1. Rad Protection & Radiobiology review
244 09

2. STAT 8 & 9 Protecting Patients & Personnel
COMMUNICATE
COLLIMATE
SHIELD

3. Ch 1 – pg 1 RHB SYLLABUS
5% population have fluoro exams
53% GI tract (1996 )
120 sec fluoro ~= ese 5 – 15 rads
Comp to ABD ~= ese mrads
Fluoro used for dynamic studies
USING FLUORO TO POSTION PATIENTS PRIOR TO TAKING FILM IS PROHIBITED
Must have fluoro permit or Supervisor & Operators Certificate from state

4. PATIENT PROTECTION LIMIT SIZE OF BEAM BEAM ON TIME
DISTANCE OF SOURCE TO SKIN
PBL
FILTRATION (2.5 mm Al 70
SHEILDING
SCREEN/FILM COMBO -OVERHEADS

5. 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

6. Fluoroscopy – OUTPUT check with a LUCITE Phantom or Water Container for consistent exposure output
MONITORED
weekly (QC)
RECORDED
Daily DURING FLUORO EXAMS)

7. DOSE REGULATIONS BEFORE 1974 - AT TABLETOP 5R/MIN (WITHOUT AEC)
5R/MIN (WITHOUT AEC) – BOOST MODE
After with AEC
10 R/MIN
20R/MIN BOOST (Stat p198)

8. Exposure Bushong – ch 39 DAP
Must not exceed 2.1 R/ma/min
2.2 R/min in RHB
DAP – dose area product
Takes in account the volume of tissue irradiated

9. CINE DOSE CINE - 2mR per frame (30 OR 60f/sec) 400 mr per “look”
WHAT WOULD BE THE PATIENT’S DOSE FOR A 5 MIN PROCEDURE
AT 60 F/SEC?

10. Permissible Occupational Dose
Annual dose:
5 Rem / year 50 mSv / year
Cumulative Dose
1rem x age mSv X age

11. OCCUPATIONAL EXPOSURES
5 REMS / YEAR
BUT NOT TO EXCEED 1.25 REM/QUARTER
OLD “MPD 5(Age – 18)”

12. Occupational Dose ANNUAL LIMITS
WHOLE BODY = 5 REMS / 5000mRem
LENS OF THE EYE = 15 REMS
EXTREMITIES = 50 REMS

14. DOSE LIMIT (DL) NCRP ? NCR ? (Stat Book) BEIR ?
DL’S imply that if received annually, risk of death would be less than 1/10,000
Based on Linear Non-Threshold
DL – Dose Limits
Occupation Exposure (rems)

16. REGULATORY AGENCIES
NCRP – National Council on Radiation Protection and Measurement
Reviews recommendation for radiation protection & safety
NRC – Nuclear Regulatory Committee
Makes LAWS & enforces regulations

17. REGULATORY AGENCIES p143/5th
BEIR - Biological Effect of Ionizing Radiation
UNSCEAR – United Nations Scientific Committee on the Effects of Atomic Radiation

18. ROOM SHIELDING PRIMARY SHIELD – PRIMARY BEAM DIRECTED AT WALL
1/16 LEAD FEET HIGH

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

20. Room Sheilding Ch. 9 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 - beyond the barrier
Use Factor (U) - % of time beam will strike a barrier (table pg 242) Primary vs Secondary
Leakage Radiation

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 – – –
?How many to reduce to 1/2 ? 1/10th ?

25. LEAKAGE RADIATION may not EXCEED
TUBE HOUSING 100mR / HR
@ 1 meter

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

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

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

30. 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

31. Personnel Monitoring Devices ACCURACY
Film Badges
TLD
POSL
Pocket Dosimeter
Ring Badge
10 mrem
5 mrem
1 mrem ?

32. Personnel Monitoring Devices $$$$$$$$$$$
Film Badges
TLD
POSL
Least cost
$2.50
?most used
$10 ?

33. Q = t x תּ
CUTIE PIE

34. RHB NOTIFICATION (EXP IN 24 HOURS) (RP Syllabus – pg 68)
IMMEDIATE reporting – WITHIN 24 HOURS
TOTAL DOSE OF 25 rems
Eye dose – 75 rem
Extremity – 250 RADS
OVEREXPOSURE – received w/in 24 hrs
Must be Reported WITHIN 30 DAYS
TOTAL DOSE OF 5 rems
Eye dose – 15 rem
Extremity REMS

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

36. measurement
(Rad + QF = REM)

37. Quality Factor “weighting factor for tissue”
See ch 7 - pg th ED
Organ tissue weighting factor
“ratio of risk of stochastic effects – rads to type of tissue

38. SOMATIC & GENETIC STOCHASTIC VS NON STOCHASTIC
A = STOCHASTIC
“CHANCE” EFFECTS
GENETIC, LEUKEMIA, CANCER
DIAGNOSTIC RADIOLOGY
B= NON-STOCHASTIC
THRESHOLD EFFECTS
DETERMINISTIC
SOMATIC EFFECTS
SKIN ERYTHEMA, CATARACTS, STERILITY
RAD -MALIGNANCIES

39. RHB – Rad Prot – CH. IX p 51 ALARA (no minimum threshold)
STOCHASTIC EFFECTS –
NON TRESHOLD (CA + GENETIC)
NON STHOCAHSTIC (DETERMINISTIC)
SEVERITY OF EFFECTS VARIES WITH RADIATION DOSE (THRESHOLD)
(CATARACTS, SKIN, BONE MARROW,
STERILITY

40. Linear vs non linear
Linear – direct response to the dose and the effects seen (proportionally)
Non linear – effects are not proportional to the dose received
S curve – rad therapy & skin erythema

42. Direct & InDirect Direct - DNA hit or with high LET
InDirect – most frequently occuring
Does not hit DNA directly – but can effect DNA through radiolysis
90% of cell damage is repairable

43. Ch 4 – pg 37 Fluoro Exam
↑ ↑ directly proportional to dose (pt & Rt)
Operator dose & pt dose
Image brightness & rad dose
mA, kvp, collimation, filtration, time, TPD
↑ ↓indirectly proportional to dose (pt & Rt)
Poor image quality
Room lighting
Tabletop absorption

44. PATIENT DOSE
RAD
MR/MAS PER EXPOSURE - At each kVp level – there is a determined output for each radiographic room
EX 70 kvp = 2.5 mr/mas
ABD done 70 kVp, 20 mas
2.5 x 20 = 50 mR for that one exposure.
LOOK AT formula: mr/mas Ch 8 Stat
CH 40 BUSHONG ( for 9/17)

45. Mr/mas A room uses 3.5 mR @ 80 kVp 2.5 mR @ 70 kVp 4.5 mR @ 90 kVp
Find the patient’s exposure (ESE) for
KUB ( 40 mAs 70 kvp) = ___ mRad

46. TOTAL = __________ mRad
A room uses
3.5 mR @ 80 kVp
2.5 mR @ 70 kVp
4.5 mR @ 90 kVp
kVp
2 views Chest
(PA) 5 mas 90 kVp
(LAT) 10 mas kVp _
TOTAL = __________ mRad

47. At 1 foot from a source the output intensity is 300 mR/hr and you were there for 20 minutes. What is your dose?

48. At 1 foot from a source the output intensity is 300 mR/hr and you were there for 20 minutes. What is your dose? NOW - What is the intensity total if you moved 2 feet away and remained for additional 40 minutes?

49. During a Fluoroscopy Procedure…..
Tube output was ma
If at 2 feet from the radiation source the intensity of exposure is 240 mR per hour and the RT remains at this location for 10 minutes, then moved 4 feet away from the radiation source and remained there for 20 minutes?
What is your dose (RT) when you moved?
What is your (RT) total exposure?
What did the patient receive?

50. ESE FOR FLUORO TLD PLACED AT SKIN ENTRACE POINT
1 – 5 R/MINUTE AVE IS 4 R/MIN
INTERGRAL DOSE –
100 ERGS OF TISSUE = 1 RAD EXPOSURE
OR 1 GM RAD = 100 ERGS

51. Pg 39 Integral Dose
Total energy absorbed from the beam
Unit is GRAM RAD (1 gm rad = 100 ergs)

52. The NCRP states that: the risk (to the embryo/fetus) is considered to be negligible at 5 rads or less when compared to the other risks of pregnancy
and the risk of malformation is significantly increased above control levels only at doses above 15 rads

53. 10 – 25 RAD Rule and Pregnancy Bush p 545
Below 10 RAD (100mgy) ther ab NOT indicated
Above 25 RAD may justify TAB
FETAL doses RARELY reach 5 RAD

54. As shown in animal experiments, deleterious effects to the embryo may be produced with doses of as little as _____ delivered to the embryo.
a. 5 rads
b. 15 mrads
c. 15 rads
d. 50 mrads
e. 50 rads

55. PERSONNEL PROTECTION PROTECTIVE APRONS – 0.25 PB = 97% ↓ TO SCATTER
THYROID SHEILDS (0.25 & 0.5)
GLOVES (0.25 & 0.5)

56. ♀ receive 3x more dose than ♂ for pelvic x-rays
Gonad shielding & dose
♀ receive 3x more dose than
♂ for pelvic x-rays
1 mm lead will reduce exposure (primary) by about 50% ♀
by about 90 – 95 % ♂

57. HIGHLIGHTS RE FLUORO & RAD PROT PG 43- lymphocytes most depressed
300 rads ♀ OVARIES = TEMP STERILITY
30 rads ♂ TESTIES = TEMP STERILITY
PG 45 – REPEAT INFO

58. GERM CELLS in Females (present at birth)
HIGHLY RADIOSENSITIVE = DEPENDS OF STAGE OF DEVELOPMENT
Mature ovum do not divide frequently
( yrs old - least sensitive)
Immature very sensitive
If exposed ova meets sperm – may contain damaged chromosomes – passing genetic damage to offspring =
CONGENTIAL ABNORMALITIES

59. GONAD SHIELDING pg 87 MUST BE . 5 MM OF LEAD
MUST BE USED WHEN GONADS WILL LIE WITHING 5 CM OF THE COLLIMATED AREA (RHB)
FLAT / CONTACT / SHADOW

60. Doses above 50 gy