Demonstration of the Cone Beam CT (CBCT) prototype on the linear accelerator B5 in the Netherlands Cancer Institute (NKI). (click on the image for the movie, no sound track)
Design of the Cone Beam CT . In 2002 physicist David Jaffrey (Princess Margaret Hospital, Toronto, Canada) publishes the concept of a Cone Beam computed tomography (CBCT) scanner with a kV photon beam that will be integrated into the linear accelerator. With this device the anatomy and the target volume in the patient can be visualized in 3D during the irradiation sessions. The accuracy of the alignment of the target volume to the trajectory of the radiation beam is checked immediately preceding the megavolt irradiation. This results in a more precise delivery of radiation to the targeted tissues, which will make it possible to decrease safety margins, reduce doses to normal tissue and decrease the risk of toxicity; it may allow a safe increase in the radiation dose to improve local tumour control and survival. This is a breakthrough in quality control and removes obstacles for the development of more complex irradiation techniques.
David Jaffray invites Marcel van Herk to cooperate in the development of his idea for the Cone Beam CT. Marcel is the appropriate partner for this with his long experience in the development of imaging software for the EPID and his strong software development group. During an animated meeting they drink to the successful outcome.
Celebrating the CBCT plans. From left to right: Jan-Jakob Sonke (NKI), Monique Smitsmans (NKI), Marcel van Herk (NKI), Leah McDermott (NKI), Jochem Wolthuis (NKI), David Jaffray (Princess Margaret Hospital, Toronto), Lambert Zijp (NKI).
Elekta, manufacturer of equipment for radiotherapy, becomes the industrial partner to realize this idea. Around Elekta a consortium of cancer centres is formed that will participate in the development and the testing of CBCT imaging. Partners in the consortium are, amongst others, the Christie Hospital and Holt Radium Institute in Manchester, Harvard Medical Centre in Boston and the Netherlands Cancer Institute (NKI) in Amsterdam. Marcel van Herk (NKI) with his unique EPID experience and strong computer programming group develops software for image processing and analyses of the CBCT-scans.
The participating institutes are also consulted by Elekta about practical details of the technical design. In 2001 representatives from the NKI visit the Elekta factory in England. The question is how the second image detector and the X-ray tube can be mounted on the accelerator in combination with the existing EPID detector, while maintaining the set-up possibilities around the patient.
The NKI delegation in the showroom of Elekta in Crawley, England. From left to right, standing: Marcel van Herk (NKI), Jan Nanninga (Elekta NL), Joos Lebesque (research board RT dept. NKI), Herman Vijlbrief (team leader radiation therapists NKI), Gerry van Oortmarssen (vice president Elekta Europe). From left to right, seated: Henk van der Gugten (technical specialist RT dept. NKI), Kevin Brown (head research Elekta).
In 2002 a 20 MeV linear accelerator is installed by Elekta in the new treatment room B5. This accelerator type is called Synergy and it is equipped with an EPID and a prototype CBCT system. Both imagers are fitted with an amorphous Silicon detection panel.