Radiopharmaceuticals: Radio activity, Measurement of radioactivity, Properties of α, β, γ radiations : Pharmaceutical Guidelines -->

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Radiopharmaceuticals: Radio activity, Measurement of radioactivity, Properties of α, β, γ radiations

Photographic plates are impacted by radioactive particles or rays released by radioactive substances.


Photographic plates are impacted by radioactive particles or rays released by radioactive substances. There are 40 radioactive elements that can be grouped into three series: uranium, thorium, and actinium. Radiation and decomposition of the radioactive elements results in emissions of radiation. This makes them radioactive. Among the radiations that are emitted are as follows:
  • Alpha rays
  • Beta rays
  • Gamma rays
Any nucleotide that does not emit radiation is considered stable. Nucleoids may possess appropriate energy levels to be stable. Nuclides that undergo spontaneous nuclear decay in order to become stable by emitting radiations are called radioisotopes or radionuclides.

There are four main categories of radiopharmaceuticals, including
  • Radiopharmaceutical precursor
  • Radiopharmaceutical preparations
  • Kit for radiopharmaceutical preparation
  • Radionuclide generator
Storage - A radiopharmaceutical should be stored in a special area and kept in well-closed containers. When storing radiation, the dose rate should be kept below the maximum level that can be tolerated. Ionizing radiation protection should be done in accordance with national regulations. The contents of a radiopharmaceutical preparation intended for parenteral administration should be protected in a transparent glass vial, ampoule, or syringe that can be viewed visually. Under the influence of radiation, glass containers may darken.

Radio activity

Some types of matter emit energy and subatomic particles spontaneously because they are radioactive. In essence, it is one of the attributes of each atomic nucleus. An unstable nucleus can spontaneously decompose into one of several more stable configurations by emitting certain particles or emitting specific forms of electromagnetic energy. There are several elements that decay radioactively, as well as isotopes that are produced artificially. The half-life of a radioactive element expresses the rate at which it decays; i.e., the amount of time it takes to decay one-half of any given quantity of the element. For some nuclei, half-lives span over 1024 years. For others, half-lives are less than 10−23 seconds. Radiation-released daughter isotopes, the by-products of radioactive decay, can themselves be unstable, in which case they will also disintegrate. As long as no stable nuclide is produced, the process is complete.

Measurement of radioactivity

Physiologist Henry Becquerel discovered the spontaneous emission of radiation from uranium in 1896, so radioactivity is measured in disintegrations per second and in Becquerels (Bq). As mentioned above, radioisotope disintegration produces radiation that interacts with matter and transfers energy. A dose-dependent and type-dependent effect determines the magnitude and gravity of a radiation injury. For instance, a small dose of ultraviolet light from the Sun is harmless to humans, but a large amount can lead to sunburn. The gray is a unit of measurement for absorbed dose (1 Gy = 1 joule absorbed per kg of matter). A concept known as "equivalent dose" has been developed to measure the biological effects resulting from radiation. The effect can then be evaluated by comparing the damage caused by different types of ionising radiation at the same dose. Sieverts (Sv) are used in this instance as the unit of measurement. X-rays of the chest consume 0.14 millisieverts (mSv), while mammograms consume 1mSv.

Properties of alpha, beta, gamma radiations

Alpha radiations

Particles or rays from these sources have a low penetration power. Strong magnetic fields can detect them because they are positive charged particles. There is two positive charges in each particle. Each amu (atomic mass unit) weighs four grams. Such rays can be emitted by heavy metals. There is no difference in the power of alpha particles. Each alpha particle has the same energy. Alpha rays penetrate less deeply as compared to other sources of electromagnetic radiation. Alpha particles, which emit alpha rays but cannot penetrate tissue, have low penetrating power, therefore they do not find application in biological applications.

Beta radiations

There are two types of these:
  • 'positrons' are positively charged particles that are electrically charged
  • Furthermore, electrically negatively charged particles are referred to as "negatron."
In comparison to alpha rays, their penetration power is greater in beta radiations. Beta particle mass is very small. Gamma radiation is usually associated with these particles. Compared to alpha particles, beta particles are weaker ionizers.

Gamma radiations

In comparison with alpha and beta rays, these rays have been more penetrating power. The characteristic of ultrashort electromagnetic waves is similar to that of x-rays. These waves are massless and chargeless. Radiation and nuclear fission produce Gamma rays when radioactive substances disintegrate. There is no charge attached to them and their ionizing power is low.
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Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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