastectomy. Other procedures being investigated include tomosynthesis.

Mammography has a false-negative (missed cancer) rate of at least ten percent. This is partly due to dense tissue obscuring the cancer and the appearance of cancer on mammograms having a large overlap with the appearance of normal tissue. A meta-analysis review of programs in countries with organized screening found a 52% over-diagnosis rate.