Tag Archives: learning ultrasound

Equipment

What’s in a name? Different types of ultrasound probes

Types of Probes:

There are three main types of ultrasound probes: curvilinear, linear and phased.

Curvilinear. This is a low frequency probe with a curved face. Typically used for abdominal, gyne, obstetrical and pleural scanning. The curved face gives and increased field of view, while the lower frequency allows for better penetration.

Linear: High frequency probe with a flat, rectangular face. Used for vascular, small parts and musculoskeletal scanning. Due to shape of probe, image is rectangular, not a curved arc. *Tip: Most units have an option to make the image widescreen, increasing the field of view.

Phased: Low Frequency rectangular shaped probe with a small face. Primarily used for cardiac scanning (echocardiography). The small face of the probe allows it to fit between ribs, but the arrangement of crystals creates a curvilinear field of view.

Videos

Sonography Week 2016!

This week is Sonography Week, celebrating ultrasound and the dedication of medical professionals who use it. Below is a link to an interesting video demonstrating the development of ultrasound in healthcare. Hopefully it will inspire you to continue to learn about all that ultrasound can do!

Video Courtesy of Society of Diagnostic Medical Sonography.

https://www.youtube.com/watch?v=sVa7PJm2okk

Equipment, Tips and Tricks

Select the right probe

When you’re starting out with bedside ultrasound, it’s tempting to save yourself a few seconds and use the probe that’s set as the default probe for whatever you want to scan. This is a rookie error. The reason there are different probes is that any single probe design and its corresponding frequency range represents a series of trade-offs. The biggest trade-off is between resolution and depth of view. The other is between scope (the size and shape of the sound beam) and resolution. For more depth, for example to see the back of the liver, you need a lower-frequency probe but this limits the image resolution or detail that is seen. High-frequency probes are great for detail work, for example with tendons or vessels, but have limited depth of penetration and are therefore limited to superficial structures.

With scope, the wider or more fan-shaped the beam, the lower the resolution. The higher resolution seen with linear beam arrays comes with a smaller lateral field of view or scope.

Therefore when scanning abdomens, use the low-frequency, curved probe (good depth, wide scope, lower detail). When scanning superficial structures such as vessels or for foreign bodies, use the high-frequency, linear probe (shallow depth, high detail, narrow scope). When scanning the heart use the small-footprint, wide-scope probe with the lower frequency. This allows you to get between the ribs (small footprint) and see all the cardiac chambers (greater depth) but does compromise on the detail which is an acceptable tradeoff with cardiac sonography.

Tips and Tricks

Optimize your image constantly – Focus

The resolution of the image generated by the ultrasound beam is not the same across all depths. The sound waves emitted from the crystal array in the probe can be focussed electronically at a level of your choosing, which you should adjust to the level of the organ of interest. This maximizes the resolution of the image at that depth. You should alter the focus level continuously during scanning as your target organ changes in depth.

When using ultrasound to guide needles in patients (for example when inserting a central line), set your focus at the level of your needle and not at the level of the target vessel. This will help you see the position of your needle more clearly.

Tips and Tricks

Optimize your image constantly – Gain

As you scan, structures of interest may dive deep in the body and will appear darker. You should increase the 2D gain control to compensate and keep your image bright enough to see clearly. When the structure becomes more superficial, you may need to decrease the gain to avoid a “white-out” of the structures of interest. Try and maintain your image in the middle of the grey scale to help different structures stand out from one another. This is called “maintaining image contrast”.

Some newer machines have an “auto-optimize” button which automatically adjusts the gain and maintains image contrast. You should push this button regularly during scanning and always after you change the depth of view.

Tips and Tricks

Optimize your image constantly – Depth of view

To get the best image quality, keep adjusting the depth of view as you scan.

As you move the probe over the patient, the organ or structure of interest will be constantly varying in depth on the screen and you want to keep this structure filling as much of the screen as possible to help you see the detail. Setting the depth too large results in shrinking the target structure to a small strip at the top of the screen while the lower screen displays useless information. Try getting into the habit of maximizing your screen resolution by filling your screen with the target.

Tips and Tricks

Why habit trumps motivation

Learning ultrasound takes a long time. Motivation is great for getting started but it wears off after time. Thankfully there is a way to keep going and achieve our goals and that is by forming a habit.

By practising ultrasound regularly and building it into your daily work routine, habit takes over after a few weeks and actually prompts you to do it.

While you scan, get into the habit of always optimizing your image: depth, focus, gain and it will soon become automatic.

Our habits are far more powerful than we realize. They often hold us back from learning but we can actually hack into this power and use them to reach our goals.

“People do not decide their futures, they decide their habits and their habits decide their futures”

F.M. Alexander

Tips and Tricks

Orientate the probe marker consistently

Each ultrasound probe has a marker at one end, usually a raised line or notch. This indicates the end of the probe transducer surface corresponding to the left hand side of the image on the screen. While you scan, keep this marker pointed towards either the patients head or right side as much as possible. Why? Two reasons: firstly by doing this consistently, your brain will learn that moving the probe in one direction on the patient will result in the image moving in a consistent way on the screen. Consistency here is the key as it will help you build up the necessary hand-eye-screen coordination much more quickly. Secondly, if you ever save an image to look at later, everyone knows that the left hand side of the image corresponds to the patients head or right side.

Tips and Tricks

Use the presets

Every machine comes with pre-installed manufacturer’s control settings specific to the body part you are scanning. Every ultrasound machine has many, many control settings and the number of possible combinations is mind-boggling. It used to be that operators would have to change these manually for each scan. Nowadays all that technical wisdom and experience have been distilled into selectable presets. These optimize the image for you automatically so you don’t have to. Use these. The quality of your images on the screen determines the quality of your interpretation from them. Give yourself every advantage and spend the extra 5 seconds selecting the right preset at the start.

Tips and Tricks

Build an ultrasound routine

Using an ultrasound unit is a complicated process and when learning anything complicated it helps to build up a start-up routine. The actual order in which you do tasks matters less than doing them in the same order consistently, this way, you are less likely to forget a step.

Try the following:

  1. Turn on machine
  2. Enter patient demographics
  3. Select probe
  4. Choose preset
  5. Apply coupling gel
  6. Check orientation of probe (marker toward head or patients right side)
  7. Start scanning
  8. Optimize image: depth, focus, gain

Each time, every time.