# Comparison of the Dose Comparison and DVH Comparison modules results

**URL:** <https://discourse.slicer.org/t/comparison-of-the-dose-comparison-and-dvh-comparison-modules-results/9655>\
**Category:** Support\
**Created:** [December 30, 2019, 6:23am UTC](https://discourse.slicer.org/t/comparison-of-the-dose-comparison-and-dvh-comparison-modules-results/9655 "2019-12-30T06:23:10Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![aseman](https://avatars.discourse-cdn.com/v4/letter/a/c0e974/32.png) [@aseman](https://discourse.slicer.org/u/aseman)\
**Post date:** [December 30, 2019, 6:23am UTC](https://discourse.slicer.org/t/comparison-of-the-dose-comparison-and-dvh-comparison-modules-results/9655/1 "2019-12-30T06:23:10Z")

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Slicer version:4.10.1  
Hi 3D Slicer experts and all  
I have 2 RT Dose (RT Dose1 and RT Dose2) and a segmentation (renamed PTV). I compared 2 dose distribution for PTV, with Dose Comparison module; and the Pass Fraction was calculated 96.46%. Also, I calculated DVHs for them with Dose Volume Histogram module and Exported them into a CSV File(figure1), which the results up to 1.7 Gy are similar; but the Agreement acceptance is 92.31%. can you help me about my questions:

1- As shown in figure1, the received dose for PTV , up to 1.7 Gy is similar with RT Dose1 and RT Dose2. so, why is the Agreement acceptance = 92.31%? shouldn’t it be more than 92.31%?

2- Pass Fraction in Dose comparison module is 96.46% and Agreement acceptance is 92.31%. what is the reason for this difference?

Thanks a lot

 ![CSV File Exportation](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/9/c/9ce7a39a99e9bd4b6f7d89633a3a444a427ff961.png)

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [January 15, 2020, 2:27am UTC](https://discourse.slicer.org/t/comparison-of-the-dose-comparison-and-dvh-comparison-modules-results/9655/2 "2020-01-15T02:27:12Z")

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@gcsharp @cpinter do you know if the results above can be normal or they are unexpected?

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**Author:** ![cpinter](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/cpinter/32/7995_2.png) [@cpinter](https://discourse.slicer.org/u/cpinter)\
**Post date:** [January 15, 2020, 9:18am UTC](https://discourse.slicer.org/t/comparison-of-the-dose-comparison-and-dvh-comparison-modules-results/9655/3 "2020-01-15T09:18:07Z")

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1. Why do you think it “should be more than 92.31%” ? The dose comparison module compares the dose volumes themselves, using the Gamma comparison method [1]. It is based on dose difference and distance-to-agreement, and has many parameters, such as the acceptance thresholds of these two components. SlicerRT’s gamma algorithm has been validated against other implementations, and it was found to have a 100% match to the baselines [2].

2. Dose comparison is based on the dose volumes themselves, while DVH comparison compares derived metrics: the DVHs, which are a considerably simplified representation of the dose volumes considering the segmented structures. The DVHs are compared using a simplified Gamma method [3], and has similar but different parameters, and different defaults for those.

[1] Low, D. a., & Dempsey, J. F. (2003). Evaluation of the gamma dose distribution comparison method. Medical Physics, 30(9), 2455. [https://doi.org/10.1118/1.1598711](https://doi.org/10.1118/1.1598711)  
[2] Alexander, K. M., Pinter, C., Fichtinger, G., Olding, T., & Schreiner, L. J. (2018). Streamlined Open-Source Gel Dosimetry Analysis in 3D Slicer. Biomed. Phys. Eng. Express, 1–23.  
[3] Ebert, M. a, Haworth, a, Kearvell, R., Hooton, B., Hug, B., Spry, N. a, … Joseph, D. J. (2010). Comparison of DVH data from multiple radiotherapy treatment planning systems. Physics in Medicine and Biology, 55(11), N337-46. [https://doi.org/10.1088/0031-9155/55/11/N04](https://doi.org/10.1088/0031-9155/55/11/N04)