3/7/2016Chapter N*31 Radiation Measurement Terminology: – Exposure rate = amount of radiation possible to receive per unit time. – Dose = total amount of radiation received. Terminology: – Exposure rate = amount of radiation possible to receive per unit time. – Dose = total amount of radiation received.

3/7/2016Chapter N*32 Radiation Exposure, Dose and Quantity Exposure is an index of the ability of a radiation field to ionize air. Dose is a measure of the energy imparted to matter, per unit mass, when an ionizing radiation field interacts with matter. OR: (The amount of energy deposited per unit mass) Quantity of radioactive material is expressed as “activity”, the number of nuclear disintegrations that occur in a sample per second.

3/7/2016Chapter N*33 Units of Exposure and Quantity Roentgen (R) Curie (Ci)Becquerel (Bq) 2.58 x coulombs / kg dry air at STP Disintegrations per second in 1 gm radium (3.7 x dps) Systeme Internationale unit: one dps

3/7/2016Chapter N*34 Roentgen Pronounced rent’gen with a hard “g” Limitations – only applies to photons – only applies in air – only applies to energies less than 3 MeV l Named after Wilhelm C. Roentgen (thus the abbr... is capital “R”)

3/7/2016Chapter N*35 Curie (Ci) Radiation hazard does not solely depend on the activity. It also depends on the type of decay (alpha, beta, photon, etc.) l Named in honor of Pierre Curie

3/7/2016Chapter N*36 Units of Absorbed Dose rad Gray (Gy) radiation absorbed dose (100 erg/gm) S.I. unit: 1.0 J/kg (100 rads)

3/7/2016Chapter N*37 Concept of Equivalent Dose For the same absorbed dose (deposited energy), different forms of ionizing radiation can have different biological effects. “Equivalent Dose” attempts to normalize these differences.

3/7/2016Chapter N*38 Equivalent Dose Equivalent Dose is the product of the dose and a modifying factor called the quality factor (QF), which reflects the relative biological effectiveness of the radiation: H T = D x QF

3/7/2016Chapter N*39 Quality Factors (QF) QF are indices of the “relative biological effectiveness” (RBE) of a radiation. RBE is a complicated function of type of radiation, energy and the biological system under consideration. QF are not measured. They are determined by a committee.

3/7/2016Chapter N*310 Quality Factors (QF) RadiationQuality Factor Photons, electrons, betas, X-ray 1 Thermal Neutrons5 Alphas, Fast neutrons, Protons 20

3/7/2016Chapter N*311 Effective Dose Equivalent Effective Dose Equivalent (EDE) is intended to reflect the total biological effect of a given exposure on a human. It is a weighted average of the individual doses to a number of important tissues: H E =  (H T x W T ) (sum is over all tissues)

3/7/2016Chapter N*312 Effective Dose Equivalent EDE is a concept, not a measurable quantity. Applies to situation where irradiation of organs and tissues is non-uniform. EDE yields the same “radiation detriment” as a numerically-equivalent whole-body dose. W T values are assigned by a committee.

3/7/2016Chapter N*313 Units of Equivalent Dose and EDE roentgen equivalent man (rad x quality factor) S.I. unit: Gy x quality factor Rem (rem) Sievert (Sv)

3/7/2016Chapter N*314 rem Dose in health record is in units of rem 1 rem = 1 Roentgen l Roentgen Equivalent Man

3/7/2016Chapter N*315 Quality Factor (Q) X-rays, gamma rays, & beta particles 1 – Neutrons & High energy protons 10 – Alpha Particles 20

3/7/2016Chapter N*316 SI Radiation Protection Units Becquerel (Bq) for Curie – 1 Ci = 3.7 x Bq Gray (Gy) for rad – 1 Gy = 100 rad Sievert (Sv) for rem – 1 Sv = 100 rem

3/7/2016Chapter N*317 Unit Analysis BASE UNIT CONVERSION TABLE Unit Unit Conversion 1 Bq 2.7 x Ci 1 Ci3.7 x Bq 1 Bq1 dis/sec 1 dis/sec2.7 x Ci 1 Ci3.7 x dis/sec

3/7/2016Chapter N*318 Unit Analysis (Con’t.) BASE UNIT CONVERSION TABLE Unit Unit Conversion 1 rem 0.01 Sv 1 Sv 100 rem 1 rad 0.01 Gy 1 Gy 100 rad 1 R 2.58 x C/kg 1 meter 3.28 ft (39.37in)

3/7/2016Chapter N*319 Old Terms Roentgen- Based on the quantity of electrical charges produced in air by X or Gamma photons 1R=2 billion pr RAD- Radiation Absorbed Dose is the work energy resulting from the absorption of one ROENTGEN or 6.24 E5 Mev

3/7/2016Chapter N*320 More Old Terms REM- Roentgen Equivalent Mammal is equal to the absorbed does in RADS multiplied by a quality factor Quality Factors Beta = 1 Gamma & X ray photons = 1 Alpha = 10 Neutrons = 20

3/7/2016Chapter N*321 New Terms sort of International Units have replaced the RAD and REM GRAY (Gy) = 100 RAD SIEVERT (Sv) = 100 REM Same Quality Factors apply to the Sv

3/7/2016Chapter N*322 Units of Radioactivity Curie (Ci) = 2.22 E12 dpm or 3.7E10 dps Becquerel (Bq) = 1 dps (Annual) Maximum Dose/year = 5 REM or 50 mSv Maximum Dose/year for Declared Pregnant Woman & Minors= 0.5 REM or 5 mSv

3/7/2016Chapter N*323 Half Life Calculation

3/7/2016Chapter N*324 Dose Response Relationships rem—No or minimal symptoms rem—Moderate to severe illness rem—Severe illness deaths start above 500 rem Above 800 rem—Fatal ***Acute whole body doses

3/7/2016Chapter N*325 Genetically Significant Dose Is an index of potential genetic damage to a population due to the irradiation of some members of the population. Is based on dose to the gonads and chances of reproduction. Is about 30 – 40 millirem per year in the U.S. No epidemiological evidence for genetic effects in humans.

3/7/2016Chapter N*326 Sources of Ionizing Radiation Cosmic rays and naturally-occurring radioactive elements Medical X-rays and nuclear medicine studies Manmade radioactive materials and radiation sources

3/7/2016Chapter N*327 Your Annual Exposure ActivityTypical Dose Smoking280 millirem/year Radioactive materials use in a UM lab <10 millirem/year Dental x-ray 10 millirem per x- ray Chest x-ray 8 millirem per x- ray Drinking water 5 millirem/year Cross country round trip by air 5 millirem per trip Coal Burning power plant millirem/year

3/7/2016Chapter N*328 Estimated Exposure To The National Population Between 320 – 360 mr/yr

3/7/2016Chapter N*329 Sources of Radiation Natural Sources – Cosmic Radiation Effects of Altitude –0.2 mSv/yr at sea level –1 mSv/yr at 10,000 ft – Terrestrial Sources Uranium & Thorium and their daughter products. – Radioactivity within the body Potassium 40 (Half-Life 1.3 x 10 9 years: 0.2 mSv/yr) Dependant on location, diet, and habits of the person.

3/7/2016Chapter N*330 Some Exposure Limits 2 mr/hr Dose rate to public 500 mr Emergency responder limit 5 r/yr Occupational 5 r/hr Turn back value 10 r Property 25 r Life saving >25r Volunteers only 2 mr/hr Dose rate to public 500 mr Emergency responder limit 5 r/yr Occupational 5 r/hr Turn back value 10 r Property 25 r Life saving >25r Volunteers only

3/7/2016Chapter N*331 Spill Response On Skin—flush completely On Clothing—remove If Injury—administer first aid Radioactive Gas Release—vacate area, shut off fans, post warning Monitor all persons and define the area of contamination

3/7/2016Chapter N*332 ALARA As Low As Reasonably Achievable—means making every reasonable effort to maintain exposures to radiation as far below the dose limits as is practicable consistent with the purpose for which the licensed activity is undertaken, taking into account the state of technology, the economics of improvements in relation to the state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations, and in relation to utilization of nuclear energy and licensed materials in the public interest.

3/7/2016Chapter N*333 Radiation Protection Decrease Time Increase Distance Increase Shielding

3/7/2016Chapter N*334 Time Minimize time spent near radiation sources Radiation Protection Reducing Radiation Exposure Distance Maintain maximal practical distance from radiation source Shielding Place radioactive sources in a lead container

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3/7/2016Chapter N*338 The radiated energy can be considered to be spread over a sphere of area 4  r 2 at any distance r from the source. Since the radiation intensity is equal to the energy per unit area : If the radiation intensity is I 0 at a distance r 0 from the source, the intensity I at any other distance r will be given by : Since the radiation dose is proportional to the intensity, the dose D can be calculated by the same type of relationship :

3/7/2016Chapter N*339 Example 1 If a nurse received a radiation dose of 100 millirems(0.1rem) by spending one hour at a distance of 2ft from a radioactive implant in a patient, how much would she have received at a distance of 4ft? At a distance of 20ft? ( 1 ft=30.48cm) Example 2 If a patient has received 100 millicuries of cobalt-60 as a therapeutic measure, the dose received by an attendant at a distance of one foot from the patient might be on the order of 200 millirems per hour. How long could the attendant spent at this distance in a week’s time? How long could he spent at 2ft? At 10 ft?

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3/7/2016Chapter N*341

3/7/2016Chapter N*342 Detecting and Measuring Radiation Instruments – Locate contamination - GM Survey Meter (Geiger counter) – Measure exposure rate - Ion Chamber Personal Dosimeters - measure doses to staff – Radiation Badge - Film/TLD – Self reading dosimeter (analog & digital)

3/7/2016Chapter N*343