The pulmonary perfusion scintigraphy records the distribution of pulmonary arterial blood flow. The most common indication for lung scintigraphy is the detection of pulmonary embolism. The most widely used radiopharmaceuticals are technetium-99m MAA (macroaggregates of albumin) or 99mTc-HAM. Other radiopharmaceuticals include sulphur colloid macroaggregated albumin, radioactive albumin microspheres and albumin labeled with I-131, or I-113m.
Perfusion imaging of the bronchopulmonary system is based on the principle of capillary blockade. The perfusion study is accomplished by injecting 40 to 160 MBq (1-4 mCi) of the radiopharmaceutical and during repeated deep inhalation. The aggregates are extracted during their first pass through the lung, thus imaging can begin immediately. Pulmonary perfusion scintigraphy is particularly useful in combination with gas ventilation scintigraphy and aerosol ventilation scintigraphy.

See also Inhalation Scintigraphy.

Reconstruction is the mathematical process by which the displayed image is produced from the raw data.
Used equipment and data processing methods to reconstruct CT images:
See also Zoom Reconstruction, Reconstruction Matrix and Multiplanar Reconstruction.

(T) The system international (SI) unit of magnetic flux density. Definition: 1 T is the field intensity generating 1 N (newton) of force per ampere of current per meter of conductor. The tesla unit value is defined as a field strength of 1 weber per square meter of area, where 1 weber represents 1 x 10⁸ (100 000 000) flux lines. One T is equal to 10 000 gauss, the older (CGS) unit. A field of 1 tesla is quite strong, the Earth's magnetic flux density, at its surface, is about 50 microteslas (µT).

X-ray tubes are devices for the production of x-rays. X-ray tubes consist of an evacuated glass vessel and two electrodes. An electrical current with very high voltage passes across the tube and accelerates electrons emitted by thermionic emission from a tungsten filament (cathode also called electron gun) towards the anode target. The electrons collide with the anode and this deceleration generates x-rays (bremsstrahlung).
The high vacuum allows the electron beam an unimpeded passage. The electron beam heats the anode (usually copper), which is cooled by water to prevent melting. A copper target emits x-rays with a characteristic wavelength. Other used metals soften or harden the x-ray beam.
The x-rays pass through a very thin beryllium (Be) foil. This beryllium window absorbs a high amount of the elastically scattered electrons (produced by the target) and allows the radiation to get out of the tube without substantial absorption.
In conventional x-ray tubes, the anode is also the target. In nanofocus and microfocus x-ray tubes, the electron beam is transmitted through a hole in the anode where it is then focused onto a small spot on the target.

See also X-Ray Tube Housing, Fine Focus X-Ray Tube, Transformer, Diode, Digital to Analog Converter and Angular Response.