The recent articles published in the Archives of Internal Medicine (Arch Intern Med. 2009;169[22]:2078-2086, 2071-2077), and several previous recent articles in the New England Journal of Medicine (N Engl J Med. 2007 Nov 29;357(22):2277-84; N Engl J Med. 2009 Aug 27;361(9):849-57) have led to a slew of new headline stories in the international media, and have further brought the issue of radiation risk from Radiology and related examinations and procedures into the spotlight. Like it or not, this issue is here to stay, and as radiologists are the physicians with the greatest knowledge of radiation safety issues, we must explore its consequences in a very detailed and in-depth manner.

While it is well-accepted that radiation is not innocuous, and may lead to the development of cancer, it is quite difficult to estimate the size of this risk. There are a number of different models used to do this. Arguably the best, or most complete, is that used by the Biological Effects of Ionizing Radiation (BEIR) committee of the U.S. National Academy of Sciences (NAS). The BEIR Committee follows the ‘linear, non-threshold’ model when determining cancer risk from radiation exposure. This means that all radiation, no matter how small, has some risk and second, if a certain amount of radiation is associated with a given risk, then half that radiation is associated with approximately half the risk. The risks are also assumed to be ‘additive’ – the more radiation you are exposed to, the greater your risk.

The risk estimates for many common procedures and examinations may be higher than what many people realize. For example, the estimated risk of developing fatal cancer specifically due to the radiation a young woman is exposed to during a single CT scan of the abdomen is estimated to be somewhere in the neighborhood of 1/800 to 1/2000, depending on the settings of the CT Scanner. Older patients, overall, have a decreased risk for a given new exposure.

A recent highly cited paper by Dr. Brenner and Dr. Hall published in the New England Journal of Medicine suggested that up to 1.5 to 2% of all cancers in the US may become attributable to radiation from CT scans if current usage rates continue.

Radiation Passport for the iPhone and iPod Touch
Mark Otto Baerlocher has teamed up with his brother, who started Tidal Pool Software to create a program – Radiation Passport - for the iPhone and iPod Touch that is meant to be useful for physicians and other healthcare professionals, as well as patients.

Radiation Passport allows physicians and other healthcare professionals to enter the age and gender of their patient, and the specific examination (modality and body part), and receive an estimate of the average associated radiation dose, and associated risk of developing cancer (total, and fatal cancers separately). The idea is that this information may then be used in part to help the physician know the estimated risk and thereby better judge the risk-benefit profile of ordering the examination, as well as helping to answer any patient’s questions about the radiation risk (particularly important, given the increasing frequency with which this topic is now in the international news).

Radiation Passport also lets patients ‘track’ their radiation exposure from medical examinations and procedures. Users enter the type of examination they had, when they had it, and Radiation Passport will record the examination and date, and assign the estimated radiation exposure associated with their specific examination. The radiation exposure is then summed for all examinations and procedures entered, and an estimate of the cancer risk due to the radiation exposure is calculated. Patients can also write notes (for example, reminders that they need to follow-up on their Radiology examination, or have a repeat examination in e.g. 12 months), and figure out the estimated risk of developing cancer for a single Radiology or related examination or procedure they are prescribed to undergo by their physician or dentist.

The overall goal of Radiation Passport is to increase awareness and education among patients about the potential risks of medical radiation. Radiology and radiology-related examinations and procedures have been responsible for tremendous and very rapid advances in the diagnosis and treatment of diseases. When these examinations and procedures are considered necessary, it is assumed that the potential benefit of the examination or treatment outweighs the potential risk. This program aims to serve as a reminder to be aware that there are assumed risks.