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

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

ALARA: As Low As Reasonably Achievable 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 Setting exposure factors Protecting ourselves and patients National Council on Radiation Protection & Measurements – Governmental body that sets standards for radiation safety ** “All ionizing radiation is harmful, and data is not available to indicate if there is a threshold below which no harmful effects will occur.” IRL: It’s easy to become lax Peer pressure Norms and habits in a clinic may not be optimal Not trying to scare you Want you to understand Respect the danger & importance of protection Same as chemo drugs, fractious cats, MRSA, etc ** From VTNE Prep Question

What are the dangers? Amounts potentially damaging but random Human body = 80% water Liquid is a conductor of electricity Radiation targets DNA Especially rapidly growing/dividing cells Most vulnerable Young people Unborn babies Some tissues/organs are more susceptible – Rapidly dividing cells of the intestinal lining, neoplastic cells, reproductive cells ** Radiation is nonselective – affects where it hits Radiation damage is random: Delivered intermittently Over long time Young patients live longer ** From VTNE Prep Question

Radiation targets DNA… 3 things can occur: No immediate effect - damage can show up later Cell is damaged – repairable or not Cell death Main concern is “latent” effects No recorded cases of death from diagnostic x-ray exposure Biggest risk to personnel: Stochastic (random probability) Malignancy Genetic effects DNA Genetic code for development and functioning of all known living organisms and many viruses. One of 3 major macromolecules essential for all known forms of life With proteins & RNA Double helix held together by hydrogen bonds Latent effects = ones you can’t see

Primary vs Secondary Radiation 2 causes of radiation danger: Primary – Direct exposure without protection Secondary – Scattered radiation: Photons still have energy after penetrating patient Produce radiation from atoms in the patient “Scattered” photons emitted from 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? Photons – Elementary particle of electromagnetic radiation Force carrier for the electromagnetic force What can increase the amount of scattered radiation? Failure to narrow the beam via collimation Using too high a kVp – nowhere for photons to go Failing to use a grid for animals over 10 cm Why is scattered radiation more of a danger? Uncontrolled Invisible rays Caused by unseen mechanism

Tissue Damage from Radiation Two types of tissue damage: Somatic – Occurring within the life of the individual Genetic – Occurring in future generations Organ systems most sensitive: Reproductive organs Hematopoietic cells Lymphocytes Thyroid gland Intestinal epithelium Lens of the eye Developing fetus Tissue damage: Somatic – Non-reproductive cells Radiation sickness Effects: Loss of hair Ulceration Fibrosis of the lungs Holes in tissue Lymphocytopenia – lower WBC’s Cataracts in the eyes Genetic – Future generations/reproduction Birth defects Organ systems most sensitive: Reproductive organs – infertility, decreased hormone production, mutations Hematopoietic cells/Lymphocytes Lowered resistance to infection Clotting disorders Thyroid gland – X-rays are causative agent, gland unprotected Intestinal epithelium Lens of the eye Developing fetus – 1st 9 days most dangerous for death 10 days-6 wks for organs

Radioactivity Radioactive disintegration or decay – The way an unstable atom achieves stability The nucleus spontaneously emits particles & energy and transforms into a form more stable Radionuclides – Atoms that are going through radioactive decay Isotopes – Variants of an atom that have differing numbers of neutrons Radioisotopes are radioactive

Radiation Intensity All radiation has the ability to penetrate tissue Linear energy transfer – The rate at which energy is transferred from ionizing radiation into soft tissue Higher LET: (Includes scattered radiation) Greater energy transferred per interaction Less ability to penetrate since energy decreases rapidly Increased potential damage because of amount of energy absorbed Lower LET: (Includes X-rays) Can travel easily through matter but deliver less radiation per intereraction Greater penetrability to tissue Fewer immediate effects on tissue

Legal Prohibitions: Exposure Prohibited from participating in radiographic procedures: Individuals under age 18 ** “Declared” pregnant women Our Radiation Safety Officer: Ms. Huff If any concerns or questions about x-ray exposure: Please let me or Ms. Huff know… Texas Department of State Health Services Radiation Safety Officer: Staff training Protection of employees, patient, and public Test equipment at least every 2 years Act as an advisor Monitoring dosage for personnel & patients X-ray signage Remember: If you are pregnant, or may be pregnant, see me ASAP! ** From VTNE Prep Question

Maximum Permissible Dose (MPD) Defined as: The dose the NRC has determined should not harm the person receiving it over their lifetime The maximum permissible dose for whole-body radiation per year that is allowed by law MPD = .05 sv/year ** or 5 rem/year ** Sievert (sv) = Unit of equivalent dosage (replaced rem) Dose equivalent = Quantity of radiation per unit of mass, taking into consideration the biologic effect on specific tissue types ** Dose of radiation equivalent to the absorbed dose in tissue ** 1 sv = 100 rem (Roentgen equivalent man) ** MPD – A quality factor to determine a dose A framework for a conversation Wilhelm Röntgen: German physicist who discovered x-rays and developed x-ray photography Won 1901 Nobel Prize. Higher for non-radiation workers because radiation workers wear PPE ** From VTNE Prep Question

MPD (cont.) Other radiation dosage units: ** Gray (gy) – Unit of absorbed dose Amount of radiation needed to deposit 1 joule of energy into 1 kg of matter Roentgen equivalent man (rem) – Traditional unit of equivalent dosage Replaced by Sv Radiation absorbed dose (rad) – outdated measurement ** 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 ** From VTNE Prep Question

ALARA ≠ MPD ALARA: As Low As Reasonably Achievable NOT a set number but a general guideline No set safe amount is known A universal principle “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 cardinal 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 Digital radiography exposes twice the amount of film radiography But fewer retakes ** From VTNE Prep Question

Pregnancy & Radiation Severity of response to the fetus is directly related to both dose and time Most critical time is 2nd to 10th week: period of organogenesis NO SAFE LIMIT HAS BEEN ESTABLISHED.

Minimizing Exposure: Time Reducing time is an important factor Use the shortest exposure time possible Use the fastest film-screen combination Proper darkroom practices Use a customized technique chart Digital radiography reduces repeats Collimate the beam down to the area of interest 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… ** From VTNE Prep Question

Personal Radiation Dosimeters Also called: “film badges” Three types: 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 ** From VTNE Prep Question

Dosimeters Thermoluscent dosimetry: Registers a charge over time if exposed to radiation Rules of usage: Must not be taken home Store away from radiation Store away from heat, sunlight Wear only at that site Attach outside thyroid collar Never wear on jacket or lab coat – Why? Must never be shared Do not leave in x-ray room ** Employed at more than one site: wear a different one at each Facility will post results periodically Most technicians average .04 rem per year vs 5rem MPD ** From VTNE Prep Question

Dosimetry Report Dosages reported in mrem (millirem’s) or 1/000 rem

Minimizing Exposure: Distance Determines the intensity of radiation at a given distance? Maximizing distance: Maximize distance from the source ** Lean/turn away from the beam Exit the room, if possible Sandbags or non-manual restraint Sedate where possible Inverse square law: The intensity of radiation is inversely proportional to the square of the distance of the object from the source Why matters? Farther = less intense but more spread out Maximizing distance: Turn or lean away Look away Not a social occasion Tape or wooden spoons to hold/move ** From VTNE Prep Question

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 ** What material is used in most shielding and why? Lead High atomic mass so shields most rays How might an apron or gloves not help you? Not properly maintained Cracks or creases Primary beam! Wearing PPE is not fun, but it is necessary The room has shielding, as well Must have appropriate signage ** From VTNE Prep Question

Personal Protective Equipment (PPE) Made of thin sheets of lead layered together The lead can crack and break without proper care Minimum safe lead thickness is 0.79 mm (book) VTNE Prep materials say 0.5mm ** Use & care of PPE: Hang aprons up by the shoulders No folding or creasing If cracks are present, they appear black when radiographed ** Clean regularly - warm water/mild soap Should fit correctly Treat thyroid collars with the same respect Rotate non-radiation workers Other helpful ways to reduce risk: Immobilization Foam blocks Cloth restraints Tie-downs Wooden spoons ** From VTNE Prep Question

Other Methods To Minimize Exposure Restrain using gear/equipment Lay gloves across quiet patient Wooden spoons, etc. Immobilize patient Cloth restraints & tie-downs Sedation Collimate carefully Avoid retakes! Against the rules – Cannot x-ray personnel

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