Internal radiation is produced by the decay of radioactive material in the body.

(IAEA) The IAEA is an independent international organization related to the United Nations system today, founded in 1957 ('Atoms for Peace' Agency) as part of the United Nations family. Its mission is to promote and supervise worldwide safe, secure and peaceful nuclear technologies. The IAEA's three main areas of work are 'Safety and Security', 'Science and Technology', and 'Safeguards and Verification'.

Interpolation is a mathematical process used to smooth, enlarge or average images that are being displayed with more pixels than that for which they were originally reconstructed.

Interventional radiology is an area of clinical subspecialty which uses various radiology techniques (such as fluoroscopy, ultrasound, computed tomography, and MRI procedures) to guide procedures such as a biopsy, inserting catheters, place wires, draining fluids, dilating or stenting narrowed ducts or vessels to diagnose or treat different conditions.

See also CT Guided Biopsy, Angioplasty, Coronary Angiogram and Interventional Ultrasound.

(IVP) An intravenous pyelogram is a radiographic study of the kidney, ureters, and bladder. After the injection or infusion of iodinated contrast materials into the vein, the contrast medium is excreted by the kidneys. Due to the higher density of the dye, contrast filled areas appear white on x-ray images.
IVPs are used to detect tumors, abnormalities, kidney stones, or any obstructions, and to assess renal blood flow. A pyelogram may also be performed with contrast media injection directly through a ureteral or nephrostomy catheter or percutaneously.

See also X-Ray Projection Imaging, Abdomen CT and Urologic Ultrasound.