Innovation is a journey not a destination
Innovation is a journey not a destination

Clinical FAQs

Questions related to the clinical use of Voxar 3D


Workflow questions

MPR reading questions

3D reading questions

Vessel analysis questions

CT colonography questions

PET/CT reading questions

 


Workflow questions

 

My Voxar 3D is not PACS-integrated. Can I load DICOM images from a DVD, CD, or USB drive?

What are Voxar 3D Live Images?

How do I restore the state from a Live Image?

How do I print my captures?

How should I finish a reading session?

 


My Voxar 3D is not PACS-integrated. Can I load DICOM images from a DVD, CD, or USB drive?

Yes. If you have compatible DICOM datasets, you can import them into Voxar 3D:

  1. In Voxar 3D, switch to the Study Browser. The Study Browser dialog box is displayed, showing the Archive tab. The Archive tab displays the studies and series in the Archive directory.
  2. Click the Import DICOM Files button. The Select Files dialog box is displayed.
  3. If the files containing the required images are in a specific folder, locate and open the folder.
  4. Select the files containing the required images. DICOM files usually have the file extension .dcm, .zap or .tmp.
  5. Click the Open button. The images contained in the DICOM files are imported.

What are Voxar 3D Live Images?

Live Images provide the ability to save, restore and share images throughout the enterprise:

  • Technologists can create MPR and 3D reconstructions
  • Radiologists can then restore prepared reconstructions and continue to interact with the images
  • Clinical colleagues can restore reconstructions and create any additional views they need

How do I restore the state from a Live Image?

From the Study Browser (non-PACS-integrated only):

  1. If you are in a viewing mode or clinical application, click Exit. The Study Browser is displayed showing the Archive tab.
  2. In the Study table, select the study that contains the capture.
  3. In the Series table, select the series that contains the capture. Series containing a Live Image capture are indicated by the Live column in the table.
  4. Click the Restore Live Image button.

From the current reading session:

  1. Switch to the Reading Manager.
  2. On the Read tab, select the series that contains the capture.
  3. Click the Restore Live Image button. If required, select a viewing mode or clinical application from the Restore Live Image menu.

How do I print my captures?

  1. Switch to the Reading Manager.
  2. On the Report tab, select the thumbnails of the capture to be printed. To select a range of thumbnails, click the first thumbnail in the range, hold down the SHIFT key, then click the last thumbnail in the range.
  3. Click the Send to Print Composer button. The Print Composer presents the images in a tiled layout on one or more pages - to view other pages, use the scrollbar.
  4. Manipulate the images and pages as required.
  5. Specify the printer that is to print the images.
  6. Click the Send button. The images are printed, and they remain in the Print Composer dialog box allowing you to print them again. The images are only removed after a reading session has finished.

How should I finish a reading session?

  1. In the viewing mode or clinical application, click the Exit button. The Reading Manager is displayed, showing the Report tab. The Report tab displays a thumbnail of each capture taken from the current reading session.
  2. If you want to archive all the captures taken during the reading session, click the Finish and Archive button. Alternatively, click the Discard and Finish button to finish the reading session without archiving captures.

 


MPR reading questions

 

How do I make an oblique MPR?

How do I make a double-oblique MPR?

How do I make a thick MIP (MIP slab)?

How do I reconstruct slices into different slice thicknesses?

Is there a way to record a movie by scrolling through an axial 3D view? I need a stack series, not a rotational series in a superior view.

What is lighting?

 


How do I make an oblique MPR?

  1. Select MPR Standard mode.
  2. Select the Align Orthos tool. A realignment controller is displayed on each orthogonal MPR view – the crosshairs indicate the position and angle of the planes in the other two orthogonal MPR views.
  3. On the specialized MPR view, click the Sagittal, Coronal or Transverse area to select a viewing plane.
  4. Drag the crosshairs of the realignment controllers to specify the axis of rotation, and drag on the orthogonal MPR views to realign the planes.

How do I make a double-oblique MPR?

  1. Select MPR Oblique mode.
  2. Select the Oblique Orthos tool.
  3. Specify the first axis of rotation for the plane by clicking the relevant orthogonal MPR view. An oblique controller is displayed on the view – the crosshairs indicate the position and angle of the planes in the other two orthogonal MPR views.
  4. Drag the crosshairs of the oblique controller to specify the position of the first axis.
  5. Drag the circle of the oblique controller to specify the angle of rotation around the first axis.
  6. Select the Define Oblique View tool.
  7. Specify the second axis of rotation for the plane by clicking the relevant orthogonal MPR view. A plane/slab controller is displayed on the view - the line indicates the position and angle of the plane in the specialized MPR view.
  8. Drag the inner circle or line of the plane/slab controller to specify the position of the axis.
  9. Drag the outer circle of the plane/slab controller to specify the angle of rotation around the axis.

How do I make a thick MIP (MIP slab)?

  1. Select MPR Standard mode.
  2. On the specialized view, click the view that you want to reconstruct.
  3. Click the Specialized tab on the right.
  4. Select the Slab check box.
  5. To specify the thickness of the slab, enter the thickness in the Slab box.

Alternatively, drag the slab handles on the plane/slab controller. To move the slab handles on both sides of the line at the same time, hold down the CTRL key and drag.


How do I reconstruct slices into different slice thicknesses?

  1. Select MPR Standard mode.
  2. From the specialized view, click the view you want to reconstruct.
  3. Click the Define Series button.
  4. To change the extent of the series manually, drag the extent handles on the stack series controller.
  5. To change the number of images in the series, on the Define Series dialog box, enter the number of images in the Images box.
  6. To change the spacing of the images in the series, enter the spacing in the Index box.
  7. Click the Capture button to save the new series.

Is there a way to record a movie by scrolling through an axial 3D view? I need a stack series, not a rotational series in a superior view.

It is possible to capture an "axial 3D view" in MPR standard or MPR oblique mode:

  1. Enter the mode.
  2. Get the plane you want in the fourth view.
  3. To view from superior, clear the automatic orientation check box and mirror the view vertically. You might also need to rotate the view if you want patient posterior at the bottom of the view.
  4. Change the slab rendering mode to VR.
  5. Apply the required VR preset.
  6. Set the slab thickness and index as required (contiguous slabs are probably best).
  7. Capture the series.

This method will not include any segmentation results. If a view of segmentation results is required, you need to have the area of interest cropped in within a 3D view then move the "slab" accordingly. Each image would need to be captured separately and then turned into an AVI when you export from the system.


What is lighting?

In some views containing a slab or volume, you can simulate the slab or volume being lit from the front – the surface facing the light is rendered in bright tones or colors, and the surface away from the light is rendered in darker tones or colors.

In addition, when the slab or volume is lit, you can specify the gloss of its surface.

 


3D reading questions

 

How do I make a virtual endoscopy view?

How do I measure tumor volume?

How do I capture a movie of a 3D view?

What is Refine in 3D Segmentation mode, and what are the options in its drop-down list?

What is lighting?

 


How do I make a virtual endoscopy view?

  1. Select MPR Endoscopic mode.
  2. On the specialized MPR view, click the diagram that indicates the direction of the curve for the volume.
  3. Click an orthogonal MPR view where you want the curve to start. A control point for the start of the curve is displayed.
  4. Click where you want the first segment of the curve to end. A control point for the end of the segment is displayed.
  5. Continue clicking to specify the end of subsequent segments.
  6. Select the Specialized (endoscopic) tab.
  7. If you are looking at contrast-enhanced vessel, change the preset to Endo (Angio) – if you are looking at airways, select Endo (Lung).

How do I measure tumor volume?

  1. In 3D Segmentation mode, make the tumor into a selection using the Shape Selection tool.
  2. After making a selection, click the Measure Select.Volume button. A measurement annotation is displayed, showing text describing the volume of the selection.
  3. Click the text to show or hide the additional measurements:
    - Volume of the selection, including holes
    - Volume of samples containing a pixel value in the selection, including holes
    - Volume of samples, or voxels, containing a pixel value in the selection, excluding holes
    - Mean, maximum, and minimum pixel value in the selection, along with the standard deviation of pixel values in the selection
    - Number of shape, line and region components in the selection

How do I capture a movie of a 3D view?

  1. Click the arrow to the right of the Capture button.
  2. From the menu, select Define Movie. The Define Movie dialog box is displayed, and the 3D view displays a movie capture message.
  3. Rotate the Volume of Interest as required.
  4. Click the End Recording button.
  5. Specify the path options as required.
  6. Check the movie description, which is used as the DICOM series description for the movie. To change the description, select the Use custom description check box and edit the text.
  7. Click the Capture button. The capture is taken and stored as a group of Secondary Capture images in the Archive directory.

What is Refine in 3D Segmentation mode, and what are the options in its drop-down list?

After making a 3D selection, you can refine a selection with the following operations:

  • Reshape – deselects tissue that is specified by a shape intersecting a selection
  • Trim region – deselects tissue at a specified location inside a selection
  • Flood fill region – selects unselected holes and involutions at a specified location inside a selection
  • Invert – selects all tissue in the standard Volume of Interest, apart from the tissue currently selected
  • Erode – decreases the size of a selection excluding a layer of voxels at its surface
  • Dilate – increases the size of a selection by including a layer of voxels immediately outside its surface
  • Open – erodes then dilates a selection, which can break thin connections inside the selection
  • Close – dilates then erodes a selection, which can close small holes and involutions inside the selection
  • Fill – selects large unselected holes inside a selection
  • Shell – excludes all voxels from a selection, apart from a layer of voxels at its surface

What is lighting?

In some views containing a slab or volume, you can simulate the slab or volume being lit from the front – the surface facing the light is rendered in bright tones or colors, and the surface away from the light is rendered in darker tones or colors.

In addition, when the slab or volume is lit, you can specify the gloss of its surface.

 


Vessel analysis questions

 

How do I set an appropriate window/level setting for vessel analysis?

Why is there a difference in area vs diameter stenosis measurements in VesselMetrix, and which one should I use?

 


How do I set an appropriate window/level setting for vessel analysis?

This article describes an effective method for setting correct window/level settings: http://www.cardiaccta.us/edge_detection.html


Why is there a difference in area vs diameter stenosis measurements in VesselMetrix, and which one should I use?

It is important to know whether an arterial stenosis is measured in terms of diameter or area because the two percentages do not correspond. The degree of area reduction is greater than the degree of diameter reduction.

A 90% area stenosis is approximately equal to a 70% diameter stenosis. Calculations are based on the following for stenotic occlusion: The residual lumen at the lesion site is compared with the lumen at a reference site. The degree of occlusion is measured in terms of the diameter or area of stenosis. The percentage of stenosis is calculated using a formula NASCET (1 – L/R) x 100, where L and R are the area or diameter of the lesion and of the reference site, respectively.

http://radiographics.rsnajnls.org/cgi/content/full/25/5/1141#T1

Some reports state that a reduction in cross-sectional area correlates better with the hemodynamic effect of stenosis than does a reduction in diameter Therefore, change in cross-sectional area has been proposed as a more accurate way of measuring arterial stenosis.

http://radiographics.rsnajnls.org/cgi/content/full/25/5/1141#T1

 


CT colonography questions

 

In ColonMetrix CAR, what does sphericity relate to and how does that influence the CAR findings?

 


In ColonMetrix CAR, what does sphericity relate to and how does that influence the CAR findings?

Sphericity is a measure of how spherical an object is. Defined by Wadell in 1932, the sphericity of a particle is the ratio of the surface area of a sphere (with the same volume as the given particle) to the surface area of the actual particle being measured.

In ColonMetrix configured with CAR, there is a Polyp Enhanced Filter (PEF) – a sophisticated filtering system that identifies defects protruding into the colonic lumen, highlights areas of the colon wall that contain raised spherical regions, and marks them for further investigation.

The sphericity threshold can be manually set with a simple slider bar, allowing the user to discriminate between real polyps and other features that may mimic the appearance of polyps (false positives) such as retained stool or haustral folds. By increasing the sphericity threshold, the user may increase specificity for true polyps. By decreasing the sphericity threshold, the user may increase the overall sensitivity, drawing attention to more irregular shaped objects.

 


PET/CT reading questions

 

Is there a standard way to draw ROIs in PET/CT Fusion so that, when comparing to priors, the area of interest always has the same dimensions?

In PET/CT Fusion, what does "BQML" mean in the region of interest annotation?

What information is required for PET/CT Fusion to calculate Standardized Uptake Values (SUVs)?

 


Is there a standard way to draw ROIs in PET/CT Fusion so that, when comparing to priors, the area of interest always has the same dimensions?

When you triangulate to an area a little pop up in the bottom left appeas giving you the SUV and HU if applicable. This must have a default setting of a certain size as no manual points need to be placed.


In PET/CT Fusion, what does BQML mean in the region of interest annotation?

BQML stands for Bequerels per milliliter. This is one unit of measurement used to represent pixels in PET images. The PET/CT Fusion application displays BQMLs if it cannot calculate SUVs.


What information is required for PET/CT Fusion to calculate Standardized Uptake Values (SUVs)?

The calculation of SUV's requires the BQML value plus the image properties described in the table below.

Pixel unit

Description

Image properties required

SUVbw
(Standardized Uptake Values (Body Weight))

[Pixel Value (bq/ml) x Body Weight (g)] / Dose (bq)

Where Body Weight is:

Patient Weight (kg) x 1000 (g/kg)

The images must be decay-corrected, they must have valid Patient Weight and Dose tags, and the original pixel value unit must be BQML.

SUVbsa
(Standardized Uptake Values (Body Surface Area))

[Pixel Value (bq/ml) x Body Surface Area (cm2)] / Dose (bq)

Where Body Surface Area is:

[Patient Weight (kg)]0.425 x [Patient Size (m) x 100 (cm/m)]0.725 x 0.007184 x 10000 (cm2/m2)

The images must be decay-corrected, they must have valid Patient Weight, Patient Size, and Dose tags, and the original pixel value unit must be BQML.

SUVlba
(Standardized Uptake Values (Lean Body Mass))

[Pixel Value (bq/ml) x Lean Body Mass (g)] / Dose (bq)

Where Lean Body Mass for men is:

[ [1.10 x Patient Weight (kg)] - [128 x [Patient Weight (kg) / [Patient Size (m) x 100 (cm/m)] ]2 ] ] x 1000 (g/kg)

And Lean Body Mass for women is:

[ [1.07 x Patient Weight (kg)] - [148 x [Patient Weight (kg) / [Patient Size (m) x 100 (cm/m)] ]2 ] ] x 1000 (g/kg)


The images must be decay-corrected, they must have valid Patient Weight, Patient Size, Dose, and Sex tags, and the original pixel value unit must be BQML.

SUV
(Standardized Uptake Value)

Note: Only available for images from Philips PET scanners.

Original pixel value (CNTS) x SUV Scale Factor

The SUV Scale Factor is specified in the Philips PET Private Group. For more information see the DICOM Conformance statements for Philips PET Scanners.

The images must have original pixel value unit of CNTS and contain the Philips PET Private Group.

 


 

Still need help?

See the Related Links at the top right of this page