CT vs Tomo vs Fluoro

I have been having some interesting discussion with Nuno Lemos aka StockZombie @ Twitter, who has compiled his due diligence on Nanox at "Nanox Vision – a fools gold?"  

Here is some feedback on some of his points. 

Can you replicate CT with Tomo?

Nanox has been misleading the public, investors, and medical professionals for quite some time that it can do CT (including the "noise-free simulation" slide shown on the TV screen near the end of the RSNA 2020 presentation, 24:04).

That simulation was supposedly done with an imaginary device with 11 sources and detectors that don't exist.

But Nanox admits in its Prospectus that it intends to do only tomosynthesis - no usable axial slices can be produced.  CT or CAT is a short-cut for Computed Axial Tomography.  See also below.

Does the proposed Nanox.Arc 2.0 have 5 or 6 x-ray sources?

The information about the 5 x-ray sources comes from a video showing the making of Nanox.Arc 2.0.  If one pays close attention at 0:19-0:20, one can see the holes of the 5 sources.  I tweeted about it and so did Nanox promoter, but he did not count the holes.  

counted by me

not counted by promoter

The CEO was lying throughout the RSNA 2020 presentation that the device had 6 x-ray sources.  If the sources were so precious and novel, he would have gotten a least the number correct, as this was the first public demo of the source.

Here is how Nanox advertised its presentation on its exhibitor page at RSNA 2020:

Nano-X Imaging Ltd Nanox is a developer of MEMs based electrons field emitter cold-cathode, enabling the manufacturing of digitally controlled, low-cost x-ray tubes. Nanox's technology is under third party review, pending 510k clearance. Please join the Virtual Meeting Room button below at 10:30 am CST on Thursday, December 3 for a Featured Demonstration as Nanox unveils a proprietary digital X-ray source based on a silicon MEMs electrons field-emission technology. The presentation debuts a novel X-ray tube that emits digitally controlled X-ray pulses and can be used across multiple medical imaging use cases. https://www.nanox.vision 

So, what is the main proposed modality of Nanox.Arc 2.0?

Page 1 of the Prospectus explains that the main use of the Nanox.Arc that Nanox supposedly plans to commercialize is tomosynthesis:

Subject to receiving regulatory clearance, the first version of the Nanox.ARC that we expect to introduce to the market will be a three-dimensional (“3D”) tomosynthesis imaging system. Tomosynthesis is an imaging technique widely used for early detection, that is designed to produce a high-resolution, 3D X-ray image reconstruction of the scanned human body part for review by a professional diagnostics expert

Slide 8 from the March 17, 2021 Oppenheimer presentation states: 

The Nanox.ARC 3D computerized tomosynthesis:  New breed of medical imaging.  

Also, if one looks carefully during the RSNA 2020 presentation video (for example, at 12:55), what Nanox appears to be doing for any "scan" is collecting 45 images (5 sources x 9 tilted positions) and creating synthetic slices from them in a plane parallel to the flat detector placed in the "box" below the arc.

Can the proposed Nanox.Arc, either single-source or 2.0, do fluoro?

According to Nanox, Nanox.Arc can do fluoroscopy (even though it is not its main use case), but Nanox can also license its proposed x-ray source to traditional device manufacturers to incorporate in their own fluoroscopy systems (the white paper addresses that second case).  Today's fluoroscopy systems are very simple - a single source (pulsed, for two reasons - to prevent source overheating, and to reduce radiation exposure) and a fast detector (10+ fps) - clearly a single-source Nanox.Arc can do it (for say, $200,000/unit) ,assuming a powerful enough hot-cathode dental source with a stationary anode (but the best price quote for a new system I have gotten is $28,500/unit FOB Shanghai, and it is not cleared yet in the USA, so it cannot be used as a predicate).  

Slide 20 of the January 2020 presentation at JP Morgan shows the multi-source Nanox.Arc device doing "3D fluoroscopy" (I guess you need a Hololens or Oculus headset for it) using 3 of the 5 sources. 

Yes, fluoroscopy has its own product code(s) for 510K clearance purposes (for example, JAA), but a system can have more than one product code for clearance purposes.

Update:  Here is the completely-misleading slide from the January 2021 JP Morgan presentation that shows that the proposed Nanox.Arc 2.0 can replace the Chinese fluoroscopy system, among others.  See also my previous post, focusing on cost.

Why Nanox.Arc has no chance for clearance

Nanox has a nice video on its front webpage titled "Understanding Nanox technology & vision"  It is extremely misleading, and, thus, extremely useful to regulators.  It proves that Nanox.Arc has no chance for FDA clearance, not this year and not ever.

How so?  Well, about 40 seconds into the video, the mesmerizing voice proclaims:

Years of dedicated development by Japanese and Israeli scientists have achieved a novel X-ray source and device that bring hope by being more affordable by orders of magnitude than the conventional X-ray technology used today.

Oops.  See, the FDA clearance pathway is only for a device that is substantially equivalent to a legally marketed device.  A novel device will be immediately rejected, as it fails the RTA checklist, and must go through either a De Novo classification request or a PMA approval submission.  Either one takes years.

Incidentally, according to the same segment in the video, the device below represents the X-ray technology used today:

Unfortunately, that is a sketch of an MRI device, which has nothing to do with X-ray technology - note the "chimney," which is actually part of liquid-helium cooling system (the superconducting electromagnets require very low temperature to operate).

Thanks to ThreadEnhancer @ AuntMinnie for the novel tip.

The video was published sometime in February or March, 2020, that is, after the supposed January 2020 submission for clearance of the single-source device.

Update:  The MRI device in the sketch is a stylized Siemens MAGNETOM.

Update (March 13, 2021):  The video, of course, is not the only place where Nanox explicitly describes Nanox.Arc as novel.

Update April 5, 2021:  Nanox got clearance for a Nanox.Cart (the ugly device).  Nanox.Arc (a multi-source one) still has no chance of clearance, unless Nanox admits that the device is not novel. 

Hypothetical predicate

Hypothetically, if someone were to submit for 510(k) clearance a single-source device like the one demoed by Nanox at RSNA2020, what would be the proper predicate (ignoring the DR detector)? 

There are 71 product codes for x-ray, of which only two appear relevant:

1. IZL is "mobile" (which includes portables, some even using dental tubes, and devices on wheels, list, annotations, 3rd party: 8):

"A mobile x-ray system is a transportable device system intended to be used to generate and control x-ray for diagnostic procedures. This generic type of device may include signal analysis and display equipment, patient and equipment supports, component parts, and accessories."

2.  KPR is "stationary." (list, 3rd party: 18):

"A stationary x-ray system is a permanently installed diagnostic system intended to generate and control x-rays for examination of various anatomical regions. This generic type of device may include signal analysis and display equipment, patient and equipment supports, component parts, and accessories."

Note:  Code MWP is not appropriate, since it is an enclosed "cabinet" system not for imaging humans directly, but has a redacted 510(k) submission by Hologic which may be potentially useful)

An interesting clearance under JAK product code (uses K160857 as KPR reference, just for hands and feet: old manual).

WHO apparently required (requires?) 11kW tube for stationary (so Nanox is out, I believe) and says mobile is not essential in many small hospitals but may be needed for orthopedic surgery.

Screenshots from Nanox RSNA2020 demo (vimeo 487071020/487132636) showing views of the single-source device "pending clearance:"

Other notes:  Two portables, Micro C (fluoro) and Fuji's Xair are waiting for years for 510(k) clearance and haven't gotten it yet.  The operator will probably need lead apron.  Fuji is supposedly doing trials in 2020. Micro C/Oxos looks like a scam (based on the hype in some local press articles and in a NASA presentation ; claims testing at Intertek for IEC 60601-1). Note: Jan 18/Feb13, 2021:  Wow, Micro-C got cleared (summary, through a 3rd party within 30 days, initially expected December 2018, but turns out submitted again November 16, 2019, and delayed).  Note Mar 30, 2021:  But Micro-C was initially promoted as a fluoroscopic device (product code JAA), instead it got cleared as a portable x-ray device only (product code IZL) for extremities (static and "serial") 

Further notes added on Jan 5, 2021:  A review of possible x-ray systems (including tomo, fluoro, C-arm, CT, etc) shows only 10 clearances in the past 5 years that involved a Third Party Review, by only two Organizations that are still active in the Program.  Here is the list:  K203216, K203187, K202564, K201053, K180727, K170789, K170716, K170221, K161920, K160315.  Time from recommendation to clearance ranged from 2 to 52 days.  Nanox is in trouble (if it ever submitted anything for clearance, of course). 

Note (Jan 15, 2021):  A potential predicate for the multi-source device (video), but not a good one, as the Shimadzu unit has a powerful x-ray tube (added Mar 11, 2011).

Update June 22, 2021:  The predicate (which Nanox could not get right in its 510K Summary) is described in this blog post.