Muhammad Naveed SaeedCardioVascular TechnologistCardiac Catheterization LaboratoryKFSH&RC Heart Centre

April 13, 2017

Radiation Hazards & Safety

Muhammad Naveed SaeedCardioVascular TechnologistCardiac Catheterization LaboratoryKFSH&RC Heart Centre

April 06, 2017

What is Radiation

PHYSICSthe emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles that cause ionization.

BIOLOGYdivergence out from a central point, in particular evolution from an ancestral animal or plant group into a variety of new forms.

Ionizing Radiation Non Ionizing Radiation

Categories

Ultraviolet radiation X-ray Gamma radiation Alpha radiation Beta radiation Neutron radiation

Ultraviolet light Visible light Infrared Microwave Radio waves Very low frequency Extremely low frequency Thermal radiation (heat) Black-body radiation

non-occupational exposure

It is well-known that there is naturally occurring background radiation exposure for everyone, everywhere. The average person in the United States receives an approximate 3 mSv per year from naturally occurring radioactive background activity from land and atmospheric sources. For example, for those individuals with atmospheric exposure at high elevation locations such as New Mexico and Colorado, there is an increase of approximately 1.5 mSv more per year than at sea level. Individuals flying on commercial airplanes on coast-to-coast round trip flights are known to accumulate another 0.03 mSv, since the high altitude fails to filter out other sources of background radiation. In addition, radon gas in homes accounts for approximately 2 mSv per year as a background exposure. In simple terms, the radiation exposure from one chest x-ray is equivalent to the amount of radiation exposure from our natural surroundings over a 10-day period.

Occupational exposure / Ionizing Radiation

Ionizing radiation is radiation that carries enough energy to free electrons from atoms or molecules, thereby ionizing them. Ionizing radiation is made up of energetic subatomic particles, ions or atoms moving at high speeds (usually greater than 1% of the speed of light), and electromagnetic waves on the high-energy end of the electromagnetic spectrum.

External Exposure / Irradiation External irradiation occurs

when all or part of the body is exposed to penetrating radiation from an external source.

During exposure, some of this radiation is absorbed by the body and some passes completely through.

Following external exposure, an individual is not radioactive.

s·

····

Local PartialBody

WholeBody

·

Internal Exposure Internal exposure is from

radioactive materials that have been taken into the body.

Radioactive material can enter the body through:

Injection Inhalation Ingestion Absorption

Once radioactive materials are in the body, they irradiate body tissues as long as they remain in the body

ThyroidLung

Liver

Bone

Cath Lab Exposure

Factors influencing radiation exposure:

Skin effects radiation exposure:

Cath Lab Exposure

In the cath lab and interventional suite, high-dose fluoroscopy may sometimes be needed. Remember the dose is approximately 10-fold for skin entrance exposures compared to normal fluoroscopy (10-50 mGy/min vs. 100-200 mGy/min). Comparing radiation exposure for diagnostic coronary angiography to coronary interventional procedures, a diagnostic study may have a total exposure of 900-1900 mGy, whereas the coronary interventional procedure often ranges from 2400-5500 mGy. With radiofrequency catheter ablation procedures, the fluoro time may increase from approximately 5 minutes for diagnostic study to 40 minutes for a radiofrequency catheter ablation study. Compare this with the average 22 minutes of fluoro time for coronary interventional procedures.

Type of Radiation

Primary Radiation:

Useful beam. Most hazardous to the

patient. Emitted directly from the x-

ray tube to the image intensifier.

Secondary Radiation:

Most commonly referred to as scattered radiation.

Scattered by object in primary beam (such as a patient).

This is most hazardous to the healthcare worker.

Measuring Units RAD (Gray) Gy- Radiation Absorbed Dose -This is the

amount of radiation the patient absorbs. One Gray is one joule deposited per kilogram of mass.

REM (Sievert) Sv –Radiation dose for healthcare providers who working with radiation producing equipment. The Sievert is used to measure radiation effects.

Radiation Dose Limits and Dosimetry

Radiation Dose Limits and Dosimetry

Personnel DosimetryDosimetry coordinator will receive monthly reports.You will receive an annual report.RSO investigate if you exceed ALARA limits. Level I = 1.25 mSv Level II = 3.75 mSv (per monitoring period)

ICRP Prescribed Limits per annum

Members of public

Radiation workers20 mSv per annum above background20 mSv to eye500 mSv to hands

1 mSv per annum above background5 mSv to eye20 mSv to hands

Pregnant women must receive not more than 5mSv during the course of pregnancy

Pregnant Radiation Workers

May declare pregnancy (voluntary).For declared pregnant rad workers:

Dose history review.5 mSv limit (to protect fetus).Fetal monitoring badge.Possible work limitations.Monthly review by the Radiation

Safety Office.

Dose Equivalence• Dose equivalence takes into account the effectiveness of the radiation to damage human tissue

• Unit is Sievert (Sv); old unit is rem

• Dose Equivalence is the product of the Dose (Gray) multiplied by a Radiation Weighting Factor (WR)

• Dose Equivalence = D x WR

Radiation Weighting factors (WR) are approximately:

Alpha particles = 20Protons, neutrons = 10Beta particles = 1Gamma rays and x-rays = 1

Why is Radiation Safety an Issue?

In most hospitals, radiation safety is the joint responsibility of the facility’s radiation safety officer and the technologists who work in the department but typically we have only minimal training. Because we are unfamiliar with all of the sources of radiation exposure, we know little about risk-reduction and safety strategies. 

Making Improvements in Radiation Safety

Radiation safety course.

Making Improvements in Radiation Safety

Radiation safety course.Speak up

Making Improvements in Radiation Safety

Radiation safety course.Speak up

Scatter and Minimize Flouro

Making Improvements in Radiation Safety

Radiation safety course.Speak up

Scatter and Minimize FlouroProper Gear and Shielding

ALARAAs Low As Reasonably Achievable

3 ALARA Principles For Reducing Radiation Exposure in Cath Lab

3 ALARA Principles For Reducing Radiation Exposure in Cath Lab

Time – less time, less dose.

3 ALARA Principles For Reducing Radiation Exposure in Cath Lab

Distance – more distance – less dose

3 ALARA Principles For Reducing Radiation Exposure in Cath Lab

Shielding – more shielding – less dose

• ALARA means keeping dose “As Low As Reasonably Achievable”

• Reducing dose wherever practicable reduces the probabilities associated with stochastic effects

• ALARA principles guide the periodic scanning of x-ray equipment for scatter and leakage as well as following the time and distance rules

Ionising Radiation and ALARA

Prescribed Limits for Dose Equivalence

• The ICRP (International Commission for Radiation Protection) is an international non-governmental organisation providing recommendations and guidance on ionising radiation protection based on current scientific evidence

Radiation Risk

ICRP data:1 mSv increases lifetime cancer risk of 1/20,000

Lifetime cancer risk for whole population is 1/4

Effect of Ionising Radiation on Humans

The effects of ionizing radiation on humans are classified in two broad categories:

• Deterministic

• Stochastic

Deterministic Effects

These effects have thresholds above which damage occurs and effects are then dose dependent e.g. lens opacification, burns, hair loss.

Determinisitic effects like the burns below suffered by those who put their hands in the path of a x-ray beam are relatively easy to avoid

Effect of Radiation on Humans

Stochastic Effects• Mutational, non-threshold effects in which the chance of

occurring rather than the severity are dose dependent.

• These affects are not predictable e.g. cancer

• Note that stochastic effects are not predictable and give rise to the notion that there is no absolutely safe dose and the concept of ALARA.

Effect of Radiation on Humans

Protecting the Provider

Patient safety remains the number-one major concern of healthcare professional. 

The healthcare providers should receive equal attention compare with other high risk departments (occupational and non occupational hazard areas).

The take home messages…

1. Use intermittent fluoroscopy. Stay off the fluoro pedal whenever possible

2. Remove the x-ray grids when appropriate to reduce patient dose

3. Use last image hold technology with electronic collimation

4. Employ automatic adjustment of beam quality to limit kVp and mA (built in)

5. Reduce image magnification when possible. (Note that at a normal mode, an entrance skin dose increases 2.4 times when magnification increases from 23-cm field to a 15-cm field and increases 4.4 times the dose when the magnification goes to an 11-cm field)

The take home messages…

6. Use pulsed fluoroscopy. (Dose reduction of approximately 20% over continuous fluoro dose at 30 pulses per second and reduction to 80% at 15 pulses per second)

7. When the time comes that an x-ray dose of CT angiography is minimal, this will likely turn out to be our best non-invasive screening tool for CAD. In the meantime, wear sun block

8. Radiology Info: The radiology information source for patients. Available at: http://www.radiologyinfo.org. Accessed January 10, 2005.

Special Thanks to Keith (Quality Coordinator)for

helping/reviewing and editing my presentation