SMS UNIQUE TEST NUMBER FOR THIS ARTICLE a41640
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1. f Focal Zone s Focal zone s enhance the resolution at a desired area of interest An increased number of focal zones will reduce the frame rate but improve the resolution 1 focal point positioned too low 2 6 M08 TIS 1 0 TIB1 0 100 2D 65 1 6 M10 TIS 1 0 TIB1 0 100 g Field of View FOV Use the smallest field of view possible which will improve the resolution for example when imaging the gallbladder and the fetal heart Portal Vein h Tints A very useful tool is to try different tints which help to highlight subtle abnormalities 12 11 Control Panel The above image is of a typical ultrasound system control panel layout All ultrasound models have the same basic layout however the buttons may be located in different places 1 TGC DGC Time Depth Gain Compensation 2 Overall Gain 3 Image Depth 4 Focal Zone s Numbers 1 4 above can be seen as physical buttons on the control panel of this particular ultrasound system The Acoustic Transmit Power Frame Rate Field of View FOV and Tints are available as on screen menu functions on the above system but could be an actual button on the control panel of other ultrasound makes and models It is important to familiarise yourself with the functionality of your particular ultrasound system s control panel and functionality 13 12 Useful 2D Artifacts An artifact is a detail which is produced artificially and does not correspond2. 20
3. Mode Amplitude Mode B Mode Brightness Mode Longitudinal section through thyroid lobe Y 100 M Mode Motion Mode A mode is seldom used today The adjacent image is of a thyroid gland which has the A mode activated together with the B mode image The image has been turned onto its side to better understand how A mode works The red indicates the A mode image which is what was used prior to the development of B mode Each echo is displayed as a vertical deflection along a time axis Each vertical deflection corresponds to a dot along the horizontal white line The horizontal white line can be moved along any part of the B mode image to display the A mode at that line of echoes The height of each echo is proportional to the strength of the echo Brighter dots have a higher deflection The time axis represents the distance or depth of the structure being examined B mode is also known as 2D mode 2 dimensional mode Each line of A Mode deflection is converted into dots of varying brightness according to their strength Rows of dots eventually accumulate to provide a 2D image in varying shades of grey The position of a moving object can be recorded at various instances The image on the left is of a common carotid artery but M mode is most commonly used in echocardiography The yellow arrows in the image indicate the arterial pulsation over time a Acoustic Transmit Power The power control varies t
4. It s the decrease in energy d b and c 10 The frequency required to do an adult abdominal ultrasound scan would be a 10 MHz b 3 5 MHz c 2 MHz d 7 5 MHz 17 Instructions to complete Multiple Choice Test On line To answer multiple choice tests on line 1 You need to be a registered user with CPD Solutions If you have not done this yet go to www cpdsolutions co za click on the Sign up button and follow the instructions from there 2 Go to www cpdsolutions co za and log in with your email address and password 3 Navigate to the multiple choice test on the Publications for page steps below On the home page click on the link Articles and multiple choice tests Click on the publication you want to view articles and test for Click on the detail block below Answer multiple choice test next to the article title This block will inform you how many CPD Solutions credits are required to complete the test Tick your choice of answers in the test and click the Submit button Your test results will appear on screen No CPD Solutions credits will be subtracted should you fail the test To view a summary of your CPD points click the My CPD Points link on the home page SMS To answer multiple choice tests with an SMS Steps 1 to 3 are required only once when you initially register with CPD Solutions 1 You need to be registered user with CPD Solutions If you have not do
5. Transcranial Frequency range 2 10 MHz 7 Probe orientation All transducers have a reference mark which corresponds to the image orientation Reference marks can vary from manufacturer to manufacturer This can be confirmed in your system user manual 8 Basic scanning planes and image orientation a Anterior approach Sagittal plane Anterior Patient s front Superior Inferior Patient s Patient s head feet Posterior Patient s back b Posterior approach Sagittal plane Posterior Patient s back Superior Inferior Patient s Patient s head feet Anterior Patient s front c Anterior approach Transverse plane Anterior Patient s front Right Left Side of Side of patient patient Posterior Patient s back d Posterior approach Transverse plane posterior Patient s back Anterior Patient s front e Left lateral approach Transverse plane Left Side of patient Anterior Posterior Patient s Patient s back front Medial Patient s midline f Similarly a right lateral approach transverse plane is shown below Right Side of patient Anterior Patient s front Posterior Patient s back Medial Patient s midline g Left lateral approach Coronal plane Lateral Side of patient Superior Inferior Patient s Patient s head feet Medial Patient s midline 9 Display Modes A
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7. CONTENTS page 1 15 BASIC 2 DIMENSIONAL ULTRASOUND PRINCIPLES page 16 Multiple Choice Test page 18 19 Instructions for answering of Multiple Choice Test On line or via SMS Tanya Reynolds Nat Dip Diag Rad B Tech Diag Rad B Tech Ultrasound Tanya is a qualified Diagnostic Radiographer and Sonographer She studied at the University of Johannesburg formally Wits Technikon Her work experience includes stints in various hospitals including Johannesburg Hospital Helen Joseph Hospital Coronation Hospital and Chris Hani Baragwanath Hospital More recently she has been employed as an Ultrasound Application Specialist with Siemens Medical Solutions She is currently studying towards a Masters Degree in Ultrasound SMS UNIQUE TEST NUMBER FOR THIS ARTICLE a41640 BASIC 2 DIMENSIONAL ULTRASOUND PRINCIPLES Ultrasound for medical diagnostic purposes was developed from SOund Navigation And Ranging in submarine detection hence the word SONAR 1 Sound Sound is the orderly transmission of mechanical vibrations through a medium Sound cannot propagate through a vacuum Gas as found in the bowel has poor sound propagation and solid structures such as bone have good sound propagation Gas and bone are poorly visualized on ultrasound but organs such as the liver and kidneys are well visualized Sound vibrations travel through a medium by a series of compression and then rarefaction of the particles Breer I esses VU eee I
8. II The closer the particles are together the better the sound transmission OOQOQOOOQOOOOOO00O000 OOQOQQOOOQOOOOOO00000 OOQOQQOOOQOOOOOO00000 QOOQOQOOOQOOOOOO00000 OOQOQOOOQOOOOOO00000 as Liquid Solid Most commonly the particles oscillate in the direction of propagation as a longitudinal wave Plotting these oscillations against time usually produces a sine wave 1 Amplitude 2 Wavelength Amplitude A The strength or height of the wave measured in decibels dB Frequency f Number of times the wave is repeated per second as measured in hertz Hz Wavelength a Distance a wave travels in a single cycle As frequency becomes higher wavelengths become shorter Sanders 1998 2 2 Pulse Echo Ultrasound Pulse echo ultrasound transducers operate by periodically sending short bursts of sound energy into the structure being examined Echoes are produced when changes in the characteristics of the structure are encountered When these echoes return to the transducer they are converted into electrical signals After processing the information received forms an image of the studied area The ultrasound system measures the time that it takes to receive the echoes after each transmitted pulse By keeping track of the time between transmitted pulses and the returning echoes the ultrasound system can determine the distance to the various reflectors Most diagnostic ultrasound systems are calibrated for a velocity of 1540 met
9. ers per second which is the average velocity of sound through human soft tissue Curry and Tempkin 1995 4 3 Piezoelectric Effect The major component of an ultrasound transducer is the piezoelectric element Piezoelectric materials are capable of converting one form of energy into another A voltage supplied to a piezoelectric element initiates vibrations at the element s resonant operating frequency The resonant frequency is related to the element s thickness The thinner the element the higher the resonant frequency of the transducer Another function of the piezoelectric element is to receive echoes that return from the structure being studied When the mechanical energy is received the piezoelectric element converts it into an electrical voltage which forms a visual image of the studied structure Although a single piezoelectric element is capable of either transmitting or receiving it cannot be used to perform both functions simultaneously Curry and Tempkin 1995 3 4 Attenuation Attenuation is the decrease in energy as a wave travels through a medium Attenuation is caused by absorption reflection beam divergence and scattering 5 Understanding Frequency One of the fundamental principles of understanding ultrasound scanning is understanding frequency Deep ultrasound scanning such as the abdominal organs uses a frequency of approximately 3 5 MHz sometimes 5 0 MHz in small adults or paediatrics giving more penetration but le
10. he amount of energy the transducer transmits to the patient Power should be used at the lowest level possible whilst still producing acceptable image quality This is for safety and resolution purposes Paediatrics and small adults will use a lower acoustic power compared to larger adults b TGC DGC Time Depth Gain Compensation TGC DGC compensates for the loss of energy that occurs by absorption scatter and reflection lt shows structures of the same acoustic strength as echoes of the same intensity whatever their depth Se O Within normal limits 1 Fre86 Too dark 100 MI1 0 10 c Overall Gain Overall gain regulates the degree of echo amplification the actual brightness of the image To prevent loss of information overall gain should not be too bright or too dark SS lt Too bright Within acceptable limits Too dark d Image Depth Image depth makes the image bigger or smaller and can vary from 1 0 cm to 30 cm depending on the transducer type and the structure being examined Set the image depth to optimally use the field of view a Too deep 1 0 100 Too shallow 1 0 Y 100 11 e Frame Rate For increased resolution use the lowest frame rate and highest line density possible Restless patients and patients who are short of breath will require a higher frame rate to compensate for movement Movement can cause the image to appear blurry or smudged
11. ne this yet go to www cpdsolutions co za click on the Sign up button and follow the instructions from there 2 You need to attach your cell phone number to your CPD Solutions profile If you have not done this yet go to www cpdsolutions co za and log in with your email address and password Click on the link CPD Solutions via SMS Enter your cell phone number in the text box provided and click the Update cell phone number button The system will generate a pin code and send it to you per SMS at the specified number 18 To interface with CPD Solutions via SMS you will need this pin code If you do not receive the pin code per SMS within 10 minutes make sure that you have entered to correct cell phone number 3 Save the CPD Solutions number in your cell phone s phone book If you have not done this yet find the number corresponding to your cell phone service provider below Vodacom 082 007 022 300 95 MTN 083 264 515 900 95 Cell C Virgin Mobile 084 003 177 000 95 Save the number to your phone book under CPD Solutions Remember If you ever change cell phone service providers you need to update this number in your phone book This applies to number porting as well You will find a complete guide to using the SMS interface when you click on the CPD Solutions via SMS link on the CPD Solutions website 4 Answer the multiple choice test To answer a multiple choice test per SMS you need the following
12. ourtesy Siemens Medical Remaining images acquired using Siemens ultrasound units 15 14 Multiple Choice Test 1 Which transducer would you use to perform a thyroid examination a Phased array b Linear array c Curvilinear array d Low frequency 2 Lower frame rates can be used in a Restless patients b Co operative patients c Patients who are short of breath d All of the above 3 Which statement is correct a Shorter wavelengths have higher resolution b Longer wavelengths have less resolution c 10 MHz has a shorter wavelength than 5 0 MHz d All of the above 4 Which of the following is not an artifact a Acoustic shadowing b Acoustic enhancement c Acoustic shadowing and enhancement d Image invert 5 Adding focal zones to your image will a Increase the frame rate and improve the resolution b Reduce the frame rate and improve the resolution c Increase the frame rate and reduce the resolution d Reduce the frame rate and reduce the resolution 6 The average velocity of sound through human soft tissue is a 1540 meters per minute b 3000 meters per second c 120 kilometers per hour d None of the above 7 Sound cannot propagate through a A solid b A vacuum c Liquid d The liver 8 Frequency is measured in a Hertz b Decibels c Frames per second d Meters per second 16 9 Attenuation is the increase in energy as a wave travels through a medium a True b False c
13. ss resolution Superficial ultrasound scanning such as the thyroid uses a frequency of approximately 10 0 MHz which has less penetration but more resolution Larger patients require lower frequencies whereas higher frequencies can be used on smaller patients The aim is to use the highest frequency possible which is capable of giving the best resolution at the required depth for the structure being examined Frequency Wavelength Display CER Each dot individually displayed EESE Two dots displayed as one dot Four dots displayed as one dot 10MHz gt In summary Higher frequencies have e Shorter wavelengths e Less penetration e Increased resolution Transverse section through thyroid qland Y 100 The above thyroid image was taken using a frequency of 10 0 MHz at a depth of 4 0 cm Lower frequencies have e Longer wavelengths e More penetration e Decreased resolution a Right liv er lobe The above liver image was taken using a frequency of 5 0 MHz at a depth of 16 0cm 6 Types of transducers and their field of view Curvilinear array oe 6 er ee SR Oe ae Se ee ee oe Primary applications Abdomen Pelvis Obstetrics Gynaecology Frequency range 2 6 MHz Linear array Primary applications Vascular Musculoskeletal Breast Small Parts Frequency range 6 17 MHz Phased array ae a TT Sa CY TS a Primary applications Cardiac
14. to an anatomical structure Most artifacts are undesirable but some are useful Acoustic shadowing Failure of the sound beam to pass through a dense structure due to reflection or absorption causing a posterior shadow It is especially useful in diagnosing calcifications It appears as a black dark shadow on the image Gallstone et Acoustie Shadowing Acoustic enhancement Sound travelling through a fluid filled structure is barely attenuated which cause the structures distal to a cystic lesion to appear to have more echoes than neighbouring echoes This is useful in diagnosing cysts It appears as a white light shadow on the image p a Nate Sata TAA AS A a nie A a p i Simple Cyst Acoustic Enhancement Renal Cyst 14 13 References CHUDLEIGH P amp Pearce JM 1997 Obstetric ultrasound 2 ed UK Churchill Livingstone CURRY RA amp Tempkin BB 1995 Ultrasonography an introduction to normal structure and functional anatomy WB Saunders Company SANDERS RC 1998 Clinical sonography 3 ed USA Lippencott Raven TEMPKIN BB 1999 Ultrasound scanning principles and protocols 2 ed USA WB Saunders Company THRUSH A amp Hartshorne T 2005 Peripheral vascular ultrasound how why and when 2 ed Elsevier Churchill Livingstone Curvilinear Linear and Phased Array Transducer images courtesy Siemens Medical CW image Acoustic Shadowing image and Acoustic Enhancement image c
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