UNIT 6 Introduction to Radiation Protection Goal of Radiation Protection: To minimize exposure to the patient and the operator ALARA Concept

What is radiation? Radiation is a form of energy; “Electromagnetic radiation”. More specifically, it is a form of radiant energy. Ionizing radiation (IR) has the ability to cause chemical and biological changes through ionization.

Electromagnetic Spectrum These are the different types of electromagnetic radiation. Cosmic radiation has the most energy on the spectrum; Infrared has the least energy. The more energy the radiation has, the more its ability to penetrate matter.

Types of Radiation Type Charge Symbol Alpha (particulate)+2 charge Beta (particulate) -1 charge Gamma (e-m) no charge X-Ray (e-m) no charge X

Characteristics of X-Rays Invisible Highly penetrating Ability to ionize matter Travel in straight lines Travel at the speed of light in a vacuum Cause chemical and biological changes (due to ionization) Produce scattered/secondary radiation

Sources of Radiation Natural Background Radiation Manmade Radiation

3 Types of Natural Background Radiation Cosmic radiation from the sun & stars Terrestrial radiation from radioactive elements in the earth Internal radiation from inside the body

Manmade Radiation from... Medical and Dental X-Rays Nuclear Reactors Radioactive Fallout

Percent exposure to various types of ionizing radiation

Most radiosensitive organs Lens of the eyes Bone marrow Gonads Thyroid

Main Principles of Protection Time Distance Shielding

Devices/Methods to Reduce Operator Exposure Reduce time of exposure Don’t hold patients during exposure Get it right the first time! Reduce repeats!

Operator Protection Utilize Shielding Available Lead Aprons, Gloves, Thyroid Shields, Pb Goggles Stand behind Pb Control Booth during exposures

Operator Protection Distance yourself from the source of Radiation (ie. The tube or the patient) Distance yourself from the patient during exposures. Patient is the greatest source of scatter- (Fluoroscopy and Mobile) Distance yourself from the X-Ray Tube (source of x-rays) Wear personnel monitoring device correctly to develop and awareness of exposure you receive. (at the collar level & outside the Pb apron when one is worn)

Devices/Methods to Reduce Patient Exposure Use of Beam Limitation - Cones, Collimators, Diaphragms, PBL (Positive Beam Limitation) This reduces patient exposure and scattered radiation

Devices/Methods to Reduce Patient Exposure Use of Filtration - Al (Aluminum) filters protect patient skin exposure 2.5 mm Al filtration is required for equipment using 70 kVp or higher

Devices/Methods to Reduce Patient Exposure High KvP / Low mAs exposures are best for the patient. mAs is directly proportional to the amount of exposure the patient receives. Use of higher kVp increases penetration thus reduces absorption.

Patient Protection For conventional systems, use of high speed film/screen systems reduce the amount of exposure required. Reduce repeats ie: use short exposure times which eliminate motion (blurry pictures), Use immobilization devices to prevent patient movement. Use gonad shielding (when indicated) to reduce patient gonad dose.

Measurement of Radiation Traditional Unit SI Unit Definition Exposure in Air Roentgen “R” Coulombs/kG (C/kG) 1.08X109 ion pairs/cc Absorbed Dose Radiation Absorbed Dose “Rad” Gray (Gy) 100 ergs/gm Dose Equivalent Radiation Equivalent Man “Rem” Sievert (Sv) Rad x QF Radioactivity Curie (Ci) Becquerel (Bq) 3.7X1010dps

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