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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 several AAPM committees, has served as secretary-treasurer for the Northwest Chapter of AAPM, and is an ABR orals examiner. Tyler dabbles in real estate investing and loves preparing breakfast for his three kiddos.
Related tags: Treatment Planning