scanning radio isotope

From Big Medical Encyclopedia

SCANNING radio isotope — a way of obtaining the two-dimensional image reflecting distribution of radio pharmaceutical drug in an organism. It is used in a wedge, practice for a research kidneys (see), liver (see), lungs (see), thyroid gland (see) and pancreas (see), detection of tumors and their metastasises in brain (see), skeleton (see), etc. S. carry out by means of the radio diagnostic unit — the scanner (English scanner the developing device) which is carrying out line-by-line movement of the detector over the studied part of a body (fig. 1).

Fig. 1. Scanner (habit view): 1 — the chart recorder creating the image on paper; 2 — the electronic block; 3 — the sensor with the collimator.

For S. the same are used radio pharmaceuticals (see), as for stsintigrafiya (see).

At S. automatic registration is carried out by the moving detector of impulses of radiation, to-rye then by means of the special electronic block are transformed to shaped marks in usual paper. Shaped lines, gradually filling the field of registration, form a skanogramma. On density of shading and its distribution judge extent of accumulation of radio pharmaceutical drug (RFP) in various sites of the studied area.

Color skanogramma it is normal (fig. 1, 3 and 4) of N at pathology (fig. 2). Various flowers designated different levels of accumulation of radio pharmaceutical drug (RFP) in fabrics. Fig. 1. Skanogramma is normal of lungs (a direct projection), registered after intravenous administration of the macrounit 99mTc. A scale of flowers from the accumulation, minimum to the maximum level: blue, green, yellow, red. Fig. 2. Skanogramma of the head of the patient with a tumor lobno - temporal area of a brain, the pertekhnetata registered after intravenous administration 99mTc. The greatest accumulation of RFP is noted in the field of a tumor (yellow — orange — brown colors). In normal tissue of a brain the level of accumulation of RFP the smallest (light-and dark green color); higher extent of accumulation — in soft tissues and bones of a neurocranium (blue and blue colors). Physiological high accumulation of RFP is defined also out of a head cavity — in mucous membranes of nasal and oral cavities, in sialadens (the bottom of a skanogramma). Fig. 3. Skanogramma is normal of a liver (a front projection), registered after introduction of 99 t of the CU colloid. A scale of flowers from the accumulation, minimum to the maximum level: pink, red, dark yellow, green, blue, lilac, light yellow, violet. Fig. 4. Skanogramma is normal of kidneys (a back projection), registered after introduction of 197Hg-Neohydrinum. A scale of flowers the same, as for fig. 3.

In color S.'s systems strokes of a skanogramma have various color. To every color a certain number of impulses corresponds in unit of time; depending on a radiation intensity color of strokes changes (tsvetn. tab., Art. 368, fig. 1-4).

Fig. 2. Black-and-white skanogramma of a liver: the arrow specified the site of the lowered accumulation of radio pharmaceutical drug — the «cold center» caused by a metastasis of a malignant tumor.

Assessment skanogramm is made by the visual analysis of the image. At the same time define situation, a form and the sizes of both all storage site of RFP, and the studied body, reveal deviations from distribution of RFP’ normal. Equitability and intensity of accumulation of RFP in the studied object are of great importance. In the analysis skanogramm specially reveal sites of excess or insufficient accumulation (the «hot» or «cold» centers), to-rye are caused by existence (not absorbing) sites functioning (absorbing) or not functioning in body or area of a body (fig. 2).

More exact quantitative and qualitative analysis skanogramm is carried out by means of electronic and computing blocks, to-rymi modern high-speed scanners are supplied. During the research the patient shall keep an immovability. However it is impossible to provide an immovability of nek-ry bodies in the course of their research that leads to certain distortions of plane images. Besides, in comparison with stsintigrafiy S. — the procedure longer (on slow-acting scanners it takes about 30 — 40 min.).

Profile S. is carried out by means of the profile scanner, one or two sensors to-rogo move over the explored area in one linear direction. At the same time instead of the shaped image of the studied body on a paper strip the curve reflecting distribution of RFP in a body of the patient in the direction of the movement of the sensor is drawn. Profile S. is applied by hl. obr. for studying of distribution of RFP in a body of the patient and in a skeleton for the purpose of search of clinically not defined metastasises and for detection large patol. centers. Its advantage is speed of a research (2 — 3 min.).

Recently S. is more and more forced out by a stsintigrafiya on the gamma cameras supplied with computers, to-rye allow to obtain in one step information on distribution of RFP in body and to investigate the fast-proceeding processes (a blood stream, ventilation of the lungs, etc.). Along with gamma cameras (see. Radio isotope diagnostic units ) in a crust, time begin to use special positron cameras; with their help make positron S., using a positron the radiating substances. The camera registers the gamma quanta formed in an organism at annihilation of a positron (see. Annihilation ).

See also Radio isotope diagnosis .

Bibliography: Zubovsky G. A. and Pavlov of V. G. Skennirovaniye of internals, M., 1973.

G. A. Zubovsky.