X-Ray imaging - The Gendex GXS-700 X-Ray dental imaging array.

[KE5FX]

Mr McMaster kindly provided teardown images at SilconPr0n:

http://siliconpr0n.org/wiki/doku.php?id=gendex:gxs700

Doesn't seem to come up for me, anyone else?

[Fraser]

It's a weird web site format.

You need to search on GXS700 using the search box (top right)

Go to the page that it finds and select 'sensor' sub page.

Fraser

[Macbeth]

I had the same trouble. Perhaps this URL will work instead?

http://siliconpr0n.org/wiki/doku.php?id=uvscada:gxs700

[Fraser]

That works fine

[cex]

Oooops!

Sorry, surely the site was restructured after I bookmarked it, and I didn't test before posting the URL.

[Fraser]

Yes he appears to have restructured the site from when I last visited it. I had missed the teardown pictures though. Thank you for leading me back to the site to capture those.

The sensor is, as expected, highly integrated with the use of BGA chips and exposed bond wires between the PCB and imaging array. Not a very friendly repair proposition unless you have the correct rework equipment. It also contains an ASIC so failures in that IC would likely render the unit scrap.

I really need to set up my dental X-Ray generator to test mine but I have no time at the moment. After Christmas maybe.

Fraser

[tommyhn]

I need a favor, if you can send me the file to calibrate the gendex gxs 700 sensor, I lost my installation disk, my computer is broken and there is no way to recover the files

[Fraser]

Calibration file is unique to each sensor. I rehomed my Gendex sensor so no longer have the file set.

[Andrew Seltzman]

I have a few of these sensors and am trying to get them to work.

I have been talking to some Chinese sellers on ebay that are selling gendex sensors. They claim to have "third party calibration files" but say that although they allow the sensor to work, the image is not perfect, though they will send the third party files along with the sensor. The pictures they post that the sensor took look resonable, though not perfect. I strongly suspect that what they've done is found a way to either change the serial number on the calibration file or the serial number on the sensor to allow them to use a calibration file for a different sensor with the one they are selling.

There's a tool to reprogram the sensor eeprom(if corrupted) and serial number, though I'm not using it except as a last resort to get a sensor working.
http://justinshafer.blogspot.com/2014/11/dexis-fusion-tool.html

Could it be as simple as changing the serial number on the calibration file name to match that of the sensor in order to fool the software to work (I know the cal files won't be correct and the image won't be as clear, but just to test the sensor with the OEM gendex software)?
Does anyone have cal files for any gendex size 1 or 2 sensor that they could post so I could have a look at them?
They should be named (where the numbers are the unique sn of the sensor):

    012345678_dark.flf
    012345678_dfm.dfm
    012345678_flat.flf

[DogP]

Has anyone opened one of these sensors up, and if so, any tips for opening non-destructively?  I recently picked up one of these sensors, but it doesn't enumerate, and the cable looks a bit lumpy at the sensor end.  I'm hoping I just need to open it up, cut the last few inches of cable, and re-terminate the cable.  Unfortunately, the sensor is sealed (as you'd expect for a dental device), so I'm looking for some tips before I just start busting it open.

Am I correct in assuming all the electronics are in the sensor end, and there's no electronics in the USB plug end?  I wish I had access to an X-ray so I could X-ray this thing.

Thanks,
Pat

[DogP]

Just to follow up... I ended up getting this open, though it wasn't exactly a success.  So, I'll post my thoughts/advice/pics for anyone else (or the future me, if I come across another really cheap sensor).

To get into the sensor, you can see a flat spot on the side where you'd expect the two halves to join together.  In this case, it's sealed, so you need to carefully cut around the edges and sorta pry it apart (I used a sharp new X-acto knife blade).  It's small, so you'll want some magnification (I did it under a microscope).

The mistake I made was cutting closer to the top of the flat spot (side that the cable goes into) instead of bottom (side that says "GENDEX").  After opening it, I can see that the bottom goes inside the top (i.e. there's a lip, which you can cut to, without the knife blade going into the electronics).  Also, specifically be VERY careful on the end where the cable points out of... the bond wires to the image sensor are RIGHT behind the plastic and completely unprotected.  Some of mine look to have gotten mangled (not sure if I put the knife through them, pushed plastic into them, etc).

I originally suspected a bad USB cable, but once I got into it, I was able to check the cable, and it was fine (cable is soldered to a flex circuit on the top, which comes down to the connector on the board).  There are no electronics in the USB plug... it's straight USB wires into the sensor.  When the sensor is plugged into the PC, it doesn't enumerate, so something on my board must be broken (in addition to the now broken bond wires).

It looks like they used a two-part gap filler, which generally don't reuse well... I dunno how hot these sensors get, but if you open it, you might want to replace it with a new gap pad or something.

Also, if you really suspect just a bad USB cable, the easiest/safest way to fix it is probably to cut the plastic lump off the top where the cable goes in, and re-terminate the cable there.  That way you don't risk damaging any other parts by opening the sensor portion.

Couple pics attached...

Pat

[drgnanam]

hi,
i have one of sensor gendex gxs 700 size 2, does any body calibration file(i know each have unique one), just to test the idea changing serial number to fool the software, i sensor, with serial number 2133632432, sensor gets identified in gx picture  with all , just need original cal file to test it, i bought it from ebay cheaply,if any body have  califration file for different one  , any other way in windows os, please chime in,

[frogg]

Wow, I'm surprised that it uses the MCP with a CCD.

1997 was kind of the turning point for amorphous silicon x-ray detectors, coupled with a scintillator. GE and EG&G were the people that made it happen.

I always figured filmless x-ray imagers worked with ASi or ASe directly behind a scintillator, but it looks like other technologies are still in use. Cheaper to produce?

[Ben321]

That Dexis sensor is tiny, and doesn't even require an external interface box to connect it to the PC. My first guess is that means it's as cheap as any ordinary USB webcam (maybe $100 at most), only this one sees X-Rays instead of visible light. However I then realize it is a specialized device intended for medical use, and so the price is probably many times my first guessed price, kinda like thermal imagers (or maybe even more expensive like like SWIR imagers).

So does anybody here know the cost for one? Their website https://www.kavo.com/en-us/imaging-solutions/dexis-platinum-digital-intraoral-sensors doesn't show any prices. From my past experience, this usually mean that the device is VERY expensive, so expensive they are afraid that showing the price will scare off any potential customers.

[Fraser]

Ben321,

Indeed they are very expensive !

Regarding the parts cost, it is the large CCD FPA that is expensive. Apart from that the electronics are nothing very special compared to modern digital camera electronics.

The price of the units is high because they are for medical use and that tends to add a zero or two in many cases ! These items are also more specialist in nature than, say, a web cam. That results in a premium on the cost. Only a few companies make these sensors for dental work and most operate in a aggressive manner in terms of initial purchase and cost of ownership Let me expand on that to explain what I mean..........

1. You buy the sensor(s) that you require for your dental practice. They replace your film based system and are mission critical assets that are also expensive to replace if they fail.

2. You buy the software to use with the dental sensors. This is bespoke software and is very expensive. Some may be an outright purchase of a licence whilst others are a subscription based software model.

3. The seller of the sensors will warn you of the risk of sensor failure and loss of the capability in your practice until replaced at great expense. They will offer you a form of support/insurance contract which provides same day or next day delivery of a new sensor if one of yours fails. This contract is comprehensive in its coverage but very expensive ! It will continue to replace failed sensors every time one fails until the contract ends and is not renewed. For a dental practice it can be a necessary evil however. With the contract comes ongoing hardware support in addition to the software support.


The sensors that appear on eBay are often the units that have failed in service and been scrapped. Common failures are cables as they get a lot of bending at end points and even bitten by patients ! Other failures include loss of identity due to a problem in the flash memory or physical damage to the module casing or CCD FPA from being dropped. These things are fragile.

So yes, they are expensive, artificially so, but that is the nature of the beast and we all know how much private Dentistry costs ! An alternative to these active sensors is the CR plate that is reuseable but captures an X-Ray that is then read by a special scanner and eraser unit. The plate looks similar to a standard film type plate but it costs a lot more ! It saves money on film and developing chemicals over the years of use though and is relatively robust compared to the active sensors.

Fraser

[Ben321]

Ben321,

Indeed they are very expensive !

Regarding the parts cost, it is the large CCD FPA that is expensive. Apart from that the electronics are nothing very special compared to modern digital camera electronics.

The price of the units is high because they are for medical use and that tends to add a zero or two in many cases ! These items are also more specialist in nature than, say, a web cam. That results in a premium on the cost. Only a few companies make these sensors for dental work and most operate in a aggressive manner in terms of initial purchase and cost of ownership Let me expand on that to explain what I mean..........

1. You buy the sensor(s) that you require for your dental practice. They replace your film based system and are mission critical assets that are also expensive to replace if they fail.

2. You buy the software to use with the dental sensors. This is bespoke software and is very expensive. Some may be an outright purchase of a licence whilst others are a subscription based software model.

3. The seller of the sensors will warn you of the risk of sensor failure and loss of the capability in your practice until replaced at great expense. They will offer you a form of support/insurance contract which provides same day or next day delivery of a new sensor if one of yours fails. This contract is comprehensive in its coverage but very expensive ! It will continue to replace failed sensors every time one fails until the contract ends and is not renewed. For a dental practice it can be a necessary evil however. With the contract comes ongoing hardware support in addition to the software support.


The sensors that appear on eBay are often the units that have failed in service and been scrapped. Common failures are cables as they get a lot of bending at end points and even bitten by patients ! Other failures include loss of identity due to a problem in the flash memory or physical damage to the module casing or CCD FPA from being dropped. These things are fragile.

So yes, they are expensive, artificially so, but that is the nature of the beast and we all know how much private Dentistry costs ! An alternative to these active sensors is the CR plate that is reuseable but captures an X-Ray that is then read by a special scanner and eraser unit. The plate looks similar to a standard film type plate but it costs a lot more ! It saves money on film and developing chemicals over the years of use though and is relatively robust compared to the active sensors.

Fraser

I wonder what an actual high resolution CCD panel would normally cost, if not used in medical equipment?

[ycrcb]

I managed to find some calibration files on an obscure dental website. GXS-700 is also called Dexis Platinum
https://www.atlasresell.com/sensordrivers
The site have instructions.

It is also possible to install the calibration files, and use GxPicture 3.8.1 with VixWin platinum 3.3 in demo mode on Windows 10.
http://www.medtec.pl/download.html

[devilmastah]

I think i need to follow this thread   (working on a diy X-ray setup, i am currently running it with a mammography screen + digital camera setup which works surprisingly well)
I orderd one of these sensors for 50 euros from china (knowing it would be a gamble). As expected its broken. But the failure mode is quite weird to me.
Seems that multiple of the bonding wires are corroded, looks like 5 are gone. I am now looking for a hobbyist that has (access to) a bonding machine in my country 

I wonder if this is a common failure on these.