Rad Protection & Radiobiology review 244 09

STAT 8 & 9 Protecting Patients & Personnel COMMUNICATE COLLIMATE SHIELD

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 100- 500 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

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

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

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

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

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

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?

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

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

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

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)

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

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

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

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

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

SHEILDING HVL? TVL? 1 TVL = 3.3 HVL

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

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 ?

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

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

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 ( 0.005 rem / (.05 msV) @ 30 cm from the source of radiation PUBLIC 2 mrem per week* (STAT)

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

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

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

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

Q = t x תּ CUTIE PIE

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 - 50 REMS

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)

measurement (Rad + QF = REM)

Quality Factor “weighting factor for tissue” See ch 7 - pg 155 5th ED Organ tissue weighting factor “ratio of risk of stochastic effects – rads to type of tissue

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

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

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

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

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

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)

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

TOTAL = __________ mRad A room uses 3.5 mR @ 80 kVp 2.5 mR @ 70 kVp 4.5 mR @ 90 kVp 5.6 mR @ 100 kVp 2 views Chest (PA) 5 mas 90 kVp (LAT) 10 mas 100 kVp _ TOTAL = __________ mRad

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

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?

During a Fluoroscopy Procedure….. Tube output was 1.5 R/min @ 2.2 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?

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

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

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

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

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

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

♀ 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 % ♂

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

GERM CELLS in Females (present at birth) HIGHLY RADIOSENSITIVE = DEPENDS OF STAGE OF DEVELOPMENT Mature ovum do not divide frequently (20-30 yrs old - least sensitive) Immature very sensitive If exposed ova meets sperm – may contain damaged chromosomes – passing genetic damage to offspring = CONGENTIAL ABNORMALITIES

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

Doses above 50 gy