What is the Radiation Dose on the radiology report?
Irish legislation (SI 256 of 2018) requires that “information relating to patient exposure forms part of the report of the medical radiological procedure.” This legislation is linked below.
What is ionising radiation?
Ionising radiation is a type of radiation with sufficient energy to remove a bound electron from an atom, thus creating an ion. X-ray ionising radiation comes from many natural sources, including radon from the ground, small amounts in food, and cosmic radiation. For further information on naturally occurring ionising radiation please see https://www.epa.ie/environment-and-you/radiation/radiation-exposure-and-your-health/your-radiation-exposure/
In Ireland medical exposures (imaging and treatment) are responsible for 10.4% of our average radiation exposure. Of this radiation treatment is the highest contributor, hundreds of times greater than most medical imaging. The remaining 89.6% comes from the natural sources described above.
What is Radiation Dose?
There are many ways in which radiation dose can be described. The figure given in your report is a measure of the amount of radiation emitted from the x-ray machine. For X-ray imaging, this is given as a DAP (Dose Area Product) reading i.e., the product of the output dose from the X-ray system and area of the radiation beam. An example of the dose in the report for X-ray, fluoroscopy case, and CT studies and and what the letters mean is presented below.
Is this amount of radiation harmful?
Prior to performing a study which involves exposing a patient to ionising radiation, the practitioner will have viewed the referral and judged that the benefits from performing the examination outweigh any small risk involved.
The amount of radiation used depends on the type of examination. More radiation is needed to create useful images to answer certain questions for some areas of the body. However, the amounts of radiation used in medical imaging are many thousand times too low to produce immediate harmful effects.
There is however a very slight increase in the chance of developing cancer many years, or even decades after the exposure. This risk represents a very small addition to the 1 in 3 chance we all have of getting cancer. The table below gives the approximate increase in risk from average radiation doses used in medical imaging. This table quotes Effective Dose, which is a calculation which includes the sensitivity of the body part exposed to the radiation. This is not the same as the figures on the report.
Is the Radiation Dose on the Radiology report always correct?
The process of inserting the Radiation Dose on the report involves transferring information between several software programs. This process is correct in >98% of studies.
There are times when the dose will not be correct. These are listed below:
- When we have performed 2 studies together – normally performed to reduce the overall radiation or medications administered to the patient.
- In this case the total radiation dose from all the reports will correctly represent the dose from all the studies. Some reports may show 0 dose while another shows the total dose.
- When we have performed corrective demographic changes in our image storage system (PACS).
- When this results in a small difference between the radiation dose received and that shown on the report, we will not issue a corrected report.
- When the radiation dose received and that on the report are significantly different, we may issue a new report. This will not affect the result (Radiologist reading of your Images) of your study.
- When the systems responsible for transferring information on dose are offline resulting in no dose showing in your report. These doses are always recorded in the radiology department and can be obtained, if required, by contacting [email protected].
If you have concerns about the Radiation Dose on your report, please email [email protected].