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ePaper created 2014-10-07, 09:31:41 | version 1.30.01
I 41 industry news _ Planmeca I cone beam3_2014 Conversely, bony structures do not show up well in MRI images, and small bones can be easily con- fused with scar tissue. “In a CBCT image, even small changes in the bone are plainly visible”, describes Mikkonen. _Thin slices, low radiation doses and a natural head position One of the many benefits of CBCT imaging is the low radiation dose compared to a traditional CT scan. Moreover, the method produces very thin slices, down to 0.16 mm. In hospitals, trauma CT scans are usually performed with a slice thickness of 2 mm, and MRI scans are sometimes performed with a slice thickness of up to 5 mm. “The thinner the slice, the more reliable it is when you are studying small things”, says Villanen. “Thin slices have better resolution and afford better meas- urements.A2mmslicedoesreveallargefractures,but small avulsion fractures might remain undetected.” Furthermore,aCBCTscancanbepost-processed to include all required slice thicknesses. “They can also be acquired in a high resolution CT scan, but that would produce an even higher radiation dose”, describes Mikkonen. Also, the patient position is better in a CBCT scan thaninaCTscan.ACTscanisacquiredwiththepatient lyingdown,whereasinaCBCTscan,thepatientissit- ting up, allowing a more natural head position. “In a lying position, the load of the head is not completely natural. All in all, radiologists should make more use of functional imaging, so that patients could be im- aged in their normal working positions, for example.” _Fast imaging increases patient comfort From the patient’s perspective, a CBCT scan is quitepleasant—inadditiontothelowradiationdose, the procedure is quick. A regular MRI scan takes about 20 to 30 minutes, and a functional MRI scan up to two hours, but a CBCT scan is complete in less than a minute. “Many patients have been surprised at the bre- vityofthescan”,saysMika Mattila, Specialist in oral and maxillofacial radiol- ogy, who is in charge of imaging the neck patients referredtoPantomoOyby Villanen. “Planmeca’s de- vice has a handy cervical spine program that sets the device automatically to the right position. The only difference in patient positioning, compared to dental patients, is that the head of neck patients must be turned with ex- treme caution.” Theopenpatientpositioningalsopleasespatients with claustrophobia. “Some patients may be very relieved by not having to go into a tube for a scan.” _CBCT images of trauma patients Some of Villanen’s CBCT patients have sustained a neck or head injury in an accident: a car accident, horse riding accident, a fall, or by a heavy object falling on their head at a construction site. The patients range from 17 to 80 years of age, and the majority of them are women. “Research shows that, all other things being equal, women are more prone to injuries in a car crash than men. The head position is crucial in a crash, and women often make the mistake of first Figs. 3a–c_Planmeca ProMax 3D Fig. 3cFig. 3b Fig. 3a CBE0314_40-42_Planmeca 30.09.14 14:18 Seite 2