Remove hearing aids before panoramic dental x-ray?

Thank you very much Surdi for your reply. By searching for someone in this field of knowledge… I appreciate very much you input. The topic though is “Remove hearing aids before panoramic dental x-ray.”

So as far as I understand from the productmanager from Signia he says “Tests are done with the hearing aids and X-rays with a power of 100kV/100mGy. More than 100kV can potentially damage the chips”.
You can assure this also, thats fine. But unfortunately you do not give any specification. So what is your opinion about the specified kV and mGy as that is the important detail missing.
I have been an academical radiologist myself and started on MRI and CT’s at the very beginning. So I have some basic knowledge, as a radiation expert, about X-rays, ultrasound and magnetic resonance, but not about memory modules in HA’s.

Of course, as you also state, magnetic metal in an MRI is not allowed! Thats why every MRI institute will ask questions like did you work in metalindustrie or are you aware of metal- implants which could be even tatoo- ink, and makeup for camouflage of skintumors or even makeup for whatsoever reason and so on!. And these can even lead to faildiagnoses even in x- ray examinations.

The kV used by panoramic dental x-rays is not in the range of 100kV and over. So the question for me stays what about the low kV in panoramic dental x-rays specific. That will be about 70kV… Maybe you can give some information about that I hope.

About your question “Why take the risk ? Why fixated on keeping your aids in during any such procedure ?” Sometimes patients arrive in the x- Ray dept. in f.i. emergency cases or you want to give them instructions during an examination they have to hear you. So my perspective is a bit different then that of the patient I can have a good conversation with. Nowadays there are HA’s wich are in the canal and not easily visible anymore in a fast inspection. And most of the time we have to ask a patient more than just if he wears HA’s. Thats why I am personaly so persistent in knowing exactly what is important to not damage HA’s.

@Emile030 said:

About your question “Why take the risk ? Why fixated on keeping your aids in during any such procedure ?” Sometimes patients arrive in the x- Ray dept. in f.i. emergency cases or you want to give them instructions during an examination they have to hear you

I have been in this situation recently (unexpected/unexplained arrhythmia and high BP). My regular HAs were out of charge when the arrhythmia hit, so I was obliged to wear my spares, which are more or less useless to me.

The interruptions in the dialogue with my medical caregivers caused by my inability to understand questions and instructions were frustrating, annoying, and potentially dangerous!

Fortunately, our hospital clearly labels forms, files - and even my person - with big blue HoH stickers, which somewhat prepare staff for the difficulty we will have communicating.

My HAs came with an easily-pocketable case, so that somewhat facilitates the logistical problems of moving around the hospital with HAs in tow (you can even duct tape a loop of paracord to the case to fashion a temporary lanyard). Too bad I still was unable to understand with the devices I was toting around!

IMO, HAs are essential during medical exams/procedures.

emile.heilbron, I am not familiar with the characteristics of medical x-rays and CT scanners, being more concerned from an electronics design and manufacturing perspective.

There has been lots of work done looking into the effects of x-ray PCB inspection methods, where the modern very small geometry Flash devices nowadays ubiquitous, have been found to be very susceptible to the effects of x-rays.

After a quick search, I have come up with a few links that may be of interest:

X-ray irradiation was performed using an ARACOR Model
4100 10-keV X-ray irradiator at a dose rate of 5 krad(SiO2)/
min.

Impact of X-Ray Exposure on a Triple-Level-Cell NAND Flash2

The total ionizing dose response of a triple-level-cell (TLC) NAND flash is shown to be low enough that data corruption can occur as a result of an x-ray inspection. Only a few seconds of x-ray exposure corresponding to a total dose of merely 50...

The total ionizing dose response of a triple-level-cell (TLC) NAND flash is shown to be low enough that data corruption can occur as a result of an x-ray inspection. Only a few seconds of x-ray exposure corresponding to a total dose of merely 50 rad(Si) in a real-time x-ray source are required to induce errors.

https://meridian.allenpress.com/ism/article-abstract/2016/1/000660/187897/Effects-of-x-ray-exposure-on-NOR-and-NAND-flash2

In this paper, we present a detailed study on the effects of x-ray exposure on data corruption in commercially available NOR and NAND flash memory devices during x-ray inspection with a high-resolution Phoenix Nanomex system from GE. We investigated role of the x-ray tube voltage, tube current, device orientation, x-ray filters and photon energy.

The dosimetry in these studies is usually reported in rads of Silicon equivalent. I do not know how that compares with the methods adopted for medical X-rays, which I suppose assume a different ,material for bodily absorption. But, for example, the ieee paper reports that doses as low as 50 rad(Si).(i.e 50 cGy(Si) can cause corruption.

Such damage is cumulative. I.e. a chip may survive one exposure of a certain dose, but repeat exposures may steadily weaken it until the data does become corrupted.

Apparently the plastic packaging of discrete components has some shielding effect on x-rays of below 10 KV, but that protection was found to be removed when some chips were de-capped before the tests. And will of course depend on the thickness of the plastic layer. I don’t know much about the construction of the actual chip assemblies inside modern hearing aids, nor whether the outer plastic casings might themselves have some shielding effect.

I came across a table here: Radiation risk from medical imaging - Harvard Health2 from which it seems that the dose from one panoramic dental x-ray is about ten times higher than that from say an arm or leg x-ray (0.01 mSv vs. 0.001 mSv)

Whereas a head CT scan could be 2 mSv. Or more.

NB. these are averages, if you look at that table they also give the ranges reported in studies, which vary considerably.

Having had three head CT scans in the past year, as well as a full cerebral angiogram, and a barium swallow test, I am becoming slightly nervous about having too many more high dose procedures.

My guess is that if anything is going to zap hearing aids, it would be having a head CT scan whilst wearing them. I have no knowledge of panoramic dental x-rays, mine are done as individual ones.

I am sorry if that is not terribly helpful, but there is research out there to find.

emile.helbron

Regarding variation of sensitivity to damage vs. x-ray voltage, you may find the following publication of interest. Table 2.0 refers.

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/rr/rr_max_sens_to_xray.pdf6

But these tests were done on plastic packaged devices (thin quad flat pack), where the plastic has been observed in other studies to provide some shielding effect at lower voltages. As I said, I am not familiar with how modern hearing aid chip assemblies are packaged, but some of them might even be using bare chips, wirebonded to a ceramic substrate that also includes the electrical circuitry.

One study, using monochromatic synchrotron radiation, found that the peak sensitivity of the devices they were testing was at the 125 kV level. Which I think is where CT scanners often operate.

I could only find data about medical x-rays considering overall body exposure, in mSieverts. What matters to electronic devices is the actual flux through the part, times the time exposed, measured in rads/cGy, and based on the material’s capture, i.e. silicon for most (but not all) chips, and something else for human tissue (mostly water ?). I have not looked up the differences yet.

@Emile030: Thank you for your appreciation of my desire to contribute to your important topic. I am simply grateful that you and other learned members are actually giving this important subject some attention.

Thank you for keeping this topic alive, Doctor.

Thank you surdi for your last three contributions and the substantiation through the supplied very relevant and interesting publications. I needed some time to read them carefully. An extensive discussion is possible on this to go into detail on these pieces. Probably more suitable for a dialogue among us nurds with Zoom or Skype or scientific publications than under this topic, which was started by mazda4me and asks for the answer to the more practical question “Remove hearing aids before panoramic dental x-ray?”. But personally I am very happy with your information.

The scientific value of this cannot be underestimated. The implications that the interface has among technical developers and users cannot be endorsed enough. The practical value for the HA user and audiologist and the user should be paramount here.

The X-ray beam used in a dental panoramic x-ray is a very special one compared to a CT and/or conventional examination. A special kind of ‘tomographic imaging’ is used. A cut slice with a depth of field/focus of a few centimeters centered along the line of the teeth. Various techniques are used to achieve the correct flat kV by means of tube voltage and focusing, including filters. And the exposure time is also very limited locally along the row of teeth. Of course, earrings, pearcings and HA are generally removed.

In practice this would mean that the radiation damage to the HAs is present. However, this is also unavoidable in nature: think of the use of aircraft at height and radiation from buildings in which we live.
As is also apparent from the articles you quoted, the Fail Bit Ratio of the memory used by the HA is undesirable, but does not necessarily have to lead to loss of function. However, it cannot be ruled out and has not to be ignored.

Even if you take the HA off for an OPT/dental panoramic x-ray, where would you like to put them safely in an x-ray dept at that moment? The same applies to your mobile phone, your creditcard and all other goods containing these chips.

By the way Surdi to go into one of your questions Computed Tomography exists in many forms. Multiple beams, but also multi energy/kV and automatic current adjustment. The more money, the more setting options in general.

In conclusion: If you are unlucky, your HAs will eventually break with or without dental panoramic x-ray. The chance this will happen is not very big, but do not take unnecesary risks. You will most of the time be asked to take them off because they can negatively influence the diagnostic value due to the disturbed imaging. In addition, this examination/potential risk is not done without a solid indication.

@Emile030: I’m chuckling at the post I’m about to upload to the Forum! The image is one that shows technology at the other end of the spectrum of sophisticated diagnostic imaging devices that you scientists are discussing. It shows the standard issue Oticon carry case for More1 hearing aids…

This little case has a smooth, flat profile that makes it easy to pocket. The gowns you make us wear for diagnostic imaging procedures are without pockets, however, so I have successfully fashioned makeshift lanyards for my case by simply GorillaTaping a suitable length of paracord (with knots tied in each end) to the underside of the case. While this getup can’t be kept on one’s person during the actual operation of the X-ray source, it is unobtrusive enough to be able to be smuggled into examination rooms so that it’s close at hand when the moment comes when one’s hearing devices must be applied or removed.

My objective in designing the SpudCap(sule)®️ was not to subvert hospital protocols, but rather, it was to ensure the proximity and accessibility of my hearing aids, when they were needed in order to dialogue with my caregivers.

[During the ER visit to which I referred in my previous post, I presented doctors with a rather different set of facts. I had recently had a cortisone injection to my sacroiliac joint. The injection must have come too close to a nerve, and resulted in such intense pain that it precipitated an arrhythmia (right bundle branch block), and abnormally high blood pressure. The DD was uncommon enough that a rather long medical interrogation was necessary, during which I was obliged to wear my hearing aids, which had never been properly fitted to give me good comprehension. The frustration on the part of my caregivers was so pronounced that a nurse actually asked me if my aids were working. My inability to understand and answer questions on the first pass made me feel old, dull-witted, and disabled.][No imaging was involved in this episode, but I was prepared!]

My point is that medical professionals should not require me to check my hearing prosthetics at the door. They are part of me, without which I cannot function, and it’s no more appropriate to treat these as “checked baggage” as it would be to ask a patient to leave their prosthetic leg at the front desk.

I had a bilateral cataract removal operation recently. There is far too much liquid around for wearing hearing aids to be possible in that situation, so I took them out and put them into my pocket as I sat on the operating table.

I had already agreed with the surgeon that I would do this and said that I would need him to speak up if he wanted to ask or tell me something, in particular about whether to proceed with the second eye once the first was done. He said “That’s ok. I will shout. I need the exercise!”

I carry my aids in a leather pouch, usually marketed for keeping e.g. air gun pellets in. A nice sturdy rigid thing, with a clip for a lanyard, where I also keep a couple of spare cells and tube cleaning wire. They come in 2.5 and 3.5" diameters. The 2.5" one is just right for my aids, and fits well in a pocket or slung around my neck, inside my shirt.

Since I am quite active and outdoorsy, reluctantly I take them out and pop them in the case when the weather becomes wet and windy. Rather common in the UK. Otherwise wear a wide brimmed hat to keep water away from them.

Current aids are Siemens Octiv M+, not waterproof. New aids, due soon, just waiting on the earmoulds to be completed, will be Phonak Nathos Novas, which are IP68 rated and “nano coated”. But I will still baby them.

At night they are put into a desiccator of my own devising, using self indicating silica gel pouches. PS: don’t put the partially used zinc-air cells in the desiccator, that may dry out the electrolyte inside them, reducing their life. I alternate the cells each day, between ears, to even out the usage, as my RH aid operates at higher power than my LH one, so gets through the cells more quickly.

These are NHS aids. The new Phonaks are the NHS version of the Phonak Marvel, at I think technology level 7 out of 9. The NHS hereabouts are set up to tweak them remotely using the MyPhonak app. and/or recall me for face-face fine tuning using e.g in ear measurements, as was done for my Siemens. Anticipating them eagerly, and looking forward experimenting with all the bluetoothery benefits, for phone calls, music streaming, making own custom settings etc.

@Surdi: Being an air rifle fanatic myself, I am familiar with that getup, however, here in Canada, they’re very pricey. When I’m out and about, I’m usually wearing cargo pants (the closest thing to fatigues I can find) so my Oticon case gets pocketed. It has the advantage of having form-fitted rubber inside the case that provides excellent water and pocket crud protection, in addition to shock protection, the Oticon case seals quite well. I’ve actually run the stream from the bathroom faucet directly around the edge of it,@; and only a drop or two of water has gotten inside.

Here’s a CT scan of my P90R.
We runned it with 125kV, 0.195mA, for 47min. Distance to tube was 110mm. Continuous exposure with industrial CT (no shutter-technique as it is used for medical devices).

Btw: the HA still works without any issue.

@Surdi: I appreciate the kindness of your offer very much - I’m not going to take you up on it, however, because I rarely have occasion to remove my HAs before bedtime.

My hospital excursions are events that I earnestly try to avoid. When I do have to head in to the ER, my wonderful wife and best friend of 32 years is with me, to hold on to my *Genuine Oticon More Carrying Case" and poke me in the ribs if I get cranky with the patient registration personnel!

That fine leather pouch would be wasted, but thank you anyway, for your kind consideration.

Wow, that’s impressive. The packaging of all that is really interesting.

I think I see three boards there, flexible interconnects. Maybe a mic. board doing analogue stuff, the digital brains, and and possibly the bluetooth board. I think there might be glob-topping of bare chips in places. And using ceramic substrates for the two digital ones (thick or thin film hybrids).

The side x-ray also.

Just my speculation.

I see how the rechargeable cells are spot welded to the connection wires, and how the charging contacts are attached. Maybe not something that a a local repairer could replace easily, unless they solder the ends of the wires onto the boards, as is shown.

I see no telecoil, nor internal “receiver”, just the connection for the external ones. but maybe that fat thing that looks like a big chip capacitor is actually an inductor for the telecoil.

My, soon to be delivered, Phonak Nathos Nova Ms, have to pack those in as well. They must be crammed.

Much respect to what is inside these things, that might not be fully appreciated by some.

Good to hear that your inspection process didn’t wipe the memory, though I dare say that that is not used on 100% of devices. That’s reassuring.

Yes, it is very impressive how cramped it is.
My full respect to the developers.
And yes, I don’t have a telecoil, I think the fat thing is a cap.
If you like, I can upload the data to a cloud server for you. And a link to a free viewer. Then you can play around and explore deeper.