Dose Comparison Tools

The gamma method may be used with the distribution of the gamma value shown on 2D and 3D images. Shown here is an example of the value of 1.0 being shown for a criteria of 3 percent and 3 mm. Dose areas with a gamma value of 1.0 or more, hence the dose disagrees by either more than 3% or 3 mm, are tinted red in this example if dose > plan, cyan if dose < plan.

See the reference in Medical Physics by Daniel Low, et. al., Vol 25(5) May 1998, pp. 656-661, "A technique for the quantitative evaluation of dose distributions."

Gamma Method on 3D Images

The same distribution may also be shown in three dimensions. Here the 3D distribution of gamma value of one is also shown (red where dose > plan, cyan where dose < plan).

And below the same for gamma of 2.0: 6% or 6 mm.

Gamma Volume Histogram

Lastly, a gamma volume historgram may be displayed, here shown for the same above head and neck case. Different volumes may be selected. Here the body volume is selected. Note the statistics for percent of points <= a gamma value of 1.0.

Dose Volume Histograms

Dosimetry Check can recompute the dose volume histogram for a region of interest and the dose volume histogram (dotted) from the 3D dose matrix downloaded from the planning sytem. In the case shown here, there were differences due possibly to tongue and groove effect for an IMRT case. The case was done twice with Dosimetry Check, once with Kodak V film (solid) and once with Kodak EDR2 film dashed. The target volume was very small, 7.4 cc, and represented a difficult IMRT case, with the CTV up next against the left eye. A small difference in the beam fluence film and that predicted could be seen. Here we show the effect of the small change in the delivery. This could not be appreciated without Dosimetry Check.

1D View Dose Profiles Together

The downloaded treatment plan profile may be shown, dotted, along with the dose computed here, solid. Shown below is the dose from a head and neck case. The translate and rotate controls are used to position the line on the display of any reformatted image that defines where the profile is taken from.

2D View Dose Together

The downloaded treatment plan may be shown (green) along with the dose computed here (magenta). Shown below is the dose from a seven field prostate case.

2D Dose Difference View

Next below we show a 2D display of the dose difference for a six field prostate case. Difference isodose lines can be plotted or tinted. Shown is 228 cGy, 3.0% in this case. Note hot spot difference of 1276 cGy plus (17%) and 246 cGy minus (3.2%), both in the build up region.

3D Dose Difference View

Here we have purposely created a case with some difference, seven fields with blocks compared to the blocks not being there and field sizes different, for a prostate case. Show below is the dose comparison in a 3D display. The red is where a larger dose was computed, the cyan where a smaller dose was computed. The bladder is colored brown and shown above, the rectum below, and the femur's to either side.

Difference Dose Volume Histogram

You may compute, display, and print a difference dose volume histogram for any outlined volume.

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