Chapter 7. Image Optimization and Knobology Adjustments

Women’s Point of Care Ultrasound

Essential Concepts Made Clear

Chapter 7 highlights basic machine functions that enhance and optimize a captured ultrasound image. There are many adjustment options on sophisticated machines used for diagnostic purposes. However, in this course only those adjustments that are most likely to be used for POCUS are presented.

This chapter enables the learner to apply knowledge about sound properties to selection of adjustment features of the machine to refine an image.

When learning computer function, basics are covered first, and then more complex processes are built upon that knowledge. Computers have great capabilities, but most people do not use the computer’s function to its full extent. This is true for ultrasound machines as well. Once the use of machine controls is mastered, it provides significant advantage in the ability to create precise and useful images. Learning all the available adjustment functions can feel overwhelming at first but understanding and practicing each will prove useful and timesaving. This is how performing ultrasound becomes rewarding.

Step 1.

As discussed in the last Chapter, the first major step in ultrasound is being able to locate a structure, then to adjust the transducer for optimal view.

Step 2.

The next step is to make additional adjustments so that the image is clearer and more readable; not just for the sake of the person scanning, but for others who may read and interpret the image for consultation.

By the completion of this Section the participant will be able to:

1. Locate the various essential functions for obtaining and optimizing an image on the machine console

a. Probe selection

b. Patient identification

c. Application selection

d. Mode selection

e. Keyboard and trackball

f. Set and freeze

g. Cine loop

h. Zoom

i. Depth

j. Measurements and caliper selection

k. Image saving and storage

2. Apply the concept of gain and its adjustment to optimize image brightness

The ultrasound machine is essentially a computer attached to a specialized “camera”, in a sense. As we have learned, a typical camera captures reflections of light waves. But the ultrasound machine, instead, captures reflections of sound waves.¹ The preceding chapters explain the properties of sound involved in this process. The ultrasound computer will capture the image and adjust it, but it must be directed by the operator in that process.

Simply stated, the ultrasound computer needs to be told what type of scan to do and how it is to be done. This is the purpose of all the functions and adjustments.

Sidebar 1. Improving the image.

Sidebar 2. Computer component of ultrasound machine.

Many now use very small, handheld ultrasound machines, especially in settings where POCUS is performed. Some of these machines have their own screen attached, but most consist of a probe that attaches to a cell phone or tablet.

Figure 1. demonstrates what is seen on an attached tablet or phone screen of 2 different types of handheld machine. Generic computer tablets or smartphones generally require a download of the product’s software to enable scanning. Some require access to an online log-in with a password to be able to use the device

Figure 1. Handheld ultrasound opening screens.

Many now use very small, handheld ultrasound machines, especially in settings where POCUS is performed. Some of these machines have their own screen attached, but most consist of a probe that attaches to a cell phone or tablet.

Figure 1. demonstrates what is seen on an attached tablet or phone screen. Generic computer tablets or smartphones generally require a download of the product’s software to enable scanning. Some require access to an online log-in with a password to be able to use the device.

Machine manufacturers are required to provide default settings for certain functions having to do with power or energy emitted. The terms power output, TI (thermal index) and MI (mechanical index) are described in more detail in the next chapter on ultrasound safety. The machine automatically alters these settings depending on the type of scan that is selected. For example, it reduces output power for obstetric scans since it aims to keep the power at a minimum for safety’s sake.

However, the operator (person scanning) needs to be aware of these indicators to practice ultrasound safely. In some cases, the person scanning can change the application in order to enhance the power settings – this is done only if necessary so as to keep the power output as low as possible in obstetric scans.

Figure 2. Machine functions versus functions controlled by the operator.

For example, selecting “application” tells the machine whether the intent is to do an abdominal, ob, gyn scan, etc. The reason this is important is that when a certain application is selected (such as first-trimester ob), the machine will auto-regulate the amount of power it transmits and allow access to a menu of measurement options (called calculations or “calcs”) specific to first-trimester ob ultrasound.

General functions - overview

This section will describe the functions of the machine that are within the control of the operator. Below are the initial selections when starting an exam:

1. Output or intensity (power) may be adjusted to a small degree but only in rare circumstances is it necessary to intentionally increase output power.¹

2. Mode choice allows you to select B-mode ( 2-d, or regular grey scale scanning), M-mode (which will help you measure heart rate), Color, or other Doppler)

3. Transducer type (linear, curvilinear, transvaginal)

4. Machine adjustments

NOTE: Every machine manufacturer will provide a user manual describing all the functions specific to that machine. Locations of knobs and adjustment features can vary widely in location on the console or touchscreen, and even in the terminology used for that function. Although this chapter highlights the general purpose of the primary functions, each clinician will need to master the functions of the machine being used.

Sidebar 3. Machine instruction “cheat sheet”.

Since multiple options need to be selected at the start of an exam, a suggestion is to have a list of the most common functions of your machine (and where to find the corresponding buttons) posted nearby as a quick reference. It is especially helpful if using the ultrasound is not done regularly, or if there is a specific function not used often. It is also good to have the machine’s operating manual in a central location for reference.

Why are machine adjustments needed?

The principal reason that adjustments are necessary after the structure is “seen” by the transducer has to do with the concept of attenuation, defined in an earlier chapter. To review, attenuation is how sound is slowed down as it travels through tissue. The amplitude strength or power of the sound wave diminishes as it travels from the transducer, and the reflection returning to the machine is reduced even more due to attenuation.

Adjustments with the knobs can assist in overcoming attenuation by boosting signals and changing image properties to eliminate artifacts and other properties that can impact image clarity.

Figure 3. Overcoming attenuation.

GETTING STARTED – locating the knobs

Basic Machine Functions^1,8

The console is where the keyboard and “knobs” are located. All ultrasound machines have many of the same basic functions described in this chapter. The primary difference is the location and position of these buttons and knobs on the console. The following section discusses the function of each of these.

Figure 4. The console.

On-off

The first button to locate is the “on-off” switch. It can be located either on the console or on the side of the machine.

When a machine is first turned on, it will remain on until actively turned off. It may be programmed to become inactive or dark when not in use to conserve energy. It is important that when you are finished using the machine for the day to turn it completely off to protect it from the potential for unexpected power surges.

Figure 5. Laptop console with additional touchscreen.

Figure 6. On-off button on a laptop ultrasound machine.

It is also important to note that the ultrasound machine should always be plugged into an adequate surge protector rather than directly into a wall outlet. A surge protector provides some protection against unexpected power surges that could ruin the electronics of the machine.

Many machines have backup battery power for greater portability or use in an area without a power source. However, It is important to pay attention to the power display on the screen to avoid machine shut-off during an exam.

Figure 7. Selection of probes and presets.

Probe selection^8,9

One of the first things to select is the transducer or probe to use. The probe can be changed at any time, even while the machine is turned on. There may be some older machines that require power off while changing the transducer. As described earlier, if there is only one transducer/probe port on the machine, it will have to be changed manually. The above image shows the selection on the screen that allows switching between two probes that are both already connected. It is important to save each image before changing probes, because when a probe or setting is changed, images may be lost if they have not been previously saved.

Note: Make a habit of saving every image as it is done.

It is not uncommon to have to switch probes, especially when doing an obstetric exam. Later chapters will describe choosing the appropriate probe for the clinical circumstances. But it is common to start with using a transabdominal probe and then change to a transvaginal probe to look for more detail (especially during an early gestation). This is done so that the scan can begin with a full bladder (able to search deeper into the pelvis), and then view more detail with an empty bladder using the transvaginal probe.

With a handheld machine, there is no need to select a transducer since the machine is its own transducer. It will display connectivity on whatever display device is used (phone or tablet). It is important to keep handhelds fully charged so that they are ready to use when needed. If they are powered by a tablet or phone, those devices must be kept charged. The handhelds cannot be operated while they are charging since they only have one cord (to connect either to a charging source or a display device at one time).

Patient identification

Patient identification is essential to create a file to archive the images. Most ultrasound machines will not allow images to be saved or archived without a designated patient. Figures 8 and 9 show examples of how to locate knobs/buttons to access the patient data entry page.

Figure 8. Patient entry button on console.

Figure 9, displays a button that designates patient information. When that button is selected, the screen (below) will provide sections to be completed. There may be guidelines on what specific patient information is required by your clinical setting.

Figure 9. Patient data entry page.

^.

When the data entry screen is displayed, there are a number of entries to complete. At the very least, the patient’s name and ID number (it might be a medical record number) are required. A date of birth is important, since many patients have a common name, and the machine will need a way to separately identify the patient apart from the name. Also, to retrieve a previous scan of a patient from the machine archives, the date of birth will help distinguish which is the correct patient. Some machines, like the one above, allow for additional information such as gravida and para. For any woman it is important to put in the LMP or last menstrual period if it is known. This way the machine will make a note of gestational age if a pregnancy is discovered. The machine will compare her actual measurement with her last menstrual period to look for consistency or discrepancy. If it is known that she has twins, that information is entered, so that when measurements are done, the computer will divide the measurement calculations into sections of Baby A and Baby B, etc. It can also be helpful to write in why the exam is being performed, for example “routine ob” or “pelvic pain”, or IUD check, as examples. Some machines will have a pre-populated dropdown with those options to select.

Another important demographic is the name of the person performing the ultrasound, as well as any other practitioner who may have ordered the exam.

Application or Preset Selection^8,9

Once the patient information is entered, an application must be selected. The application selector allows selection of the type of scan desired. Application has to do with the general type of exam – whether it is an abdomen exam, a cardiac exam, a vascular exam, or, for women’s POCUS, a gyn exam, a first trimester exam, a second trimester exam., etc. When selecting an application, the machine then directs itself to apply the depth and gain settings that are most appropriate for that type of exam. For ob exams, for example, the machine will create the best output energy settings within the parameters of what is safest for a pregnancy. Settings can be changed during an exam, - for example if a deeper penetration is needed, the setting can be changed to “abdomen” with the understanding that you will no longer have GYN or OB measurement packages to select. Keep in mind that doing that creates a slight risk of increased heat exposure to the fetus.

Figure 10. Application selector button.

Shown in Figure 11 is an example of the screen view showing a dropdown menu of options for the type of scan desired. As shown, this machine has options of either first trimester ob, second and third trimester ob, 2 different pelvic presets, fetal heart, abdomen, etc.

Figure 11. Additional applications to select.

Figure 12. Application selection on handheld touchscreen.

On the handheld, there is a function key at the bottom of the screen called Presets, and when that is pressed, this view allows scrolling up and down to select the type of scan. Presets are similar to applications, but can refer to a more specific type of exam.

Mode

Once the patient ID is complete, the next step is to choose the Mode selector. As described in earlier chapters, there are 3 basic modes used in ob/gyn ultrasound: 2-D or B-mode (grey scale), M mode, and Color Mode.

The default scan mode is 2D or B-mode (unless programmed otherwise). When selecting this mode, it will continue in this mode until changed. When scanning in another mode and the need is to change back to 2D, simply push this button again and it will revert back to B-mode.

On the hand-held units, the mode function can be accessed by touchscreen, and they are identical to those functions on a more complex machine (Figure 13).

Figure 13. Mode selection on handheld screen.

When ready to record a heartbeat (usually a fetal heartbeat), M-mode (or motion mode) is the desired selection.

Figure 14. M-mode selection button.

Selecting M mode will bring up a split screen –one above the other. The top screen shows in 2D real-time the heart beating. A moveable vertical line is present that can be moved with the trackball (or touchscreen) so that it intersects with the part of the heart with the most visible motion. Placing the line so it intersects with a moving structure (such as a heart valve) is best. This will be discussed in more detail in the First Trimester OB Course. Once the vertical line is placed over the area of the heart that is moving the most, then push the M mode button again to activate the bottom screen. The bottom screen will be a scrolling, moving series of lines that should have “blips” reflecting the movement that is transected by the line on the top screen. Once a series of “blips” (usually at least 4-5) is seen, then freeze to stop the scrolling. To calculate the actual rate, calipers are placed on one blip, set, and then another caliper is dragged over 1 to 2 blips over and set again. This is how the machine calculates the heart rate and displays it.

Figure 15. M-mode split screen view.

Figure 16 shows what M-Mode looks like on a handheld screen

Figure 16. M-mode on a handheld screen.

The third mode we will describe is color mode or C mode. It may also be called Color Flow or Color flow wave. When this is selected, the image continues to be in grey-scale, but blood vessels will be seen with shades of red or blue within them, indicating the direction of flow. More detail is covered in later parts of the course, but it is important to know that the red does NOT indicate artery, and the blue does NOT indicate vein. The colors have to do with flow direction. In general, the way to interpret color in doppler is use of the acronym “BART” (Blue Away, Red Toward the transducer).²³

Figure 17 is an example of what color flow Doppler looks like on the screen.

Figure 17. Image of right ovary showing color flow of nearby iliac vessels.

Keyboard and Trackball

The keyboard has the same text keys as a computer keyboard. You can type, or backspace, or do page-up, enter, etc. The function keys on the top row have uses that are specific to ultrasound, and each machine is different. So read the machine manual to learn what each function key does.

Figure 18. Keyboard on laptop ultrasound machine.

Trackball

The next thing to see is the trackball. Some older machines have a touchpad, but most have trackballs. This enables movement of the cursor more easily than using the up and down keys, and gives control for accurate placement of a caliper. It also allows selection of a location on the image to place text so you can annotate or give additional information about the structure you are looking at.

Figure 19. Trackball.

With a handheld device, no trackball is needed; touchscreen allows movement with touch

Figure 20. Touchscreen instead of trackball on handheld.

Freeze

The freeze button is one that is probably the most frequently-used. When a structure is viewed in the right plane to capture, pushing freeze will capture that image so the functions of labeling, annotating, and measuring can be done. Keep in mind that freezing an image stops the transmission of energy into the body from the transducer. This means that the transducer can stay in contact with the body without concern for extended exposure to sound waves. A hand can keep the transducer in the same location to enable rapid return to the same area just scanned, without having to “find” that structure all over again. Freezing also enables the Cine Loop (rewind) mode, which is described next.

Figure 21. Freeze button.

Handheld ultrasounds use various icons, but typically the icon representing ‘Freeze” is designated with a snowflake.

Figure 22. Freeze button on handheld.

Handheld ultrasounds use various icons, but typically the icon representing ‘Freeze” is designated with a snowflake.

Cine Loop

One of the functions of the trackball is to activate a re-wind of the prior set of views, called a Cine Loop. While scanning, the computer is capturing a video clip of everything seen up to the point that freeze is selected (up to a certain length of time or frames prior to the freeze). Sometimes a structure is seen as optimal but moves out of the display prior to freezing, (usually due to movement from the person scanning, the baby or the woman). Rather than starting over again to try to re-find that image, the trackball can be used to ‘scroll back’ to the frame with the desired view. This becomes the view that is used for measurement and then saved.

Cine-loop is a “re-wind”

1. Machine captures a burst of images

2. Allows the operator to scroll back through the most recently achieved images during that scan time and select the best image

Figure 23. Cine loop function.

The Cine function on the handheld displayed in Figure 25 not only allows scrolling back in time, but it can display tiny views of each previous frame to allow selection of a particular view.

Figure 24. Cine loop function on handheld screen.

Set

The set Button is what allows one to set or “stick” the cursor or measurement caliper to a certain place. For example, when measuring the distance between two areas, one must “set” the first caliper on one side of the structure. and then drag the line over to the other side; then “set” the second caliper. When selecting “set” on the second caliper, the machine then makes the calculation.

Set buttons are often located adjacent to the trackball on larger machines, making them easier to access without having to search. In Figure 25. the set button is labeled and is above the trackball. But typically the set buttons are on either side of the trackball, and may not be labeled.

Figure 25. Set button.

Menu

The ‘menu’ is a general setting that may include more advanced choices like how to select options for saving or archiving. Each machine has its own menu described in the user manual.

Figure 26. Menu selection.

Zoom

Zoom is a function that allows one to “zoom in” on an area to enlarge it. Zooming in on an area does not increase the frequency, so there is not an increase in more detail; it simply makes the area of interest look larger.

In performing ultrasound, it is preferrable to make the structure or area you are viewing occupy at least one-third of the screen. However, just as with use of Zoom on a camera, the enlarged image may lose some resolution.

Figure 27. Zoom.

On a handheld screen zoom is performed by using both fingers touching the screen. There may be a window at the top right highlight the part of the image being zoomed. This is very similar to using the zoom function on a digital or phone-based camera.

Figure 28. Zoom on touchscreen.

GAIN^1.35

Gain is the term we use to describe the darkness or lightness of the image being displayed. But the intensity or brightness of the pixels on the display are proportionate to the strength of the returning sound signal. So the receiver “boosts’ or “amplifies” those signals to make them brighter. It is like turning up the volume on a radio or sound device. This does not send more power to the radio station; – instead the incoming signal is amplified. By boosting the signal, the resulting pixels on the screen become brighter.

Figure 29. Gain enhances returning signals.

Gain is a function that can enhance almost every image obtained. it is an adjustment that typically precedes any other option such as measurement. Gain is adjusted through the receiver.

The receiver is one of the ultrasound machine’s components that was described in a previous chapter. The receiver is like a radio or TV receiver. It identifies signals coming into it and amplifies them so that they can be converted into a visual display. The strength of the returning sound signal is typically very low, and the machine must greatly amplify the signals to be recognizable.

Figure 30. Receiver controls

When an ultrasound image is too dark or too light, gain can be adjusted in several ways. The two most common gain settings are:

1) Overall gain

changing the brightness of the entire image on the screen, where the machine is amplifying the entire image equally.

2) Time Gain Compensation

amplifying or brightening the image at selected depths. In other words, part of the screen can be selected to brighten and or darken separately from the other sections.

Figure 31. Overall gain versus time gain compensation.

In Figure 32. the image on the left is a cross section of a fetal abdomen. As seen, it is dark, with some of the structures too dark to see well. It has similar darkness throughout the entire image. If overall gain is increased, shown on the right, the entire image is brightened, allowing for improved view of internal structures.

Figure 32. Gain differences demonstrated on fetal abdomen image.

With time gain compensation, each separate depth of the view can be brightened or darkened separately. Each slider (Figure 33). has a corresponding depth of the image that it enhances. If the slider is shifted toward the left, it darkens that horizontal section of the screen; moving to the right brightens it.

The top sliders correspond to those areas of the image toward the top, which represent a shallower area being viewed. Further down, the sliders correspond with progressively deeper areas of the body or structure. This allows gain toward the top of the screen to be increased, while allowing the deeper layers to remain as they are.

Figure 33. Time gain compensation sliders.

In Figure 34. the image of a placenta demonstrates another use of gain. Since the placenta is toward the maternal back and deeper in the body, the deeper area needs to be adjusted so that it brightens the deeper tissue.

Figure 34. Image of placenta demonstrating time gain compensation.

In Figure 35 the image of a left ovary shows that the area beyond the ovary (deeper) is blacked out. Sliding the lower slider(s) toward the right can brighten that deeper area. Without adjustment to that area structures or masses might go undetected.

Figure 35. Image of ovary demonstrating time gain compensation.

Some machines divide the image into 2 sections – upper and lower – and designate them as:

Near field

The area or structure nearest to the transducer, and

Far field

The area or structure deepest or farthest from the transducer

These machines will typically have a knob or button allowing selection of either of these.

Figure 36. Near and far field gain.
^{Near and far field gain. Photos from DDowdy archives. 2020}

Some machines divide the image into 2 sections – upper and lower – and designate them as:

Near field

The area or structure nearest to the transducer, and

Far field

The area or structure deepest or farthest from the transducer

These machines will typically have a knob or button allowing selection of either of these

Figure 37 demonstrates how gain appears on one type of handheld device screen. With this machine, swiping the screen side to side increases or decreases gain to brighten or darken the image.

Figure 37. Gain function on handheld touchscreen.

Depth

Depth is a function used often to adjust the size of the object being viewed. While scanning, there may be a structure that is out of range and below the area seen on the screen. Instead of changing the probe or increasing power, the depth function can be used to view deeper structures. Some machines will also have an option called “penetration”, which essentially does the same thing. The disadvantage of using this is that although it penetrates deeper, everything in the image is reduced in size, reducing the resolution. However, if general measurement is what is important, rather than details, depth is very helpful to use. Most machines will allow the operator to toggle back and forth to various depths.

Figure 38. Depth button.

On most ultrasound images, there is a bar along the right side of the screen that displays specific centimeters of depth in the image. On a handheld machine, depth can be changed by swiping up or down on the screen rather than using a button or toggle.

Figure 39. Depth on touchscreen.

Some machines have an option of placing a cursor or an arrow on the image to annotate that point or area to be described.

Figure 40. Cursor selection.

^.Measurement

Once the ideal image is captured, frozen, and optimized, measurement is the next step. It is helpful to “memorize” the location of that button for quick access. When the correct “Application” (such as gyn or first trimester) is in use, a drop-down list of measurement options (sometimes called calcs, short for calculations) will be displayed. This may also be called “Calc” for calculations. The button on the console may be labeled as “measure” or “calc”, or just have an icon indicating measurement (such as a “ruler”). For example, while in the first trimester application, the measurement options that will be displayed for selection would be CRL (crown rump length) or GS (gestational sac), etc. Whereas these measurement options would not be in the gyn application.

Figure 41. Measurement selection.

When measurement is selected, a dropdown of options will appear that correlate with the type of scan that was done. Calculations packages are pre-determined sets of measurements in the computer that convert measurements into, say, a gestational age. They also will calculate volume measurements of certain structures if you take views in each of 3 axes. These are very useful for measuring ovarian volume, as an example. They also will make a comparison of whether these measurements agree with the given gestation based on last menstrual period. When entering the patient data (at the beginning of the scan) the LMP (last menstrual period) gives the ultrasound computer a gestational measure to compare the actual measurements obtained by the scan.

Figure 42. Calculations options.

Once the image is frozen, and the type of measurement or calc is selected, then the machine will give an option of how the measurement is to be obtained: either a straight line, ellipse, or a trace line. End-calipers are displayed either one at a time, or as in Figure 43 (handheld device) both are displayed at once. The clinician can select either of them to move around to adjust caliper placement. Once the measurement is made, the “set” button is selected, and the the machine will automatically display the measurement number. If it is a gestational measurement, then it may also display the gestational weeks correlating with that measurement.

Figure 43. Types of calipers.

Annotation

Annotation simply means writing text on the image to further describe what is seen, and indicating location and surrounding structures. This is critical in documentation of what is seen and describing specific locations of pathology.

“Text” is a function to select once the image has been captured and frozen. elects text or annotation to be written on the image. After typing the text description, the text can be dragged to the area on the image needing the annotation. The button to select “text” can be found in various locations depending on the machine use. Sometimes it is located as a button on the console, sometimes it is on the keyboard.

Some machines have a button labeled as “text” and other machines have specific buttons on the console for text. If an error is made while typing an annotation, there will be a key that allows deletion of the text. Measurements can also be removed with this same delete key. However, the machine may store even deleted measurements, affecting cumulative calculations. So at the end of the scan it is good to pull up the final report and remove any incorrect measurements.

Figure 44. Text selection.

Many machines have something called auto-text. So instead of having to type out something like “right ovary” on the screen, you can go to auto annotation, select the Rt Ovary button, and it will automatically type it on the image where you have placed the cursor.

Figure 45. Auto-text or auto-annotation selection.

Figure 46. Auto-annotation on handheld.

This is another example of what is seen on the screen using a handheld. These machines also have pre-set wording that you can insert. Touch the button and then drag that wording close to the area to be annotated.

Figure 47. Auto annotation options on handheld.^{Auto annotation options on handheld. Photos from DDowdy archives. 2020}

This is an example of what is seen on the screen using a handheld. These machines also have pre-set wording that you can insert. Touch the button and then drag that wording close to the area to be annotated.

Saving and storing

Storing or archiving may also be done using a button called “Save”. This is a very important function since it stores the images in the hard drive of the machine. The machine has already created a folder with the patient’s information, and when pushing “save” or “store’, all the images from the current exam are put into that folder. It is very important to save every image while scanning. If it is not saved, it cannot be retrieved or re-created once the woman has left. It is better to save as many images as might be useful, then later delete if substandard or unnecessary. Most machines allow the options of saving either still images or video clips. This function may be in one of the “other function” settings.

Video clips, such as fetal movement or fetal breathing movement, are important to save since they demonstrate activity better than a still image.

Figure 48. Image storage.

The handheld will save and store the images to the patient’s file, saved either in the viewing device (phone or tablet) or to an online site. The machine will allow retrieval of these images to review. Figure 49 shows an example of how this would look on a handheld screen.

Figure 49. Image storage on handheld.

^{Image storage on handheld. Photo from DDowdy archives. 2020}

Printing is an option if a printer is attached. Many newer machines do not have actual printers but do have a port for inserting a flash drive (external storage device) to save the images for the patient. She may need copies to take to another provider or have as a keepsake. Keepsake imaging will be reviewed in the chapter on documentation. Most imaging societies do not recommend performing ultrasound for entertainment but do allow for images to be shared with a patient during a medically indicated exam.

Some machines have several print buttons – one designated for an actual printer, one for a CD or DVD recording device, and yet another one for archiving to another area (say, sending it to an outside radiology lab). These buttons can be configured in the machine settings to determine where the image is sent.

Figure 50. Print selection.

This slide shows a thermal printer on a stand connected to a regular sized ultrasound unit, and the picture on the right shows what a thermal print looks like. It essentially prints what is on the screen, but only in grey scale.

Figure 51. Printing options.

SUMMARY: Steps to achieve optimal settings

Ultrasound machines have many functions that enable the user to obtain, optimize, and store images.

Each machine differs somewhat in the location of these operations, so it is important to be familiar with the machine that will be used most frequently.

The functions most often used in POCUS are:

Transducer selection
Mode and Application selections
Keyboard and trackball
Set and freeze buttons
Zoom and depth changes
Measurements and caliper selection
Annotation
Image storage
Gain

NOTE: If the simple POCUS exam does NOT answer the clinical concern, a more advanced study done by a sonographer or specialist is required.

Table 1. represents a list of common steps that can be taken to improve the image using knobology.⁸ There are other functions in the machine for that purpose but these are the easiest to apply. Keep in mind that POCUS exams are often time-limited. If an image answers the practitioner’s clinical question there is no need to go into the sophisticated image adjustments done by a sonographer or radiologist.

Figure 52. Steps to optimize images with knobology.

Foundations of Women's Point-of-Care Ultrasound

Chapter 7 Image Optimization: Knobology