An aerosol ventilation scintigraphy is a nuclear medical imaging procedure that records the distribution of an inhaled radioactive aerosol within the bronchopulmonary system.
Aerosol ventilation in the gamma camera section does not constitute a significant radiation hazard to personnel. Patient compliance is an important factor to minimizing the dose. Clear instructions and practice are a vital part of the diagnostic imaging procedure.

See also Lung Scintigraphy, Aerosol Method, Gas Ventilation Scintigraphy and Inhalation Scintigraphy.

Scintigraphic imaging of the lungs is a sensitive diagnostic imaging tool to detect certain kinds of pulmonary abnormalities in correlation with clinical data and chest radiographs. Pulmonary scintigraphy is particularly useful in diagnosing medical conditions such as pulmonary embolism, bronchial carcinoma and chronic obstructive pulmonary disease.
Lung scintigraphy can be performed with radioaerosols, gaseous radiopharmaceuticals and technetium-99m-labeled perfusion agents that are localized by temporary capillary blockade.

Different types of lung scintigraphy include:
The choice of the radioactive tracer varies and depends on the pulmonary function to be imaged. The radioactive tracer distribution within the lungs can be displayed on a computer screen via a gamma camera, a scanner or some other similarly suitable detector that records the radioactive disintegrations emitted by the patient. The images obtained present chromatic variations proportional to the regional radioactivity.

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.

X-rays are a part of the electromagnetic spectrum. X-rays and gamma rays are differentiated on the origin of the radiation, not on the wavelength, frequency, or the energy. X-rays are emitted by electrons outside the nucleus, while gamma rays are emitted by the nucleus. X-rays have wavelengths in the range of about 1 nanometer (nm) to 10 picometer (pm), frequencies in the range of 10^-16 to 10^-20 Hertz (Hz) and photon energies between 0.12 and 120 kilo electron Volt (keV). The energy of rays increase with decreased wavelengths. X-rays with energies between 10 keV and a few hundred keV are considered hard X-rays. The cutoff between soft or hard X-rays is around a wavelength of 100 pm.
Because of their short wavelength, X-rays interact little with matter and pass through a wide range of materials. These interactions occur as absorption or scattering;; primary are the photoelectric effect, Compton scattering and, for ultrahigh photon energies of above 1.022 mega electron Volt (MeV), pair production.
X-rays are produced when high energy electrons struck a metal target. The kinetic energy of the electrons is transformed into electromagnetic energy when the electrons are abruptly decelerated (also called bremsstrahlung radiation, or braking radiation) similar to the deceleration of the circulating electron beam in a synchrotron particle accelerator. Another type of rays is produced by the inner, more tightly bound electrons in atoms;; frequently occurring in decay of radionuclides (characteristic radiation, gamma ray, beta ray). The energy of an X-ray is equivalent to the difference in energy of the initial and final atomic state minus the binding energy of the electron.
Wilhelm Conrad Roentgen discovered this type of rays (also called Roentgen-rays) in 1895 and realized that X-rays penetrate soft tissue but are absorbed by bones, which provides the possibility to image anatomic structures; the first type of diagnostic imaging was established. Radiographic images are based on this difference in attenuation for tissue and organs of different density. Today ionizing radiation is widely used in medicine in the field of radiology.

See also Exposure Factors, X-Ray Tube, and X-Ray Spectrum.