Planmeca low-dose 3D images for precision dentistry
Planmeca has developed smart technologies that help decrease the amount of radiation required to produce medical images without compromising the diagnostic quality of the images. The algorithms developed for 3D imaging help produce more detailed images and diagnostics than ever before.When scientific studies regarding the subject were published around a decade ago, Planmeca began to develop its own dose measurement solutions that could help decrease ionising radiation doses in medical imaging.
Low-dose imaging is particularly significant for children, as a child’s body has comparably more radiation-sensitive red bone marrow than the body of an adult.
Juha Koivisto, Planmeca’s Chief Physicist, observed: “We noticed during our research that we could decrease the radiation dose without affecting the diagnostic quality of our images. When we compared our low-dose imaging solution to traditional methods, we discovered that the radiation dose could be reduced by 77%.
“Before the company could develop the new product, it first needed to create a real-time dosimeter which includes a patient model called a phantom, which has sensors that measure radiation doses. When a phantom is exposed to a radiation beam produced by a CBCT unit or another X-ray device, these sensors measure residual dose levels in tissues in order to derive effective doses.
“This allows us to gain an understanding of the organs the beam reaches and the makeup of the effective dose in the head region. Different organs have different weighting factors.
“For example, bone marrow, which is renewed at the fastest rate, has the largest weighting factor. If it is exposed to radiation, the effective dose is larger than a dose aimed at skin or the brain. The dosimeter was then used to review every imaging protocol used by Planmeca.”
Planmeca is developing its clinical 3D imaging applications for implant and orthodontic treatments, respiratory tract and sinus examinations, and maxillofacial surgeries. Thanks to Planmeca’s technology dentists and radiologists can now base the right imaging protocols and radiation doses on each patient’s specific diagnostic needs.
Koivisto continued: “If, for example, one wants to diagnose a patient’s frontal or maxillary sinuses, or plan orthodontic treatments, a smaller radiation dose is usually enough to obtain a sufficiently detailed image. Implant or root area treatments, however, require more enhanced and detailed 3D images, and the imaging of these smaller regions often requires larger radiation doses.
“In practice, the low dose imaging process has been made to be as quick and easy as possible – all you need to do is press a green button. The goal is to decrease cumulative radiation exposure in the populace. While the statistical risk of radiation is very small for an individual, this figure can still be significant at the wider population level.
“We want to decrease the cumulative risk radiation poses to the populace by decreasing the radiation doses of our devices to the lowest level possible, in fact we can now capture medical 3D images with a dose as low as 12 microsieverts – which is equivalent to four days of background radiation in Finland. Another example, on a transatlantic flight you would be exposed to around 80 microsieverts of radiation, nearly four times higher.”
Today, medical images are acquired using both 2D and 3D imaging devices. Among other things, 3D images can help reveal cases where the root of a patient’s tooth is tangled around a nerve canal. If not spotted, the nerve canal could be damaged during the removal of the tooth, which could potentially result in facial paralysis.
Antti Airisto, an Area Export Manager at Planmeca, takes up the thread: “When comparing 2D and 3D images one can clearly see the information that a 2D image cannot capture. For example, in the case of a patient who has been kicked in the head by a horse the 2D image shows how the crown of the tooth has been chipped and the maxillary sinuses are asymmetrical, which could indicate bleeding.
“Because the 3D image of the teeth can be rotated in different directions the physician can inspect the damaged area from different angles. We can then see that the root of the tooth has snapped and the upper jaw has been shattered. This was not visible in the 2D image.
“This provides much more information on whether the tooth can be saved and what other types of corrective measures are needed. The shattered jaw can be replaced with artificial bone and later we can proceed with intelligently guided dental implants for a more stable outcome.
“Dentists use 3D images to plan implant treatments to discover the amount of bone present to estimate the optimum size of implant. They can also see the condition of the bone, which determines whether grafts might be needed. The 3D image also helps locate the mandibular nerve, all of which is key information for planning any treatments.”
Planmeca’s algorithms function on three different levels: in the imaging unit itself, in 3D image rendering, and in the software.
Airisto continues: “A 3D image is constructed from a few hundred 2D images. When the imaging arm rotates around the patient, it generates pulsated x-ray beams, each pulse producing a single 2D image. These data are then fed into a computer where a Planmeca algorithm calculates and reconstructs their three-dimensional volume.
“We have also developed algorithms to correct the image generated during the imaging process which might include streaks and shadows caused by implants, root treatments, braces and all denser materials. We can fix all of these in the final image.”
Airisto adds: “The greatest algorithm-related breakthrough has been a correction tool for patient movement. Even the smallest movement can decrease image quality, but thanks to our technology we can remove these movement effects, which is particularly useful when imaging small children. However, studies have shown that over 40% of patients move during the imaging process, requiring the image to be retaken, now it can be corrected first time by smart technology.”
According to Maarit Vannas, Planmeca’s Vice President of Marketing and Communication, algorithm development has been key in the company's success. She explains that such algorithms are extremely difficult to copy, as they result from long experience and in-depth expertise in machine intelligence, machine intelligence which will be further developed for ever more sophisticated applications.
Airisto concludes: “Planmeca has extensively developed its hardware and the Romexis software platform to simplify the production of precision 3D images for an increasing catalogue of treatments − from implant planning to maxillofacial surgery. Our software developers are constantly thinking of new ways to get everything we can from 3D images.
“Our mechanical and electronics design processes are key to ensuring that everything works together to provide the most versatile imaging geometry possible. Our latest technology has been developed from previous models, meaning we can update older 2D systems to 3D. We can also add new features to our older existing models with software upgrades.
“In many regional markets, the market share of 3D imaging devices is still relatively small. While the fastest increase in the use of 3D imaging is in China, largely due to the fact that the country skipped the digital 2D imaging phase altogether, France has begun to subsidise the adoption of 3D imaging, digitalisation and renewal of older devices.
“In the United States, a great number of clinics still rely on 2D devices, which should make the market very interesting in the near future.”
For more information, visit https://www.planmeca.com/imaging/3d-imaging/key-benefits/
A version of this article was originally published in Finnish by Bonnier Business Forum Oy.