High-precision X-ray Imaging System
reduces time needed for complex neurosurgical treatment
High-precision X-ray Imaging System. A 40-year-old patient at the Clatterbridge Centre for Oncology in the UK received a single session of radiosurgery on a Clinac linear accelerator equipped with an On-Board Imager, a new device for enhancing precision using three-dimensional (3D) X-ray images. The system was used to track the exact location of the patient's solitary brain metastasis.The device enabled clinicians to pinpoint the location of the tumour using special conebeam computed tomography (CT) images and then complete the treatment in less than one hour. Usually, this type of treatment took up to four hours. "The time-consuming nature of this sort of treatment has meant that we would normally have had to carry it out in the evening on specialised machines, after our routine work has been completed," says Angela Heaton, research radiographer at Clatterbridge Centre. "It could take up to two hours to check calibrations before we could even begin treating, and the whole process could take several hours, which was inconvenient for both the patient and staff, and made it a relatively difficult treatment."Using the accelerator's 120-leaf multileaf collimator to shape a 1.5-mm beam, clinicians delivered a 15Gy stereotactic radiosurgery treatment from eight angles, carefully checking the patient's head position between each treatment field. The entire treatment took less than one hour, of which approximately 20 minutes were required for patient positioning on the couch using a head frame, two minutes for conebeam CT image acquisition, five minutes for online image matching and about 20 minutes for the actual treatment delivery. "At present we would expect to do between ten and twelve of such treatments a year," adds Dr Haylock. "These patients have previously been treated out of hours because of time constraints so this did not become routine. it is now important that we do everything we can to improve the efficiency as well as maintain treatment accuracy and improve patient comfort. That is why we want to move all our stereotactic procedures across to the Varian machine, which also has the versatility to handle routine radiotherapy treatments when it is not being used for neurosurgical cases." (Photo courtesy of Emory University)
Varian Medical Systems.