Radiation Passport: Radiation Exposure iPhone App

April 17, 2009 · Written by MDPhysics.com · mdphysicsblog@gmail.com

iphoneTidal Pool, a Canadian software company, has developed and released a radiation exposure app for the Apple iPhone and iPod Touch. The app is being sold online for $2.99 at the Apple App Store. Before you get all excited like I did, you should know that the app was not developed for medical physicists (or physicians), but rather for the everyday individual interested in keeping track of and calculating their cancer risk due to exposure to ionizing radiation (e.g. medical-related imaging) as well as background radiation due to lifestyle and location. In fact, the purpose of the app as stated by the developer is: “…to educate about the radiation and cancer risks associated with medical imaging exams and procedures that physicians want you to undergo.

That said, it would be interesting to know how the app calculates actual radiation exposure to the patient for each imaging test as well as the associated cancer risks. For example, just how much does one’s chance of getting cancer go up by getting a CAT scan? Is this app going to deter patients from getting imaging tests for fear of getting cancer?

While this app raises a lot of questions for me, as a medical physicist, it also highlights the absence of any real iPhone apps out there for the medical physics community.

That said, If a decent app comes out that would be of use in medical physics, I might be inclined to go out and buy an iPhone. Until then, though, I’ll stick with my Blackberry, thank you very much.

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6 Responses to “Radiation Passport: Radiation Exposure iPhone App”

  1. RS on April 18th, 2009 12:02 pm

    I have a blackberry as well, so I don’t know about this software and iPhone apps that much. However, I am very interested to find out what kind of data and algorithms have been used in this application and am interested to find out how accurate the results are. Before I use this application or recommend it to one of my family members to use, I think I would like to see independent research–a paper, for example, in a journal that evaluates the validity of the algorithms and data. I’m interested to hear other medical or health physicists’ comments on this issue.

  2. Mark on May 1st, 2009 7:37 am

    I can provide some insight I think into your questions.

    The program is only available for the iPhone and iPod Touch as of now – we’re looking into how difficult it would be to create it for the Blackberry.

    The program itself is intended for both patients and physicians. Patients may enter their radiological exams, including the date at which they had them, and be presented with an estimate of the associated cancer risk both for that individual exam, as well as their sum total.

    Physicians may use it to look up the estimated cancer risk associated with an individual exam – we have a paper under review that shows there is a lack of knowledge regarding radiation risk (part of the motivation for this program).

    In terms of the model used to estimate risk, we grappled with which model to use early on. There are many potential methods by which to estimate associated risk, each of course with its own disadvantages.

    The model we chose to use in the end was that used by the BEIR committee – i.e. the LNT (linear non-threshold) model. If the dose response is not is fact linear at low doses (e.g. x-ray), then the risk estimates of course could be much different. However, I think the BEIR VII is arguably the most thorough investigation and review of the available evidence.

    We also assumed that the risks are cumulative/additive – BEIR also assumes this risk (though granted, there have been papers both in support and in contradiction to this assumption).

    The risk estimates per effective dose are provided within the BEIR VII report (which I think is available online through ?Googlebooks maybe).

    The estimates also reflect the age at which a patient has received their exam – a 40-year-old man who had received a CT when they were 20 years old has a different associated risk than a 40-year-old man who had the same CT when they were 25.

    In terms of the doses assigned to each type of exam – there is clearly a range depending on the machine used, the settings, the patient size, etc. There are several ‘catalogs’ published in the literature (Mettler’s catalog of radiation doses is probably the best; however, there are a few others). For the exams left, I did OVID Medline searches for each individual exam.

    We also left an option for patients/physicians/others to simply ‘write in’ a custom value, if they knew it. In the future, I wouldn’t be surprised if radiation doses are given out to patients following their exam (particularly for CT and nuc’s). (I also wouldn’t be surprised if a formal consent will eventually be required).

    There are some effects, for example, hormesis, that are not included in the risk estimates. This is still controversial – and as the BEIR VII chose not to include it following their review of the relevant literature, we did the same.

    Finally, an estimate is only as good as the model used – and nearly any model, by definition of being a model, has flaws. The primary purpose of this program is to help increase medical radiation risk awareness.

    If anyone tries it, and has any comments/suggestions/etc, please let us know. I included my email above, but it’s:


    We hope to update the program with requested changes, additional exams (e.g. low-dose CT screening), etc.


  3. Mark on May 1st, 2009 7:48 am

    One further note – one of the questions posed above was:

    “For example, just how much does one’s chance of getting cancer go up by getting a CAT scan? Is this app going to deter patients from getting imaging tests for fear of getting cancer?”

    Brenner and Hall’s Nov/2007 NEJM paper suggested that up to 1/3 of CT’s may not be medically indicated in the US, including up to 1 million pediatric CT’s (again, in the US alone).

    Some patients already ‘decline’ a e.g. CT in some cases due to radiation risk. I would bet that this is going to be a more frequent occurrence, as more become aware that there are likely, in fact, some risks associated with imaging exams and procedures.

    I’m sure some people would rather that this sort of radiation risk information not be spread among the public – but I think most would hopefully agree that if there are risks or thought to be risks associated with a medical exam/procedure, it’s our duty to give full disclosure and tell patients about the risks.

  4. Jane on June 12th, 2009 1:21 pm

    Interesting – and thanks for the returned comments. I have both an iPhone and an iPod Touch (dont’ ask me why I have both). I’ve had cat scans in the past as well, so I’m curious what the estimated risks are.

  5. Bioactive on August 1st, 2009 2:55 pm

    I have a blackberry and an iphone (the former is free from my work; the latter is what I bought). I have the program on my iphone and use it now every couple of days when asked by a patient about the risks for less than common exams (I memorized the estimated risks for the most common obviously – CT abdomen, CT head, CT chest, chest x-ray). It’s actually quite useful.

    I think you would do well if you wrote the program for blackberries as well (if you haven’t since the postings above). We’re given blackberries for work, not iphones (unfortunately…)

  6. Mark Baerlocher on August 3rd, 2009 5:24 pm

    Out of interest – a news article just came out in the Canadian Medical Association Journal about this:


    Thanks to the suggestion about rewriting it for Blackberry.

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