Wednesday, June 13, 2007 X Limit By Zosimo T. Literatus, R.M.T. Breakthroughs
“THEREis no royal road to diagnosis,” wrote late American surgeon Robert Tuttle Morris in his book Doctors Versus Folks.
But dangerous road to diagnosis? Maybe.
In industrialized countries, diagnostic x-ray exams have been reported at 200 to 2,000 per thousand inhabitants yearly. In some patients, accumulated doses of low-level radiation can cause adverse health effects, such as leukemia and other cancers. Government guidelines pegged the annual radiation limits at 20 millisieverts (mSv/y). Many standard procedures assumed a net benefit because radiation exposure per procedure is relatively low. However, if an average person accumulates too much radiation through these procedures, not every case would have a net benefit. But instead a net detriment.
In a recent study, J. Douglas Hall, Marshall Godwin, and Tessa Clarke assessed 250 charts randomly chosen from six practices at the Queen’s University Family Medical Center (200 charts) and from a community physician’s practice in Kingston, Ontario (50 charts). Eligible charts had at least 20 years of medical history and of patients 45 to 65 years old. Hall is a second-year med student at Queen’s University in Kingston (Ontario, Canada). Godwin was director of the Centre for Studies in Primary Care also at Queen’s. And Clarke is a family physician in Kingston.
Results published in the Canadian Family Physician (August 2006) show an average lifetime radiation exposure at 14.94 mSv. No patient has exceeded the proposed lifetime exposure limit (400 mSv). However 4.4 percent of the patients have exceeded the annual exposure limit of 20 mSv at some point during their lives.
“Our methods probably underestimated the actual radiation exposure,” Hall observed. Dental x-ray exams were excluded; charts often had not the entire history; some imaging procedures were omitted from consultant reports, or the results might not have been sent to family physicians’ offices. Older x-ray machines, too, deliver more radiation.
What’s interesting: The annual diagnostic radiation exposure of the patients steadily increased over the past 45 years by 50 percent (three percent yearly).
Diagnosis supposedly makes cure easier. But the above trend suggests that diagnosis may be more dangerous in the future.
And there’s one fact that even doctors know. “The fact that your patient gets well,” observed late US physician-physiologist Samuel J. Meltzer, “does not prove that your diagnosis was correct.” (For comments and suggestions, please text to 0927-979-3519 or email to zim_breakthroughs@yahoo.com.)
