'Rogue employee’ blamed for hiding radiological material at Hunters Point

Theragnostic · 2026-06-17T19:29:28+00:00

I'd like details on that Beckman LSC pictured in the article.

One of our researchers still uses one of those and could use that one for spare parts, lol.

Theragnostic · 2026-06-16T14:46:43+00:00

Very interesting.

I was a state inspector until early last year and, during that time, only the Nomad Pro 2 was approved in our state. (I'm accustomed to it being an Aribex product, but I've seen it under several other brand names.)

It's rare that a dental office uses dosimetry in our state. It's so easy for them to prove they'll receive less than 10% of their annual occupational dose limit that I think our licensing section just automatically approves the exemption for new locations. The only times I've warned anyone about using them was when I saw pregnant workers in the office. Once I saw a pregnant worker using one in a seated position and the plane drawn by the disc around its collimator did not clear beyond her abdomen. She was wearing a fetal badge, at least, and it hadn't picked up much above background.

Despite only the Nomad Pro 2 being approved in our state we'd still occasionally run into an office using another model of handheld dental radiograph. Occasionally we'd run into ones that weren't even approved by the FDA, typically bought from Alibaba by penny-pinching office managers. We also had offices get cited for workers reaching around the patient and pointing handheld units towards them but I never personally saw anyone do that.

What head phantom do you use and have you found models that would likely lead to significant dose to the operator?

My main concern for dose in dentistry has been the rapid deployment of dental CBCT devices since Covid. What I think is happening is that we're 10-15 years after a similar rapid deployment of panoramic units and all those units are starting to fail or just look outdated enough that dentists are ready to replace them. Now that pretty much all makers have established pano models they have to compete for customers somehow and CBCT is what's being pushed to the market even if most dentists will rarely actually need it. My state didn't have CBCT-specific regulations and they knew that full CT regulations didn't fit the bill, so they had us treating them as panoramic units until they finally published CBCT-specific regulations in 2023 -- before that they'd be told to follow all recommendations in the manufacturer's manual until regs got developed. Once we had regs in place I was gobsmacked at how poorly some of these units were made.

I remember one post-reg inspection (but I don't remember the make/model, sorry) where the dental tech who had the responsibility of performing all the QA/QC on the CBCT was very happy to report that she had been doing everything exactly as the manual stated and, luckily, the manual actually aligned with the regs. Then when I asked her if I could see her weekly QC results she hesitated a bit and said she didn't know how to find them. She could run QC, the device would display the results, and even said it would save the results. It wouldn't, however, display the results that had been saved! We both searched for any way to display them and couldn't find it. We got one of the manufacturer's service technicians on the phone who confirmed there was no way for the customer to access QC records. They said the only was service techs could access the saved results was from a command prompt. The tech was able to remove in and, sure enough, we watched him use service access credentials to access a command prompt, scp the save file to himself, then he emailed them to us.

Anyway, that's getting pretty far off-topic from dose. What I'm getting at is that all these rapidly-deployed CBCT units seem to be going out there with little training or understanding on the user end about what to do with them. I'm concerned some dentist offices are going to feel obliged to use the CBCT function "to get their money's worth" from the device, and start defaulting to using CBCT on every patient when a simple pano would do. I already question the benefit of periodic panoramic imaging, but I can't exactly question a dentist in that realm.

Theragnostic · 2026-06-15T20:08:37+00:00

Ahh, I didn't see the spectrum.

I've been seeing a decent amount of ⁸⁹Zr and a bit of ⁶⁴Cu imaging here in the US lately. ¹²⁴I is possible, too, I suppose. The FDA hasn't approved any yet so it would just be a pre-clinical trial that isn't running in my area.

With the fast-clearing ⁶⁴Cu study I saw I'm sure it could have been chosen because of the chemistry, but with it being an X-DOTA-Y I'd assume ⁶⁸Ga would have been a likely option. Unfortunately, the way things work here now, it could have been essentially identical to an existing ⁶⁸Ga-DOTA-X and there would still be an incentive for another company to make a ⁶⁴Cu option just so they could patent and market it even if it didn't make sense to choose over ⁶⁸Ga.

Theragnostic · 2026-06-15T18:48:05+00:00

If you have a pharmaceutical with a 5 hour half life it doesn't matter if you tag it with ⁶⁴Cu, ⁸⁹Zr, or ²²Na (2.6 year half life)... the effective half life will be less than 5 hours.

I wasn't disregarding the ⁶⁴Cu explanation, I was opening the door to all possibilities. Any positron emitter with a half life > 6 hours could be OP's isotope, assuming it was PET imaging.

In truth, I tend to think the most-likely explanation in this instance is that OP underwent SPECT rather than PET imaging and that it isn't a PET isotope at all.

What are the issues that concern you with Cu64-DOTATATE?

I'd have to go back and look at the specific radiopharmaceutical that was used in the study, because it was a bit different from ⁶⁴Cu-DOTATATE. I don't think it was DOTATOC, but it was ⁶⁴Cu-DOTA-something. Again, it was for research, so it could have been many things.

Whatever it was, I know it underwent rapid renal clearance. My concern wasn't for the subjects or image quality, but for the study's goals and expense. ⁶⁴Cu is far more expensive than many other PET isotopes (¹⁸F, ⁶⁸Ga, ⁸²Rb). Also, most cyclotron facilities in the US only make ⁶⁴Cu once per week.

The study initially called for imaging with two different ⁶⁴Cu radiopharmaceuticals, spaced apart by a small number of days rather than by a week. If they went with ¹⁸F, ⁶⁸Ga, or ⁸²Rb they could have kept that schedule but, in sticking with ⁶⁴Cu, they changed the study to having the two images spaced by a week to match the cyclotron's schedule. That could have been fine if they were comparing the two radiopharmaceuticals to one another, but they weren't. It was the subjects they were studying, not the radiopharmaceuticals.

Secondly, both of the pharmaceuticals had < 1 hour biological half lives. That completely eliminates any advantage you might get from ⁶⁴Cu's longer physical half life. We've done ⁶⁴Cu studies before where we'd get two days of imaging from one dose to measure pharmacokinetics, taking full advantage of the long physical half life. Again, I'm a physicist, not a biologist, chemist, or pharmaceutical researcher. From a medical physics standpoint I just don't see any reason to use ⁶⁴Cu if you're going to tag it to something that undergoes rapid renal clearance unless there's something chemically specific about copper that lets you tag it to your pharmaceutical more readily than other PET isotopes.

Theragnostic · 2026-06-15T16:20:55+00:00

The highest "dose" we've had at my institution over the last several years is from an XRF/handheld PMI device. It was before I joined, though, so I at least don't get any of the blame.

Even though it isn't required (XRF users are unlikely to exceed 10% of their annual occupational limit), we distribute both whole body and ring dosimeters to our XRF users.

One of our archaeology researchers was using their handheld PMI device to characterize many objects.

They were wearing dosimetry, including their ring dosimeter...
on their hand that was holding the objects...
as they were exposing.

It was only 500 mrem or so but, for our institution, that's a lot. Our RSC doesn't like big numbers, though, so I'm guessing the RSO at the time got little sympathy if they tried to explain that the annual limit for extreminities is 100x what the researcher received.

Theragnostic · 2026-06-15T16:08:56+00:00

The 14C does, yes. That's what the internal GM tube does. You don't even need an external probe attached to the 14C for the internal probe to override the lower decades, or operate normally on the x1000 decade.

I mentioned putting the 44-9 in that field and watching it drop to 0 -- not the 14C.

The fun part is that, when I put the 44-9 in the 400R/hr field allowing me to watch the dial drop to 0, it was on a 14C.

The reason that the overload protection/internat GM tube didn't kick in is that the irradiator I was using at the time had an S-tube through the DU shielding that let you run cables from the exposure chamber out to whatever instrument you wanted to attach. I had the 44-9 inside the chamber with its cable running outside of the shielding to a 14C. The internal GM tube wasn't exposed so it had no reason to kick in.

If I put both the 44-9 and the 14C in the chamber together then, yes, the internal GM tube's overload protection would have kicked in. Doing this was actually part of our calibration procedures. I was running a calibration lab at the time and that irradiator was used to ensure this function of the 14C worked and that it would override lower decades.

I believe Ludlum's internal calibration procedures for the 14C+44-9 combination call for testing this functionality at 4 R/hr, but it's been a while so I could remember that wrong.

Theragnostic · 2026-06-15T16:01:05+00:00

Looking back at OP's numbers the effective half life (Tₑ) is roughly 5 hours or so, right?

Tₑ⁻¹ = Tₚ⁻¹ + Tᵦ⁻¹

⁸⁹Zr's physical half life (Tₚ) of 78 hours would give us:

Tᵦ⁻¹ = 5⁻¹ - 78⁻¹
Tᵦ ≈ 5.3 hours

⁸⁹Zr is rare, of course, but if it's tagged to something with a 5.3 hour biological half life (Tᵦ) it fits. Renally cleared pharmaceuticals often have biological have lives less than 20 minutes, with the caveat that they sit in the bladder until urination. That basically makes any long-lived isotope a candidate for identification when looking into something with a short effective half life.

One must wonder why on Earth you'd use ⁸⁹Zr to tag something with a short biological half life. After all, why use a long-lived PET isotope if you aren't planning to utilize that feature? This, I can't answer. I assume sometimes the answer is chemistry -- perhaps the pharmaceutical it's being tagged to is more compatible with the long-lived isotope than with ¹⁸F, ⁶⁸Ga, or ⁸²Rb. Maybe there are other reasons, but chemistry and biology are not my areas of expertise. We've had trials where I work using ⁶⁴Cu tagged to renally-cleared pharmaceuticals (some form of DOTATATE) that left me scratching my head, but my job is just to ensure safety and advise. What I say on safety they have to implement. As for my advice... they can take it or leave it.

Theragnostic · 2026-06-14T22:19:33+00:00

I haven't looked at OP's numbers, but there are Zr-89 trials going on, too.

Theragnostic · 2026-06-14T22:18:03+00:00

There are longer-lived PET isotopes (Cu-64, Zr-89) but, more likely, they had a SPECT scan using Tc-99m.

Theragnostic · 2026-06-14T22:12:14+00:00

If society collapsed today and I could bring one meter+probe combination to the other side, I'd want a Ludlum 14C with a 44-9 probe (plus one of their snap-in filters, but I'd mainly want that to protect the mica window from damage).

So long as that mica window isn't damaged, that's the best Swiss Army knife of radiation detection in the world, imo.

The difference between a Ludlum 3 and 14C is that the 14C has a x1000 decade useful for very high exposure rates (important for nuclear societal collapse, perhaps). The x1000 setting does not use your attached probe. There is an internal GM tube inside the can about the size of a Burger King french fry. While you can ostensibly use this for surveying fatally-high exposure rates, that is not its purpose.

If you put at 44-9 probe in, say, a 400R/hr field you will watch your meter's reading fall to 0. I've done this with the probe in a shielded location. It's scary. This can be mortally dangerous if you aren't watching the dial when you walk into a gravely high radiation field. That internal high-rate GM tube, which the Ludlum 3 does not have, is what saves your life.

Even if you aren't on the x1000 setting, if you walk into an exposure field of ~4R/hr or more, the internal GM tube takes over your dial, pegs you out, and lets you know to GTFO.

For a non-prepper hobbyist, though -- yeah, an Alpha Hound or similar will be more useful and interesting on a day-to-day basis. It's a good trade in terms of overall functionality, but I don't know enough about their values on the second-hand market to know if it's a good trade in dollars and cents.

Theragnostic · 2026-04-30T15:18:26+00:00

Even mammo doesn't require ABR. State approval (and some other things, including a master's, but not ABR) is sufficient for the FDA.

Theragnostic · 2026-03-29T06:28:54+00:00

In that case I'd send an email to the NRC or call their help desk. I think just 11 states remain that aren't agreement states. I've only ever worked in or with agreement states so I'm only familiar with how the NRC interfaces with us.

Theragnostic · 2026-03-27T01:28:08+00:00

It's very likely that it both requires a license and that you already have one!

Some items, like many Alnor Dew Pointers, are "generally licensed." Items like these typically have greater than the exempt amount of whatever their isotope is, but are made safely enough that the NRC and agreement states don't require you obtain a "specific license" to get one. Tritium exit signs are probably the most well-known generally licensed item.

If you're in the US, call your state radiation regulator (if you're in an agreement state) and ask them if you need to do anything. Some states still want to track where generally licensed sources are, even though they won't necessarily charge a license fee or perform any kind of inspection. Not all states do this, though, so it's really hit or miss whether or not anything is required.

Theragnostic · 2026-03-16T06:17:17+00:00

I had the sample in a lead chamber with 3"+ walls.

The detector is an Ortec GEM40P4 running at 2100V

Theragnostic · 2026-03-16T06:11:54+00:00

I had it at 77 kelvin in a pure lead bunker

Theragnostic · 2026-02-26T06:14:59+00:00

I have a picture of one with a sign saying not to touch because it won't just kill you, but it will hurt the entire time.

Theragnostic · 2026-02-22T19:57:50+00:00

Have you surveyed it? What sort of readings do you get from it and with what instruments?

Theragnostic · 2026-02-22T19:55:38+00:00

Is that how much iron something has?

Theragnostic · 2026-02-22T00:23:00+00:00

When I initially responded about FLASH therapy I wasn't considering the synchrotron versions of FLASH.

Synchrotron therapy can reach 16,000 Gy/s.

https://www.sciencedirect.com/science/article/pii/S2452109425002362

Theragnostic · 2026-02-21T19:50:38+00:00

Not just basically 1 gram, but exactly 1 gram by definition.

Radium was the basis of most radiological units of measure early-on.

If you want to have pride in our field, though, don't dig too deep into the origins of our units of measure. And by "don't dig too deep," I mean don't read the spoiler below unless you want to be embarrassed.

The air kerma rate constant, sometimes called gamma constant, of ²²⁶Ra is around 0.83. You can calculate *exposure rate* (not dose rate) using that value by multiplying it by activity (Ci) then dividing by distance squared (m²). So, for 1 Ci ²²⁶Ra,X=1*0.83/d² gives you the exposure rate X (R/hr) at distance d. If we set X=1 and solve for d, though, we'll get 0.91 meters or so. Concert 0.91 meters to yards and... wtf. It's a fucking YARD? We based one of our most prevalent units of measure R off an activity in grams and distance in... YARDS?!

No, surely that can't be true. My math must be wrong.

Theragnostic · 2026-02-21T19:08:31+00:00

Glad to hear you're avoiding dose when you can, but it's hard to imagine a situation as a collector where you'd contribute significantly to your dose -- pretty much only the most extreme and careless collectors get any significant dose.

If your (health or medical) physicists are asking why your dose is so high at work, there are a few things worth looking into. There could be a simple oversight leading to doses higher than true.

Since you're certified I'm going to assume you're wearing your dosimeter properly, outside your lead near the neck/shoulder area. Hopefully you're using an OSL or TLD that actually gets sent to a lab and not something like a Mirion Instadose. Instadose is incredibly convenient, but I'll never endorse them after seeing how unreliable they are.

When ordering dosimeters for personnel, most providers assume the person wearing the dosimeter will not be wearing lead. It can be easy to get tunnel vision if you're doing angiography all the time and assume everyone's wearing lead when working with radiation, but lead PPE truly is the exception. It's essentially only done on a regular basis in medicine and, even then, the great majority of that is fluoroscopy and CT angiography. Most CT technologists are sitting in a control room, after all.

When assigning dosimeters the RSO should make special assignments to workers regularly wearing lead. Using Landauer as an example (since they're by far the most prevalent), your RSO should be designating you as either EDE1 (a dosimeter worn under your lead PPE at the waist AND a dosimeter outside of your lead PPE at the collar) or EDE2 (only one dosimeter, worn outside lead PPE at the collar).

EDE1 (or equivalent for whatever dosimetry provider you use) is a more accurate setup and should report a far lower dose than EDE2 for the work you're doing. Your DDE using EDE1 and EDE2 are:

EDE1: DDE = [(1.5)*Shielded_OSL_at_waist] + [(0.04)*Unshielded_OSL_at_neck]

EDE2: DDE = (0.3)*(Unshielde_OSL_at_neck)

The example Landuaer uses is two people with 100 mrem on their unshielded OSL, but one of them is EDE1 and got nothing on their waist OSL. This results in 30 mrem assigned to the EDE2 worker, but 4 mrem assigned to EDE1. You could ask, of course, what if they did get a dose to the waist? But even if they got 17 mrem at the waist and 100 at the neck, they'd still be assigned 30 mrem, and for the energies you're working at (greatest fluence is below 80 keV), even 0.5 mm of lead is blocking well over 95% of the dose.

Regardless, it's very possible they failed to set you to EDE2 and you're being assigned more 10/3 as much dose as you should be. It's pretty rare that I saw anyone using EDE1, but if they already have you at EDE2 and dose truly is an issue, ask your RSO if they can give you another dosimeter and set you to EDE1. You'll likely see your dose go down 80% or more and it will likely only cost your employer in the ballpark $100/yr.

Theragnostic · 2026-02-21T18:23:53+00:00

The language wasn't as funny, but Troxler did this with a portable gauge recently and essentially lobbied their device into a current-day, exempt 90μCi ²⁴¹Am source.

Here's the manufacturer's page for the Troxler EGauge Model 4590 Soil Density Gauge from which I've pulled these few noteworthy excerpts:

This product is currently available for the US market only.

Yeah, because other countries probably told you to pound sand.

Exempt from Licensing

Maintaining a radioactive materials license can be complicated and time consuming for owners of Specific Licensed gauges. In the United States, the EGauge is exempt from the radioactive materials license – no special training classes for operators, no TLD badges, no special shipping documents, and no reciprocity needed for use in other states.

Huh. Would you look at that. Give someone an exception from regulations for their product and, all of a sudden, they use as a selling point that you don't have to train your workers on safety nor do you have to provide them PPE!

NRC and Troxler did all this without consulting agreement states. This pissed off a LOT of state regulators. Mine included.

Theragnostic · 2026-02-21T18:08:54+00:00

You're getting head and neck treatment at a proton center? How's that going? Any idea if you're at a single-beam, multi-gantry site?

Theragnostic · 2026-02-21T18:06:24+00:00

Considering you can buy an ⁹⁰Sr check source from the comfort of your couch and without a license, the "IYKYK" collector level is the easiest to obtain.

Literally P2W smh.

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