Radiation Protection Room Shielding begin Radiobiology & 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

What type of RADIATION are you providing PROTECTION for THE TECHNOLOGIST ? & THE PATIENT ???

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

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

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? Another way radiographers can improve understanding and reduce fear and anxiety for the patient is to use the BERT, BERT is based on an annual U.S. population exposure of approximately 3 millisieverts per year (300 millirems per year).* Using the BERT method in this context has the following advantages:

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……

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?

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

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

What determines the type of shielding needed?

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

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

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

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. 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. The quantity that best describes the weekly radiation use of a diagnostic x-ray unit is called its workload (W). Workloads are specified either in units of milliampere-seconds (mAs) per week or milliampere-minutes (mA-min) per week. radiographic x-ray suite is in operation 5 days per week. The average number of patients per day is 20, and the average number of images per patient is three. The average technical exposure factors are 90 kVp, 300 mA, and 0.1 sec. Find the weekly workload. Note that the kVp is not used in the workload calculation. It is, however, an important parameter in the calculation of barrier-shielding thickness. A diagnostic x-ray suite, walls are struck by radiation to some degree for some fraction of the weekly beam-on time. The use factor (U) is a quantity that was introduced to select this fractional contact time. The occupancy factor (T) is used to modify the shielding requirement for a particular barrier by taking into account the fraction of the workweek during which the space beyond the barrier is occupied.

Use Factor Primary Barrier Full use (U = 1) Floors of radiation rooms except dental installations, doors, walls, and ceilings of radiation rooms exposed routinely to the primary beam Partial use (U = ) Doors and walls of radiation rooms not exposed routinely to the primary beam; also, floors of dental installations Occasional use (U = ) Ceilings of radiation rooms not exposed routinely to the primary beam; because of the low use factor, shielding requirements for a ceiling are usually determined by secondary rather than primary beam considerations

Location Occupancy Factor (T) Administrative or clerical offices; laboratories, pharmacies, and other work areas fully occupied by an individual; receptionist areas, attended waiting rooms, children's indoor play areas, adjacent x-ray rooms, film reading areas, nurses’ stations, x-ray control rooms 1 Rooms used for patient examinations and treatments 1/2 Corridors, patient rooms, employee lounges, and staff rest rooms 1/5 Corridor doors‡ Public toilets, unattended vending areas, storage rooms, outdoor areas with seating, unattended waiting rooms, patient holding areas 1/20 Outdoor areas with only transient pedestrians or vehicular traffic, unattended parking lots, vehicular drop-off areas (unattended), attics, stairways, unattended elevators, janitors’ closets 1/40

Measurements Report No. 147 New Shielding Guidelines Item New Approach Workload More realistic use of contemporary survey data Leakage and scatter Explicit barrier calculations Use factor Adjusted for beam direction data reflecting actual usage patterns Occupancy factor Realistic assumptions of occupancy of low-occupancy areas (e.g., stairwells) *

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

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 / hour @ 1 meter

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

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

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

OFF FOCUS RADIATION

SHADOW OF SOMEONE’S HEAD = OFF FOCUS FROM TUBE

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* 1. A permanent sign bearing the words “Caution Radiation Area” must be conspicuously posted in any area accessible to individuals in which radiation levels could result in an individual receiving a dose equivalent in excess of 0.05 mSv (0.005 rem) in 1 hour at 30 cm from the radiation source or from any surface that the radiation penetrates7. 2. A permanent sign bearing the words “Caution High Radiation Area” must be conspicuously posted in any area accessible to individuals in which radiation levels could result in an individual receiving a dose equivalent in excess of 1 mSv (0.1 rem) in 1 hour at 30 cm from the radiation source or from any surface that the radiation penetrates.7

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 As part of a successful radiation safety program, “caution signs” must be posted in any room or area where “radioactive materials or radiation sources are used or stored.”7 To ensure safety of all persons approaching a radiation area or a container containing radioactive materials, the signs should be obvious and easy to read. The word “caution” usually appears at the top of the sign, followed by the conventional three-blade radiation symbol and then specific words such as “radiation area,” “high radiation area,” or “very high radiation area” to make persons approaching the area aware of the radiation hazard present. The signs that are posted are required to have the radiation “symbol colored magenta, purple, or black on a yellow background

CARDINAL RULES OF RADIATION PROTECTION TIME DISTANCE SHIELDING

Protecting Patients & Personnel COMMUNICATE COLLIMATE SHIELD ↑ kVp ↓ mAs

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

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?

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

1. Collimate the x-ray beam to include only the anatomy of interest. 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

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

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

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

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

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

What is the difference between X-ray & Gamma? BEGIN RADIOBIOLOGY What is the difference between X-ray & Gamma?

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)

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)

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

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

Quality Factor “weighting factor for tissue” See ch 9 pg 197 6th 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

LET linear energy transfer The amount of energy that may be deposited in tissue as radiation passes Factor in assessing potential damage to organs/tissues LET to RBE (pg 114 Stat) LOW LET – X-RAY / GAMMA HIGH LET ALPHA FAST NEUTRONS

SED = SKIN ERYTHEMA DOSE LINEAR – NONTHRESHOLD DEPENDANT ON DOSE RECEIVED PERIOD OF TIME OVER IT WAS RECEIVED AREA OF IRRADIATED TISSUE SENSITIVITY

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 11 Stat CH 40 BUSHONG

Time to start some dose calculations……. Mr/mas A room uses TUBE OUTPUT 3.5 mR @ 80 kVp 2.5 mR @ 70 kVp 4.5 mR @ 90 kVp 5.6 mR @ 100 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

EXPOSURE RATES FLUORO MA IS 0.5 MA TO 5 MA PER MIN AVE DOSE IS 4 R / MIN IF MACHINE OUTPUT IS 2 R/MA/MIN = WHAT IS PT DOSE AT 1.5 MA FOR 5 MIN STUDY?

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 1 foot from the radiation source the intensity of exposure is 240 mR per hour and you remain at this location for 10 minutes, you then moved 2 feet away from the radiation source and remained there for 20 minutes? What is your dose when you moved? What is your total exposure? What did the patient receive?

Pregnancy & Exposure Tech & Patient Safety

Declared Pregnant Worker Must declare pregnancy – 2 badges provided 1 worn at collar (Mother’s exposure) 1 worn inside apron at waist level Under 5 rad – negligible risk Risk increases above 15 rad Recommend abortion (spontaneous) 25 rad (“Baby exposure” approx 1/1000 of ESE) www.ntc.gov/NRC/RG/08/08-013.html

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

DOSE TO FETUS VS ESE

“Embryo approx 1/50 mother ESE dose”

10 day rule No threshold for exposure Leukemia , congential abnormailies cancer induction, reasbortion or death of the embryo and genetic effects Therapetuic Abortion “not justified” 25 rads or less – no injury seen ABSORBED DOSES – 50 RADS – could result in a spontaneous abortion

FETAL EFFECTS Most sensitive in first trimester - large number or stem cells First two weeks – death by spontaneous abortion A dose of 10 rad (.10 gy) - expected death rate occurs at 10% higher than that would normally exist

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

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

PREGNANT PATIENTS ASCERTAIN LMP - IF FETUS IS EXPOSED PHYSICSTS WILL NEED INFORMATION: WHICH XRAY MACHINE USED (MR/MAS) # OF PROJECTIONS (INC REPEATS) TECHNIQUE FOR EACH EXPOSURE SID PATIENT MEASUREMENT AT C/R FLUORO TIME & TECHNIQUE USED PHYSICIST WILL CALCULATE FETAL DOSE

What is affected – 1st trimester SKELETAL SENSITIVE WK 2 – 10 CNS Wk 8 – 15 & organs CNS MOST PREVALENT TUMORS / METAL RETARDATION MORE ON FETAL EFFECTS LATER THIS SEMESTER IN RADIOBIOLOGY SECTION…

ADVISORY AGENCIES –Ch9 NCRP NCR BEIR BERT ICRP

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

NCRP

During Fluoro, for an under the table tube, the maximum intensity of scatter from the patient is received at a scatter angle of: A. 90 B 45 C.135 D. 30 degrees

During Fluoro, for an over the table tube, the maximum intensity of scatter from the patient is received at a scatter angle of: A. 90 B 45 C.135 D. 30 degrees

If you convert 12 millisieverts (mSv) to Rems you will obtain A 1.2 Rem B 120 Rem C 0.012 Rem D 12 Rem

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

Each time an x-ray beam scatters, its intensity at 1 meter from the scattering object is what fraction of its original intensity? A. 1/10 B. 1/100 C. 1/500 D. 1/1000

List one RECORDING method that HAS LOWER PATIENT DOSE: ______________________

Between spot film cassettes and photospot films, the_____will increase patient dose. However, between the two the ______will produce better image quality.

The x-ray tube current automatically increases to ________level of mA when a spot film is taken.

♀ 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 _______♀ by about ______ for ♂

RADIATION PROTECTION The Patient is the largest scattering object Lower at a _____ DEGREE ANGLE from the patient + PRIMARY BEAM AT 1 METER DISTANCE - ________ OF INTENSITY PRIMARY XRAY or _____

RADIATION PROTECTION The Patient is the largest scattering object Lower at a 90 DEGREE ANGLE from the patient + PRIMARY BEAM AT 1 METER DISTANCE - 1/1000 OF INTENSITY PRIMARY XRAY or 0.1%

Radiographic Exposure - Bushong At worst – you will have a life span shortening of 10 days/ 1 RAD RT is a SAFE profession

The END – Be Careful !!!