3 ms·

> The key is knowing exactly where to aim. While the MRI machine took readings, Elias ran a test at a low intensity to see if he could gently heat up the spot o

> The key is knowing exactly where to aim. While the MRI machine took readings, Elias ran a test at a low intensity to see if he could gently heat up the spot on Doby’s thalamus he was targeting. Satisfied with the result, he then proceeded to blast an area millimeters wide with 6,000 joules of focused sound energy for a few seconds. A graph on his monitor showed the temperature jumping to about 60C (140F). Everything around it stayed at a normal 37C. Other than a brief sensation of heat inside his head, Doby said he didn’t feel a thing. Elias repeated the process three more times, checking the tremor after each. By the fourth, it was gone. Leaving it at "knowing where to aim" is severely underselling the problem, because then the next step is how to aim. Back in 2003 when I still studied physics I attended a talk back by a Dutch biomedical researcher who worked on shock wave lithotripsy - a procedure where ultrasound is used to break kidney stones. So same idea as this, except kidney stone So what he pointed out was that the human body is not a medium of uniform density, so the way the sound waves propagate is hard to calculate. Worse, the human body tends to move, even when the patient is under anesthetics. Even if you sedate someone enough to lie perfectly still, the heartbeat means blood vessels grow and shrink, breathing causes miniscule motions that can throw off the ultrasound beams. Maybe this is specific to kidney stones though, maybe kidneys are just a lot more "floppy" organs and maybe kidney stones move a lot. Maybe the brain is a lot more "stable" in the skull. And I suppose the method of destruction is different (kidney stones need to be shattered by ultrasound waves, whereas this method uses heat), so that might also be an influence. I'm not being critical of this technology btw, just trying to point out that the engineering problems involved are likely a lot more interesting than that this article is suggesting. [0] https://en.wikipedia.org/wiki/Lithotripsy https://en.wikipedia.org/wiki/Lithotripsy

saas_sam 2y ago
Interesting. Maybe part of the solution is better predicting and controlling the motion inside the human body. I could imagine using a method to guarantee a particular organ be at a certain place at a certain moment: perhaps by accelerating the body a certain way to shove the organ into a position for a moment. Or maybe by injecting microscopic machines to surround and hold an area still. Someone will figure it out.
kelsey98765431 2y ago
Science needs more cadavers! Bring out ya dead
FiatLuxDave 2y ago
In radiation therapy, respiratory gating is a common method to deal with the problem of breathing movement: https://www.oncolink.org/cancer-treatment/radiation/support/respiratory-motion-management-devices-respiratory-gating-dibh-abdominal-compression-surface-imaging https://www.oncolink.org/cancer-treatment/radiation/support/... I was not aware of respiratory gating being used in SWL. So, I did a brief search and saw that the efficacy of gating had definitely changed over the years: https://pubmed.ncbi.nlm.nih.gov/7858616/ https://pubmed.ncbi.nlm.nih.gov/7858616/ (1994) https://pubmed.ncbi.nlm.nih.gov/22471349/ https://pubmed.ncbi.nlm.nih.gov/22471349/ (2012) https://pubmed.ncbi.nlm.nih.gov/38515108/ https://pubmed.ncbi.nlm.nih.gov/38515108/ (2024) So, it looks like that engineering problem has been worked on a lot since that talk in 2003.
randerson 2y ago
I once had to have a Heart MRI, which was fascinating because movement normally messes up an MRI. For the heart, they attach a pulse monitor and the MRI machine pauses its movement for a split second each time the heart beats.

saas_sam 2y ago

Interesting. Maybe part of the solution is better predicting and controlling the motion inside the human body. I could imagine using a method to guarantee a particular organ be at a certain place at a certain moment: perhaps by accelerating the body a certain way to shove the organ into a position for a moment. Or maybe by injecting microscopic machines to surround and hold an area still. Someone will figure it out.

kelsey98765431 2y ago

Science needs more cadavers! Bring out ya dead

FiatLuxDave 2y ago

In radiation therapy, respiratory gating is a common method to deal with the problem of breathing movement: https://www.oncolink.org/cancer-treatment/radiation/support/respiratory-motion-management-devices-respiratory-gating-dibh-abdominal-compression-surface-imaging https://www.oncolink.org/cancer-treatment/radiation/support/... I was not aware of respiratory gating being used in SWL. So, I did a brief search and saw that the efficacy of gating had definitely changed over the years: https://pubmed.ncbi.nlm.nih.gov/7858616/ https://pubmed.ncbi.nlm.nih.gov/7858616/ (1994) https://pubmed.ncbi.nlm.nih.gov/22471349/ https://pubmed.ncbi.nlm.nih.gov/22471349/ (2012) https://pubmed.ncbi.nlm.nih.gov/38515108/ https://pubmed.ncbi.nlm.nih.gov/38515108/ (2024) So, it looks like that engineering problem has been worked on a lot since that talk in 2003.

randerson 2y ago

I once had to have a Heart MRI, which was fascinating because movement normally messes up an MRI. For the heart, they attach a pulse monitor and the MRI machine pauses its movement for a split second each time the heart beats.