Hugo Chavez said regarding his cancer:


What he is missing is that the odds of a person getting cancer are about 50%, with 90% of cancers occurring after the age of 45. The cancers he refers to could be explained by sheer luck.

But then again mice with suppressed immune systems, can easily be infected with cancer.

So, let's assume that state actors have access to technology not available to ordinary criminals, like free electron lasers (XFEL) or a similar device that can create x-ray beams sufficiently collimated and intense as to reach a distant (e.g. 100m) target. Also the device is sufficiently small as to be able to fit inside a room or even a truck. Also assume that the rate is low enough as to avoid Acute Radiation Syndrome.

Such crimes can be prevented in two ways.

  1. Either the damage to the victim is prevented or
  2. the criminals are exposed.

Therefore, examining the following in the answers might be useful:

  • Counter-measures that can prevent or reduce the dose (e.g. house walls material, clothing material, diet, etc)
  • A detection of radiation would be considered a counter-measure, since it would no longer be stealthy. Could an ordinary journalist detect such incidents? I'd love a detailed analysis of radiation detecting devices.
  • Specific signs and symptoms that indicate exposure to x-rays or gamma rays (e.g. skin redness, nausea)
  • Diagnostic tests indicative of such exposure.

I know cancer is a random process and not all people will get cancer by being irradiated. Also cancer patients can often live for decades. However, I am absolutely certain that if it's possible to be done without being detected, then it is done against high value dissidents or high profile political targets that would otherwise be active and efficient for decades to come.

A 30% success rate within 5 years at the cost of 1 million $, is something many governments would love.

Note: Although rather impossible due to complexity, honeypots and lack of access to devices and facilities, please avoid describing methods that ordinary criminals can use. I'd like to know what a multi-billion dollar actor with diplomatic immunity and access to state-of-the-art technology can do. But most importantly, how to get them behind bars.
Also, this question is not about radioisotopes that require inhalation or ingestion. It's about x-rays and gamma rays.

On the bright side, perhaps this method has serious constraints in range due to ionization of the air.

  • 1
    $\begingroup$ I'm pretty sure most of your questions can be found with a quick google search. In addition, increased radiation is done with high dosing. Small doses do increase the risk of cancer, but as you say they can walk around for decades if you inly do it slightly. With the added risk of being caught in these years compounding, it is just too much risk. Both politically as well as that the target can get away. With doing it in a few months by higher dosing you can kill someone more quickly, though it's still easy to detect. $\endgroup$
    – Trioxidane
    Jul 13, 2021 at 10:32
  • $\begingroup$ @Trioxidane indeed some of the information I need can be found online. However I think it's not gathered in a single location (this answer). Also, personally I have studied quite a bit of dosimetry and can answer my question, but first I'd like other people's point of view. I ll probably post an answer in a few weeks. $\endgroup$
    – user
    Jul 13, 2021 at 12:22
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    $\begingroup$ Tony Hillerman had a novel based on giving a radioactive amulet to a group that the perpetrator wanted dead. They would wear it next to their skin. That suggests that instead of using some ray gun, the government could take over the laundry and soak the person's underwear in radioactive material. That would be never suspected. $\endgroup$
    – David R
    Jul 13, 2021 at 14:39
  • $\begingroup$ Out of curiosity, with a 50% natural causal chance, how would you know if your efforts to foil the State were successful? $\endgroup$
    – JBH
    Jul 13, 2021 at 19:10
  • $\begingroup$ @JBH Unfortunately it's impossible to establish the cause of cancer currently under the aforementioned conditions. $\endgroup$
    – user
    Jul 13, 2021 at 21:24

5 Answers 5


The cheapest way of detecting such a weapon in use would be by using wearable badge dosimeters.

These are cardboard-like sheets impregnated with substances that (ideally) exhibit the same radiation absorbance as a human body in a given spectrum (X rays, gamma rays, etc), and decay into byproducts with specific chemical properties (usually a different pH). It is then very easy to mix these substances with litmus pigments that will change color and visually display the extent of the absorbed dose.

Another simple method employs unexposed photographic film. This also reacts to penetrating radiation, but the effect is only visible after developing the film, which can be awkward.

Just wear some dosimeters under the clothes, and check them periodically.

Another method would be using active dosimeters or detectors; these are vacuum tubes that will display scintillation or other effects (e.g. a resistance drop) when hit by specific radiations. A scintillation counter will then calculate the intensity of the incoming dose. These systems are bulkier and require a battery at least, but they are much more sensitive and precise; also, they can give the alert as soon as they detect the radiation.

A dosimeter at the bottom of a metal cylinder (can) will receive radiations only from a very restricted zone, the one in front of the cylinder opening: it can then be used as a directional finder to locate precisely the radiation emitter.

As a defense, you'd need to line rooms and clothes with metal (the densest metals stop radiations; at low intensities you shouldn't need much) or radiation-absorbing material (e.g. water).

portable dosimeters

Apparently, current portable dosimeters can be as small as a ring, but require a reader to decode the chemical and physical changes radiation induced into them and translate them to an exposure figure. The smallest reader is large as a large cellular phone; the most sensitive is as big as a camera case.

So, unobtrusively and frequently checking one's exposure is not really possible, unless you employ some sleight of hand - take off the detector ring, pass it to a bodyguard who replaces it with an identical, fresh one before scuttling somewhere private to check the readings.

There were chemical, throw-away detectors once, though. I have seen them in use back in the '80s, they weren't very accurate nor sensitive, but could be checked visually - they were dark orange stripes with a creeping brown that grew with radiation exposure, you wore them on your lapel. They probably make them no longer.

One of them appears in Heinlein's The Long Watch:

Dahlquist twisted a knob on the Geiger counter; the instrument stopped clicking. He had used a suppressor circuit to cut out noise of "background" radiation at the level then present. It reminded him uncomfortably of the danger of staying here. He took out the radiation exposure film all radiation personnel carry; it was a direct-response type and had been fresh when he arrived. The most sensitive end was faintly darkened already. Half way down the film a red line crossed it. Theoretically, if the wearer was exposed to enough radioactivity in a week to darken the film to that line, he was, as Johnny reminded himself, a "dead duck."


As he passed the counter it chattered again. He stopped short. He pushed one hand close to the counter. Its clicking picked up to a steady roar. Without moving he reached into his pocket and took out his exposure film. It was dead black from end to end.

  • $\begingroup$ When you say active detectors are bulkier, are we talking something you'd put in the back of a truck, or more the size that, say, a bodyguard could carry in an attache case? $\endgroup$
    – Cadence
    Jul 13, 2021 at 11:48
  • 1
    $\begingroup$ @Cadence you can find reliable palm-sized ones on Amazon. It's more difficult for neutrons, which aren't EM spectrum and have a wide range of energies, but X and gamma can be tracked on the cheap. $\endgroup$
    – LSerni
    Jul 13, 2021 at 11:51
  • $\begingroup$ Are there any jewel-like dosimeters? Such that can be checked for visual indications of radiation without special process? $\endgroup$
    – user
    Jul 13, 2021 at 16:28
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    $\begingroup$ @user not that I know of, but you could make one using a doped lithium fluoride crystal in a ring cast. The crystal would absorb the radiation, which could be quantified by placing the ring into a special heater (it's called thermoluminescent dosimetry). It would also be possible to use one of those liquid crystal rings that change color with the body temperature, filling them with extreme UV photographic gel and coating them with UV-filtering paint. Only radiations would then enter the crystal, which would slowly change color in response to radiation. Not very precise, but it would work. $\endgroup$
    – LSerni
    Jul 13, 2021 at 16:37
  • 1
    $\begingroup$ @user it turns out someone else had very much the same idea :-D - there is also a thermoluminescent bracelet. landauer.com/saturn-ring-dosimeter $\endgroup$
    – LSerni
    Jul 13, 2021 at 16:40

Concrete bollards on wide footpaths. Spacious front yards. Penthouse apartments.

The xrays must come from a truck parked on the street, so maximise the distance from any truck to a target using architecture.

Bollards and big yards around a spacious mansion should keep any xray truck hundreds of meters away from the target.

If in a big city - put the targets home in a penthouse on top of skyscraper. It's hard to get a truck up there, and theres a few hundred floors to absorb any angled shots. Even if they get it in the building you only need to secure the top few floors - the metal or concrete of the floors will absorb huge amounts of radiation.

Use helicopters, tunnels, or just a lift down to a subway platform in order to avoid walking a street level during commutes.

Employ short, petite people

Your government employs the smallest people they can find. The energy absorbed from an xray at a given distance is proportional to surface area of the target, and skinny and short people have less surface area to hit.

They're also harder to aim at, making more work for the bad guys and requiring them to be closer to the xray machine - more on that later.

Find them using an ir camera - or look for missing snow.

Xrays penetrate a wall imperfectly, and some energy goes into heating it up. This should show up on a thermal camera as an ellipse or circle of yellow or orange, depending on the impact angle. Highly visible on the otherwise cold black wall.

A truck or room running an xray machine at these power outputs is going to also heat up from all that power. To find an xray truck in the middle of an attack, just look for the red coloured truck on your thermal camera.

In snow itd also be the truck with no snow on it, or if launched from a house itd be the house with no snow on its roof. Apparently this is how cops find cannabis installations in cold climates.

Look for hospital admissions for radiation sickness for those operating the machine.

Notice how the dentist leaves the room when using the xray machine? Even though its aiming at your face, that little bit of reflected xray can hurt the machine operator over time.

The bad guys running the machine / guarding it / aiming it at the target are going to get tiny doses of xrays themselves, and theyll need treatment for that eventually.

  • 1
    $\begingroup$ Good list, but don't forget dosimeters. Feed the data into a location tracker app and the victim will be able to tell people when and where they were zapped, massively assisting any investigation. $\endgroup$ Jul 13, 2021 at 11:16
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    $\begingroup$ Distance is indeed an effective measure since, unlike ordinary light, X and gamma rays are absorbed by air quite a bit. If I recall correctly a 2MeV gamma ray drops to about half intensity within 100m. Lower energy beams (that is X-rays) are absorbed much faster. $\endgroup$
    – user
    Jul 13, 2021 at 12:29
  • $\begingroup$ Depending on who your protecting, the architectural techniques have the bonus of being the same techniques used to protect against car bombings and suicide vans. $\endgroup$ Jul 13, 2021 at 18:34
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    $\begingroup$ Smaller people may have less surface area to absorb radiation in absolute terms, but they also presumably are more susceptible to it so that less radiation will have the same effect. Taking it to the logical extreme, if you pointed your cancer ray at a room containing animals of a wide range sizes, you wouldn't expect just the large ones to get cancer. On the contrary, I'd expect larger animals to be more resistant because they have more volume relative to the surface area exposed to the ray. But presumably the ray can simply be tuned for the proper dose, given the target. $\endgroup$
    – kaya3
    Jul 14, 2021 at 9:53

This probably isn't going to work.

A rough estimate of lifetime cancer risk due to radiation is about 5% per Sievert for whole-body exposure.

A 5-Sievert dose over a fairly short time will produce death in about 50% of the victims within a month. The symptoms are pretty obvious - nausea and vomiting, loss of appetite, weakness, hair loss, internal bleeding, diarrhea, headache, fever, drop in platelet and neutrophil count. The nausea, fever and diarrhea are typically of very rapid onset, and last part of a day to a few days. There follows an apparent recovery which lasts several days, followed by the other symptoms as the lymph system atrophies and and blood cell production nosedives. Secondary infections become a problem.

There are other symptoms associated with higher exposure levels, but I assume you're not interested in that sort of overt attack. You'll want to keep the radiation levels below about 1 Sievert to avoid discovery.

  • $\begingroup$ Interesting. Could you add some links for the 5% per Sv and perhaps if you know at what dose of (say >2MeV gamma) there are visible signs? I believe they are doing it with lower doses to avoid such symptoms over large periods of time. Unless there are obstacles which I don't know about. $\endgroup$
    – user
    Jul 14, 2021 at 7:23
  • 1
    $\begingroup$ See Table 2, imagewisely.org/Imaging-Modalities/Computed-Tomography/… And are you really under the impression that researchers have done the sort of controlled exposure which would allow the determination of thresholds for specific energies? Really? Do your own Google research. Use "Radiation Sickness" as a search criterion. $\endgroup$ Jul 15, 2021 at 0:33
  • $\begingroup$ They actually have. Radiotherapy usually includes radiation that penetrates the skin to reach the target area. There's a huge variety of energies and types of radiations so my guess is that it has been studied either in humans (in a therapeutic setting or accidents) or animals. $\endgroup$
    – user
    Jul 15, 2021 at 7:23
  • $\begingroup$ Btw my comment wasn't antagonistic. I liked your answer and upvoted. I simply needed some more details if you happened to have it at hand. If not, that's ok. I ll look it up. $\endgroup$
    – user
    Jul 15, 2021 at 7:25

Frame challenge

Such a weapon would be banned by international agreements, conventions, or law. Rather than prevent (or detect) attacks using this weapon, the defending state's goal would be to prevent the existence of the weapon.

Monitoring for the possible development and production of the weapon is a focused and targeted intelligence operation, which is feasible; if your intelligence reveals that your adversary is developing this weapon, then you strike before the weapon is ready, and you have a justification for doing so which is accepted by the international community.

On the other hand, defending or monitoring every possible opportunity for the weapon to be deployed against you is a monumental task simply because almost every situation is an opportunity for the weapon to be used, if such a weapon exists. This strategy would be less cost-effective - and less effective - than preventing the weapon from existing in the first place.

Compare with biological weapons such as manufactured viruses: if at any moment, your adversary could unleash a novel virus designed to kill as many of your citizens as quickly as possible, there is practically nothing you can do to react to such an attack. In the real world, biological weapons are banned.

  • $\begingroup$ This would indeed be useful in limiting such weapons' use to some extend. Unfortunately biological and nuclear weapon non-proliferation and no-research treaties are not signed by many big players. $\endgroup$
    – user
    Jul 14, 2021 at 10:58
  • $\begingroup$ @user Indeed, but even if the adversary isn't a signatory to some agreement, covert monitoring and proactive strikes to prevent them from developing such weapons would still be the best defense. Consider the US invasion of Iraq in 2003 - their justification was that Iraq (supposedly) had or was developing weapons of mass destruction, and the condemnation from the international community was largely about the fact that evidence showed otherwise, rather than that this wouldn't be a justification at all. $\endgroup$
    – kaya3
    Jul 14, 2021 at 11:45

Opening: "Are there any counter-measures that can prevent or reduce the dose (e.g. house walls material, clothing material, diet, etc)?"

Thin aluminium shielding will do

A working Röntgen laser would be deadly.. and very difficult to shield, but it is only a theoretical option, it would not be mobile because of its energy consumption. A free electron laser involves acceleration of electrons, reaching the subject as beta radiation.. I wonder how that will work out distance-wise, because electrons don't travel easy through atmosphere. At night it would not be usable for surprise attacks, there would be a visible glow.. and I found info suggesting a thin aluminium armour could shield off electrons completely.. https://www.nuclear-power.net/nuclear-engineering/radiation-detection/detectors-of-ionization-radiation/detection-of-beta-radiation-beta-particle-detector/

  • 1
    $\begingroup$ Aluminum would indeed stop beta, but FELs emit photons, not electrons. There are some electrons as a byproduct close to the device, but they do not reach the target, since as you correctly pointed out, they get absorbed by the air (lose energy). $\endgroup$
    – user
    Jul 14, 2021 at 7:13

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