Have the same Z (protons) Isotopes have the same A (atomic mass) Isobars have the same neutrons Isotones Electron volt (eV) Kinetic energy acquired by an electron accelerated through potential difference of 1 volt Electron charge (e) Quantity of charge possessed by electron e= 1.602x10-19 coulombs wave theory and value or c c=λf  c=speed of light in a vacuum 3E+8 m/sec particle theory and value for h E=hf h=6.626e-34 Planck's constant Energy in Joules what is 1eV in joules 1.602E-19 Joules where does X-rays come from? electron where does gamma rays come from? from nucleus What are the characteristics of neutron radiation? Have high energy (several Mev) Long range due to lack of charge High H content materials for shielding Internal and external hazard. can make something radioactive Discovered uranium to be weakly radioactive? Becquerel what is Stopping power S average linear energy lost by a charged particle per unit distance of travel depends on: particle energy absorber z absorber density These have high LET alpha and neutrons these have low LET beta, gamma, X-rays Which beta undergoes annihilation? produces 2 .511 Mev photons at 180 degrees Beta Positron Unit for density of thickness of material mg/cm2 Fast/ high energy neutrons are: > 1MeV Slow /thermal or low energy neutrons < 10eV Coherent scattering photon energy <= 15-30 keV around 10kev Compton effect is higher for. for hydrogen (water) Pair production threshold energy 1.022 MeV Triplet production threshold energy 2.044 MeV Photodisintegration threshold photon energy >7 Mev HVL = 0.693/mu (cm-1) 1 Ci= in DPM 2.22E12 DPM 1 Ci in Bq 3.7E10 Bq Activity Equation A=Ae^-(.693t/T1/2) Equation to look for the number of radioactive atoms? Ai=0.693/T1/2X N1 1R = in C/Kg 2.58 E-4 C/Kg Estimation of gamma exposure X=6CEn/D2 C=activity in CI Distance in FEET Exposure rate using gamma constant x=r (Q/D2) distance in CM 1 foot = cm 30.48 cm ICRP exposure standard for SKIN 50 rem/yr ICRP exposure standard for EXTREMITIES 50 REM/YR ICRP exposure standard for MINORS 10% OF ANNUAL LIMITS ICRP exposure standard for EMBRYO/FETUS 500 MREM IN GESTATION PERIOD ICRP exposure standard for GENERAL PUBLIC 100 MREM/YR Gas Filled Detector Curve 6 regions 1-Recombination region 2-Ionization region 3-Proportional region 4-Limited Proportional region 5-Geiger-Mueller region 6-Continuous Discharge region Radiation in a mammogram exam? .13 mSv What is the Annual Limit on Intake? ALI 20mSv What is the assumed radiation risk for workers? .04 Sv-1 for fatal cancer .008 Sv-1 for non fatal cancer and severe genetic effects what is the assume radiation risk for members of the public? .05 Sv-1 for fatal cancer .01 Sv-1 for non fatal cancer .013 Sv-1 for severe genetic effects what are the public dose limits? 1mSv /year  based on stochastic effects 15 mSv/year to lens of the eye 50 mSv/year to skin, hands, and feet 2 mSv to the women's abdomen once pregnancy has been declared. Based on deterministic effects What is the total average annual population exposure worldwide due to low LET radiation? .9 mSv Recombination Region low applied voltage < 50V Ionization chamber region increase applied voltage 200-300 V Advantages of Ion chambers -can measure low exposures (microR/hr)(natural background) -Reasonably flat energy response -Good for beta, gamma, and x-rays -No dead time concerns Ion chambers Disadvantages -sensitivity depends on volume -can be slow, erratic -non-unifor exposure leads to under estimate of dose -environmental effects Proportional region 3 applied voltage further increases: >500 V Advantages of proportional counters -measure energies of incident radiations -useful in mixed fields Disadvantages proportional counters dead time (0.5 to 10 micro se) voltage fluctuations requires gas supply heavy and expensive Region of limited proportionality as applied voltage increases: gas multiplication factor changes. Geiger-Muller region treshhold voltage: 900-1000 V Advantages of GM counters -High sensitivity -fast response time -simple design, low cost Disadvantages of GM counters -Low dead time (100 to 300 micros) -strong energy dependence (over responds at low energies) -Saturation Continuous discharge Voltages above GM region are not used what is scintillation? absorption of photon energy by substance and re-emission as visible light scintillation prompt? Photoluminescence <10^-8 sec Scintillation delayed? Phosphorescence (delayed) ei TL and OSL 3 types of scintillation detectors Solid scintillaiton Portable counters Liquid scintillation Advantages of solid scintillation high sensitivity for gamma high efficiency Disadvantages of solid scintillation expensive and fragile advantages of portable counters high sensitivity for beta and gamma flat energy response if tissue equivalent (mcrorem meter) disadvantages of portable counters expensive high background advantages for liquid scintillation high sensitivity for beta best method for low energy beta disadvantages for liquid scintillation expensive quenching (LSC) liquid waste semiconductor detectors create: a charge "depleted zone" at junction -zone is sensitive volume -sensitivity depends on depleted zone size -size of zone depends on applied voltages output pulse collection of ions lead to this What are the advantages of semiconductors detectors? energy resolution can be used for particles by making N layer very thin (2 atoms) -smaller depleted zone, but sufficient to stop particle -alpha spectroscopy Disadvantages of semiconductors detectors? detectors must be cooled to very low ten (liquid nitrogen) (-196 C or 410 F) formula to calculate detector efficiency efficiency=CPM/DMP What are the advantages of digital pocket ion chamber? -small, compact -reasonably sensitive and accurate -immediate readout -store exposure record to extended period of time -data download for storage What are the disadvantages of a digital pocket ion chamber? -expensive -limited exposure range -no permanent, legal record what is Doubling Dose? Radiation dose, if delivered to large population, would double the number of spontaneous mutation. What is the estimated ICRP human doubling dose? 100 Rad Uranium Miners Increase risk of lung cancer demonstrated. Atributed to radon and daughters exposure What is WLM working level month Unit of radon decay product exposure Rule of thumb: 1 WL about 120 pCi/L radon concentration No lung cancer <120 WLM; highest risk 120 to 600 WLM--Today: 1 to 2 WLM/yr (5 lung cancer death/106 person-yr/WLM) How many days biological half life for Class D? < 10 days biological half life How many days of biological half life for Class W? 10 to 100 days biological half-life What is workload (W) the amount of time the X-ray unit is in operations. number of exams at a given technique. Averaged over a year if possible what is 1 R in rad (tissue) .97 Rad what is 1 R in rad (air) .87 Rad what is T? Occupancy factor: fraction of the beam on time that a shielded area is occupied by a given individual. What are the three sources of radiation? Primary, leakage, and scatter what is shielding task? barrier is acceptable if it decreases the radiation dose behind the barrier to P/T How is Workload specified? (W) mA*min per week How many days of biological half life for Class Y? >100 days biological half life what is the average annual exposures worldwide to natural radiation sources (high and low LET)? 2.4 mSv range of 1-10 mSv Leakage for xray tube housing shouldn't be more than: 100 mR/hr How far must patients be from collimator? 15 cm for skin sparing what is PBL? Positive beam imitation are electronic sensors in image receptors that adjust collimtors so the xray beam is no larger thanimage receptor. how much is inherent filtration? .5mm of Al equivalent what is total filtration? 2.5 mm. and it's checked annually For equipment design, what do we want exposure reproducibility to be? Variability of 5% or less what do we want exposure linearity to be? less than 10% what reduces pt dose in film screen? use of intensifying screenings faster screen film systems higher KVP when do you use grids? body parts of >10cm increase dose but improves contrast relationship of airgap technique and dose? it doesn't eliminate increase in dose what should SSD source to skin distance must be to reduce effects of inverse square fall of >30 cm Advantages of image intensifier in fluoro -increased image brightness -saves time for radiologist -requires lower mA so lower dose what is the exposure rate limit at table top with image intensifier 12" above it. 10 R/min what is the exposure rate limit with high level control or boost mode? 20 R/min what should SSD be for fixed and mobile fluoroscopy? fixed=no less than 15cm mobile=no less than 12cm what are the advantages of minimzing OID in fluoro? -reduces magnification -reduces unsharpness (blur) -allows image intensifier to intercep more scatter -decrease occupational exposure what are the repercussions of using large OID? -small SSD -increased magnification -more geometric blur -more occupational exposure how thick should lead apron be? .25 mmPb equivalent if bucky and spot film curtain are not used, exposure can be more than? 100mR/hr at 2 feet from side of table what is the exposure at 1ft of the table with no arm drape? 200mR/hr Characteristics of a controlled space? -occupational exposure -Individuals monitored -limitation 100 mrem/week max characteristics of uncontrolled spaced? -incidental public exposure -individuals not monitored -limitation is 2 mrem/week maximum what is the conversion of R to Rad? 1 R=.87 Rad in air 1 R=.97 Rad in tissue Unit for Air Kerma Gy The sum of the weighted equivalent for all irradiated tissues or organs Effective Dose E=sum Wt X HT How much time the x-ray unit is in operation? Workload ma*min per week What is the fraction of the beam-on time that a shielded area is occupied by a given individual? Occupancy Factors=T What is the shielding task? barrier is acceptable if it decreases the radiation dose behind the barrier to P/T what are the assumed conservative distances? .3 meters out .5 meters up 1.7 meters from floor below up what are the 3 sources of radiation? primary leakage scatter primariy rad=useful beam second rad=scatter+leakage How high do we shield walls? 2.1 meters Lead dimensions for Radiographic and CT rooms. radi and fluo=1/32" and 1/16" CT=1/16" bone density and mammo=none how bad was the contamination of radioactive waste discharged to the Techa River? 2.75 MCi in the 1960 what is RDD Radiological Dispersal Device Designed to spread radioactive material through a detonation of conventional explosives or other  nonexplosive mean "dirty bomb" ei. po-210 poisoned ex KGB agent what is SRD? Simple Radiological Device.  Causing  radiological exposrue without an explosion. Radioactive waste waste contaminated iwth or containing radioisotopes transuranic waste 100 mnograms per gm of alpha emittng radioisotopes beyond uranium on periodic table. t1/2 20yrs high level radioactive waste hily radioactive; fission products (spent fuel) Low Level Radioactive waste (low activity/high vol) not high level or transuranic waste Uranium Mill tailings from the mining and milling of uranium ore NORM Waste naturally occuring rad material not regulated by NRC NARM NORM or Accelerator-produced Radioactive material not regul by NRC Mixed waste Radioactive and hazardous Due to chemical or biological materials class A waste classification -usually segregated wastes -lowest isotope concentration -95% LLRW is clas "A Packagin reqs for class A - <1% reestanding liquid, -carbard/fibergboard boxes unnaceptable, -non-explosive, not biological and non-ppyrophoric Class B waste class -intermediate isotope concentration -special stability reqs Must be able to maintain its physical form -Container structural reqs Class C waste -Highest allowable isotope conce -Meet reqs of class B -Special precautions to protect against HUMAN INTRUSION Current US radioactive waste disposal sites are in? Handford WA Evirocare in Clive UT New in Texas What is Waste Isolation Pilot Plant (WIPP) World's first underground repository licensed to safely and permanently disposed of transuranic waste from research and production of nuclear weapons wasted stored in salt mine 2150 feet underground near Carlsbad NM Yucca Mountain DOE site for highly radioactive spent fuel from nuclear power plants and high level waset from weapons program Located in Nevada was supposed to open in March 2017 NRC Lessons learned after Fukosh -Mitigation strategies to respond to extreme natural events resulting in the loss of power and plants -Ensuring reliable hardened containment vents -Enhancing spent fuel pool instrumentation Major radionuclines of concern in Chernobyl accident Cs-137 and I-131 ARS and associated fatalities did not occur among the general poplation of Chernoble accident Radioactive Waste discharged to the Techa River when? early 1950-1960 2.75 Mci discharged Could not use as drinking water source...ban ignored External radiation was up to 120 times bkgd What happened in Kyshtym accident? stem explosion 29sep 1957 200 died of radiation sickness in years following accident Slow evaquation, increase dose what happened in Karachay Lake incident 120 MCi discharged beggining 1951-53 Low precipitaion allowed lake level to recede. Contamination was 3-9mrem/year They are concerned wih drinking water Which are the two bomb accidents? Mars Bluff, SC march 11 1958 -B-47 accidently released bomb, several injured GOldsboro, NC janu 24 1961 -B-52 caught fire, exploded. 3 crew killed. -2 bombs released. bomb 1-4 out 4 arming devices activated bomb 2-plunged into a muddy field. Effects of Normal explosive? 500-2000 lbs TNT Blast (100%) Effects of Nuclear Detonation? Blast 50% Thermal Energy 35% Radioactive 14% Electromagnetic pulse 1% Economic and social disruption Environmental damage what is RDD? Radiological Dispersal Device Designed to spread radioactive material through a detonation of conventional explosives or other non explosive materials can be silent inteded to spread in food or water. ei Po-210 poisoning of agent RDD possible outcomes? -contamination of people and environment can deny the use of facilities and areas will most probably have significant economic impact may hamper emergency response efforts and can delay hospital treatment -material and weather dependent What happens with the use of RDD? Explosion spreads radioactive material (contamination) Nuclear detonation does NOT occur Extreme Caution Radiation Boundary: 10,000 mR/hr High Radiation Boundary: 1000 mR/hr Medium Radiation Boundary? 100 MR/hr Low radiation boundary? 10 mR/hr Incident in Goiania Brazil? CS-137 was rubrued expsing 250 people, killing 4. Dose ranged 50-300 What is Simple Radiological Device (SRD)? Causing radiological exposure without an explosion. Ex. P-32 in the water cooler at NIH, lunch at MIT I-125 in food at Brown university Radiation Area Caution sign means? Rad levels could result in an individual receiving a dose equivalent in excess of .005 rem in one hour at 30 cm from rad source What does High Radiation Area Caution sign mean? dose equiv could result in excess of 0.1 in one hour at 30 centimeters  What does Very High Radiation Area mean? dose of 500 rads in one hour at 1 meter from radiation surface Examples of Engineering Controls Fume hoods Glove boxes ventilation systems vacuum systems hot cells shielding rooms interlocks, mazes, "fail-safe" Examples of PPE Lead lined gloves lead lab coats Cover alls Shoe covers or boots HEad covers Respirators Preventive contamination -Containment: primary and secondary, engineering controls -Spill control -Liquid transfer techniques -handling precautions -protective clothing Administrative controls: -licensing and permits -stay times -Radiation surveys -Leak tests and shutter tests -Inventories -Enforcement options Leaking source legal limit? 0.005microCi 12 Commandments of radiation safety awareness avoidance time distance source shielding source reduction dispersal personal barrier contamination control effect mitigation optimal technology limit other expsures Lethal doses? 3.5-4.5 Sv First clinical sign of Chronic Radiation Syndrome -reduction in blood leukocytes -reduction in platelet counts  -bone marrow hypoplasia -Leucopenia is generally associated with a reduced number of granulocytes -Lymphocyte counts is less affected' but at high doses >4Gy usually lead to pronounced persistent leucopenia Haematopoietic changes accompanied by: changes in immune, nervous, cardiovascular, muscoloskeletal systems and in the GI tract -High doses 4.5Gy-Encephalomyelitis-type changes -Reduced resistance to infection Dysfunction in othe organs -Reduced secretary funtion of the gastric mucosa, mild thyroid dysfunction,  What is the approx background radiation in the US? 300 mREM Quality Factors: Gamma, Xray, beta, Hw=1 Thermal Neutrons=2 Fast Neutrons, Protons=10 Alpha=20 What is CEDE? Committed Effective Dose Eq Represents radiation risk from internal radioactivity that is equivalent in risk to uniform whole body external exposure of the same numerical number What is TEDE (Total Effective Dose Equivalent): Sum of external deep-dose equivalent and internal dose equivalent (CEDE) Summation is not required if estimated dose is less than 10% of he annual dose Internal Dose classes: Class D: < 10 days biological half-life Class W 10-100 days biological hal-life Class Y >100 days biological half-life Problems with cancer risk models: -cancers are indistinguishable -Long latency period -Cannot perform human experiments -Studies may suggest radiation as the cause of cancer but  *33% natural backgorund risk  Multiple causes of cancer Effective dose in a chest xray 0.08mSV Early Effects to Skin, Blood, and Thyroid dysfunction. DETERMNISTIC Erythema-200-500 rads Epilation 400 rads Ulceration >1000 rads Lymphocite decrease 25-30 rads Thyroid dysfunction 30 rem Classic symptoms of high doses? -nausea -vomiting -anorexia -possibly diarrhea depending on dose. Acute Effects with Dose: Hematopoietic Syndrome-2-5 Gy GI Syndrome-5-12 Gy Cerebrovascular Syndrome-100 Gy Vomiting with ARS begins with doses of: 6-8 Gray Delay time of 1 hour chance of developing cancer from a 1 rem whole body dose? 0.02% Skin Cancer and Leukemia common in: early xray workers, physicists and engineers Lung cancer common in: -pichblende miners in Saxony -Uranium miners Bone tumors common in: -Radium Dial workers -20s and 30s radium treast ments for TB and Ankylosing Spondilitis 3 types of chromosonal abberrations lethal to cell: Dicentric Centric Ring Anaphase Bridge 2 Important Non-lethal chro rearrangements: Symmetric Translocations Deletions(Interstitial and Terminal) Radiosensitivity of Lymphocytes: Single most sensitive cell Threshold about 25 rem Few hundred rem results in sever drop in circulating lymphocyte count within hours