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Treatment Planning FAQ: Acuros XB Dose Reporting Mode
Which dose reporting method for AXB (and other MC-based algorithms) is best for clinical use: dose-to-water or dose-to-medium?
What’s the difference?
Hot spot to bone within a PTV calculated as 82.3Gy, 76.8Gy, and 73.3Gy for Dw, AAA, and Dm, respectively.
Carles Muñoz-Montplet, et al. European Journal of Medical Physics
Arguments in favor of D w:
- Dosimetric commissioning measurements and dose calibration are done in water.
- Our historical clinical experience for tumor response has been using dose-to-water calculation algorithms.
- There are inherent issues involved in using material conversion tables to convert HU values in determining tissue composition for Dm calculations.
Arguments in favor of D m:
- The dose-to-medium mode best represents the true dose based on tissue composition.
- Reporting as Dw requires a stopping power ratio conversion, and there is uncertainty in this conversion.
- Differences in the two reporting modes are not significant for most tissues.
With the debate being far from settled, which reporting method do you use? A Twitter poll of clinical users revealed that 53.8% prefer Dm while 30.8% use Dw in the clinic for patient calculations (and 15.4% aren’t sure). Two other votes were provided via email, both in favor of dose-to-medium reporting. What does your clinic use?
Written by Tyler Blackwell
Tyler is a board-certified medical physicist with extensive clinical experience in radiation therapy. He is active in the medphys community including several AAPM committees, the AAPM Board of Directors, and as an ABR orals examiner. Tyler dabbles in real estate investing, loves preparing breakfast for his three kiddos, and enjoys playing adult coed soccer.
Related tags: Treatment Planning