Cancer risks from diagnostic radiology

Abstract

In recent years, there has been a rapid increase in the number of CT scans performed, both in the US and the UK, which has fuelled concern about the long-term consequences of these exposures, particularly in terms of cancer induction. Statistics from the US and the UK indicate a 20-fold and 12-fold increase, respectively, in CT usage over the past two decades, with per caput CT usage in the US being about five times that in the UK. In both countries, most of the collective dose from diagnostic radiology comes from high-dose (in the radiological context) procedures such as CT, interventional radiology and barium enemas; for these procedures, the relevant organ doses are in the range for which there is now direct credible epidemiological evidence of an excess risk of cancer, without the need to extrapolate risks from higher doses. Even for high-dose radiological procedures, the risk to the individual patient is small, so that the benefit/risk balance is generally in the patients' favour. Concerns arise when CT examinations are used without a proven clinical rationale, when alternative modalities could be used with equal efficacy, or when CT scans are repeated unnecessarily. It has been estimated, at least in the US, that these scenarios account for up to one-third of all CT scans. A further issue is the increasing use of CT scans as a screening procedure in asymptomatic patients; at this time, the benefit/risk balance for any of the commonly suggested CT screening techniques has yet to be established.

A Radiation Safety Training Program Results in Reduced Radiation Exposure for Orthopaedic Residents Using the Mini C-arm

“…Mastrangelo et al [12] suggested that orthopaedic surgeons in a hospital with poor radiation protection had a substantially greater incidence of cancer. The concern regarding the effects of radiation exposure has led to the use of ALARA (as low as reasonably achievable) techniques with healthcare workers [7]. According to the National Council on Radiation Protection and Standards, the recommended maximum annual dose of radiation to the whole body is 5000 mR and 50,000 mR to the extremities [20].…”

Accuracy of physician-estimated probability of brain injury in children with minor head trauma

“…12,13 Variability could also be explained by factors beyond the probability of injury that affect the balance of risks and benefits for a specific patient. For example, recent studies have highlighted the increased risk of harm for younger patients from ionizing radiation used in CT. 14,15 We did not find effect modification by age on the relationship between estimated probability and decisions, but physicians did underestimate the risk of pathology in children less than 1 year. This underestimation of risk likely reflects the difficulty inherent in assessing infants.…”

ALARA, Image Gently and CT-induced cancer

“…Although many radiology publications indicate that cancer risks from CT scans are extremely small, this is unfortunately not always the case [4,11,23,32,[35][36][37][38][39][40][41][42].…”

“…There is, however, growing evidence that earlier assumptions that CT scanning causes cancer, lack final absolute proof [16][17][18][19][20]63]. Almost all evidence is based on regression models from data from exposure to extremely high radiation dose from the Hiroshima atomic bomb [25,32,35,38,57]. These models assume and claim that there is no threshold for radiation toxicity and that even the tiniest radiation dose from a CT scan has some toxicity.…”