Pressure, Intensity and the Decibel (dB) Scale | Ultrasound Physics | Radiology Physics Course #3

High yield radiology physics past paper questions with video answers
Perfect for testing yourself prior to your radiology physics exam 👇
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We've seen that sound is propagated through a medium via regions of local pressure changes (compression and rarefaction). These pressure changes can be represented graphically. The amplitude of the graph corresponds to pressure. The power of the wave is proportional to amplitude squared. Power is measured in Watts. This power spread over an area is what is known as intensity. Intensity changes (such as increasing gain or attenuation in tissue) can be described using the decibel scale. We can also describe spatial and temporal intensities within a beam.
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Not sure if the question banks are for you?
If you're here, you're likely studying for a radiology physics exam. I've spent the last few months collating past papers from multiple different countries selecting the most commonly asked questions. You'll be surprised how often questions repeat themselves!
The types of questions asked in FRCR, RANZCR AIT, ARRT, FC Rad Diag (SA), ABR qualifying Core Physics and MICR part 1 are surprisingly similar and the key concepts remain the same throughout. I've taken the most high-yield questions and answered them in video format so that I can take you through why certain answers are correct and others are not.
Happy studying,
Michael
#radiology #radres #FOAMrad #FOAMed

[@Objectra]

Came across the US probes explanation and also decided to watch the whole playlist. While im familiar with most of this information (i build medical ultrasound probes as part of my job), it was great to defragment my knowledge and put it in order based on your videos. A refresher is also a huge plus. Thank you so much for making it so easy to understand and follow.

[@radiologytutorials]

Cheers. I'm glad they were still helpful! Still have a lot to learn myself!

[@brandideruiter6067]

Im studying for me spi after years of being out of my field of cardiovascular ultrasound tech. These videos are helping a lot.

[@fabrizziogaliano515]

Finally I know what is the db bottom for... thank you very much...

[@masoodandalib8676]

you are so great and a unique teacher.

[@Roomso1]

Stumbled across your video of time gain compensation, and it was so good that I decided to watch through this entire series. These four videos that i’ve now watched have all been great! Thanks for making these ❤

[@radiologytutorials]

Oh wow! Thank you. Hope you find the series useful 🙂

[@prathamgupta3117]

Honestly these videos are helping me alot for my exams

[@RosemaryWairanya]

You are helping me much 🙏

[@rukhsanaarshad1465]

Thank you very much sir

[@hartisify]

Great explanation and you have a fantastic voice.

[@radiologytutorials]

Thank you 😊

[@annabee1734]

Great work

[@radiologytutorials]

Thank you so much 😀

[@nickogalo2892]

Great job

[@radiologytutorials]

Thank you!

[@sohamrasal7054]

Thank you so much for making these videos sir❤ I have one query Why we put decibel in the area section? If it is change in intensity then it should go along with it right?

[@radiologytutorials]

Good question. Mainly due to space. Strictly speaking it should be in neither the time or distance domains (it is a relative measure containing no time or distance units). But mainly because there was no space on the slide 😊

[@nyssaangelipura6076]

Can I please ask for your book references? ❤

[@jacquelineb.6721]

Hey, I love your videos ! :) I have one question. In video 4 (Pulse Echo Ultrasound Parameters) you say the PRF can vary depending on the depth of tissue you want to measure. If I understood correctly that means by determining the depth of tissue the PRF is automatically (?) adjusted. Here in this video you say that the frequency of the transducer determines the depth of tissue that the ultrasound can reach. So how does that work together when there is the frequency of the pulses and the frequency in which the pulses are sent that influence the measuring depth? Like what if my choice of transducer and frequency of the ultrasound waves is inconsistent with my choice of measuring depth which only has an influence on the receiving time and PRF and not on the pulse itself ? I hope you understood my question, I am from Germany 😂😂

[@radiologytutorials]

Hi Jaqueline. Sorry for the delay. I’ve been on holiday. Great question. So attenuation is in part determined by frequency - high frequency waves get attenuated quicker over a shorter distance than low frequency waves. However, we do not use frequency to determine the depth shown on the ultrasound display. PRF (ie the number of pulses we send into tissue per second) determines the depth displayed - as you’ve correctly said. If we set a low PRF it means in theory we can display ultrasound information to a greater depth. This is because the pulse repetition period will be longer - allowing enough time for waves to travel deeper and return to the transducer before the next pulse is sent out. However, the actual ability for that wave to travel to that depth is determined by the frequency of the wave. If we use a frequency that is too high there will be no returning echoes from deeper tissue because the wave is attenuated too soon. This will look black in the ultrasound screen if we set the depth too deep using the PRF. So the PRF is automatically adjusted as we select a certain depth but whether we’ll get any information from that depth depend on the transducer frequency (that’s why we use high frequency probes for superficial structures and lower frequency probes for deeper ones) I hope that makes some sense 😅

[@jacquelineb.6721]

@@radiologytutorials Ah okay I see, thank you ! But is it possible to use a higher transducer frequency for better resolution and still gain depth information with the help of TGC? Or will I get false data ?

[@nazaninsaleh3938]

well done

[@radiologytutorials]

Thank you!

[@tcc9826]

This chapter is too complicated. I suggest splitting it into two.

[@dradityakumar3157]

Please add MRI physics videos or take MRI physics classes also…

[@radiologytutorials]

Absolutely. Once ultrasound is done, we move on to MRI 🙂

[@samarkayfan2546]

@@radiologytutorials Fluoro before MRI?

[@shakhawansalih5601]

little hard to understand but very very nice explanation ,needed many repeat hearing to understand it

[@radiologytutorials]

Thank you. Yeah, these concepts can take time to grasp. Don’t get too caught up in the details. A broad understanding is often for than enough!

[@qura-tul-ainmuzaffar9367]

​@@radiologytutorialsplz guide about how and what to study for FRCR 1 exam...plz

[@dalalyousef6513]

you're the only person who helped me get through ultrasound and MRI physics thank youu🤍

[@radiologytutorials]

Thanks so kind! So happy to help 🥰