Radiation protection
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Radiation protection

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Radiation protection Radiation protection Presentation Transcript

  • Radiation Protection Dr. Muhammad Bin Zulfiqar PGR 1
  • Why are x-rays harmful? 2
  • 13
  • Permissible Occupational Dose • Annual dose: • 5 rem / year 50 mSv / year • Cumulative Dose • 1rem x age 10mSv X age 14
  • Occupational Dose ANNUAL LIMITS • WHOLE BODY = 5 rem / 5000 mRem • LENS OF THE EYE = 15 rem • EXTREMITIES = 50 rem 15
  • PUBLIC EXPOSURE • 10 % OF OCCUPATIONAL • (MUST BE MONITORED IF ABOVE 10%) • NON MEDICAL EXPOSURE • .1 rem OR 100 mrem OR 1 mSv • .5 rem OR 500 mrem OR 5 mSv (Freq) (Infreq) • UNDER AGE 18 & STUDENTS • .1 rem OR 1 mSv • Pg 116 RTA BOOK 16
  • OCCUPATIONAL EXPOSURES • 5 rem / YEAR BUT NOT TO EXCEED 1.25 rem/QUARTER 17
  • 18
  • Reduction of Occupational Radiation Exposure • Radiography as a profession is very safe .. if you follow the ALARA rules • Most technologist exposure occurs from fluoroscopy exams and mobile exams – During all fluoroscopy and mobile exams technologists should wear a protective apron – The primary beam should never be pointed at the tech or other staff… primary at the patient! 19
  • ALARA • ALWAYS KEEP RADIATION EXPOSURES AS LOW AS REASONABLY ACHIEVABLE • Can you think of ways to do this? 20
  • CARDINAL RULES OF RADIATION PROTECTION • TIME • DISTANCE • SHIELDING 21
  • 22
  • TIME • The exposure is to be kept as short as possible because the exposure is directly proportional to time. • 20 rem = 2min • 10 rem = 1min 23
  • DISTANCE • Distance from the radiation source should be kept as great as possible • Physical Law: – Inverse Square Law 24
  • INTENSITY IS SPREAD OUT… 25
  • Position • When primary beam is on.. Your distance should be kept as great as possible • The closer you are to the patient or primary beam the more exposure you are receiving. 26
  • Holding patients • STUDENT RADIOGRAPHERS ARE NOT PREMITED TO HOLD PATIENTS FOR PROPER POSITIONG DURING EXPOSURES • Mechanical devices should be used 27
  • Holding patients • Otherwise, a relative or friend accompanying the patient should be asked to help • Occasionally, other hospital employees such as nurses and orderlies may be asked to help • Radiology staff should never hold patients 28
  • If holding a patient is required… • Use shielding – Apron, gloves, thyroid shield, glasses • Avoid exposing assisting person to the primary beam. 29
  • SHEILDING • A lead protective shield is placed between the x-ray tube and the individuals exposed, absorbing unnecessary radiation 30
  • Wall Shielding Often unnecessary for labs However, same principles employed for X-ray rooms should be applied to assess requirements for Radiochemical Laboratories
  • 32
  • Primary Barriers 33
  • SHEILDING TECHNOLOGIST . 25 mm LEAD • LEAD APRON, GLOVES • THYROID SHIELD, GLASSES PATIENT – GONAD SHEILDING . 5 mm LEAD 34
  • GONAD SHIELDING • MUST BE . 5 MM OF LEAD • MUST BE USED WHEN GONADS WILL LIE WITHIN 5 CM OF THE COLLIMATED AREA • KUB. Lumbar Spine Pelvis • male vs. female shielding 35
  • TYPES OF SHEILDING •FLAT /CONTACT •SHAPED •SHADOW 36
  • Flat/Contact 37
  • 38
  • Shadow Shield 39
  • Local Shielding 1  Vial Shielding – – emitters Perspex Vial shields & Storage emitters Tungsten Vial shields & lead-lined box for Storage
  • Local Shielding 2 Nuclear Medicine Syringes – emitters - Tungsten syringe shields lead-lined box for Storage
  • Perspex L Bench emitters
  • Minimizing radiation exposure • Is easy when technologist and student technologist are informed! • Collimation • Protective apparel/Gonadal shielding 43
  • Personnel Dosimeters • Desirable characteristics – Should be lightweight, durable, and reliable – Should be inexpensive • Types of personnel dosimeters – Film badge – Pocket ionization chambers – Thermo luminescent dosimeters (TLD)
  • Film Badge • • • • • • • • Most widely used and most economical Consists of three parts: – Plastic film holder – Metal filters – Film packet Can read x, gamma, and beta radiation Accurate from 10mrem - 500rem Developed and read by densitometer A certain density value equals a certain level of radiation Read with a control badge Results generally sent as a printout
  • Advantages And Disadvantages Of The Film Badge • • • • Lightweight, durable, portable Cost efficient Permanent legal record Can differentiate between scatter and primary beam • Can discriminate between x, gamma, and beta radiation • Can indicate direction from where radiation came from • Control badge can indicate if exposed in transit • Only records exposure where it’s worn • Not effective if not worn • Can be affected by heat and humidity • Sensitivity is decreased above and below 50 keV • Exposure cannot be determined on day of exposure • Accuracy limited to + or - 20%
  • Pocket Dosimeter • The most sensitive personnel dosimeter • Two types – Self-reading – Non self-reading • Can only be read once • Detects gamma or x-radiation
  • Advantages And Disadvantages Of The Pocket Dosimeter • Small, compact, easy to use • Reasonably accurate and sensitive • Provides immediate reading • • • • • Expensive Readings can be lost Must be read each day No permanent record Susceptible to false readout if dropped or jarred
  • Thermo luminescent Dosimeters • • • • • Looks like a film badge Contains a lithium fluoride crystal Responds to radiation similarly to skin Measured by a TLD analyzer Crystal will luminescence if exposed to radiation, then heated • More accurate than a film badge
  • Advantages And Disadvantages Of The Thermoluminescent Dosimeter • Crystals contained in TLD interact with ionizing radiation as tissue does • Determines dose more accurately • The initial cost is greater than that of a film badge • Can only be read once • Records exposure only where worn
  • Occupational radiation monitor does NOT protect against radiation exposure! 51
  • Occupational radiation monitor • Should be a life time dose record • Should NOT be worn when YOU are the patient • Should be left at the hospital for safe keeping • Should be stored in a radiation free area 52
  • Radiation Survey Instruments • • • • • Area monitoring devices Detect and measure radiation Measures either quantity or rate Generally gas filled Major types of survey instruments – Ionization chamber - cutie pie – Proportional counter – Geiger-Müller detector – Calibration instruments
  • Ionization Chamber (Cutie Pie) • Measures x or gamma radiation generally - can be equipped to measure beta • Measures intensity from 1mR/hr to several thousand R/hr • Most commonly used to measure patients receiving brachytherapy or diagnostic isotopes
  • Proportional Counter • Generally used in laboratories to measure beta or alpha radiation • Can discriminate between these particles • Operator must hold the counter close to the object being surveyed to obtain accurate reading
  • Geiger-Müller Detector • • • • • • Generally used for nuclear medicine facilities Unit is sensitive enough to detect individual particles Can be used to locate a lost radioactive source Has an audible sound system Alerts to presence of radiation Meter readings are generally displayed in mR/hr
  • 57
  • Pregnancy & Embryo Mother – occupational worker (5 rem) • Baby – (500 mrem) • .5 rem/ year .05 rem/month • 5 mSv/ year 0.5 mSv/month 58
  • Declared Pregnant Worker • Must declare pregnancy – 2 badges provided • 1 worn at collar (Mother’s exposure) • 1 worn inside apron at waist level Under 5 rad – negligible risk Risk increases above 15 rad Recommend abortion (spontaneous) 25 rad 59
  • Fetal Exposure • (“Baby exposure” approx 1/1000 of ESE) • ALWAYS ASK LMP before exposure made … any females that could be exposed to primary or scatter 60
  • Reduction of unnecessary patient dose • TIME • DISTANCE • SHIELDING 61
  • Reduction of unnecessary patient dose • Unnecessary exam – If the order is unclear…clarify – If the order is wrong.. Fix it • Repeat exams 62
  • Patient Positioning • When ever possible primary exposure to the gonads, breasts, lenses of the eyes and thyroid should be avoided. • Especially female patients… perform exams PA as apposed to AP – PA = posterior anterior – AP = anterior posterior 63
  • Minimizing radiation exposure • Is easy the equipment is designed to ! • Filtration • Protective barrier 64
  • Filtration REDUCES PATIENT EXPOSURES • REMOVES LOW ENERGY PHOTONS 65
  • Thank you…………..….Questions? 66