Sonography Practical
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Revision as of 16:27, 1 December 2018 by Zuzana Pálková (talk | contribs) (I described the procedure of the practical part in detail.)

Introduction

What is Sonography?

Sonography is a painless non-invasive medical procedure that uses high-frequency sound waves to produce visual images of organs, tissues, or blood flow inside the body. Depending on the situation, sonography may be used to examine the abdomen, genitalia, heart and capillaries etc.  

Brief Explanation

  Sonography is based on ultrasound (frequency above 20 KHz). When high frequency sound waves travel forwards, they continue to move until they make contact with an object. Then a certain amount of the sound bounces back.   

For example, sound waves go through areas that are hollow or fluid-filled such as the bladder and blood vessels, these areas appear black on the screen because all sound waves are reflected at their surface and nothing passes through them – in fact they produce a vertical shadow under them. Areas filled with tissue allow some penetration and reflection of sound and produce a grayish-white image. Really hard structures such as bone produce a bright white image as the sound waves completely bounce back to the transducer. A layer of aqueous gel is applied over the skin to make sure that the sound has an air-free path to the organ.The ultrasound waves penetrate the body, strike the organ moving through various types of tissue with different acoustic impedances and reflect back to the surface.The reflected waves are processed by the computer into a 2D image that appears on screen. The image is called as Sonogram.   

Importance in Clinical Medicine 

Ultrasound examinations can help to diagnose a variety of conditions and to assess organ damage following illness. 

Ultrasound is used to help physicians evaluate symptoms such as: 

  • Pain 
  • Swelling 
  • Infection 

Ultrasound is a useful way of examining many of the body's internal organs, including but not limited to the: 

Heart and blood vessels, including the abdominal aorta and its major branches, liver, Gallbladder, Spleen, Pancreas, Kidneys, Bladder, Uterus, ovaries, and unborn child (fetus) in pregnant patients, Eyes, Thyroid and parathyroid glands, scrotum (testicles), Brain, Hips and  spine in infants 

Ultrasound is also used to: 

  • Guide procedures such as needle biopsies, in which needles are used to sample cells from an abnormal area for laboratory testing. 
  • Image the breasts and guide biopsy of breast cancer. 
  • Diagnose a variety of heart conditions, including valve problems and congestive heart failure, and to assess damage after a heart attack. Ultrasound of the heart is commonly called an “echocardiogram” or “echo” for short. 

Doppler ultrasound images can help the physician to see and evaluate: 

  • Blockages to blood flow (such as clots) 
  • Narrowing of vessels 
  • Tumors and congenital vascular malformations 
  • Less than normal or absent blood flow to various organs 
  • Greater than normal blood flow to different areas which is sometimes seen in infections 

With knowledge about the speed and volume of blood flow gained from a Doppler ultrasound image, the physician can often determine whether a patient is a good candidate for a procedure like angioplasty.

Literary Review  

Sonography is when a sound wave strikes an object, and  it gets partially reflected and by measuring these echo waves, it is possible to determine how far away the object is, as well as the object’s size. As compared to other non-invasive techniques for viewing the internal organs like x-rays, MRIs or CT scans, the ultrasonography technique comes out on the top as it has lesser risk compared to the benefit unlike the other methods which have similar benefit but greater risk with as it is non-ionising (compare CT which is ionising) and does not involve very strong magnetic fields (as MRI), moreover it is a very good diagnostic tool. 

How does it work? 

Ultrasound has a frequency in the range of 2 to 20 MHz meaning that people are unable to hear them.  The wave then moves through various types of tissue with different acoustic impedances affecting the magnitude of the wave that are reflected. The detector inside the device then picks up these different intensities of refections and converts them into an image of the said area. The image received is in 2D as this makes it most clear to the professional operating the machine and because a single planar scan is most accurate with ultrasound measurement devices. 

Advantages: 

  • Noninvasive examination, doesn’t need needles or any injections.  
  • Not painful.   
  • Widely available, easy to use and less expensive than any other imaging tests.  
  • Extremely safe, and doesn’t use any ionizing radiation.  
  • Gives clear picture of soft tissues which can’t be seen well by x-ray images.  
  • The preferred imaging for the diagnosis and monitoring of pregnant women, and unborn babies.  
  • Provides real-time imaging.

Disadvantages: 

  • Can't penetrate bone or gas. 
  • If the body size of the patient is too great, this will effect the imaging quality negatively. 
  • Completely depends on the operator's/sonographer's expertise. 

Imaging Principle:

The basic calculations of ultrasound imaging have to do with acoustic impedance. Acoustic impedance can be summarized as, opposition to the flow of sound through a surface. Also the equation listed below describes the very nature of this term. 

Acoustic impedance = Density*Velocity 

If a targeted object is deep one must use a low frequency whilst when something superficial is observed, it is necessary to use a higher frequency. This way more clear images can be observed due to the fact that low frequencies can travel farther whilst high frequencies provide a better image but at shorter ranges.

Ethics: 

  • In case of the fetal sex, disclosure can be done only with an adequate consent process. 
  • In obstetric sonography, the procedure  can be performed only after 18 weeks and sessions must not exceed the limit prescribed in the guidelines. 
  • There must be a Doctor-patient confidentiality. 

Risks 

For standard diagnostic examination, there are no known harmful effects on humans.  

Practical part

Task 1: Image of phantom structures

Record and log (or print) the image of the phantom structures in the best possible quality from different perspectives.

Task 2: Identification of internal phantom structures

Identify the individual internal phantom structures and measure their dimensions.

For the purposes of the practice, we divide phantoms (identified structures) into 2 groups:

Cysts - typically anechoic (dark, to black), often rounded, smooth, regular surface

Tumors - Typically echogenic formations (appear light, white), various, irregular shapes, with rough surface with bumps

Further classification of findings requires many other parameters and data and is therefore beyond practical exercises.

Device description

For this particular examination we use the SonoSite 180 plus. It is a portable, software-driven and fully digitized ultrasound device. The system also allows ECG measurement, biopsy and any manipulation of captured images. In addition, downloaded data can be viewed on the monitor, transferred to a personal computer, or subsequently processed.

SonoSite 180 plus controls

1. Power switch

2. Near - Profit driver in the near field

3. Far - Profit driver in the far field

4. Gain - Total gain controller

5. Driver menu

6. Optimization, Depth and Magnification

7. Control ball

8. Patient - device setup menu

9. Function button

10. LCD screen brightness control

11. Battery charge indicator

12. LCD Contrast Controller

13. LCD screen

14. Arrows search in the last image loop

15. Buttons to select display mode

Important Notes: 

  • For safety reasons, the device should only be used for sonographic imaging on the provided dummy, and not on real human structures.   
  • Accompanying the sonography device is a convex sector cardiological probe with a mean operating frequency of 2 MHz. The shape of the probe allows for a fan shaped image, where it will be narrow when close to the probe and wider as depth increase into the provided dummy. The lower frequency of the probe allows for improved imaging of deeper internal structures. However, the probe does not allow for high quality imaging for more superficial structures.   

Workflow

The device is operated manually. In a normal procedure, the treated object is treated with a surface-applied gel. In the case of the practice, ordinary water is sufficient to eliminate unwanted reflections. (TIP! Choose a system when looking for structures, for example, from top to bottom, and then you can better navigate.)

1. Turn on the ultrasound device by pressing and holding the power switch on the back left side of the instrument handle, then the device will beep and the screen will light up. Before working on the task, make sure that there are no pictures of previous practices in the device, and if so, delete them.

2. Create a new profile for the patient on the device. Press the patient and select exam / patient information in the menu that appears next. Another options will appear, select the new patient option (at the same time deleting the previous patient data). A menu with the labels name, id, accession, exam, LMP or HR will pop up. Write the group number as the name, you do not have to fill in the other information. Pressing Patient returns you to the normal view.

3. Get to know the device, its controls, and usage options. The head of the ultrasound you are examining a phantom with needs to be correctly rotated, the image reflects reversed (depends on its position). Also, set the correct depth on your device from which you are examining. Use the Depth button. The probe should be used on the surface covered with the liquid (gel). Note that you will need to save, transfer to the PC, print or draw the relevant images you capture and measure (the procedure for transferring, viewing, and printing images will be described below).

4. Record a distinct and clear picture of the internal structures of the phantom. Capture the structure you find from different, ideally perpendicular, angles. Then sketch it and describe it in the log.

5. Measure the dimensions of each identified internal structure. Distance measurement is done using a control ball that moves the cursor to the selected locations. Use the freeze button to "freeze" the image so that you get a recorded structure on it. You will see two colorful dots (blue and green) on the screen, or cursors that can be scrolled through the control balls to different locations on the screen (in your case, to the start and finish of the structure). After the first cursor is fixed using the Select button, the second cursor is released. Then fix the second cursor in another place and press the Select button again. The measured value is displayed at the top left of the screen. Take a scale placed on the table, measure the actual dimensions of the structure. Write the results in the log and compare to  each other.

6.Transfer images to your computer. To do this, use the Site Link Image Manager program. In the Sono Praktikum folder (folder documents, desktop shortcuts), in your groups’ of folders, create a new folder with the number of your group. Set the image saving to your folder in Site Link Image Manager. Choose Configure in the top menu bar, select Image Files Location, set Documents and settings \ USER \ Documents \ Sono Practitioner \ Your Circle Components \ Your Group Folder and Confirm. To start the transfer, click Start, the Image upload complete message appears when the transfer is done.

7. Viewing files. You may use any graphics software on your computer to view the files. You should find the pictures in the folder you created in the Patient Name.No and Exam Date.YYYY Month DD.

8. Print pictures. To do so, use Picture and Fax Viewer. Once you have opened the image in the program, click on the print icon and click Next, then mark all the images you print and confirm. Confirm the printer option and then print 4 images per page. Click Finish.

9. Delete pictures from the device.

Conclusion   

In conclusion, Ultrasonography is considered one of the best non-invasive techniques used to locate objects within the body. With this technology it is possible to examine the human body without the need for surgery or other procedures. And in medicine they use this device to detect changes, appearance, and counter( WHAT IS COUNTER?) of an organs, vessels and tissues. 

The Future of Ultrasonography

In the first-generation units, image conversion was carried out by inbuilt hardware, thereby making the systems quite bulky. The current generation of ultrasound equipment uses external computing systems that perform the scan conversion and image display. This has resulted in device portability and enhanced the computing power with major improvements in image quality. Developments in signal multiplexing technology have enabled the adoption of a new generation equipment: 3-D and 4-D systems. It is expected that with these factors in mind, manufacturers of 3DUS and 4DUS devices will continue their efforts toward improving calculation power.    

References

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