Radiation is energy that comes from a source and travels through space at the speed of light. It can be described as waves or particles and has an electric and a magnetic field associated with it. There are two main types of radiation: ionizing and non-ionizing. Ionizing radiation, such as X-rays and gamma rays, has enough energy to remove electrons from atoms, posing a health risk by damaging tissue and DNA. Non-ionizing radiation, like visible light and radio waves, does not have enough energy to remove electrons from atoms. Radiation can come from unstable atoms undergoing radioactive decay or be produced by machines. It is important in various applications, including medical procedures and energy production [1][2][3][4][5].
Key Radiation Safety Facts
The key facts about radiation safety include the three basic protective measures: time, distance, and shielding. These principles are aimed at lowering radiation exposure risks. The guiding principle of radiation safety is “ALARA,” which stands for “as low as reasonably achievable.” This principle emphasizes minimizing the time spent near a radiation source, maximizing the distance from the source, and using shielding to reduce exposure. Additionally, there are dose limits for radiation workers and the general public, with the dose limit for a member of the general public being 100 mrem per year, not including exposure to natural background radiation[16][17][18].
The three basic principles of radiation protection are justification, optimization, and dose limitation. “ALARA” is a key principle that emphasizes minimizing radiation exposure as much as possible. Any amount of radiation exposure increases the risk of developing malignancy, and the duration of exposure, distance from the source, and physical shielding are crucial in reducing exposure[20].
It is important to note that the higher the radiation dose, the greater the chance of developing cancer, and cancers caused by radiation do not appear until years after the radiation exposure[19].
Radiation Safety Courses
Radiation safety is a crucial concern for patients, physicians, and staff in various medical fields, such as radiology, interventional cardiology, and surgery[12]. Several resources and programs are available to ensure radiation safety and provide comprehensive overviews of all aspects of radiation safety:
1. SNMMI’s Radiation Safety+ Review and Essentials: This 7.75-hour program covers topics such as CT, X-ray, fluoroscopy, MRI, optimizing radiation exposure, and more. It includes 90 CE questions for the five modules and a “Mock Exam” of 100 questions to better prepare for the exam[11].
2. NCB’s Radiation Safety Exam: Unlike the CT exam, there are no specific didactic requirements for those sitting for this exam. The program is designed for nuclear medicine technologists but is invaluable for anyone wanting an update in radiation safety[13].
3. UNC-Chapel Hill Radiation Safety Review Course: This course is designed for those who have had experience working with radioactive materials and serves as a reminder of radiation safety concepts and radiation safety policies and procedures[14].
4. Human Research Radiation Safety: Any human research protocol involving the administration of ionizing radiation to subjects must be reviewed by the appropriate Radiation Safety Committee (RSC). The protocols must include written Clinical Protocols and Dosimetry Reports[15].
These resources and programs aim to ensure that healthcare professionals and researchers have a thorough understanding of radiation safety and can apply this knowledge in their practice to minimize radiation exposure and risks.
Radiation Review Facts
- We are, like all matter, composed of atoms.
- All atoms have a core of neutrons and protons surrounded by a cloud of one or more electrons.
- The nucleus (neutrons and protons) of some atoms is unstable.
- Unstable atomic nuclei decay (break apart) at random times, releasing energy in the process.
- Half-life is the time for half of the amount of a radioactive substance to decay.
- When atomic nuclei decay, they can release different types of particles as radiation.
- An ion is an atom with a positive or negative charge due to the number of negatively charged electrons compared to positively charged protons in the nucleus.
- Ionizing radiation is radiation, traveling as a particle or electromagnetic wave, with sufficient energy to detach electrons from atoms or molecules, thereby ionizing them, that is, turning them into ions.
- Ionizing radiation emitted from atomic decay can cause chain reactions of further breakdowns.
- One “becquerel” is the activity of a radioactive material which has one nucleus decay per second, or 1 count per second (CPS).
- One petabecquerel (Pbq) is a unit of measurement of radioactivity equal to a quadrillion becquerels or 1×10^15 or 1,000,000,000,000,000 decays per second.
- One Pbq = 16.666 trillion (16,666,666,666,666.666…) counts per minute.
- Becquerels measure activity but does not tell if the activity is an alpha particle, a beta particle or a gamma photon.
- There are different types of radiation emitted and some do more damage than others.
- The number of protons and neutrons in an atom determine what the atom is and how it behaves.
- The number of electrons an atom has determines how it reacts (binds or repels other atoms).
- An atom that is an ion reacts differently than a neutral atom.
- Alpha particles (also called alpha rays) are emitted clusters of 2 protons and 2 neutrons.
- Alpha particles are highly ionizing; they make ions by causing atoms to gain or lose electrons.
- In passing through matter, charged particles lose energy until their energy is near zero.
- Beta particles have a range of energies from soft betas around 300keV to hard betas 2 MeV
- Beta radiation is stopped by around 1 meter to 9 meters (29.5 feet) of air.
- A photon is a packet of electromagnetic radiation which acts as both a wave and a particle.
- The higher the photon’s frequency, the higher its energy.
- Photons with a certain narrow range of frequencies are seen by us as visible light.
- Photons make up radio waves, microwaves, visible light, x-rays and gamma rays.
- X-rays with high photon energies above 5–10 keV, are called hard X-rays.
- X-rays with lower energy (and longer wavelength) are called soft X-rays.
- X-ray photons carry enough energy to ionize atoms and disrupt molecular bonds.
- X-rays are a carcinogen according to authoritative sources.
- There is no consensus for a definition distinguishing between X-rays and gamma rays.
- Gamma radiation is often used to kill living organisms, in a process called irradiation.
- Gamma rays travel in a straight line at the speed of light and they interact with electrons.
- 35 m (114.8 feet) of air is needed to half the intensity of a 100 keV gamma ray beam.
- A special camera released by Hamamatsu Photonics in 2013 can see Gamma ray areas.
Radiation Safety Review
- The higher the ionizing effect, the greater the damage will be to living tissue.
- Radioactive alpha decay can be stopped by a few centimeters of air, or by the skin.
- A stopped alpha particle absorbs 2 electrons from its surroundings to become a Helium atom.
- DNA is made of atoms and like all other matter made of atoms, can be broken by ionizing radiation.
- Broken DNA is repaired, discarded or ignored.
- Changed DNA which is not fixed or discarded may cause cells to divide out of control, resulting in cancer.
- Beta radiation is less ionizing than alpha, but is more 100 times more penetrating.
- Beta radiation can be mostly stopped by a few millimeters of aluminum.
- Beta radiation while being stopped generates secondary more penetrating gamma rays
- Beta particles moderately penetrate living tissue and can cause spontaneous mutation in DNA.
Citations:
[1] https://www.snmmi.org/Education/Content.aspx?ItemNumber=25332
[2] https://www.asnc.org/radiation_safety
[3] https://www.ncbi.nlm.nih.gov/books/NBK557499/
[4] https://ehs.unc.edu/training/self-study/radiation-safety-review-course/
[5] https://research.weill.cornell.edu/compliance/human-subjects-research/radiation-safety-committee-rsc/human-research-radiation-safety
[6] https://www.cdc.gov/nceh/radiation/what_is.html
[7] https://www.iaea.org/newscenter/news/what-is-radiation
[8] https://www.nrc.gov/about-nrc/radiation/health-effects/radiation-basics.html
[9] https://en.wikipedia.org/wiki/Radiation
[10] https://www.epa.gov/radiation/radiation-basics
[11] https://www.snmmi.org/Education/Content.aspx?ItemNumber=25332
[12] https://www.ncbi.nlm.nih.gov/books/NBK557499/
[13] https://www.asnc.org/radiation_safety
[14] https://ehs.unc.edu/training/self-study/radiation-safety-review-course/
[15] https://research.weill.cornell.edu/compliance/human-subjects-research/radiation-safety-committee-rsc/human-research-radiation-safety
[16] https://safetyculture.com/topics/radiation-safety/
[17] https://ehs.virginia.edu/Radiation-Safety-Facts.html
[18] https://www.cdc.gov/nceh/radiation/safety.html
[19] https://www.epa.gov/sites/default/files/2015-05/documents/402-k-10-008.pdf
[20] https://www.ncbi.nlm.nih.gov/books/NBK557499/
