Types of Radiation Units

Transcription

1 RADIATION UNITS

2 Types of Radiation Units Exposure in air - amount of ionization produced by or radiation in air. Unit - (R) or / (c/kg) Absorbed Dose energy transfer of / (unit of energy) of any. Used to express in. Unit - Rad ( ) or (Gy) 1 rad = 1cGy

3 Occupational Exposure of Dose Equivalent - of. Used for. Unit Rem ( ) or (Sv) 1 Sv = 100 rem To find total dosage use formula: Rem = rad x quality factor (QF) or Weighting Factor (Wr) Quality or Weighting factors: -X-rays & gamma 1 -alpha 20 -neutrons 10-20

4 Radioactivity- measure rate of ( decay) of a material. or.

5 Detection of Radiation Dosimetry- the determination of of the,, and of emitted from a of. Classes of instruments used to detect ionizing radiation: - -

6 Field survey instruments Records amount of in

7 Personnel monitors monitors personal exposure. - - (OSL) - (TLD) -

8 Where to Wear a Personnel Monitoring Device Routine radiography at or Fluoro at

9 Dosimetry badge reports - & regulations requires that the of the be recorded in a precise fashion and maintained for review.

10 Radiation Area Signs Radiation area area where could result in individual receiving than but less than in 1 hr. Requirements: - - Sign reading Caution Radiation Area

11 High radiation area Levels could result in an individual receiving than in. Requirements: -Entrances must have (door interlock) to and inadvertent. Very high radiation area levels could result in and individual receiving an of (cgy) in.

12 Occupational Exposure Occupational exposure exposure of an individual to in a in the course of.

13 Dose Equivalent Limits Area Exposed Limits Annual whole body 5 rem/yr (50mSv) Lens of eye 15 rem/yr (150 msv)

14 Other organs Skin Extremities Pregnant Worker Student Radiographer General public 50 rem/yr (500 msv) 50 rem/yr (500 msv) 50 rem/yr (500 msv).5 rem/yr (5 msv).1 rem/yr (1mSv).5 rem/yr (5mSv)

15 Cumulative Dose Formula Cumulative dose limit rem = 1 x age or msv = 10 x age Example: A technologist is 25 years old, their cumulative dose limit is? 1 x 25 = 25rem or 250 msv

16 Protecting the Radiographer

17 Cardinal Principle of Protection Time- spent in area of - time to.

18 Distance- way to exposure is to as from source as possible. At a distance of from a - the of radiation in fluoro is to of its.

19 Inverse square law- The of varies with the of the.

20 2 I new = D old I old 2 D new Rule of thumb: Double distance intensity is ¼ Half distance - intensity is 4x s Distance will affect the area covered by beam

21 Shielding- most common material - Fixed Barriers -Primary barrier- any or other that can be by the ( Must be at least and contain of lead equivalent - Secondary barrier- beam can t be it. Control booth, ceiling, etc. ( Must contain of.

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23 Lead aprons- In general radiography including must have mm lead and in aprons should have equivalent. Lead gloves must have equivalent

24 Thyroid shield- worn in fluoro to protect Protective eyeglasses- protects of from radiation.

25 Mobile shields- can be moved around the room

26 Other Methods of Protection Control booth - must be within. Control panel must indicate the conditions exposure and indicate when the ex-ray tube is.

27 Mobile radiography- cord must be a feet. Holding patients- Person other than should hold patient.

28 Fluoroscopy 5 minute audible timer indicates how Foot pedal- Exposure at table top can t exceed

29 Curtain in front of must contain equivalent to scatter Lead apron & gloves

30 Bucky slot cover Use highest practical KV

31 C-arm AP imaging will rate of. from patient.

32 The Pregnant Radiographer Radiographer must decide to. Fetus cannot receive more than for entire. Pregnant Radiography cannot be against.

33 PROTECTING THE PATIENT IN RADIOGRAPHY

34 Technique Selection (Exposure factors) - Use for part with mas.

35 Filtration- placed in the of the beam to energy x-rays, so that the patient is. Equipment operating above must have Al.

36 Compensating filters- for in part density. Good technique for entire body part.

37 Grids- device placed between and to absorb. When grid is used, technique is. Use a grid when: - body part is over - using over

38 Position and Protection- Certain projections are better as far is concerned. Ex. PA skull there is less to than in an AP skull. IVP - AP KUB the contrast filled bladder will. PA KUB will not.

39 Image Receptor (IR) Computer Radiographer (CR) versus Direct Radiography (DR) DR needed than CR. Faster screen/film -.

40 Beam Limitation (collimation) -PBL - - automatically collimates Radiographer should always to only. Other collimation devices: - / - -

41 Shielding- use shield unless it with of. FDA recommends shielding if are within of primary beam Types: ( use during scoliosis exam)

42 Immobilization sometimes used to prevent. - - ( sandbags, sponges, tape) Pediatric patient- use,,. -

43 Repeat Exposures average repeat rate - - Exposure errors most common cause in - Positioning errors most common cause in Equipment report all equipment problems.

44 Protection for Children Use Place on table baby is

45 Protection in Fluoroscopy -Exposure rate cannot / -Use - Minimum focal distance Mobile - Fixed - Angio and Cardiac Cath use fluoro dosage is very high

46 with patient Protection in Mobile Radiography All persons should Everyone who stays in is exposures Correct grid screen/technique Check positioning exposure Check to see what technique was used. Using higher KV - margin of & patient

47 Protecting the Pregnant Patient The pregnant patient Ask patient if they might be pregnant. of ( elective procedures) should be in the and trimesters.