Testing the Accuracy of Your DVH Calculations

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As an industry, we’ve spent decades talking about testing and improving the accuracy of 3D dose calculations. We’ve invented countless products – both hardware (e.g. dosimeters) and software – to help us along the way, and many AAPM Task Groups have published reports of various flavors and angles on this topic. None of this is too surprising because accurate dose calcs, especially in and around complex tissue shapes and varying densities, are not an easy thing.

3D dose calculation results are primarily used – in conjunction with 3D anatomy contouring – to produce dose volume histograms (DVH) for each target and organ-at-risk. The irony is that for a long time (again, decades), as an industry we’ve forgotten that assembling DVH curves requires calculations itself, and not all of these are created equal. How are anatomy volumes simulated and at what resolution? How are anatomy superior and inferior “end caps” modeled and what is assumed to happen in between axial slices? How does anatomy interplay with an orthogonal 3D dose grid, and what are the effects of that dose grid’s spatial resolution?

DVH calculations are not standard, folks. Not by a far cry.

Together with Vladimir Feygelman, Ph.D. and other scientists at Moffitt Cancer Center (Tampa, FL), we’ve done some really important work studying DVH accuracy and recommending standardized datasets and methods to validate your TPS software. We’ve published our first work in Medical Physics (August, 2015), and you can link to it here.

I hope you can take some time to read our new publication. If you’re a physician, physicist, or dosimetrist (or, just as important, if you’re a TPS software vendor) it will be well worth your time.

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