Gammex 405 GSX LE, User Manual

Page 1: ...User s Guide 405 GSX LE Precision Resolution Grey Scale Phantom ...

Page 2: ...GreyScaleTargets 12 Pin Targets 12 Resolution Target Group 12 Phantom Specifications 14 Physical Specifications 14 Tissue Mimicking Background Material 14 Harmonic Imaging 15 GreyScaleApplications 16 System Linearity 17 Quantitative Measurement 19 Baseline Test 19 Subsequent Tests 19 Qualitative Measurement 21 Phantom Desiccation 22 Charts and Graphs 22 Product Warranty 23 Sales and Service 24 ...

Page 3: ...r quality control purposes when monitoring these important image characteristics 1 axial resolution 2 lateral resolution 3 dead zone target imaging 4 vertical and horizontal distance accuracy 5 image uniformity The triangular grey scale targets in the phantom can be used to test the resolution of high performance ultrasound scanners Unique to the 405 GSX LE are two horizontal cross fibers located ...

Page 4: ...siccation Weigh your 405 GSX LE to monitor desiccation Weigh the phantom when you first receive it and then every 6 months Record the values on the data sheet Do not drop or damage the phantom Return the phantom for inspection and or repair if it has been dropped or damaged Physical damage to the case will cause premature desiccation Gammex recommends annual servicing of your 405 GSX LE to ensure ...

Page 5: ...aby oil or lanolin based gels as a coupling medium Poor transmission is a result of insufficient coupling Do not press the transducer into the scanning surface This damages the scanning surface and will shorten the life of the phantom For curved transduc ers use water or a thick gel layer Clean the scanning surface immediately after use Use a soft cloth or paper towel and soap and water if needed ...

Page 6: ...cking gel in the 405 GSX LE is ultrasonically similar to human tissue This allows the use of normal scanner control settings and ensures that the performance measured closely approximates the scanner s performance in a clinical examination Scanning is the best way to familiarize yourself with the features and functions of the 405 GSX LE A guided tour is provided on the following pages ...

Page 7: ...m You may notice that the tissue echoes near the bottom of the phantom fade into noise The depth at which usable echoes disappear is called the depth of penetration The depth markers on the phantom label will help you determine the depths of the targets The phantom comes ready to scan Do not peel off surface mate rial Never press the transducer into the scanning surface Always clean and dry the sc...

Page 8: ...gets The vertical pins have 2 cm spacing while the horizon tal pins have 3 cm spacing Use these pin targets to determine vertical distance accuracy and horizontal distance accuracy Note that the highest dead zone pin you can see should be the point of reference not the scanning surface 6 Freeze an image of the resolution target group at 1 cm Examine the horizontal row of pins at the top of the tar...

Page 9: ...ocal zone The pin width demon strates the width of the ultrasound beam at that depth and approximates the lateral resolution of the scanner 7 Decrease the image depth and examine the axial resolution target group at 3 cm Notice how the images of the lower pin targets may begin to merge The smallest distance between two pins that can be clearly resolved with no vertical overlap is called the scanne...

Page 10: ...k appearance and well defined edges Bright specular echoes at the top and bottom of the targets are normal Measure the dimensions of the 6 mm cystic target to check the image geometry Use the calipers to measure from top to bottom and side to side Repeat with the other cystic target groups as part of the cyst imaging test 9 Decrease image depth to the minimum and examine the dead zone target group...

Page 11: ...point at which you eliminate noise in the anechoic cyst lower the gain until it just disappears Record this gain setting and use it for future grey scale measurements Freeze the image and visually evaluate the grey scale targets Match each target with a step on the grey bar in the image Make a hard copy and compare the hard copy with the image on the scanner 11 When you are done scanning the phant...

Page 12: ... m s Temperaturedependenceonspeedofsound 1 5m s ºC Contrast low scatter 6 dB 6 dB high scatter relative to background Pin Targets Diameter 0 1 mm Vertical spacing 2 cm at 2 16 cm deep Horizontal spacing 3 cm at 2 and 12 cm deep Cross fibers 0 2 mm at 2 and 6 cm deep Resolution Target Group at 3 8 and 14 cm deep All acoustic measurements made at 4 5 MHz 22ºC Due to our philosophy of continuous qual...

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Page 14: ...ofilament Tissue Mimicking Background Material Water based gel with appearance of human tissue Speedofsound 1540 10m s Attenuationcoefficient 0 7 0 05dB cm MHz 0 5 0 05dB cm MHz refer to phantom side label Nonlinearity parameter B A 6 6 0 3 6 7 Accepted value for human liver tissue All acoustic measurements made at 4 5 MHz 22ºC Due to our philosophy of continuous quality improvement all specificat...

Page 15: ... attenuation as there would be if the higher frequency were used to generate the pulses at the transducer So higher frequency resolution occurs for greater depths within the subject than if conventional ultrasound was used The ratio of B A quantifies the rate of transfer with respect to propagation distance of ultrasonic fundamental frequency energy to harmonic frequencies The greater the amplitud...

Page 16: ...ately the metastases may not be detected The Quantitative Measurement ensures that the grey level signal is measured consistently The Qualitative Measurement ensures that grey levels are displayed on the monitor consistently By performing these tests the user can determine the optimal system settings for measuring grey levels which can then be used in clinical applications ...

Page 17: ...nt the contrast or difference in bright ness between different echo levels will remain constant If the shape of the S curve changes the relative image brightness for each echo level will also change For example image post processing techniques help the user identify subtle tissue vari ations by modifying the shape of the S curve to emphasize certain ranges of echo levels Degradation in the system ...

Page 18: ...ved to B 1 Bo 1 and B 1 Changes in the system response can be identified by measuring the average pixel value of the grey scale targets and the background material as displayed on the video monitor Pixel values can be estimated by eye or measured with image analysis tools provided on some ultrasound instruments or computers equipped with video frame grabbers and special software ...

Page 19: ...rform the test in the same manner each time Method Define a region of interest and measure the average echo level Procedure Baseline Test 1 Scan the grey scale targets and display them as large as possible Freeze the image 2 Measure the echo level of the anechoic target Adjust the system gain so that the measurement is approximately 1 This ensures that the system s noise floor is barely reaching t...

Page 20: ...he anechoic target Use as close to the same ROI as the target as possible Unfreeze the image 5 Perform this process three times and record the average echo level for each grey scale target and for the background material on the data sheet Analysis Contact your service engineer if target 2 3 or 4 varies from the baseline by 10 or more ...

Page 21: ...troduce variations in your data and potentially invalidate your results Method Assign a step on the grey bar to each grey scale target and the background Procedure 1 Assign a unique number to each grey level on the grey bar 2 Scan the grey scale targets and display them as large as possible Freeze the image 3 For each target determine which step on the grey bar is the same brightness as the target...

Page 22: ...e controlled environments the phantom weight should be checked every six months Phantoms used in high temperature low humidity environments or in mobile situations should be tested more frequently As the phantom desiccates the scanning surface may flatten out It is suggested that the phantom be sent in for rejuvenation once it has lost 10 15 grams of its original weight If the phantom has lost mor...

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Page 25: ...25 Notes ...

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