Ultrasound Physics - Transducer arrays

[@mrshonestopinion]

This was so well explained. I wish my teacher could follow from you. Thank you very much.

[@aungma21]

my life saver for my Ultrasound degree

[@jamesmasciandaro6233]

Franco has the best down to earth physics reviews, and I've learned a lot from him! But all the arrays are "lined up in sequence." What drives their firing is very different. Sequential arrays fire one element after the other (in sequence), depending on what depth is set. True phase array's fire nearly all the elements at once, with nanosecond time delays to steer and focus the beam. But you have to think about sonar transmission and receive as very different events with an ultrasound probe. With phased arrays, transmit & receive time delays allow for the steering, and listening, of the beam off axis by creating concentric wave-fronts in the direction of the steering (elements farthest from the direction of the steering are fired first on transmit), this is what creates the off axis line Franco draws across his phase array diagram while showing the beam being steered to the side on transmit. By creating a concentric wave front, the off axis response is better because it creates stronger reflections off axis, otherwise you can still listen off axis because the elements themselves really transmit acoustic waves in all directions, but are strongest on-axis, or directly in front of the element, so you'd get a poor off axis response without a time delay and concentric wave front formation. But to make a scan line, it takes two elements to localize a returning echo, just like we need two ears to localize a sound that we hear. Time and intensity differences between a sound arriving at each ear (or between 2 probe elements) tells us where the sound came from. A sound coming from our right, reaches our right ear first, and has slightly more intensity than when it reaches our left ear a very short time later - our brains can translate those differences into a unified perception of where a sound came from. And this is why ultrasound probes always have an even number of elements: probes need two elements to locate returning echos, and create each scan line. For shallow echos, the elements are close together, but for deeper echos, the elements must be farther apart, and this is why it takes a bigger physical aperture to focus a returning echo that is at a deeper depth - the deeper the returning echo, the further 2 elements have to be apart from each other. For example, I can tell where a voice is coming from within a room with my eyes closed, but it would take two people, standing several feet apart from each other to localize a gunshot coming from miles away. Our ears use phase information to locate sounds that are lateral to and behind us, ultrasound systems use phase information to fill in the gaps as the beam spreads. Thanks, Franco!

[@PAn-su3wy]

Thanks for your explanation. I got lost when he kept saying sequential arrays were lined in a sequence and but didn't address that phased arrays were also lined in a sequence. The firing of the elements is what makes the difference.

[@Sonogirl]

Thank you so much for this!! I’ve been struggling with differentiating the different transducer because I’m a visual learner and the books don’t help explaining to this detail. So helpful!! Thank you!! 🙏

[@patientlywaiting1805]

Very well described. I had forgotten that rocking sensation that the annular did way back then!

[@kenrolt8072]

Steering directs the sound beam in the direction, or angle, you want. Steering can be done in transmit or in receive. If you don't steer the sound beam, then the sound exits (and returns) to the transducer perpendicular to the transducer face, and the time delays from focusing are symmetric about the transducer center line.

[@examrefresh]

I use a blank document and photoshop to write on it with a pen tablet. Then I use either screen flow or camtasia to record my computer screen. It works really well for these lessons.

[@carolinebrown7829]

thank you for showing USPhysics

[@alizajoon]

What an excellent video. I look forward to more of your tutorials!

[@noahmcdougall5638]

Thank you! Great basic illustration of the differences.

[@nnenna.s]

Thanks for this, you really simplified it 😊

[@jessicaryan3805]

clear understanding tutorials, thank you.

[@snandrs9559]

very easy to understand, Thank you !

[@zicotitoo]

thanks sir we hope more videos about ultrasound and doppler great thanks for this marvelous videos

[@mounaabed340]

Thank you so much.really very helpful.does help me alot especially im struggling with ultrasound physics.

[@kelsiepulliam3610]

Awesome video this made so much sense I understand it a lot better now. These videos are very helpful preparing for my SPI thank you so much:)

[@gungunmasti5438]

excellent way of explanation

[@rolahamdeh6478]

Thanks soo much for the lesson. It really helped me a lot. I wanted to know if you can put more info on how to know or remember which transducer is fixed, electronic or mechanic transducer.

[@user-hj8cq1vv2b]

Thank you so much!

[@rolahamdeh6478]

Thanks soo much! It really helped

[@kharlyr2870]

Hi i was watching your video..to complement my class and book cuz is not easy to get it at first and only reading...i went to your website and I found the truth about learning I am that king of person that learns thru drawings and colors I tried to learn that way physics but sadly has been online classes due to the virus and the teacher explains not that good so it's been more like self study...im gping to review this video more times and see what else from your website...will be very helpful for the test too thank you

[@kuiranjiao442]

what type of transducer array does EUS (endoscopic ultrasound) use? curved phased?

[@examrefresh]

Thanks!

[@RataJC91]

great work

[@Amanraj90]

Hi I have a question You said Linear Phased Array fires in phases and not all at once. My book says that with linear phased Array all of the active elements are fired to create each sound pulse. “All” And for linear sequential array transducers... a small group of active elements are fired to create each sound pulse. It’s the opposite of what you saying. The book Nand is understanding ultrasound physics by Sidney Please let me know if I’m missing some information... have a test coming.

[@funfactz4986]

I have a question. Why single element transducer has low temporal resolution than array-based transducers?

[@brotosynthesisbs8894]

SO good thanks!!!

[@irahi9501]

you are the best

[@luluvang]

what happened to the other videos? I was still watching one of them and not it's not available no more?

[@kenrolt8072]

The focusing cartoon at 9:58 isn't right. The elements at each end of the transducer aperture fire first. The central element fires last. This causes a focus to occur on the main axis of the array. If the focal point is steered to either side, the element furthest away fires first, and the closest element fires last. I think you drew the illustration with the center firing first, which would cause beam splitting into two. The trace of the firing order for focusing is a curve in all cases. The amount of the curvature (of the firing time) determines whether the focus is shallow (highly curved) or deep (gradual curve). When the elements fire at the same time, there is no intentional focus other than those created by the axial nearfield maxima, which is a natural nearfield focus. Otherwise, thank you for the review, it's very helpful.

[@maimadkour9946]

what is the type of the transducer of a transeosophageal echocardiography probe ?

[@rebeccagonzalez1628]

Me gustaria saber si hay algun video de estos en español

[@katherineperez8218]

we want MORE!!! :)

[@FrauenarztpraxisDrSiewe]

great vid...thanks

[@drgadham]

excellent

[@minkycat66]

What do you mean by steering?

[@kumarp.r5515]

trans vaginal is curved phased array?

[@idosadeh6955]

great lesson, but dude... spice it up a bit, your voice almost got me sleepy