Radiation Safety for Licensed Practitioners Using

Radiation Safety for Licensed Practitioners Using Fluoroscopic X-Ray Equipment

Description

Content contact:

This course is radiation safety for physicians using fluoroscopic x-ray equipment.

Douglas Simpkin, Ph.D.Radiation Safety OfficerPhone: 649-6457Pager 222-7298

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Radiation Safety for Licensed Practitioners Using Fluoroscopic X-Ray Equipment

Douglas J. Simpkin, Ph.D., DABR, FAAPMMedical Physicist & Radiation Safety OfficerAurora St. Luke’s Medical Center414-649-6457, pager [email protected]

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Summary: To Minimize Patient Dose

• ONLY X RAY WHEN YOU ARE PREPARED TO VISUALLY INTERPRET THE FLUORO IMAGE ON THE MONITOR.

• Minimize x-ray beam on-time• Fluoro at low frame rates• Fluoro at low dose rate settings• Minimize amount of ciné/DSA• Utilize distance

- Keep the patient skin far from the x-ray tube - Keep the image receptor close to the patient

• Empty patient bladder of iodine for pelvic procedures• Cone-in to the smallest practicable beam size• Minimize patient skin dose by spreading x-ray over a

larger area by small changes in projection

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Summary: To Minimize Worker Dose

• Each worker must wear a lead apron• Each worker must wear their radiation badge (if one has

been assigned)• Each worker should stay as far from the patient as

possible• The operator should

- ONLY X RAY WHEN THE PHYSICIAN IS PREPARED TO VISUALLY INTERPRET THE FLUORO IMAGE ON THE MONITOR.

- Minimize x-ray beam on-time- Fluoro at low frame rates- Fluoro at low dose rate settings- Minimize amount of ciné/DSA- Empty patient bladder for pelvic procedures- Cone-in to the smallest practicable beam size

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Introduction

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Regulatory Requirements of Operators

• The State authorizes only licensed practitioners to independently use fluoroscopic x-ray equipment.

- Physicians, Podiatrists- Nurse practitioners, Physician Assistants- Radiologist’s Assistants- Dentists, Chiropractors- licensed in the state of Wisconsin

• Initial radiation safety training is required by WI.• Annual radiation safety retraining is required by

Joint Commission.

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Fluoroscopic X Ray Imaging

• X rays are produced in an x-ray tube, and the invisible beam of x-rays is put onto the patient

• Those parts of the patient that are thick, dense, or of high atomic number, absorb more x rays than surrounding tissues.

• The x-ray beam transmitted through the patient is imaged by an image receptor.

X-ray Tube

Image Receptor

X-ray Beam

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X ray imaging delivers radiation dose to the patient

• Countless patients over the past century have benefited from their physician being able to visualize function and anatomy using x-ray imaging.

• All x-ray imaging delivers radiation dose to the patient. There are two concerns from this dose:1. Any dose increases the risk to the patient of

developing cancer. This small increase in risk mustbe greatly outweighed by the benefit of enhanced diagnostic information.

2. If the radiation dose is sufficiently high, the skin of the patient will be damaged.

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Skin damage from prolonged x-ray exposure in interventional procedures

at 6 weeks at 18 months

The effect of ~20,000 mGy from 3 angioplasty

procedures on the same day.

The effect of the patient draping his arm on the lateral x-ray tube in a

biplane room.

at 3 weeks at 12 months

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Skin damage from prolonged x-ray imaging in interventional procedures

These must be considered

unacceptable consequences

of medical imaging!

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FDA and Joint Commission Requirements• By 1994 the FDA had called attention to the problem of skin

burns from fluoroscopy, and recommended methods for minimizing skin dose.

• In 2006 FDA required new x-ray fluoro units to monitor patient skin dose.

• In 2007 the Joint Commission deemed any fluoroscopic skin dose in excess of 1,500 rad (15,000 mGy) to be a Sentinel Event.

• This presentation will assist you in understanding - How to minimize your patient’s dose and thereby avoid such effects.

- How to minimize your occupational dose while performing procedures

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Modern Fluoro X-Ray Machines

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Continuous vs Pulsed Fluoroscopy

• Continuous fluoroscopy- X-ray beam is on continuously as long as the foot pedal is

activated- The image receptor is read and the image on the monitor

updated in real-time (30 times per second)• Pulsed fluoroscopy may be available

- X-ray beam is on for short bursts, each lasting ~3 to ~10 msec• Short burst needed to freeze patient motion

- The rate of these pulses is user-selectable:• Real time: 30 frames per sec (fps), or pulses per sec (pps)• Less than real time:

• 15 fps• 7.5 fps• etc

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Pulsed Fluoroscopy

• Patient dose (and dose to those in the room) may be reduced using pulsed fluoroscopy

- 30 frames per sec (real time) = same dose as continuous fluoro

- 15 fps = 1/2 the dose of continuous- 7.5 fps =1/4 the dose of continuous

• The price is poorer temporal resolution, since the image is not updated as often

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Pulsed Fluoroscopy: low frame rate = low dose

Time

X ray pulses

Fluoro images

30 fps

Time

X ray pulses

Fluoro images

15 fps

33 msec

67 msec

½ THE DOSE!

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Use Last Image Hold (LIH) in Fluoroscopy

• “Last Image Hold” on a fluoro system displays the last acquired fluoro image even after the x-ray beam is turned off

• “Last Image Hold” has been found to be useful in allowing the physician to interpret the information on the fluoro monitor without additional radiation exposure.

Time

X ray pulses

Fluoro monitor shows the

same image

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Fluoroscopy Dose Rate Settings

• Modern x-ray units may allow the user to fluoro at various radiation dose rates (by adjusting mA and filter)

- GE: • “Low Detail” (= lower dose rate) vs • “Normal Detail” (= higher dose rate)

- Siemens:• “Fluoro –” (= lower dose rate) • “Fluoro normal”• “Fluoro +” (= higher dose rate)

• Higher dose rate fluoro - Generates images with less noise - But, delivers higher patient and operator radiation doses

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C-arm Fluoroscopy Dose Rate Settings

• Modern C arm x-ray units may allow the user to fluoro at various radiation dose rates

• GE / OEC C arms: - “Normal Fluoro” (typical 30 fps live fluoro)- Pulsed Fluoro (8 pulses per sec) = 25% of the dose

rate of Normal Fluoro- “Low Dose” Fluoro = 40% of the dose rate of Normal

Fluoro- “High Dose Rate Fluoro” typically gives ~85% MORE

dose than Normal Fluoro

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Mini-C-arm Fluoroscopy Dose Rates

• Mini-C arm x-ray units - Operate the x-ray tube

at very low mA and not more than 81 kV

- Have small x-ray beams, and so generate relatively little scatter

- However, they still generate x-rays and must be used with caution

X-ray tube

Image Intensifier

X-ray beam

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Basic Physics

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The Radiation Intensity Varies with Distance from the Source

• Consider a source of radiation, for example- The x-ray tube focal spot (for the primary beam), or- Scatter generated in the patient

• The intensity (dose) of radiation varies with distance from the source as 1/distance2

distance

Dose meter

X-ray source

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The Radiation Intensity Varies with Distance from the Source: Examples

100 cm

100 mGy

200 cm

25 mGy

50 cm

400 mGy

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The Radiation Intensity Decreases with Increasing Distance from the Source

200 cm

25 mGy

100 cm

100 mGy

50 cm

400 mGy

Doubling the distance cuts the x-ray intensity to 1/22 = 1/4 of its original value

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The Radiation Intensity Increases with Decreasing Distance from the Source

100 cm

100 mGy

200 cm

25 mGy

50 cm

400 mGy

Cutting the distance in ½ increases the x-ray

intensity by 2 2 = 4 times greater than its original

value

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The Radiation Intensity Varies with Distance from the Source

100 cm

100 mGy

200 cm

25 mGy

50 cm

400 mGy

“It’s hotter closer to the

fire”

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Automatic Brightness Control (ABC)

• Fluoroscopy and cine fluorography use a feedback system to maintain the brightness of the image at an acceptable level.

• Automatic Brightness Control (ABC):- ABC measures the radiation intensity seen at the

image receptor- ABC adjusts the x-ray technique (mA, kV, beam filter,

pulse width) in order to compensate for patient attenuation, distance from x-ray tube, etc to maintain a constant x-ray intensity at image receptor input

• ABC strives to maintain optimal image quality

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Automatic Brightness Control (ABC)

patient

X-ray tube: creates x rays

Measures x-ray intensity, tells generator to adjust technique to maintain a constant x-ray intensity to image receptor

ABC feeds back to generator to adjust technique

X-ray generator (Sets kV, mA, pulse width, beam filter)

Image receptor

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ABC sets the dose

• The image receptor sees less x-ray intensity for more patient attenuation

Thin patient body part

X-ray tube

Image receptor

More intensity seen, ABC asks for fewer x rays

Thick patient body part

X-ray tube

Image receptor

Less intensity seen, ABC asks for more x rays

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ABC requires thick patients to get higher skin dose

• The image receptor sees less intensity for more patient attenuation

Thin patient body part

X-ray tube

Image receptor

Less patient skin dose

Thick patient body part

X-ray tube

Image receptor

More patient skin dose

Imaging thick body

parts requires

more skin dose

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ABC requires higher skin dose when imaging through highly attenuating objects in patient


Less patient attenuation

X-ray tube

Image receptor


More patient attenuation e.g. bladder full of iodine

X-ray tube

Image receptor

More patient skin dose

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ABC requires higher skin dose when imaging through highly attenuating objects in patient


Less patient attenuation

X-ray tube

Image receptor


More patient attenuation

X-ray tube

Image receptor

More patient skin doseImaging through a urinary bladder full of iodine contrast medium will cause the skin dose to be at least twice what it would be if the bladder was empty.

For lengthy procedures in the pelvis , have the patient urinate to remove the iodine.

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ABC sets the dose

• The image receptor sees more x-ray intensity at short Source-Image receptor Distances (SID)

patient

X-ray tube

Image receptor

patient

X-ray tube

Image receptor

Less intensity seen, ABC asks for more x rays

Long

SID

More intensity seen, ABC asks for fewer x rays

Sho

rt S

ID

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ABC will minimize patient skin dose if the image receptor is kept close to the patient

• The Object-to-Image Receptor distance should be minimized to minimize patient skin dose

patient

X-ray tube

Image receptor

patient

X-ray tube

Image receptor

More Patient Skin Dose

Less Patient Skin Dose

Keep the image receptor close to

the patient to minimize skin

dose

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ABC will keep the x-ray intensity at the image receptor constant , BUT…

• For short distances from x-ray tube to patient, the skin dose will be large

patient

X-ray tube

Image receptor

patient

X-ray tube

Image receptor

Patient farther from x-ray tube

Patient close to x-ray tube

X ray intensity at image receptor is

the same

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ABC will keep the x-ray intensity at the image receptor constant , BUT…


patient

X-ray tube

Image receptor

patient

X-ray tube

Image receptor

Less Patient skin Dose

More Patient skin Dose


the same

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ABC will keep constant the x-ray intensity at the image receptor , BUT


patient

X-ray tube

Image receptor

patient

X-ray tube

Image receptor

Less Patient DoseMore Patient Dose


the same

Keep the patient as far from the x-ray

tube as possible to minimize the skin

dose.

Raise the table for under-table tube

techniques

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Keep patient away from the x-ray tube

• Even a small increase in x-ray tube – to –skin distance helps:

- Raising the table 10 cm (~4 inches) from 55 to 65 cm distance from the x-ray tube will decrease the skin dose to (55/65)2 = 0.72 of its value at 55 cm.

- That’s a 28% skin dose savings from just a 10 cm (~4 inch) raise of the table .

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And don’t let any part of the patient get too close to the x-ray tube!

• If part of the patient (e.g. an arm) gets too close to the x-ray tube (e.g. in a lateral projection, especially in a biplane interventional room) skin doses can be very high, possibly leading to this:

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X Rays Interact with Matter

• X rays interact with matter (e.g. in the patient or the image receptor) by either

- Absorption by the photoelectric effect• The energy of the x-ray is transferred to the

medium• The X ray disappears

- Compton Scatter• The original x ray disappears, and a second

(often lower-energy) x ray is sent out in a different direction

X ray’s energy absorbed here

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Scatter degrades contrast in the image

X-ray tube

Opacified artery (iodine contrast material stops more x rays than surrounding tissue)

Scatter x rays fill in the shadow of the artery,

diminishing its contrastImage receptor

patient

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Scatter exposes others in the room

X-ray tube

patient

Scattered x-rays from the patient are the main source of exposure to workers in the room.

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Bigger x-ray beams create more scatter

Bigger beam = more scatter = greater loss in contrast

Smaller beam = less scatter = less loss in contrast

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Scatter exposes others in the room: bigger beams generate more scatter

X-ray tube

patient

Larger, less tightly collimated beam

Bigger beam = more primary x rays = more scattered x-rays formed = more exposure to workers nearby

•So cone-in!•Less scatter generated

•Better contrast in image•Less exposure to workers in the lab

•Smaller area of the patient exposed to radiation

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Dose, DAP, and Effective Dose Equivalent

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Radiation Dose Specifications - Dose

• Absorbed Dose (or simply “dose ”)- Is the ratio of absorbed radiation

energy to the mass of the medium in which the energy is absorbed

- If the medium is air, the dose to air is the Air Kerma (“kinetic energy released per mass of air”)

- Dose to a tissue is a good predictor of biological effects due to cell killing (called “deterministic effects”) from large radiation doses

• Skin damage is predicted by dose

Energy Deposited

Mass

Mass

DepositedEnergyDose=

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Radiation Dose Specifications - Dose

• Units of absorbed dose or kerma- Traditional Units (used for regulations in USA):

• rad or millirad, where 1 rad = 1,000 mrad- SI (metric) Units (used by rest of the world):

• Gray (Gy) or milliGray (mGy)• 1 Gy = 1,000 mGy• For example, 15,000 mGy = 15 Gy

- Note: • 100 rad = 1 Gy, so 1 rad = 10 mGy• And 1,500 rad = 15 Gy = 15,000 mGy

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Doses to different regions don’t add!

First 10 mGy here

then 10 mGy here

10 mGy to whole area

10 mGy + 10 mGy is not 20 mGy

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Doses to overlapping regions do add!

First 10 mGy here

then 10 mGy here

10 mGy20 mGy to overlapped area

10 mGy + 10 mGy is 20 mGy to overlapped area

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Skin doses to different regions don’t add!

If you keep the C arm stationary for the procedure, the same patch of skin gets exposed to a large dose

If you angle the C arm slightly during the procedure, you spread out the dose over a larger area of skin, minimizing the dose to any one patch of skin

6 Gy 3 Gy 3 Gy

Possible burn Probably no burn

•You may be able to spread the dose across a larger area of the patient skin by angling the C arm during the proced ure.

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Radiation Dose Specifications - DAP

• Dose-Area Product (DAP)- DAP = Dose in x-ray beam × Area of Beam- DAP is independent of distance from x-ray tube (since change in

beam area exactly matches the change in dose via the 1/r2 law- DAP is measured by some x-ray units by

• Estimating the dose (from the x-ray technique or exposure through the collimator)

• Knowing the beam area from collimator settings- DAP is therefore easy to measure and specify

• Units of DAP measurement - Gy cm2

- cGy cm2 (= 0.01 Gy cm2)

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Radiation Dose Specifications - DAP

The DAP is the same at these two locations

At skin of patient

At collimator

•Dose-Area Product, DAP, is easy to measure

X-Ray Tube

If you know the area of the beam at the skin of the patient, then the

Skin Dose = DAP/Area

So if the DAP is 200 Gy cm 2

and the x-ray beam area at the patient skin is 100 cm 2, then the skin dose is 200/100 = 2 Gy = 2,000 mGy.

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Radiation Dose in the Primary Beam is Reported by the Modern X-Ray Unit

• FDA requires interventional x-ray units manufactured since 2006 to show the radiation dose (and dose rate) in air at a point in the primary radiation beam

- This “Interventional Reference Point” is typically 15 cm from the unit’s isocenter, toward the x-ray tube

- This approximates the location where the beam enters the patient skin

• This dose may be - Calculated by the unit knowing the x-ray techniques (kVp, mA,

exposure time, filter, etc), or,- Measured as DAP at collimator / beam area at “Interventional

Reference Point” implied from collimator settings

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Radiation Dose in the Primary Beam is Reported by the X-Ray Unit

X-ray tube

Image receptor

Isocenter

15 cm from isocenter

“Interventional Reference

Point”

The gantry / C-arm rotates around isocenter

•At the “Interventional Reference Point”

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Radiation Dose in the Primary Beam is Reported by the X-Ray Unit

X-ray tube

Image receptor

Isocenter

15 cm from isocenter

The “Interventional Reference Point” approximates the point where the x-ray beam enters the patient skin.

Dose to air at this point ≈ skin dose .

Patient

Air dose is reported at the “Interventional Referen ce Point” which approximates the position of the patient skin

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Radiation Dose in the Primary Beam is Reported by the Modern X-Ray Unit

•Air dose at the “Interventional Reference Point” is reported

• In mGy (GE and most Siemens units)

Reported in the procedure room and at control panel

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Patient Dose Rates: Mini-C-arm Fluoroscopy

• Depending on the patient thickness and attenuation, distance from x-ray tube to skin, beam size, and x-ray unit calibration, the dose rate to the skin of the patient using mini-C-armfluoroscopy (such as is used in orthopedic surgery) is

- Typically 2 to 5 mGy per minute of fluoro operation

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Patient Dose Rates: Normal Fluoroscopy

• Depending on the patient thickness and attenuation, distance from x-ray tube to skin, beam size, and x-ray unit calibration, the dose rate to the skin of the patient during fluoroscopy is

- Typically 10 to 50 mGy per minute of normal fluoro operation (for continuous or 30 fps fluoro)

- And this must not exceed (per regulation) a maximum of 100 mGy per minute for standard fluoro operation

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Patient Dose Rates: “ High Dose Rate ” or “ Fluoro Plus ” Fluoroscopy

• When accessing this higher dose rate mode of operation, you may have to use a special foot switch, and a special light and sound tone may come on to remind you of the higher doses being used

• In high dose rate fluoro, the skin of the typical patient will receive 20 to 90 mGy per minute of fluoro operation (for continuous or 30 fps fluoro)

- And this must not exceed (per regulation) 200 mGy per minute maximum for High Dose Rate fluoro

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Interventional Patient Dose Rates: Fluorography (ciné)

• Depending on the patient thickness and attenuation, distance from x-ray tube to skin, beam size, and x-ray unit calibration, the dose rate to the skin of the patient during fluorography (digital ciné or recorded imaging) is, for typical frame rates (ciné done at 3.75 fps and fluoro done at 15 fps), about 10 to 15 × the dose rate (per minute) for fluoro.

• Only use ciné when absolutely necessary.• There is no regulatory limit to the ciné dose rate.

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Dose = Dose Rate x Time

• The radiation dose to both the patient and workers in the procedure room is primarily determined by the TIME that the physician has his/her foot on the exposure pedal.

• Longer fluoro/ciné times = higher dose.• While no one may tell a physician how to

practice medicine (e.g. how long to fluoro), the physician must be aware that the he/she controls the dose received by the patient and your fellow caregivers.

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Radiation Dose Specifications - EDE

• The Effective Dose Equivalent ( EDE) is the single dose value that best states the risk to a person for “stochastic radiation effects” (cancer and genetic mutations)

- The higher the EDE, the higher the risk of cancer or mutations

• EDE Determination- Determine the dose equivalent to those organs in a person that

are at risk for cancer or inheritable genetic mutations- Multiply each of those organ dose equivalents by an organ

weighting factor, wt , based on the risk of that organ becoming malignant (or passing on a genetic mutation), moderated by the response of the cancer to treatment

- Accumulate the sum of these weighted organ doses

EDE = sum of { dose to ea organ × that organ’s weighting factor}

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Organ doses contributing to EDE

Thyroid ( wt=0.03)

Lungs ( wt=0.12)Breasts ( wt=0.15)

Gonads ( wt=0.25)

Bone Surfaces (wt=0.03)

(The Effective Dose is a similar but more modern concept, using a more complete list of contributing organ doses. US regulators have not yet migrated to Effective Dose.)

Remainder of abdomen/thorax (wt=0.30)

wt=organ dose weighting factor toward EDE

Bone Marrow ( wt=0.12)

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Radiation Dose Specifications - EDE

• Units of EDE- Traditional Units:

• rem or millirem, where 1 rem = 1,000 mrem- SI (metric) Units:

• Sieverts (Sv) or milliSieverts (mSv)• 1 Sv = 1,000 mSv• For example, 5,000 mSv = 5 Sv

- Note: • 100 rem = 1 Sv, so 1 rem = 10 mSv• And 5,000 rem = 50 Sv = 50,000 mSv

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Regulations

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State of Wisconsin Regulates use of X-rays in Medicine

• Use of X Rays in medicine is regulated by the State of Wisconsin Department of Health Services

• Physician operators of fluoroscopy equipment are required to be trained in radiation safety per DHS 157.76(11)(e)

• The State enforces the dose limits (described later)• You have the responsibility to report any unsafe radiation

situations to your Radiation Safety Officer • You have the right to call the State at (608)-267-4787 with

concerns about radiation use at the hospital that you believe are not being addressed.

• For additional information go to http://dhs.wisconsin.gov/dph_beh/BEH/Xray/index.htm

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Types of Radiation Exposure a person may receive:

• Background radiation- Radon-222 gas seeping up from the ground into

your home- Radium-226 in your drinking water- Cosmic radiation from outer space- Terrestrial radioactive sources around and in us- The average American receives an EDE of 3.1

mSv annually from background radiation

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• Medical exposures as the patient- CT, nuclear medicine, interventional radiology

exams- The average* American receives an EDE of 3.0 mSv

annually from medical radiation

* The average is just the estimated dose per procedure × # procedures done in the country ÷ population size. Any one patient will receive much more than the average dose!

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• Medical exposures- There is no limit on the amount of

medical exposure a patient may receive , since all such exposure is medically indicated.

- However, the Joint Commission has deemed a radiation dose to the skin of the patient in excess of 15,000 mGy (=1,500 rad = 15 Gy) from fluoroscopic x rays to constitute a Sentinel Event

- ….more about that in a few moments….

7,800 mGy at 2 weeks

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• Occupational exposure- Radiation dose received while earning your

paycheck.- The amount of occupational exposure a worker

receives: • Is required by State regulations to not exceed

specified dose limits• Is monitored in accordance with State

regulations

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• When averaged over the whole population, the average American receives a total EDE of 6.2 mSv annually from all sources.

• Everyone gets some radiation!• But remember that this is an average:

- Individual patients will receive much more than this.- Individual workers may receive much more than this.

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State-regulated Occupational Dose Limits

• The EDE from occupational radiation to a worker can’t exceed 50 mSv (=5,000 mrem) per calendar year .

• Since most radiosensitive organs are protected by the lead apron in fluoro, the EDE is less than 30% of the collar level badge reading.

• For a worker with both a collar-level badge and an under-apron waist badge, the EDE is calculated by adding 4% of collar reading to 150% of waist reading.

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State-regulated Occupational Dose Limits

• Occupational dose to the lens of the eyecan’t exceed 150 mSv (15,000 mrem) per year

• Occupational dose to any one organ, the skin, or an extremity can’t exceed 500 mSv (50,000 mrem) per year

• Dose to the fetus of a pregnant radiation worker is limited to 5 mSv (500 mrem) for the whole term, and should not exceed 50 mrem in any one month.

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A Pregnant Radiation Worker

• Pregnant workers may declare their pregnancy in writing to the Radiation Safety Officer.

• An additional “baby” badge will be issued, to be worn at waist level inside the lead apron to monitor fetal exposure.

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“ALARA”

• As Low As Reasonably Achievable• The hospital is pledged to keeping workers’

exposure levels as low as reasonably achievable.

• Your radiation badge readings are reviewed by the Radiation Safety Officer quarterly and Radiation Safety Committee if applicable.

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Radiation Badges Monitor Occupational Dose

• Radiation Monitoring Badges are given to fluoroscopy operators and anyone who might receive an occupational dose of radiation in excess of 10% of the dose limit- Your Radiation Safety Officer may have

identified some classes of radiation workers whose occupational dose is so low that monitoring is not required.

• The badges monitor your exposure to radiation. They do not protect you from radiation.

• If you have been assigned a badge, wearing the badge is not optional …They are required by State Law!

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Radiation Monitoring Badges in Interventional Labs

• In some interventional labs two badges are assigned to each worker:

• Yellow Badge- Is to be worn at waist

level inside the lead apron (“yellow belly”)

• Red Badge- Is to be worn at the

collar level outside of the lead apron (“red neck”)

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You must wear both badges correctly!

• The calculation used to determine your occupational dose presumes that you’ve worn both badges, in the locations assigned.

• If you don’t wear the badges properly, your dose reading will be wrong!

NO…(She’s got her waist badge outside the apron!!)

( ) ( )WaistCollarEDE ×+×= 5.104.0

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NO… (Both badges are inside the apron)

NO… She’s not wearing any badges!

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Photo of person with apron wearing both badges correctly

Red collar badge is outside apron

Yellow waist badge is inside apron. Note that you can, if you like, tape the badge (without the grey holder) to the inside of your apron with the front of the badge facing away from you. It might be more comfortable.

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Radiation Monitoring Badges in most other Departments

• A single Black or Red Badge is assigned

- Is to be worn at the collar level outside of the lead apron

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Know your Radiation Monitoring Badge

• Do not tamper with the badge• Store your badge in a safe, low exposure area• Exchange badges on the 1st of the month (or the day

specified by your Radiation Safety Officer)• The badges are the property of Aurora Health Care to monitor

your exposure while you are a worker here• The Radiation Safety Officer evaluates the exposure of the

badges on a routine basis and investigates any abnormal exposures

• Annually, you will be given a copy of your radiation exposure readings (if the readings exceed 10% of the dose limits)

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How to Minimize Your Dose

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Rules for Minimizing Your Occupational Radiation Exposure

• Scatter off the patient is the main source of your radiation exposure.

• Intensity of the scatter depends on - The dose rate at the skin of the patient- The size of the beam hitting the patient - Your distance from the patient

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• Typical scatter intensities at 3 ft from where the x-ray beam enters the patient:

- Mini-C-arm: 0.0004 mGy per minute of fluoro - Normal fluoro (C-arm and other fluoro units): 0.01 to

0.05 mGy per minute of fluoro- Ciné: 0.1 to 0.75 mGy per minute of ciné

3 ft

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• Minimize the time spent near a radiation source- Fluoro for the minimum time needed for the procedure

• Maximize the distance between you and the x-ray beam in the patient

• Maximize the shielding between you and the source of radiation

- You must* wear a lead apron during the procedure, (preferably a wrap-around with a thyroid collar in an interventional procedure)

- (*except in mini-C arm procedures, for workers farther than 2 feet from the patient)

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Rules for Minimizing Your Occupational Radiation Exposure: Minimize Time

• Minimize the time spent near a radiation source- As the physician in control of the foot switch, the

amount of radiation dose delivered to your patient, those assisting you in the procedure, and to you is primarily determined by

• How long you fluoro, and, • How many ciné runs you do!• Minimize these and you’ll minimize everyone’s

dose!- To remind you of the passage of time, the x-ray unit

will sound an alarm every 5 minutes of fluoro use.

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Rules for Minimizing Your Occupational Radiation Exposure: Minimize Time

• ONLY X-RAY WHILE YOU ARE LOOKING AT THE FLUORO IMAGE.

• If you are looking anywhere other than the fluoro monitor, DON’T X RAY!

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Rules for Minimizing Your Occupational Radiation Exposure: Maximize Distance

• The intensity of the scatter decreases as you move away from the patient

Scatter off patient

Scatter off patient

Double the distance = ¼ the dose

Maximize the distance from the patient to minimize your dose.

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Rules for Minimizing Your Occupational Radiation Exposure: Maximize Shielding

• You must* wear a Lead Apron when in a fluoro procedure,- Lead aprons are required by State regulation

(*except in mini-C arm procedures, for workers farther than 2 feet from the patient)

- Aprons cut the dose to the covered body parts by 95-98%.

• Also, all x-ray rooms have shielding built into the walls- Stay behind the control booth if you don’t have your

lead apron on.- Keep the room doors closed during the procedure.

• Operating Rooms will have been evaluated for shielding requirements, and may or may not require lead shielding

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Also…

• Never put your hand in the primary x-ray beam, especially before it enters the patient

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How to Minimize the Patient’s Skin Dose

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Regulations to Minimize the Patient’s Dose

• By regulation, all fluoroscopic imaging must be done with a Licensed Practitioner present to interpret the real-time image.

• Know the pregnancy status of your patient before beginning any diagnostic x-ray study. Procedures on pregnant patients must be approved by the physician before the procedure.

• Gonadal shielding is required by State regulation if the patient’s gonads are in the primary x-ray beam but they are not required to be in the image.

• Avoid repeats; a repeat doubles the radiation exposure

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Effects of Radiation Dose on The Skin

• The severity and time-course of effects on the skin depend very strongly on the radiation dose delivered.

• High skin doses will cause effects that - Are apparent within weeks, and- May last longer than a year, and, - May require plastic surgery to repair.

Wound from 20,000 mGy at 18 months

Same wound after skin graft

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Effects of Low Skin Doses

Skin DoseWithin1 month

1 month to 1 year After 1 year

0 to 2,000 mGy

No effect expected

No effect expected

No effect expected

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Effects of Intermediate Skin Doses



2,000 to 5,000 mGy

Transient erythema, hair thinning

Hair recovery

No effect expected

5,000 to 10,000 mGy

Transient erythema, epilation

Recovery, but prolonged erythema at high doses

Recovery, but possible permanent skin changes at high doses

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Effects of High Skin Doses



10,000 to 15,000 mGy

Erythema, epilation, moist desquamation

Permanent epilation, prolonged erythema

Telangiectasia, induration, weakened skin

> 15,000 mGy

Erythema, epilation, moist desquamation, possible ulceration at very high doses

Dermal atrophy, ulceration, dermal necrosis. Destruction of skin/ tissues to ~cms depth. Surgical intervention often required.

Telangiectasia, induration, dermal atrophy, ulceration. Anyhealing without plastic surgery will lead to scar tissue, weak skin

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To Address Concerns with Patient Skin Doses, and to Satisfy Joint Commission:

• Aurora St. Luke’s Med. Ctr. Policy #219 “Patient Skin Radiation Monitoring in Interventional Cardiology” has been instituted in the Cath Lab

• Aurora Health Care Policy #2314 “PATIENT RADIATION DOSE MANAGEMENT IN INTERVENTIONAL RADIOLOGY” has been implemented in IR.

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To Address Concerns with Patient Skin Doses, and to Satisfy Joint Commission:

• Its purpose:- “…to prevent significant radiation-induced skin injuries

associated with interventional fluoroscopy and fluorography in patients in interventional cardiology and interventional radiology. The goal is to provide immediate notification as well as prompt response and evaluation to all unexpected health events of this nature to patients.”

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“Patient Skin Radiation Monitoring in Interventional Cardiology and Interventional Radiology” Requires:

• Training- All interventional physician operators should meet

institutional requirements for fluoroscopic credentialing. This shall include documented competency following content in ACCF/AHA/HRS/ SCAI (2005) “Clinical Competence Statement…”Circulation, 111:511-532.

- All other staff involved in guided diagnostic or interventions in IR, Cath lab and EP lab shall receive initial and annual review in patient radiation management.

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• Patient consent :- Given the severity of these skin burns as an

unintended consequence of the interventional procedure, patients will be consented prior to the interventional case.

- Radiation risks associated with interventional procedures should be discussed with patients as part of the pre-procedure informed consent process. There is a radiation-specific section on hospital provided informed consent documents.

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• During the interventional procedure, every effort should be made to minimize the patient skin dose :

- Operate at the lowest fluoroscopic dose rate that yields adequate images, using the least amount of fluoroscopic time and acquisition of the least number of cine/fluorographic images consistent with achieving the clinical goals of the procedure.

- Appropriate collimation should be used.- The x-ray tube-to-image receptor distance should be maximized

and the patient-to-image receptor distance minimized.- C-arm angles are varied slightly from time to time if this does

not interfere with the conduct of the clinical procedure, in order to the spread the dose across larger areas of skin

- If imaging through the pelvis, urge the patient to urinate (or use a foley catheter) during the procedure in order to minimize the accumulation of iodine contrast in the patient’s urinary bladder

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• During the interventional procedure the accumulated skin dose (displayed by the interventional x-ray unit) will be monitored by staff in the room.

- The physician will be notified verbally of the accumulated dose once it reaches 4,000 mGy (or a DAP of 400 Gy cm2)

- The physician will be updated verbally of the accumulated dose every 1,000 mGy (or a DAP of 100 Gy cm2) thereafter.

- If the dose reaches 12,000 mGy (or a DAP of 1200 Gy cm2), the physician makes the decision to continue or discontinue the procedure. The physician will be aware that severe skin damage may result. It is the physician’s prerogative to continue as medically indicated. The reason for continuing the procedure is then documented by the physician in the medical record.

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• After the interventional procedure- The total skin dose is recorded in the medical record.- If the skin dose exceeded 5,000 mGy (or a DAP of 500

Gy cm2)• Arrangements for follow-up are made with the patient. The

patient will be given a “For Your Well-Being” instructing him to notify both the procedural physician and the hospital department two weeks after the procedure to report if any skin reaction is seen.

• If needed, the physician will have access to Wound-Care for follow-up.

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• After the interventional procedure- If the skin dose exceeded 15,000 mGy (or a

DAP of 1500 Gy cm2)• A Sentinel Event may have occurred• The Radiation Safety Officer will be notified to

perform a more detailed analysis of the skin dose.• You will be required to participate in a Root-Cause

Analysis to investigate the procedure

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A Sentinel Event is very unlikely for a portable C arm procedure

• For normal fluoroscopy, the dose rate at the patient skin is typically in the range of 10-50 mGy per minute of fluoro.

• Therefore, a 15,000 mGy Sentinel Event requires

- Fluoroscopy on a typical patient: 5 to 25 hours of normal fluoroscopy, or

- High Dose Rate fluoroscopy on an obese patient: 1¼ hours at maximum permitted fluoro dose rate

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Other Effects of Radiation on Humans

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Effects of Radiation on Humans• There are two categories of radiation effects

- Deterministic effects• Due to large doses killing cells• The larger the dose, the more severe the effect• The effect is not seen unless the dose exceeds a

threshold• Described by the radiation dose (in mGy)

- Stochastic effects• Due to radiation modifying cells• The larger the dose the greater the risk for

radiocarcinogenesis and radiomutagenesis• The severity of the effect does not depend on the dose • Described by the effective dose equivalent (EDE, in mSv)

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Deterministic Effects Can:

• Kill a person by the Acute Radiation Syndrome- 4,500 mGy given acutely to every organ gives a 50/50

chance of dying of the hematopoetic syndrome within 2 months

• Decrease fertility- 500 mGy will temporarily decrease male fertility- 4,000 mGy will cause permanent sterility in both sexes

• Cause cataracts- 8,000 mGy chronically will cause a cataract

• Damage skin

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Deterministic Effects on the Embryo/Fetus

• Large doses (>5,000 mGy) to the fetus early in pregnancy will terminate the pregnancy

• During the 8th-15th week, radiation dose above 100 mGy will decrease the mental capacity of the child

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Stochastic Effect: Radiocarcinogenesis

• Exposure to radiation increases the risk of cancer. - A single exposure causing an EDE of 100 mSv is estimated to

cause 1% of an exposed population to develop cancer, with lower cancer risks at lower doses.

- For interventional procedures delivering 2,000 mGy of localized skin dose, the risk to the patient for radiocarcinogenesis is less than 1%, and much less for patients over 50 years old.

• This risk is on top of a huge naturally occurring incidence rate: 42% of Americans will be diagnosed with cancer during their lifetimes.

• The risk to radiation workers who do not exceed the dose limit is not greater than the risk to workers in the safest occupations.

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Stochastic Effect: Mutagenesis

• Mutagenesis, or the genetic effect, occurs when- The reproductive organs of the parents are

exposed to radiation- The parents then conceive- The baby has incorrect genetic information

• The risk for the genetic effect is no greater than that for radiocarcinogenesis, and has never been seen in humans

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References

• ACCF/AHA/HRS/SCAI (2005). Clinical Competence Statement on Physician Knowledge to Optimize Patient Safety and Image Quality in Fluoroscopically Guided Invasive Cardiovascular Procedures: A Report of the American College of Cardiology Foundation/American Heart Association/American College of Physicians Task Force on Clinical Competence and Training. Circulation, 111:511-532.

• ACR (2013). ACR–AAPM technical standard for management of the use of radiation in fluoroscopic procedures. Accessed at http://www.acr.org/~/media/ACR/Documents/PGTS/standards/MgmtFluoroProcedures.pdf

• Balter S, Hopewell JW, Miller DL et al.(2010). Fluoroscopically Guided Interventional Procedures: A Review of Radiation Effects on Patients’ Skin and Hair. Radiology 254:326-341.

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References• Centers for Disease Control (CDC). Cutaneous radiation injury: fact sheet

for physicians.” Accessed at www.bt.cdc.gov/radiation/criphysicianfactsheet.asp.

• Miller DL, Balter S, Schueler BA, Wagner LK, Strauss KJ, Vañó E. (2010) Clinical radiation management for fluoroscopically guided interventional procedures. Radiology. 257(2):321-32

• National Council on Radiation Protection and Measurements (NCRP). (2010). Radiation Dose Management for Fluoroscopically-Guided Interventional Medical Procedures, NCRP Report No. 168 (National Council on Radiation Protection and Measurements, Bethesda, Maryland).

• Stecker MS, Balter S, Towbin RB et al. (2009). Guidelines for Patient Radiation Dose Management. J Vasc Interv Radiol 20:S263–S273.

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References

• Steele JR, Jones AK, Ninan EP. (2012). Quality Initiatives; Establishing an Interventional Radiology Patient Radiation Safety Program. RadioGraphics 32: 277–287.

• Thabet A1, Kalva SP, Liu B, Mueller PR, Lee SI. (2012) Interventional radiology in pregnancy complications: indications, technique, and methods for minimizing radiation exposure. Radiographics 32(1):255-74.

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Further Questions?

• Contact Douglas Simpkin, Ph.D., the Radiation Safety Officer of Aurora St. Luke’s Medical Center,

- Telephone: 414-649-6457- Fax: 414-649-5118- Pager: 414-222-7298- Email: [email protected]