A history of frequent dental X-rays, particularly at a young age, is tied to an increased risk of developing meningioma, the most common type of primary brain tumour in the United States, according to a new study that’s the largest of its kind.
“This research suggests that although dental X-rays are an important tool in maintaining good oral health, efforts to moderate exposure to this form of imaging may be of benefit to some patients,” wrote Dr. Elizabeth Claus, a neurosurgeon at Brigham and Women’s Hospital (BWH) in Boston and the School of Medicine at Yale University in New Haven.
Claus and her colleagues detail their findings in a paper published April 10 in the journal Cancer.
Meningiomas arise in the meninges, or the lining of the brain, and account for about 33 per cent of all primary brain tumours in the United States. Primary refers to the part of the body where the cancer starts.
The most consistently identified environmental risk factor for this type of cancer is exposure to ionizing radiation. For Americans, the most common way to encounter this exposure is by having dental X-rays.
Claus and her colleagues are careful to point out that their conclusions do not refer to modern X-rays.
“It is important to note that the dental X-rays performed today use a much lower dose of radiation than in the past,” Claus said.
For their study, researchers examined records of 1,433 patients who were between 20 and 79 when they received a diagnosis of meningioma during the period May 2006 and April 2011. They compared their data to a group of 1,350 matched controls.
The results showed that the risk of developing meningioma was nearly three times greater among participants who reported having a panorex dental X-ray once a year or more. Having the test while under the age of 10 increased the risk by 4.9 times, compared to controls. A panorex exam shows the upper and lower jaws, as well as teeth, on the same film.
The results also showed an increased risk was associated with a type of dental X-ray known as a bitewing exam, which shows the crowns of the lower and upper teeth at the same time.
Those participants who reported having such an exam annually or more frequently were 1.4 to 1.9 times more likely to develop a meningioma than were people in the control group.
Engineers at Stanford University have demonstrated how a tiny, wireless, externally controlled medical device is able to propel itself through blood.
Head researcher Ada Poon said such devices could “revolutionize medical technology” and offer applications from diagnostics to minimally invasive surgery. Poon’s lab is developing devices that can travel through the bloodstream. Once perfected, these devices will be able to perform tasks such as drug delivery, analysis of target sites, and possibly breaking up blood clots or zapping away plaque in sclerotic arteries.
Earlier this year, at the International Solid-State Circuits Conference (ISSCC) in San Francisco, Poon presented a study that suggests the day when people are invited to “swallow the surgeon” as part of a diagnostic test may be closer than imagined.
“There is considerable room for improvement and much work remains before these devices are ready for medical applications. But for the first time in decades the possibility seems closer than ever,” she said in a March communication from Stanford.
While small implantable medical devices have been around for a while, most are limited by power constraints. Their batteries are large and heavy, taking up nearly half the device’s size, and have to be replaced from time to time.
Poon’s lab is developing a new type of device that can be implanted or injected into the body and powered wirelessly via electromagnetic radio waves transmitted remotely from outside the body. Requiring no battery or cables means it can be small and unencumbered.
