RT 244 / 328 REVIEW & REVISIONS

9.21.12RHB SYLLABUS on

Fluoroscopy & Radiation Protection

1

2

RHB NOTIFICATION (revised 2012) (RP Syllabus – pg 68 Fluoro Syllabus pb 53)

IMMEDIATE reporting –TOTAL DOSE OF 25 rems• Eye dose – 75 rem• Extremity – 250 RADSWITHIN 24 HOURS• TOTAL DOSE OF 5 rems• Eye dose – 15 rem• Extremity - 50 REMSALL other OVEREXPOSURE – (received w/in 24

hrsMust be Reported WITHIN 30 DAYS

3

Report at least every quarterPreserved for indefinitely - individuala minimum of 3 years (employer)*(“all other records” pg 52)

4

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 % ♂(STAT)

Pg 13 RHB –RP:0.5 mm ↓ 92% (inc internal scatter)Pg 43 300 Rads 30 Rads -temp sterility♀ ♂

5

MONITORING PG 75

• CONTROLLED AREA – Used by occupationaly exposed personnel (monitored)

• 100mrem / WEEK

• UNCONTROLLED AREA – PUBLIC• 2 mrem per week*

6

• 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)

7

DOSE REGULATIONS

• Fluoroscopic tubes operate at currents that range from0.5 to 5 mA with 3ma the most common

• BEFORE 1974 - AT TABLETOP• 5R/MIN (WITHOUT AEC) Reg & Boost• After 1974 with AEC (1993 )• 10 R/MIN 20R/MIN BOOST– Some books ave is 4 R/min if not given

8

Over vs under the table fluoro tubes

pg 116 dose to operator

9

DOSE

• CINE - 2mR per frame (60f/sec)• 400 mr per “look”

10

SSD – TUBE TO SKIN DISTANCE

• FIXED UNITS• 18” PREFERRED• 15 “ MINIMUMMOBILE UNITS ( C-ARMS)• 12’ MINIMUM• 5 min AUDIBLE ALARM

11

KEEP I.I. CLOSE TO PATIENT

12

Patient Protection

• Tabletop exposure rate– Maximum 10 R/min– Typically 1 – 3 R/min

13

Patient Protection

• Minimum source-to-skin distance– 12” for mobile equipment– 15” for stationary systems

• Audible alarm at 5 mins.• Same rules for collimation

Shielding to Scatter

Pg 70 Fluoro RHB: ScatterRT: 0.25 = ↓ 97% 0.5 = ↓ 99.9%

14

15

Lead curtain & dose reduction

16

Units of Dose – App #3 pg 79

100 R = 1 C/kg1Rad = 1/100 Gray1 Rem = .01 Sievert

(Rad + QF = REM)1 REM = 10 mSv

1 Rem = 1000mRem

17

Pregnancy & Embryo

Mother – occupational worker (5 rem)• Baby – (500 mRem)• .5 rem/ year .05 rem/month• 5 mSv .5 mSv / month

18

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

19

• 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

20

Kell Factor• The ability to resolve objects spaced apart in a

vertical direction.• More dots = more scan lines = more/better

resolution• Kell factor for 525 line system is 0.7VERTICAL RESOLUTION = VER - TI- K- AL

• RATIO OF VERTICAL RESOLUITON• # OF SCAN LINES

more dots(globules) = more scan lines = more/better resolution

21

Bandpass/Horizantal Resolution

• Horizontal resolution is determined by the bandpass.

• Bandpass is expressed in frequency (Hz) and describes the number of times per second the electron beam can be modulated.

• The higher the bandpass, the better the resolution