Radioactive materials that are inhaled or ingested can be measured by looking for content in urine or by direct measurement on the whole body. However, at this point in time it would be very unlikely that anything would be found. Radioactive iodine is one of the more common radioactive materials that could have been detected from the Fukushima incident, but by now it would have decayed away. Other materials which may stay radioactive for longer periods also leave the body with time.
Radiation exposures from an external source (i.e. not inhaled or ingested) cannot be measured after the fact, but only during the exposure if one is wearing a radiation monitoring device. There are certain blood tests that can indicate if someone was exposed to very high levels of radiation, however it is extremely unlikely that you would have been exposed to such high levels.
Health Canada can perform some of these tests if an individual is referred by their physician, although the whole body measurements to check for inhaled or ingested material are only performed in Ottawa. There are other commercial facilities in Canada that can also provide these tests for a fee. If you wish, we can provide you with a list of some that may be close to you, depending on your location in Canada.
In regards to the flights being scanned, that may depend on where you were at the time and where your flight left from. There was some discussion in Canada about whether routine flights coming back to the county from Japan should be scanned, however after reviewing the available information it was determined that this was not necessary. If you have more specific information on your flight and other flights that may have been scanned for radiation exposure we may be able to provide a more detailed response to this part.
If you are interested in some numbers on the radiation levels in Japan from the Fukushima incident, there is some data in a report recently released by the World Health Organization entitled, “Preliminary Dose Estimation from the nuclear accident after the 2011 Great East Japan Earthquake and Tsunami.” This is a rather long report and is sometimes technical, but it does contain some useful numbers. Specifically, section 3.3 of the report, entitled, “Geographical Distribution of Doses” (page 41) summarizes the doses that one would receive over an entire year in various areas in and around the Fukushima prefecture and the rest of Japan. These values are also summarized in a table on page 44 of the report. Keep in mind that these doses would have been accrued over an entire year, so depending on how long you were in Japan only a fraction of those values may apply in your case.
The figure on page 52 of the report goes on to provide some practical comparisons between the radiation levels calculated in the report and typical doses from background radiation, medical exams, etc. A copy of this report can be found at the following link.
Overall, if you were not near Fukushima at the time of the incident, you would not have been exposed to any significant level of radiation.
I hope we have been able to address your concerns. If you have any other questions, please feel free to contact us again and we will be happy to respond.