Radiation Safety Lavin: Chapter 16 CTVT: 566-570 Test Friday– Must pass with an 80% to be able to participate in labs

Learning Objectives: Chapter 16 Understand radiation risks Differentiate ALARA and maximum permissible dose Understand the use of personal exposure dosimeters List practical methods personnel can use to reduce exposure Describe and understand the importance of personal protective equipment (PPE)

Radiation Doses to Staff ALARA NOT a set number, but a general guideline The workplace program developed to ensure that radiation dosages are kept as low as possible Governs everything we do in lab Setting exposure factors Protecting ourselves and patients National Council on Radiation Protection & Measurements Governmental body that sets standards for radiation safety

What are the dangers? Concern is not high doses, it’s the diagnostic dose over time Human body = 80% water Liquid is a conductor of electricity Radiation targets DNA Especially rapidly growing/dividing cells Young people Unborn babies Certain tissues/organs are more susceptible

Radiation targets DNA… Radiation is nonselective – affects where it hits 3 things can occur: No immediate effect – latent effects Cell is damaged – repairable or not Cell death Main concern is “latent” effects No recorded cases of death from diagnostic x-ray exposure (today’s safety standards) Biggest risk to personnel: ___________ effects Malignancy Genetic effects

Two Causes of Radiation Danger 1. Primary – Direct exposure to the primary beam 2. Secondary (scattered radiation) Photons still have energy after penetrating patient Produce radiation from atoms in the patient *Most important impact on healthcare workers What can increase the amount of scattered radiation? Why is scattered radiation more of a danger than primary?

Tissue Damage from Radiation Two types of tissue damage: Somatic – Occurring within the life of the individual Genetic – Occurring in future generations (gene mutations) Organ systems most sensitive: Reproductive organs Hematopoietic cells Thyroid gland Intestinal epithelium Lens of the eye Developing fetus

Legal Prohibitions Prohibited from exposing radiographs: Individuals under age 18 Declared pregnant women Most critical time is first trimester: period of organogenesis No safe limit has been determined Concerns in clinic should be directed to your Radiation Safety Officer VTI = Ms. Huff *If you are pregnant, see me ASAP!

Maximum Permissible Dose (MPD) The dose the NCRP has determined should not harm the person receiving it over their lifetime The maximum permissible dose for occupational whole- body radiation/year that is allowed by law: MPD = 5 rem/year Sievert (sv) = the unit for dose equivalent Dose of radiation equivalent to the absorbed dose in tissue 1 sv = 100 rem

MPD (cont.) Other radiation dosage units: How much is too much? Gray (Gy) – Unit of absorbed dose Amount of radiation needed to deposit 1 joule of energy into 1 kg of matter How much is too much? No one really knows Dose limits for non-radiation workers > radiation workers Radiation worker: An individual who could be exposed to radiation from man-made sources during their work

ALARA ≠ MPD ALARA: As Low As Reasonably Achievable NOT a set number but a general guideline No set safe amount is known “Keep exposure as low as possible” MPD: Maximum Permissible Dose Amount of ionizing radiation a person may be exposed to supposedly without being harmed Is a set number Assumed to be safe, but no one knows for sure

Minimizing Exposure 3 rules of protection: Time – Minimize time spent near radiation sources Distance – Maximum practical distance from radiation source Shielding – Placing a shield between the subject and source

Minimizing Exposure: Time Reducing time is an important factor Use the shortest exposure time possible Use the fastest film-screen combination Use a customized technique chart Dosimeters must be worn by anyone working with or in the vicinity of an x-ray machine Measures radiation dose for one person in one location over time

Minimizing Exposure: Distance What determines the intensity of radiation at a given distance? Maximizing distance: Maximize distance from you to the primary beam Lean/turn head away from the beam Exit the room, if possible Sandbags or other mechanical restraint Sedate if needed

Minimizing Exposure: Shielding Positioning a barrier between you and the radiation source greatly reduces the level of radiation exposure. What you can do: Wear aprons, gloves, glasses, thyroid shield, etc. Wearing gloves provides no protection from primary x-ray beam!

Personal Protective Equipment (PPE) Made of thin sheets of lead layered together Minimum safe lead thickness is 0.79 mm VTNE Prep materials and old edition say 0.5 mm… Use & care of PPE: Hang aprons up by the shoulders No folding or creasing! Clean regularly - warm water/mild soap Should fit correctly and be tied tightly Shoulders AND waist Treat thyroid collars with the same respect Eye wear should be stored in protective case

Personal Radiation Dosimeters Whole body dosimeters Worn above the waist but below the head Monitors exposure of the thyroid and lenses of the eye Outside other protective equipment Extremity dosimeters Fetal dosimeters Worn in conjunction with other gear Worn on the belly under other equipment Film badge Thermoluminescent (TLD)

Dosimeters Thermoluminescent dosimetry: Registers a charge over time if exposed to radiation Rules of usage: Remain in radiology room at all times Store away from radiation Store away from heat, sunlight Must be worn EVERY time you are in the lab while exposure is happening Attach outside of thyroid collar