Radiation Protection Room Shielding begin Radiobiology & RHB regs

1. Radiation ProtectionRoom Shielding beginRadiobiology & RHB regs Stat Ch 3,4, 9, 10, 11 & 12 BUSH: Ch. 38 & 39 + beginning some RHB – Rad Prot Syllabus RTEC 244 – 2011 WEEK 3 DAY 1 & 2

2. What type of RADIATION are you providing PROTECTIONfor THE TECHNOLOGIST ? & THE PATIENT ???

3. The average person in the United States receives about 360 mrem every year whole body equivalent dose. This is mostly from natural sources of radiation, such as radon

4. Artificial, radiation. Sources of artificial ionizing radiation include the following: •Consumer products containing radioactive material •Air travel •Nuclear fuel for generation of power •Atmospheric fallout from nuclear weapons testing •Nuclear power plant accidents •Medical radiation

5. BERT • BERT is based on an annual U.S. population exposure of approximately 3 millisieverts per year (300 millirems per year) • AKA - GSD – gonadal significant dose • What does this mean • What does it compare?

6. An analysis of available data on ionizing radiation effects suggests that 64-slice coronary CT angiography scans • put young women at a greater risk of developing cancer later in life than any other patient, • according to a study in the July 18 issue of the Journal of the American Medical Association. • More on this later……

7. Which type of radiation is predominant above 80 kvp ? WHAT ARE THE 2 MAJOR INTERACTIONS IN THE BODY? How much of the radiation received by the patient?

8. COMPTON(in the body – scatter radiation) • PHOTOELECTRIC(in the body = absorption)

9. RADIATION PROTECTION AT 1 METER DISTANCE - • 1/1000 OF INTENSITY PRIMARY XRAY or 0.1% • LEAKAGE RADIATION • TUBE HOUSING 100MR / HR @ 1 METER

10. What determines the type of shielding needed?

11. ROOM SHIELDING • PRIMARY SHIELD – • PRIMARY BEAM DIRECTED AT WALL • 1/16 LEAD - 7 FEET HIGH

12. ROOM SHIELDING • SECONDARY – NO PRIMARY BEAM • 1/32 LEAD • CONTROL BOOTH (SECONDARY) • BEAM SCATTERS 2X BEFORE HITTING • LEAD WINDOW – 1.5MM LEAD EQ

13. Primary & Secondary Barriers What would this be used for? Which type of equipment? What type of barrier is the control booth? Why?

14. PERSONNEL PROTECTION • STANDING BEHIND A PROTECTIVE PRIMARY (1/16TH pb) BARRIER: • PRIMARY RADIATION EXPOSURE – 99.87% REDUCED • PORTABLE BARRIER = 99 % REDUCTION

15. Room Shielding • Workload Factor (W) -ma/sec/week – how much time during the week is the beam on (or ma/min/wk) • Occupancy Factor (T) - # of people in room during workweek - beyond the barrier • Use Factor (U) - % of time beam will strike a barrier (table pg 301) Primary vs Secondary • (given in fractions • Leakage Radiation For each wall, door, and other barrier in an x-ray room that is to provide protection against radiation, the product of W × U × T must be determined. The workload is generally fixed by the overall use of the x-ray unit, whereas the use and occupancy factors are usually different among various barriers.

19. Measurements Report No. 147 New Shielding Guidelines *

20. Units of mA-minutes/week are used to determine what for a specific room? • a. Workload • b. Use factor • c. Occupancy factor • d. Distance

21. SHEILDING • HVL? • TVL? • 1 TVL – 3.3 HVL

22. SHEILDING PG 72 RHB • HVL – expressed 2 ways • HOW MUCH IT REDUCES THE ORGINAL BEAM INTENSITY • HOW MUCH IS REQUIRED FOR BARRIER THICKNESS (amount needed to attenuated the beam

23. HVL TVL • The amount of material required to reduce the energy of the beam by…….. • HVL _______________________ • TVL _____________________ • Examples 100 – 50 - 25 – 12.5 – 6.25 - 3.12 • ?How many to reduce to 1/2 ? 1/10th ?

24. LEAKAGE RADIATIONmay not EXCEED • TUBE HOUSING • 100mR / hour • @ 1 meter

25. RADIATION PROTECTION AT 1 METER DISTANCE - • 1/1000 OF INTENSITY PRIMARY XRAY or 0.1%

26. PERSONNEL PROTECTION • SCATTER FROM THE PATIENT • TABLE TOP, COLLIMATOR, TUBE HOUSING, BUCKY • STRAY RADIATION – LEAKAGE OR SCATTER RADIATION

27. SCATTER FROM THE PATIENT TABLE TOP, COLLIMATOR, TUBE HOUSING, BUCKY STRAY RADIATION – LEAKAGE OR SCATTER RADIATION PERSONNEL PROTECTION

28. OFF FOCUSRADIATION

30. SHADOW OF SOMEONE’S HEAD = OFF FOCUS FROM TUBE

31. HIGH RADIATION AREA – • 100 mRem ( 0.1 rem / (1 msV) • @ 30 cm from the source of radiaton • RADIATION AREA – • RHB: 5 mRem ( 0.005 rem / (.05 msV) • @ 30 cm from the source of radiation • PUBLIC 2 mrem per week* (STAT)

32. MONITORING • CONTROLLED AREA – Used by occupationaly exposed personnel (monitored) • 100mrem / WEEK • UNCONTROLLED AREA – PUBLIC • 2 mrem per week*

33. A “controlled area” is defined as one • that is occupied by people trained in radiologic safety • that is occupied by people who wear radiation monitors • whose occupancy factor is 1

34. CARDINAL RULESOF RADIATION PROTECTION • TIME • DISTANCE • SHIELDING

35. Protecting Patients & Personnel • COMMUNICATE • COLLIMATE • SHIELD • ↑ kVp ↓ mAs

36. Limit motion / repeat exams • Communication, Collimate, Shield, • Immobilization • Reduce exposure time • Faster Image receptors (F/S)

37. Review • At a 90-degree angle to the primary x-ray beam, at a distance of 1 m (3.3 feet), the scattered radiation is what fraction of the intensity of the primary beam?

38. If a radiographer stands 6 m away from an x-ray tube and receives an exposure rate of 4 mR/hr, what will the exposure rate be if the same radiographer moves to stand at a position located 12 m from the x-ray tube? • A.1 mR/hr • B.2 mR/hr • C.3 mR/hr • D.4 mR/hr

39. Which of the following are methods that can be used by a C-arm operator to reduce occupational exposure for himself or herself and other personnel? • 1. Collimate the x-ray beam to include only the anatomy of interest. • 2. Use the foot pedal or the hand-held exposure switch with their cables extended away from the machine as far as possible whenever making an exposure. • 3. Use magnification whenever possible to better visualize body parts. • A. 1 and 2 only • B. 1 and 3 only • C. 2 and 3 only • D. 1, 2, and 3

40. Of the following factors, which is considered when determining thickness requirements for protective barriers? • 1. Occupancy factor (T) • 2. Workload (W) • 3. Use factor (U) • A. 1 only • B. 2 only • C. 3 only • D. 1, 2, and 3

41. According to your California syllabus, list more 6 things that will reduce patient exposure: • Collimating to the area of interest • Using last frame hold • Keeping the pt. / detector distance to a minimum • Using high kv low mA • Pulsed Fluoro with low frame rates • Using the largest II mode

42. The greatest contribution of unnecessary radiation exposure to the patient comes from the x-ray operator’s failure to ?

43. The greatest contribution of unnecessary radiation exposure to the patient comes from the x-ray operator’s failure to COMMUNICATE COLLIMATE SHIELD

44. Radiation Hormesis p158 Stat • Suggest that • There is a beneifcial consequence of radiation for populations continuously exposed to moderately high levels of radiation

45. What is the difference betweenX-ray & Gamma? BEGIN RADIOBIOLOGY

46. PARTICULATE (HIGH LET) ALPHA BETA FAST NEUTRONS More destructive ELECTROMAGNETIC (LOW LET) XRAY GAMMA (damaged caused by indirect action = free radicals – can be repaired) TYPES OF RADIATON(ALL CAUSE IONIZATION)

47. Quality Factor • How dangerous the type of radiation is - the biological effect on tissue • Alpha + fast neutrons = 20 • X-ray, Beta, Gamma . = 1 • (Rad + QF = REM)

49. BUNNY A Received 200 rads BUNNY B Received 200 rads Why did the bunny die??

50. BUNNY A 200 rads of X-RAY = 200 RADS BUNNY B 200 rads of alpha = 4000 rads Why did the bunny die??