MED
In the literature: open
Transcranial focusing without a prior CT scan
In plain words
The skull bends and absorbs sound unevenly, smearing the focus inside the head. Correcting for it currently needs an x-ray scan of the skull.
Precise statement
Achieve transcranial focal placement accurate to 1 mm and pressure prediction accurate to 10 percent at 0.2 to 1 MHz without computed tomography of the skull, by inferring the skull acoustic properties (sound speed $2.4\,\mathrm{x}\,10^{5} \text{ to } 3.0\,\mathrm{x}\,10^{5}\,\mathrm{cm}/\mathrm{s}$, density, absorption, shear conversion) from ultrasound or magnetic resonance data. An answer is a method with verified focal position and amplitude in human skulls.
What would settle it
Hydrophone measurement inside ex vivo human skulls, and in vivo displacement or thermometry confirmation, against the predicted focus.