Scintigraphy

Scintigraphy ("scint," Latin scintilla, spark) is a form of diagnostic test used in nuclear medicine, wherein radioisotopes (here called radiopharmaceuticals) are taken internally, and the emitted radiation is captured by external detectors (gamma cameras) to form two-dimensional images. In contrast, SPECT and positron emission tomography (PET) form 3-dimensional images, and are therefore classified as separate techniques to scintigraphy, although they also use gamma cameras to detect internal radiation. Scintigraphy is unlike a diagnostic X-ray where external radiation is passed through the body to form an image.

Read more about Scintigraphy:  Function Tests