How it's done.

If CC001 was enough for you to start hippocampal avoidance WBRT tomorrow, you should get familiar with the protocol and associated planning techniques so that it’s done right. HA-WBRT requires an IMRT technique with inverse optimization. The whole brain is delineated as are both hippocampi. A hippocampal avoidance structure is then created that extends an extra 0.5 cm. This avoidance structure is subtracted from the brain volume to create the PTV_3000. HA-WBRT plans take some getting used to. The goal is for 95% of the PTV to receive 30 Gy, 98% to receive at least 25 Gy, and at most 2% to receive 37.5 Gy. That’s right, the D2% (not just Dmax) is 125% of prescription. In practice, it can be challenging both to know what’s too hot and to know how much “moderately hot” dose (i.e. 105+%) to allow. Hippocampal objectives are D100% ≤9 Gy and Dmax ≤16 Gy. Optic structures must receive 30 Gy or less. A variety of techniques have been described for HA-WBRT including fixed beam arrangements, tomotherapy, and VMAT. TBL: If embracing HA-WBRT in your practice, get used to a whole new way to evaluate whole brain plans. | Brown, J Clin Oncol 2020


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