How to Prevent Patient Burns During MR Imaging

How to Prevent Patient Burns During MR Imaging

Leave a comment Magnetic Resonance Imaging, Radiation Safety

In this article, we review eight ways you can use to prevent patient burns during MR imaging. Watch the full explanation below in our YouTube video provided by Eric from Olympic Health Physics.

Eight Tips For Preventing Burns on MRI Patients

Download your free copy of the FDA’s poster on MRI Burn Prevention: Tips For Keeping Patients Safe to follow along with us. 

1. Screen Your Patients

The first process to implement that can prevent burns during MR imaging is to screen your patients before entering Zone 4. This includes screening for anything metallic, such as implants or medical devices. It’s a good rule to assume that anything unknown in or on your patient is not MRI safe. 

2. Screen Any Objects Going Into Zone 4

In addition to screening your patients, you also want to screen anything going into the MRI scan room. All objects entering Zone 4 need to be MR Safe or MR Conditional. If any MR Conditional objects enter the scan room, match them to the MR Conditional devices with your scanner. Remember that all metals, even non-ferromagnetic metals, have the potential to cause burns during MR imaging. 

3. Have Patients Change Into Hospital or Medical Gowns

Whenever possible, have your patient change out of their street clothes into a medical or hospital gown before entering Zone 4. This can prevent any metallic items, such a metallic fabrics, buttons, zippers, or embellishments, from unknowingly being exposed to MRI equipment. In addition, it prevents a patient from accidentally having metallic objects in their pockets and bringing them into Zone 4.

4. Ensure The Patient Isn’t Creating Conductive Loops

Next, you want to ensure that your patients aren’t creating any conductive loops themselves. For example, when a patient needs to be scanned with their arms over their head, you want ensure they don’t have their hands clasped. Your patient also shouldn’t cross their arms or feet. This avoids creating magnetic loops, which helps with burn prevention.

5. Use The Manufacturer Provided Padding

You want to use the manufacturer provided padding to pad the sides of the bore or in between the patient to insulate the patient. While you can use sheets and pillows, they should only be used for patient comfort. All padding and insulation should use manufacturer-supplied padding. 

6. Cables Should Run In A Straight Line From The Scanner

Another way to prevent burning the patient is to run any cables to and from scanner in a straight line. Check that the cables running from the coil into the magnet are not forming loops.

7. Use The Lowest SAR In Normal Operating Mode

While operating in normal mode try to keep the lowest SAR possible. If you have an SA monitor, keep an eye on the SA level to ensure that you’re within limits. 

8. Stay In Communication With Your Patient

Remain in communication with your patient at all times. Stay in visual contact when possible and using an intercom for verbal communication is essential.

Ensure the patient has the squeeze ball and give them directions on how and when it’s appropriate to use before you start the scan. 

Some MRI suites don’t allow you to keep eyes on the patient the entire time based on the orientation of the control room. If that’s the case, have some other way that you can monitor the patient.

Stop the scan and investigate the possible cause if the patient does communicate with you and tell you that they feel burning or feel something heating up.

And that wraps up the eight different ways that we can try to prevent MRI burns in MRI departments. 

You can find the FDA’s MRI burn prevention poster by clicking here 

Don’t forget that we also provide a variety of courses, including MRI Safety for MRI Professionals.

If you have questions about MRI or MRI safety, feel free to drop us a note and we’ll be happy to take a look at your situation and see if there’s something that we can do to help you.

Click the image above to download the file

We perform physics testing for all makes and models of MRI scanners.  For a complete description of our physics testing, check out our MRI Physics Tests.  In addition to our MRI Physics Testing, we also provide MRI Safety Audits for facilities wanting a comprehensive MRI safety assessment.

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Understanding The Difference Between kVp and mAs

Leave a comment Quality Control, Radiography

What are KVp and MAs?

To understand the difference between those two, you should first know that kilovolts (kV) and mAs are the two primary controls that we have with an X-Ray tube. They control the amount of radiation and the quality of the radiation beam or the X-ray beam.

In this week’s video, Eric from Olympic Health Physics talks about the difference between kilovolts (kV) and mAs and how each can be used because sometimes these two terms can be confused with each other.

What Does an X-Ray Tube Look Like?

The components that we’re going to be talking about with our X-Ray tube, in particular with kV and mAs is going to be the Heated Filament, the Anode which rotates around an axle or spindle and the Evacuated Chamber, which is where X-Ray production will take place.

Charges: Basic Electrostatic Force

Before we get too far into the operation of the X-Ray tube itself, let’s talk a little bit about charges

  • If we have two positive charges, they will repel from each other. 
  • If we have two negative charges, they will also repel from each other as we see here.
  • If we have two opposite charges, they’re going to be attracted towards each other.

The Anode And Cathode In an X-Ray Tube

If we apply those previous charges to the anode and cathode in an X-Ray tube, the cathode is held at a negative charge and the anode is held at a positive charge. When we put an electron in between the two, that electron is going to be attracted to or pulled towards the anode by the anode because an electron carries a negative charge. 

In conclusion, that electron is going to be pulled towards the anode and at the same time it’s being pulled towards the anode by the positive charges. It’s going to be pushed by the cathode because the negative charges on the cathode are going to repel or push the electron towards the anode.

The X-Ray Tube And The Heated Filament

In our X-Ray tube, the heated filament is going to boil off electrons.

The electrons are going to be created. If the filament is held at a negative charge and our anode is held out of a positive charge, the electrons will flow from the cathode towards the anode. Once they strike the anode, they will create X-Rays. 

We’re not really going into the formation of X-Rays and how they are formed, except to say that the interaction of the electrons with the anode will create two kinds of X-Rays.

How kVp is produced?

To understand how kVp is produced you should first know that within the X-Ray tube we can apply a potential difference.  This is a voltage difference between the cathode or the filament and the anode. This is where we create a potential difference. 

The bigger the voltage difference is or the stronger positive charge that we have on the anode, the stronger negative charge that we have on the cathode. 

The electrons will traverse the gap at a much higher rate. The velocity that the electrons accelerate across the gap of the chamber will be higher and higher as we increase the voltage of the tube. 

So that’s the voltage you’re seeing in the image above. If we have higher and higher energy electrons hitting the anode, the resultant X-Rays will also be higher energy. With higher energy of those, we end up with more penetrating power or the ability for the X-Rays to penetrate thicker and more dense body parts. 

In conclusion, the voltage difference between the cathode and the anode is kVp. 

As we increase the kVp or the voltage difference, we increase the speed at which the electrons traverse the chamber. They impact the anode at a higher and higher energy and create higher energy X-Rays.

If we decrease the voltage, then we will see a decrease in the energy of X-Rays and the X-Rays become less penetrating.

mAs: Introduction

mAs is milliamps seconds. It’s going to be directly proportional to the number of electrons that come off of the filament and are accelerated across the gap.

What exactly does that look like?

We have an X-Ray tube and we have a cathode. The electrons are moving across the tube towards the anode. It will produce a certain number of X-Rays with a certain number of electrons. If we increase the mAs, we increase the number of electrons and the number of X-Ray formed.

Remember that’s kVp, but we’ll increase the actual number of electrons and that’s going to increase the number of X-Rays.

So mAs is a control that’s directly proportional to radiation dose. If we double the mAs, then we’re going to double the radiation dose to the patient. 

What is mAs?

As was mentioned before, mAs is milliamp hour times seconds or times time. We can get rid of the “m” part and what we’re left with is just amps and seconds. 

What is an Amp?

An amp is just a Coulomb per second. 

What's a Coulomb?

A Coulomb is a unit of charge and electrons carry charge.  If we have our amps times seconds, that’s really just coulombs per second time because the seconds cancel out and we’re left with just Coulombs. 

Coulombs is a unit of charge and that’s going to be proportional to the number of electrons, which is going to be proportional to the number of X-Rays. 

So this is how we go from mAs (milliamp seconds) to the number of X-Rays. 

X-Ray Tube: Elements Explanation

Heated Filament

This is where the electrons come off and are accelerated towards the anode over this gap.

The Anode

The anode is going to be held at a positive charge and the voltage difference between the negative cathode and the positively charged anode. The higher that voltage difference is between these two, the faster the electrons will move from the cathode towards the anode and the higher energy the X-Rays will be that we produce. 

 And if we increase the mAs,  it’s going to be increasing the number of electrons that come off of the cathode and are accelerated towards the anode, increasing the number of X-Rays that are generated. 

kVp and mAs

kVp will control the penetrating power of your X-Ray beam or how energetic the X-Rays are and mAs will control the number of X-Rays. 

It is important to remember that If we increase the kVp or we increase the mAs, we’re going to see an increase in radiation dose. 

With increases in mAs, we’ll see better image quality in general. A better image quality because we’ll have less noise in the image. However, we want to weigh or balance the amount of mAs or radiation dose that we give against the resultant image quality

How Much Image Quality Do We Need?

We don’t want to just use as much mAs as possible. We want to be judicious with it because it does contribute to the radiation dose of the patient. 

Finally that was pretty much all you needed to know about the differences between kVp and mAs.

If you have any questions for us, feel free to drop them in the comments below and let us know how we can help. 

Click the image above to download the file

Our team is dedicated to ensuring that your facilities’ radiation safety program functions in accordance to regulatory standards, sound radiation safety principles, and most importantly serves to protect staff, patients, and the general public from the hazards associated with ionizing radiation. To this end, Olympic Health Physics can provide a physicist to your organization to fulfill the Duties of the Radiation Safety Officer. To learn more, check out our RSO Services or click the link below. 

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Patient Radiation Safety in CT: What You Need To Know

Leave a comment Computed Tomography, Radiation Safety
Patient Radiation Safety in CT - What You Need to Know

In this week’s video, Eric from Olympic Health Physics explains the 10 pearls of radiation protection of patients in CT, as recommended by the IAEA (International Atomic Energy Agency) for the Radiation Protection of Patients (RPOP).  This help will give some guidance on the best ways that we can employ to protect our patients when using computed tomography imaging. 

1. Perform The Scan Only If It's Indicated

Try to avoid any unnecessary exams.

Remember that the lowest radiation exposure to a patient is the radiation exposure that doesn’t occur. This is why it’s important to know that if there’s an exam that shouldn’t be performed, then we shouldn’t be scanning the patient.

2. Consider The Use of Alternative Imaging Options

You can use alternative modalities to potentially answer the same clinical question.

Ultrasound or MRI don’t use radiation and they could be alternatives depending on the diagnostic question that’s trying to be answered. If a patient can be imaged using ultrasound or MSI from a radiation dose perspective, then it can be an excellent option when those modalities are appropriate.

3. Always Check If Your Patient May Be Pregnant​

We don’t want to unknowingly image or do a CT on someone who is either pregnant or potentially pregnant. That’s the reason why you always need to verify the patient, whether or not they could be pregnant before doing their exam.

You can do this by having postings in the department that say, “Please notify the technologist if there’s a possibility that you’re pregnant”. Another option is to directly ask the patient if there’s any possibility that they could be pregnant.

4. Start Using Images With Some Noise Without The Loss of Diagnostic Information

Always check if your patient may be pregnant.

It’s important to know that high-quality, detailed, and crisp images look really nice, but they may not be necessary for answering the diagnostic question.

You could potentially use a lower radiation dose and still answer the diagnostic question. The trade-off is that we’re going to introduce some noise and potentially lose some image quality. However, that loss and image quality are not going to necessarily change the diagnosis or the outcome for the patient.

We want to make sure that you’re using the right radiation dose for answering the clinical question.

5. Use Indication-Specific CT Protocols For Each Body Part

We want to use indication-specific protocols where they’re applicable. For example, not every chest CT should be a full chest image. We could do a low-dose screening, a lung screening chest protocol, and also potentially do a low-dose nodule follow-up protocol.

We want to use very specific protocols for the type of exam that we’re trying to do. The reason is that oftentimes those very specific protocols can be acquired at a lower radiation dose to the patient.

6. Multiple Pass or Multiphase CT Should Not Be Performed Routinely

It’s important to know that multiple pass or multiphase CT should not be performed routinely. We want to try to limit the amount of passes that we make through the patient. Only do the passes that are actually necessary and potentially combine different protocols.

This is why multiphase CT studies can often be 2 to 3 times the amount of radiation dose as just a regular CT.

7. Adjust Exposure Parameters According To The Patient And Body Part

We want to adjust the technique that we’re using to image our patient for the actual patient size. First, we want to take into account the size of the patient and the exam. Then, adjust any technique that we’re using so  it’s specific to the patient and the body part that we’re imaging.

The reason for this is to get away from a one size fits all technique and move to very patient-specific techniques. That way, smaller patients receive lower radiation doses than larger patients.

8. Know Your Equipment, Including the AEC System

Another important aspect is to know your equipment. For example, understand how the AEC (Automatic Exposure Control) works or the tube current modulations and how that works for your system. 

How Does CARE Dose 4D Work?

If you’re scanning on a Siemens scanner, make sure you understand CARE Dose4D. And if you’re scanning on a GE scanner, make sure you know how AutomA works. This way you can use the scanner to the best of its ability and it will help you give the right radiation dose to your patient.

To learn more about the Siemens CARE Dose4D system, check out our previous post here. And for information on the GE AutomA system, you can find our latest post here. 

9. Use Good Technique

Use good technique when we’re talking about good technique. These are things like:

•  Making sure that your patient is iso-centered within the gantry. This is in both the lateral direction as well as the AP direction.

•  Confirm that the patient is iso-centered, particularly while using tube current modulation.

• Check that your scan length is covering only the anatomy that’s absolutely necessary. We don’t want to scan the diagnostic portion of the CT.

The one caveat to this is with a scout. When using a scout, it’s better to use a little bit longer of a scout than what you intend to cover with your diagnostic scan. Keep in mind that he diagnostic scan should be shorter than your scout.

10. Pay Attention To Radiation Dose Values

Don’t forget to pay attention to your radiation dose values, such as the pre-scan CT because you need to make sure that you’re falling within your pre-determined dose values and dose limits.

Click the image above to download the file

Review the doses that you’re using on a monthly basis to see if there are any adjustments that you can make. Consider things like your protocols, your techniques, and how you’re scanning patients. From this information, you can have a pretty good idea of what your doses should actually be, what they have been and what they should be for the equipment that you’re using as well as for what your radiologists are accustomed to looking at.

Now you know that there are ten different ways to protect your patients, reduce their radiation dose and make sure that they’re getting the right radiation dose for the type of exam that’s been ordered.

Click here to download your copy of the IAEA’s 10 Pearls of Radiation Protection of Patients in CT.

Our team is dedicated to ensuring that your facilities’ radiation safety program functions in accordance to regulatory standards, sound radiation safety principles, and most importantly serves to protect staff, patients, and the general public from the hazards associated with ionizing radiation. To this end, Olympic Health Physics can provide a physicist to your organization to fulfill the Duties of the Radiation Safety Officer. To learn more, check out our RSO Services or click the link below. 

Contact Us for a No Obligation Quote

253-254-6988
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How To Use a Geiger Counter

Leave a comment Nuclear Medicine, Quality Control, Radiation Safety
How To Use a Geiger Counter

In this week’s video, Eric from Olympic Health Physics explains how to use a Geiger Counter. Throughout the video, he demonstrates the Ludlum 14C with a pancake detector. He provides an overview of how to test the battery, how to ensure the counter is working properly, and how to read the panel.

What Is A Geiger Counter?

A Geiger Counter or Geiger Meter is an electronic instrument used to detect and measure the amount of ionizing radiation levels. They are widely used in various applications, including radiation protection and safety, radiation dosimetry, and the nuclear industry. If you work in a Nuclear Medicine department, you likely have a Geiger Counter to measure radiation in different aspects, such as wipe tests, area surveys, or exposure rate measurements.

Three Essential Checks Before Using Your Geiger Counter

When you’re using a Geiger Counter, there are three things that you need to check before you start using it. Throughout this post, we will be showing the Ludlum 14C with a pancake detector. Please note that there are many different Geiger Counter makes and models, so check your user manual for specific criteria for your equipment. 

1. Is The Geiger Counter's Calibration Valid?

The first thing is you need to make sure that the Geiger Counter is in calibration. You need to look at the calibration label on it to make sure that it is still within calibration.

The calibration certificate usually includes the last date of calibration and the expiration date. The sticker also includes other useful information such as the model numbers, serial numbers, and efficiencies. 

Geiger Counter Calibration Certificate

2. Is The Geiger Counter Responding Appropriately?

The second thing that you need to do is make sure that the instrument responds to a radiation source.

On this specific instrument, we have a check source with a window that we can we can open. We can then put our pancake detector over the cesium button source located on the side of the instrument to ensure the instrument is actually responding to radiation.

3. Are the Batteries Operating Within the Test Range?

The last thing you want to do is check the batteries to ensure the batteries are operating within the battery test range.

To test the batteries, first remove the pancake detector from the front of the Geiger counter. Then, turn the Geiger counter on and turn the knob to the lowest range setting. Test the battery by depressing the battery button and looking to make sure that the indicator stays in the battery test range. As long as the indicator stays within the battery test range, the battery is operating effectively. 

Geiger Counter Battery Test Button

Understanding the Instrument Scale Readout

Understanding how to properly read the instrument scale readout is important to ensuring you have the correct information.

You’ll note on the Ludlum 14C Geiger counter instrument there are three different scales on the face of the survey meter. The first scale or the bottom scale is in milliroentgen per hour. You can also notice that the very bottom scale indicates “X100 ONLY”. The second scale or the mid-range scale is also in milliroentgen per hour. The upper scale that goes across the top  of the readout is in counts per minute.

Instrument Scale Readout

Below the instrument scale readout on the top of the meter are the various potentiometer values you can set for the Geiger counter. On this particular model, the Ludlum 14C, there are five potentiometer value setting options you can select. The value selected determines the multiplication factor for any reading that you see on the face of the survey meter. 

The bottom three options include X0.1, X1, and X10 coincide with the middle and top readout. X100 is used for the bottom readout only. And the X1000 option is used for the internal probe only. 

Potentiometer Value Options

To understand how the potentiometer options and scale readout work together, consider the following example:

You select the value of X1 from the options available. When you scan the radiation source with the pancake detector, the needle on the readout stops at blue line on the example readout photo. In this example, the appropriate reading would be on either the middle or top scale range, depending on what information you require. In addition, the potentiometer value is X1, meaning the multiplication factor is only one. Therefore, the value seen is the actual measurement. So for this example, the reading is either 4,000 counts per minute or 1.2 milliroentgen per hour.

Suppose you had selected X10 and the needle result was the same. You would them multiple your readout results by 10 to determine your final measurement reading. 

Sometimes on your survey meter, you may notice no deflection of the needle at all. If this happens, it can often be caused by having it set on too high of a scale. To fix this, flip down to the lowest potentiometer scale and you should start to see needle deflection. 

Audio and Speed

The Ludlum 14C Geiger Counter also offers two additional options: audio and speed.

To turn the audio on, flip the switch up and you will hear the audible clicks of radiation being detected. There is also a speed setting for fast or slow. The fast speed setting is good when looking for any kind of contamination. The slow setting is ideal when making a direct measurement of the check source. 

Audio and Speed Options
Click for a downloadable version.

So now you know the three things that you need to check before you use the instrument. Check the battery, check the calibration sticker to make sure that it’s still within calibration and check against a radiation source to make sure that the instrument responds to radiation. We also covered how to read the different scales on the Ludlum instrument so that you know which scales to use and how to use the the dial setting to select the right potentiometer on the instrument.

Questions and comments about radiation safety? Feel free to shoot them over to us. We’ll be happy to respond to any questions or comments that you have around radiation safety programs and be a resource for you.

Our team is dedicated to ensuring that your facilities’ radiation safety program functions in accordance to regulatory standards, sound radiation safety principles, and most importantly serves to protect staff, patients, and the general public from the hazards associated with ionizing radiation. To this end, Olympic Health Physics can provide a physicist to your organization to fulfill the Duties of the Radiation Safety Officer. To learn more, check out our RSO Services or click the link below. 

Contact Us for a No Obligation Quote

253-254-6988
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