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Analytical X-Ray Safety Guide

Analytical X-Ray Safety Guide

Analytical X-Ray Safety Guide

77 Massachusetts Avenue, Cambridge, MA 02139 (617)-452-3477 [email protected] ehs.mit.edu Delegation of Authority Typical Cabinet X-Ray Device Area Monitoring and Safety Mechanisms • X-ray machines are assigned monitoring badges to verify MIT has a standing institute Committee on “X-Rays On” that radiation levels in the area of the equipment are not elevated. to oversee all uses of Indicator • are changed quarterly. radiation at the Institute and its associated Call RPP to request the results for a particular machine! off campus locations. They give the RPP authority to stop any experiment or process Conventional involving radiation that is deemed unsafe. Other, <0.1% Radiography Internal , 5% Leaded Glass (medical), 5% Consumer, 2% Viewing Windows Cosmic , 5% Administrative Controls Fluoroscopy Terrestrial (medical), 7% Nuclear Medicine (rock/soil), 3% • Area “Caution” postings (medical), 12% • Normal Operating Procedures approved Radon/Thoron, by RPP and device’s user manual are Interlocked CT (Medical), 37% available to the user Chamber Doors 24% • All users are registered with RPP Key Switch • Hands-on training with the equipment Man-made 50 % You receive about 1-2 Natural Occurring 50 % millirem per day due to Caution Labels Status Indicators: Source: Values from NCRP Report No. 160 background radiation Hazards Interlocks · Shutters ·

X-Ray Generation Living next to a <1 Cosmic Radiation 80 Main Hazard: Skin Burns mrem (Denver) mrem Exposure to the primary beam could result in plant a radiation burn, which can occur around Exposure Rates Example Eating 1 banana a 3.5 Radon in Avg. 228 200 rads. Symptoms may not be present day mrem Home mrem until well after the exposure. Itching, tingling, swelling, or redness at the site of exposure Terrestrial 21 Whole Body CT 1000

Radioactivity mrem (1-time) mrem may arise. Go to MIT Medical if a burn is suspected, Cosmic Radiation 30 Radiation Worker 5000 (sea-level) mrem Limit (Whole Body) mrem and inform RPP immediately of any exposure to the primary beam! • The main hazards associated with an X- ALARA Ray machine are from exposure to the primary beam, leakage radiation, and As Low As Reasonably Achievable = 100 scatter radiation. mrem • Very high exposure rates can be found 0 1 2 Annual radiation dose comparison. Data from epa.gov/radiation/radiation- just outside the collimator. sources-and-doses • All exposure rates outside the cabinet Minimize Maximize Use Plan ahead Inspired by xkcd.com/radiation Time Distance Shielding must be less than 2 mR/hr at 5 cm. X-Ray Registration Using the to Perform a Leakage Survey

While operating an X-Ray device, it is best practice to perform a survey of the area to ensure the dose rates around the 1. Contact RPP prior to ordering any X-Ray equipment. device are less than 2 mR/hr at 5 cm. 2. Fill out registration form and submit to RPP for • Check calibration date on detector • Scan the work area by holding detector face ~1 cm approval. • Check battery above surface moving slowly (about 5 cm/s). 3. RPP Officer will perform a hazard assessment and help • Check response using source on instrument. • Survey along door openings and operators station. write Normal Operating Procedures. • Measure the background exposure rate in an area • Notify RPP if exposure rate is greater than background. known to have no radiation.

Definitions Counts Per Milli- Per Minute (cpm) Hour (mR/hr) : The energy imparted per unit of material. Measured in , where 1 rad = 0.01 per of absorbing material. The SI Unit is the (Gy). Fast/Slow Note 1 Gy = 100 rad = 1 J/kg. Needle Response X-Rays: The electromagnetic radiation produced by the deceleration of a charged particle when Battery Test deflected by another charged particle, such as an electron Audio deflected by an atomic nucleus. On/Off Characteristic X-Rays: X-rays emitted from heavy Needle elements when their electrons make transitions between Reset the lower atomic energy levels. (Zero)

Dose Equivalent: The product of the absorbed dose and Battery Power & the appropriate quality factory for the type of radiation. Compartment Multiplier Measured in rem. The SI Unit is the (Sv). Switch Note 1 Sv = 100 rem. : A passive form of monitoring ionizing Geiger radiation, typically without a direct-reading capability. Muller Dosimeters may be assigned to and worn by personnel or (GM) posted in a lab to monitor area radiation levels. Survey along door Detector Exposure: A measure of the ionization produced in air by x-ray or gamma radiation. Measured in Roentgen (R), openings and seams where 1 R = 2.58 x 10-4 per kilogram of dry air at STP. Leakage Radiation: Radiation which penetrates (or “leaks”) through cracks, voids, holes or ill-fitting equipment, such as misaligned cabinet doors or seams between When to Contact RPP shielding panels. 9 Traits of a Positive Safety Culture Primary Beam: Radiation which passes through an aperture of the source housing by a direct path from the x- • Leakage radiation detected significantly above background 1. Leadership Safety 6. Environment for Raising ray tube or a located in the radiation Values and Actions Concerns source housing. • Suspected or possible exposure Radiation: Energy transmitted in the form of to the primary or scatter beam 2. Problem Identification 7. Effective Safety electromagnetic waves or subatomic particles. Communication • Prior to performing equipment 3. Personal Accountability modifications Survey Meter: A direct-reading instrument capable of 8. Respectful Work detecting (e.g. ). 4. Work Processes • Prior to performing any Environment X-Ray: An electromagnetic wave of high energy and very operations requiring bypassing of 5. Continuous Learning short wavelength with a high penetration ability and the interlocks (or beyond Normal 9. Questioning Attitude capability to ionize atoms (called “ionizing radiation”). Operating Procedure’s scope) Rev 2.0 06/11/2020

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