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21

Phantom Desiccation

Over time, the phantom’s water-based gel will slowly lose moisture. This process is 
accelerated by high temperatures, incorrect storage, and damage to the case or scan-
ning surface. Consistently storing the phantom in an air-tight container will contribute 
greatly to long phantom life. Properly storing your phantom will reduce the amount of 
moisture lost per year. For instructions on how to properly store and take care of your 
phantom, go to the Caring for Your Phantom section.

For most climate-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 rejuve-
nation once it has lost 10-15 grams of its original weight. If the phantom has lost more 
than 20 grams, Gammex cannot guarantee that the phantom will be able to rejuvenate 
successfully.

Charts and Graphs

Refer to the Charts and Graphs section of the manual CD to find the appropriate charts 
and graphs for your 404GS LE phantom, which include:

Phantom Weight Chart
Data Sheet
Quantitative Measurement
Qualitative Measurement

Summary of Contents for 404GS LE

Page 1: ...404GS LE Precision Small Parts Grey Scale Phantom Gammex User s Guide...

Page 2: ...12 Pin Target 12 Resolution Target Group 12 Phantom Specifications 14 Physical Specification 14 Tissue Mimicking Background Material 14 Low Scatter Anechoic Cysts 14 GreyScaleTargets 14 Harmonic Imag...

Page 3: ...for testing for Axial and lateral resolution targets at 1 3 5 and 6 cm for precise resolution mea surements Low scatter cyst imaging at 1 2 and 4 mm Attenuation coefficients of either 0 5 or 0 7 dB cm...

Page 4: ...cation Weigh your 404GS 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 p...

Page 5: ...y 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...

Page 6: ...l in the 404GS LE is ultrasonically similar to human tissue This allows the use of normal scanner control settings and ensures that the performance measured with the phantom closely approximates the s...

Page 7: ...ou 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...

Page 8: ...onic calipers to measure the distance between two of the vertical pin targets Repeat for two of the horizontal pin targets The vertical pins have 5 mm spacing while the horizon tal pins have 10 mm spa...

Page 9: ...tal width of the pin targets in the near mid and far fields of the image Notice how the pin targets are narrowest in the focal zone The pin width demonstrates the width of the ultrasound beam at that...

Page 10: ...e normal Measure the dimensions of the 4 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...

Page 11: ...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 wit...

Page 12: ...eter 7 mm Placement 3 cm deep Pin Targets Diameter 0 1 mm Vertical spacing 5 mm at 1 9 cm deep Horizontalspacing 10mmat1and5cmdeep Resolution Target Groups 1 3 5 and 6 cm deep All acoustic measurement...

Page 13: ...13...

Page 14: ...e of speed of sound 1 5 m s C Attenuation coefficient 0 7 0 05 dB cm MHz 0 5 0 05 dB cm MHz refer to phantom side label Low Scatter Anechoic Cysts Speed of sound 1540 10 m s Temperature dependence of...

Page 15: ...uch 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 convent...

Page 16: ...tely 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 t...

Page 17: ...nt the contrast or difference in brightness 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 Fo...

Page 18: ...ed 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 Pix...

Page 19: ...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 M...

Page 20: ...d by locating a grey bar step that approximates the brightness of the region of interest Note It is absolutely critical that all system control settings be precisely reproduced for these tests Errors...

Page 21: ...d 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...

Page 22: ...f the defect and d which are found to be defective by Seller upon Seller s examination Buyer shall pay all transportation charges Products manufac tured by third parties must be returned to Seller wit...

Page 23: ...epartment hours are Monday through Friday 7 30 am to 5 00 pm Central Time 1 800 GAMMEX 1 426 6391 1 608 828 7000 1 608 828 7500 Fax e mail sales gammex com Service Department hours are Monday through...

Page 24: ...24 Notes...

Page 25: ...gammex com e mail sales gammex com Gammex RMI LTD Broadway Business Centre 32A Stoney Street Nottingham NG1 1LL United Kingdom 44 0115 9247188 Fax 44 0115 9247189 e mail uksales gammex com Gammex RMI...

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