1. RADIATION PROTECTION
Presented by Rose Aehle RT (R,M) MS Program Coordinator, Montgomery College

2. REFERENCES
Bushong Radiologic Science for Technologists, Eighth Edition
Ehrlich, Patient Care in Radiography, Sixth Edition
Callaway, Mosby’s Comprehensive Review of Radiography
Saia, Lange Q & A Radiography Examination, 6th Edition
Sherer, Radiation Protection in Medical Radiography, Fifth Edition
2008 ARRT REGISTRATION HANDBOOK
The College of St. Catherine, Development Testing Program for Radiography

3. PLEASE TURN ALL CELL PHONES TO VIBRATE MODE

4. WHAT THE REGISTRY WANTS YOU TO KNOW (2008 ARRT handbook)

5. BIOLOGIC ASPECTS OF RADIATION
Dose response curves (Sherer)
Line 1
No level of radiation can be considered safe.
Response to exposure is directly proportional
Diagnostic imaging
Line 2
Threshold is assumed, response expected at lower doses
Cataractogenesis
Radiation Therapy

6. BIOLOGIC ASPECTS OF RADIATION
Dose response curves (Sherer)
Line 3
Non linear (sigmoid or hypothetical sigmoid) dose response
DIAGRAM B
Non linear, threshold dose response used in radiation therapy

7. BIOLOGIC ASPECTS OF RADIATION
FRACTIONATION
A fraction of a dose of ionizing radiation given over a period of time
How to read a nonlinear threshold dose response curve
Death/ Repair
PROTRACTED DOSE
A low amount of ionizing radiation given continously
Damage/eradication of abnormal cells
Repair

8. Linear quadratic nonthreshold dose response curve
Risks associated with low dose levels of low LET radiations
Stochastic somatic and genetic effects
“Leukemia, breast cancer and heritiable damage assumed to follow this curve”
Sherer

9. ????????????????????????????
College of St. Catherine

10. ANSWERS D C

12. LET, RBE, QF
Which comes first?
LET? RBE?
QF?

13. LET – AMOUNT OF ENERGY DEPOSITED BY RADIATION PER UNIT LENGTH OF TISSUE TRAVERSED calloway
RBE- QUANTITATIVE MEASUREMENT OF BIOLOGIC EFFECT
QF – NUMERIC UNIT GIVEN TO RADIATION BASED ON RBE TO DETERMINE REM

14. Facts about LET SPARSELY IONIZING RADIATION GAMMA AND X-RAY
LOW LET OF 3 KEV per micrometer OR LESS
ARE PENETRATING
INTERACT RANDOMLY ALONG ITS TRACK (STOCHASTIC)
AS LET INCREASES SO DOES RBE
HIGH LET
LOW PENETRATION
SLOW MOVING
Direct Effect

15. Effective dose (E)=Wr X Wt x absorbed dose
Wr -Radiation weighting factor
Wt –Tissue weighting factor
number assigned to different types of ionizing radiation. Dependent of the LET of particular radiation
Tissue radiosensitivity of irradiated material

16. FACTS ABOUT RBE
DOSE OF STANDARD RADIATION NECESSARY TO PRODUCE A GENETIC EFFECT
DOSE OF TEST RADATION NECESSARY TO PRODUCE THE SAME EFFECT
STANDARD RADIATION IS TYPICALLY 250 kVp (Bushong has a range of 200 – 250 kVp)
Test radiation can range for x-rays to other types of ionizing radiation
RBE for x-rays is one
Higher LET’s have Higher RBE = Higher QF

17. WT factors -which is more radiosensitive?
What is more radiosensitive?
Stomach or bladder?
Gonads or red bone marrow?
Colon or breast?
Thyroid or skin?

19. FACTS ABOUT QF
REM IS CALCULATED BY MULTIPLYING THE QF OF A PARTICULAR TYPE OF RADIATION X RAD
QF FOR X-RAYS IS 1
THEREFORE ONE RAD OF EXPOSURE TO X-RAY = ONE REM
QF FOR ALPA IS 20
HIGH LET
SLOW MOVING
LOW PENETRATION
THEREFORE ONE RAD OF EXPOSURE TO ALPHA = 20 REMS

20. LD 50
LD 50/60
THE AMOUNT OF RADIATIONTHAT WILL CAUSE 50% OF EXPOSED INDIVIDUALS TO DIE WITHIN 60 DAYS

22. WHAT DOES THE LAW OF BERGONIE AND TRIBONDEAU SAY Re RADIOSENSITIVITY?
Stem cells are_____________
Mature cells are ____________
Cells with _________metabolic and ___________mitotic activity are radiosensitive
Cells which are differentiated are _____________
Radiosensitive
Radioresistent
High/high

23. SOMATIC EFFECTS STOCHASTIC aka PROBALISTIC effect NONSTOCHASTIC
aka Deterministic Effect

24. SOMATIC Short Term ARS Locally Erythema 300-1000 RADS Epilation
Hemopoietic (BONE MARROW SYNDROME) RAD
25 RADS CAN DEPRESS BLOOD COUNT
Gastointestinal ( RADS)
CNS (5000 RADS
Locally
Erythema RADS
Epilation
Delay/suppress menstruation 10 RADS
Temporary sterility (both sexes – 200 RADS
LONG TERM
THOSE EFFECTS THAT CAN BE DIRECTLY RELATED TO HIGH DOSE OF RADIATION ARE CLASSIFIED AS NONSTOCHASTIC
Cataract
Reduced fertility
Fibrosis
Organ atrophy
Sterility
LONG TERM STOCHASTIC
CANCER
EMBRYOLOGIC EFFECTS

25. CARCINOGENESIS
The cancer that can be ALMOST classified as radiounique is leukemia
Has a short latency period
Has a linear nonthreshold dose response curve
Epidemiologic studies indicate a higher incidences in leukemia after large exposures
Radium watch dial workers –bone ca
Uranium miners – lung ca
Early medical radiation workers – leukemia
Thymus gland treatment – thyroid ca
Children of Marshal Island – thyroid ca
Atomic bomb survivors – leukemia/breast, lung and bone

26. WHAT CAN HAPPEN WHEN IONIZING RADIATION HITS THE CELL?
a) Nothing
b) Direct effect
c) Indirect effect
d) All of the above

27. HIGH LET is associated with which effect?
No effect
Direct effect
Indirect effect
Radiolysis of water

28. The following is true regarding indirect effect
I) DNA is impacted by free radicals
II) Some free radicals may chemically combine to form hydrogen peroxide
III) DNA is directly struck by radiation
The minority of the damage to body is caused by indirect effect
I only
I and II only
I, II and III only
All of the above

29. TARGET THEORY THE DNA IS DIRECTLY HIT
ONLY SOME CELLS HAVE MASTER MOLECULES THAT DIRECT CELL ACTIVITY
ONE CANNOT DETERMINE IN ANY CELL DEATH IF THE DEATH WAS RESULT OF DIRECT OR INDIRECT EFFECT

30. EMBRYONIC AND FETAL RISKS

31. Spontaneous abortions during first 2 weeks of pregnancy-- 25 RAD or higher
2nd week to 10th week – major organogenesis –IF radiation is high enough can cause congenital abnormalities
Principle response after that may be malignant disease in childhood

32. PREVENTING ACCIDENTAL IRRADITATION TO PATIENT
FIRST TWO MONTHS, CRITICAL
10 DAY RULE
ELECTIVE BOOKING
QUESTIONAIRE
POSTING

33. IF A PREGNANT PATIENT MUST BE X-RAYED
TIGHT COLLIMATION
HIGH KVP
SHIELDING
REDUCED # OF IMAGES
MAKE SURE TO CHECK WITH YOUR SUPERVISOR AND BE AWARE OF THE SITE’S PROTOCOL

34. GSD GENETICALLY SIGNIFICANT DOSE 20 mrem estimated dose
Equivalent dose to the reproductive organs received by every human would cause the same genetic injury as the actual dose received by individual population members

35. The pregnant radiographer
WHICH OF THE FOLLOWING IS (ARE) TRUE?
5 mSv for the period of pregnancy
500 mrem for the period of pregnancy
0.5 mSv per month
0.05 rem per month
Two badges
TRUE

37. LET’S PICK UP THE PACE NOW!
KEEP THE PATIENTS SAFE!!!

38. WHAT KIND OF EXPOSURE FACTORS ARE BEST FOR PATIENTS?
NAME FACTORS TO KEEP PT DOSE DOWN
AS SID increases, what happens to the intensity? What do we adjust and do we increase or decrease this adjustment?
Which of the following impacts PT dose?
Inherent filtration?
Added filtration?
SID?
Focal spot size?
Screen speed?

39. WHAT GIVES HIGHEST CONTRAST BUT INCREASES PATIENT DOSE?
COMPTON?
CHARACTERITIC?
BREMSSTRAHLUNG?
PHOTOELECTRIC?

40. DO GRIDS DECREASE PATIENT EXPOSURE?

41. MINIMIZING PATIENT EXPOSUER
SHIELDING
Gonadal shielding females reduces gonad dose by 50%
Gonadal shielding males reduces gonad dose by 95%
Flat, shadow shields
COLLIMATION
DID YOU KNOW THAT THERE ARE A HIGHER SET OF LEAD SHUTTERS PLACED NEAR THE X-RAY TUBE WINDOW TO ABSORB OFF-FOCUS RADIATION?

42. FILTRATION
INCREASED FILTRATION (HVL) INCREASES THE AVERAGE BEAM ENERGY
No filtration on a 70 kVp tube (0-70) would produce an average energy of 35 kVp
However, if you filter out the lower energies (30-70 kVp) is 50 kVp
Inherent
Added
_________is required for machines operating at 70 kVp

43. HVL
How many HVL’s are required to reduce the intensity of the beam to less that 15% of its original value
A) 2
B)3
C)4
D)5

44. WHERE SCATTER ALWAYS MATTERS!
FLUOROSCOPY
WHERE SCATTER ALWAYS MATTERS!

45. READING NOMOGRAMS What kind of info do you need?
From Appleton and Lange
What is the approximate patient ESE from an AP projection of the abd. made at 105 cm, 70 kVp, 300 mA, 0.2 sec (60 mAs)and 2.5 mm AL total filtration

46. SCATTER STATS
Each time the x-ray beam scatters, its intensity at 1 meter from the scattering object is one thousandth of its original intensity
or it decreases 1000 times!!!!
Or 1/1000 or
0.1%

47. FLUOROSCOPY PULSED (DF)
X-RAY TUBE OPERATES IN RADIOGRAPHIC MODE WHICH MEANS USING TECHNICAL FACTORS THAT ARE USED FOR OVERHEAD EXAMS
HOWEVER
THE TIME REQUIRED TO REACH THE SELECTED MA AND KV (INTERROGATION TIME) AND THE TIME FOR THE X-RAY TUBE TO BE SWITCHED OFF (EXTINCTION TIME) IS LESS THAN 1 MS
THEREFORE IN DR FLUORO A 5 MINUTE STUDY WILL RESULT IN A PATIENT DOSE OF 10 RAD VS 20 RAD FOR A CONVENTIONAL FLUOROSCOPY STUDY

48. Conventional fluoroscopy
mA less than 5
Use of magnification mode increases patient exposure

49. All types of fluoro Intermittent fluoro Field size
Focus to table distance (15” stationary, 12” mobile

51. PERSONNEL PROTECTION
Let’s keep safe!

52. THE ENVIRONMENT CONTROLLED AREA OCCUPANCY FACTOR UNCONTROLLED AREA
USE FACTOR
WORKLOAD
Badged personnel
Who,what is where
Everyone else!
% of time primary beam is directed at a particular wall
# of x-ray exams per week

53. Primary barrier
7 feet, 1/16 inch of lead
Secondary barrier
Extend to ceiling
1/32 inch of lead

54. Which of these regulations are accurate?
DL for eye is 50 mSv?
Cumulative whole body is 10mSv x age?
Leakage radiation – 100 mR/hr at 2 meters?
Lead aprons at mm pB equivalent?
ESE in 10R/min in fluoro?
Exposure cord on portable must be 1 meter long?
Pregnant radiographer DL for fetus is 500 mrem for period of pregnancy?
The public exposure DL is 100 mrem per year?
Bucky slot cover and protective curtain, minimum of 0.5 pB equivalent?

55. FINALLY!!!

56. CARDINAL RULES OF PROTECTION PERSONNEL MONITORS
ALARA
CARDINAL RULES OF PROTECTION
PERSONNEL MONITORS
TLD’S VS OSL VS. FILM BADGES VS DOSIMETERS
Lithium fluoride vs aluminum oxide vs x-ray film vs.gas
INVERSE SQUARE LAW WITH EXPOSURE RATE

57. If a radiographer receives 25 mR standing 3 feet from the source for one hour how much would he receive if he stands 2 feet from the source at 20 minutes?
25mR 2 feet squared
X 3 feet squared
25 mR feet
x feet
4 x = 225
X = 56 mR per hour
20 minutes/60 minutes = .33
56 mR x .33 = mR at two feet for 20 minutes

58. SEE YA!!! GOOD LUCK TO ALL THE GRADUATES OF 2012!!!!!