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X ray laser safety training blackboard version 2021 - medical students
- 1. 1 Radiation Safety In-service for Operating Suites Presented by: Environmental Health and Safety Radiation Safety
- 2. 2 "Life on earth has developed with an ever present background of radiation. It is not something new, invented by the wit of man: radiation has always been there."
- 3. 3 Definitions Radioactivity: a natural and spontaneous process by which unstable radioactive atoms decay to a different state and emit excess energy in the form of radiation
- 4. Definitions Exposure – is related to the amount of energy transferred from an X-Ray field to a unit mass of air Absorbed Dose – absorbed energy per unit mass of tissue 4
- 5. Definitions Equivalent Dose – is a radiation weighted dose quantity which takes into account the type of ionizing radiation producing the dose. 5
- 6. Definitions 6 Ci or Bq Activity (RAM) Exposure (air) Absorbed Dose (tissue) C/kg or mR Rad or Gy
- 7. 7 Ionizing Radiation Ionization: The removal of electrons from the atom Ionizing Radiation: Particles or electromagnetic waves with sufficient energy to remove electrons from atoms
- 8. Ionizing Radiation Ionizing radiation can ionize atoms and molecules, possibly altering structure and function. The ionized atom causes changes which MAY damage cells, which MAY cause health effects. 8
- 9. Types of Ionizing Radiation High Energy Radiation – Electromagnetic Waves: Gamma rays X-rays UV – Particles alpha beta neutron 9
- 10. Sources of Ionizing Radiation Radioactive Materials – Unsealed Sources (contamination risk) – Sealed Sources (reduced contamination risk) Irradiators 10
- 11. Radiological Contamination External contamination occurs when particles come in contact with the skin (generally a liquid or solid) 11
- 12. Sources of Ionizing Radiation Imaging Machines – X-Ray – Fluoroscopy – CT Linear Accelerators 12
- 13. 13 Non-Ionizing Radiation Non-Ionizing Radiation: Radiation that does not have sufficient energy to dislodge orbital electrons – Excites electrons
- 14. Sources of Non-Ionizing Radiation Low Energy – Lasers – Radio Frequency – Microwaves 14
- 15. Whole Body Effects Acute (Early) – Evident hours to a few months after exposure. Late (Delayed) – Exhibit themselves over years after acute exposure. Somatic Genetic Teratogenic 15
- 16. 16 Radiation Exposure There are two ways to be exposed to a radiation source. Both are of equal concern External Internal
- 17. 17 Routes of Internal Exposure (Radioactive Material) Radiation can enter the body in four ways Ingestion Inhalation Absorption Injection
- 18. Routes of External Exposure (Imaging Machines) Primary – Collimated Scatter – Patient – Table Leakage – Tube Head 18
- 19. 19 Personnel ALARA Techniques (As Low As Reasonably Achievable) Time Distance Shielding Control Methods – Administrative – Engineering
- 20. 20 Time The longer the exposure the greater the dose Greater dose leads to a greater amount of potential damage
- 21. 21 Distance 1 Meter 2 Meters 400 mR/hr 100 mR/hr The closer you are to a source of radiation the greater the exposure. By doubling distance exposure decreases by a factor of 4.
- 22. 22 Shielding Shielding – any material between you and the source of radiation – Alpha particles (α) stopped by paper – Beta particles (β) stopped by wood or Plexiglas – Gamma (γ) and X-rays (X) stopped by lead or concrete – Neutrons (η) absorbed by hydrogen-rich materials
- 23. Patient ALARA Techniques Time - can be reduced by the radiographer through decreasing repeat images and decreasing fluoroscopy X-ray beam time. Distance - making sure that examinations are being performed at a proper source to image distance (SID). 23
- 24. Patient ALARA Techniques Shielding - should be used whenever it will not compromise the image by covering the anatomy not being imaged. 24
- 25. Personnel Monitoring Personnel requiring dosimetry – Radiology personnel operating x-ray producing machines – Radiation Oncology personnel – Those likely to exceed 10% of annual limits – Those working in “Caution Radiation Area” – Personnel working with beta emitters with energies greater than 1 MeV or gamma emitters in quantities exceeding 5 mCi. 25
- 26. Annual Dose Limits for Radiation Workers Whole body limit - 5,000 mrem – Equal to about 500 Chest X-Rays – 50,000 - 100,000 mrem is when we would expect to start to see observable effects Lens of the eye limit - 15,000 mrem Extremities (Skin) limit - 50,000 mrem 26
- 27. Pregnant Female Worker Declare pregnancy in writing to Radiation Safety Pregnancy Consult – Issued a fetal dosimeter (Baby Badge) Fetus/Embryo exposure is monitored Occupational permissible dose, 500 mrem for the gestational period Un-declare in writing to Radiation Safety 27
- 28. Quality Assurance Annual QA/QC, Licensed Medical Physicist – Scatter radiation levels – Collimation – Radiation Output – kVp, mA, timer accuracy Lead aprons are checked annually for tears, holes 28
- 29. Laser Safety LASER – Light Amplification by the Stimulated Emission of Radiation Visible – 400 to 700 nanometers Invisible – Infrared and Ultraviolet 29
- 30. Laser Safety Personal Protective Equipment (PPE) – Eyewear (Goggles) with proper optical density (OD) for the wavelength employed Specular reflective surfaces must be covered. 30
- 31. Laser Hazards Eye Damage: retina, cornea, lens Skin Damage: burns Non-laser hazards: flammable, electrical, chemical, biological 31
- 32. UTMB Laser Use Permit, Laser Registration and Training Laser Use Permit required for Research protocols involving lasers Lasers requiring registration – Class III b & Class IV designation Laser Safety Training for the Users – Annual Online Training 32
- 33. Radiation Safety Program Info Materials Management Bldg. 1302 Mechanic St., – Suite 2.112 Ext. 2-2279 Rt. 1111 Fax Ext. 2-8921 33
- 34. 34 The End
Editor's Notes
- Although people often can experience fear when discussing exposure to radiation, the reality is that we are exposed to radiation all the time. Our species has evolved in an environment where we are constantly being bombarded by ionizing radiation. Although radiation needs to be respected, there is no need for irrational fear of radiation.
- Granite countertops – Uranium, Thorium, If present, uranium, thorium or radium will decay into radon, a colorless, odorless, radioactive gas Smoke detectors Americium 241 - Alpha particles from the americium source ionize air molecules, allowing positive and negative ions to flow between charged plates in the smoke detector. The smoke alarm triggers when smoke particles disrupt the constant flow of ions. Some procedures in the OR involve injection of radioactive material into a patient; this radioactive material injected into the patient demonstrates radioactivity.
- Exposure – is related to the amount of energy transferred from an X-Ray field to a unit mass of air Classical - Roentgen SI - Coulombs/kg By being in an OR where x-rays or radioactive material are being used, you are receiving exposure to radiation. Absorbed Dose – absorbed energy per unit mass of tissue Classical – Rad (100 erg/g) SI – Gray (Joule/kg)
- Equivalent dose is what our regulations require us to monitor; it considers the form of radiation you are exposed to, as well as the relative biological effectiveness of that radiation. Classical - Rem SI - Sievert
- How much radioactivity we have with radioactive material is measured not in typical units of mass (kg, lbs) but instead with measures of activity (curies [Ci] or becquerels [Bq]).
- We are concerned with trying to keep exposure to ionizing radiation as low as reasonably achievable (ALARA) so as to avoid any health effects caused by this damage.
- Forms of ionizing radiation can be described as being either an electromagnetic wave or as a particle. In the OR environment, the form of ionizing radiation of greatest concern is x-ray radiation, which is an electromagnetic wave.
- There are many forms of ionizing radiation exposure on the UTMB campus. Some of these you may experience in the OR Environment.
- Radiological contamination is only a risk if you are involved in procedures involving unsealed radioactive material. X-ray producing devices do not contain radioactive material, and therefore, there is no risk of radiological contamination. Some procedures, like Y-90 therapies, involve radioactive material that can be accidentally released and cause contamination to personnel or property.
- X-ray producing devices are used frequently in the OR environment. These devices generate x-rays that are then used to diagnose or treat a medical condition. They do not contain any radioactive material, and only emit radiation when they are turned on and the exposure pedal/switch is activated. Just like a light switch, if it is turned off, there is nothing being emitted. Procedures involving imaging machines, especially fluoroscopy, can be complex and can require extensive use of radiation (sometimes hours of fluoro time), which can create potential for patient or employee over-exposure.
- You are also exposed to non-ionizing radiation in the OR. Non-ionizing radiation does not have enough energy to be able to remove an electron from around the atom.
- In the OR environment, the type of non-ionizing radiation you are most likely to be exposed to is laser radiation, as lasers are used in many different types of medical procedures.
- Health effects from exposure to ionizing radiation can be described as being acute effects and late effects. Acute - Non Stochastic (threshold dose); these types of health effects have a known threshold of dose beyond which you will experience the health effect, and below which you will not. As you continue to increase the dose, the severity of the health effect increases. Examples of acute health effects include hair loss, skin reddening, and desquamation of the skin. Late - Stochastic (no threshold); these types of health effects do not have a known threshold of dose; any increase in dose is associated with increased probability of experience this health effect. An example of a late health effect is radiation-induced cancer. All of our radiation safety principles are intended to entirely prevent acute health effects, and to minimize the probability of the stochastic health effects. Somatic – limited to exposed individual Genetic – not to irradiated individuals but immediate or remote offspring Teratogenic – effects to developing fetus, between 2 and 15 weeks, actual threshold dose for no effects not known but thought to be in the range from 5-15 rad Abdominal radiograph 0.25 rad Barium enema 0.8 rad CT pelvis 1-10 rads 1 rad = 1cGy = 10mGy
- Scatter is the primary route of external exposure.
- Spend less time around the x-ray machine, or avoid the “lead foot” and minimize exposure time for the x-ray machine (best for both the patient and for you).
- Doing something as simple as stepping back a couple of feet can significantly reduce your dose.
- In the OR environment, lead aprons are going to be the primary source of shielding used. For any procedure in the OR with fluoroscopy, you should be wearing a full apron with thyroid shield, or a vest/skirt with thyroid shield (all with a minimum lead equivalency of 0.35 mm).
- These are maximum limits; anyone who exceeds one of these limits is to be reassigned to work that doesn’t involve exposure to radiation for the rest of the calendar year.
- In order to make sure that the x-ray equipment is functioning correctly, it is tested on an annual basis by a licensed medical physicist. This testing covers several different aspects of the equipment’s operation. In addition, lead aprons are inspected each year. Before you pick up your lead apron, do a quick visual check and make sure it has been tagged as inspected.
- Lasers are used extensively in the Operating Room and can create significant risk of injury for healthcare workers if not appropriately protected.
- You must make sure that the laser eyewear being worn is of the appropriate wavelength and has the minimum required optical density for use with that specific laser. If you aren’t sure, contact Radiation Safety. One of the major hazards with lasers is the potential for specular reflections (reflections off of a mirror-like surface) redirecting the beam into someone’s eyes.