Application of “StatPhantom” Software for Image Quality Evaluation

George Davydenko ,

Victor Gurvich,

Mark Smekhov

•Is ideal for teaching, training and research.

•Enables you to randomly change the position of test elements in the image of any phantom.

•Uses statistical technology and computer power to determine probabilities of detail detection.•Delivers reliable, unbiased and rapid quality control results using very simple techniques.

•Provides a navigation system allowing to locate a test element by its coordinates or to determine the coordinates of a detected test element.

•Allows statistical processing of the image of any phantom with fixed disposition of test elements.

•Allows statistical processing of different images of the same or different phantoms simultaneously.

•Helps choose optimal physical and technical conditions for diagnostic procedure.

•Helps achieve and maintain excellent image quality.

StatPhantom - software for image quality evaluation

StatPhantom Works with various image files:

•Helps achieve excellent image quality

•JPEG

•GIF

•DICOM (greyscale, without compression)

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

StatPhantom Provides basic image operations:

scaling rotation Brightness adjustment

contrast adjustment

•Helps achieve excellent image quality

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

StatPhantom has navigation system which helps to locate test elements

test elements

labels

coordinates of cursor position

•Helps achieve excellent image quality

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

StatPhantom how to work: step 1 – set one of selection patterns

circle (default)

square

ellipse

rectangle

•Helps achieve excellent image quality

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

StatPhantom how to work: step 2 – make selection by pressing left mouse button and dragging

selection shape was set at Step 1

circlesquareellipserectangle

•Helps achieve excellent image quality

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

StatPhantom how to work: step 3 – switch to Make selection mode and double click at point which you want to be the center of selection

•Helps achieve excellent image quality

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

StatPhantom how to work: step 4 – activate pop up menu by clicking right mouse button and add selected fragment to the selection set

Select Add selection with test element if fragment contains test element

Select Add selection without test element if fragment does not contain test element

Set of selections

•Helps achieve excellent image quality

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

StatPhantom how to work: step 5 – adjust selection set:

clicking right mouse button on selection activates context menu

which enables to change brightness and contrast of selection or delete it

All selections can be deleted by pressing Delete button

Order of selections can be randomly changed by pressing Rearrange button. If flag Rotate from Options menu is set they are also rotated at random angle

User can save selections into file choosing Save selections from File menu

•Helps achieve excellent image quality

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

StatPhantom how to work: step 6 – set likelihood of the existence of a test element in selection:

Set flag Hide image in View menu if you want to display selections only

Select appropriate likelihood for every selection from drop down combo boxSet 100 if you

are sure test element exists

Set 75 if you almost sure test element is in selection

Set 50 if you can say nothing about presence of a test element

Set 25 if you almost sure test element is not in selection

Set 0 if you are sure test element isn’t in selection

•Helps achieve excellent image quality

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

StatPhantom how to work: step 7 – get results

Press Calculate button to get results

Some results of calculation

To see all results of all experiments select item Show results table from View menu

Probability of true positive answer and its error

Probability of true negative answer and its error

Probability of true answer and its error

Signal-to-noise ratio of complete diagnostic system

Diagnostic preference of observer

To save results in Excel file press Save button

To clear table press Clear all

To delete some rows from table select them by mouse and press Delete selected rows

•Helps achieve excellent image quality

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

Set minimal probability of true answer

Set flag if you want to activate quality control

StatPhantom how to work: step 8 – quality control

check item Quality control in Options menu to bring up quality control dialog box

If you activate quality control, then after every calculation Pdet is compared to minimal value of true answer. If it is less, FAILED message pops up, otherwise PASSED message appears

•Helps achieve excellent image quality

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

StatPhantom Example: compare two images of different quality of the same phantom

•Helps achieve excellent image quality

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

1.Higher quality image

Selections made from this row

2.Lower quality image

StatPhantom Example: compare results

•Helps achieve excellent image quality

•Is ideal for quality control, training and research•Uses simple and reliable statistical techniques

•Can be used for all imaging modalities

Fragment from image 1 (higher quality)

P(Y/s) = 0.90

P(Y/n) = 0.05

Pdet = 0.93

S/N = 2.93

Fragment from image 2 (lower quality)

P(Y/s) = 0.75

P(Y/n) = 0.20

Pdet = 0.78

S/N = 1.52