PC-based image processor speeds radiotherapy-treatment simulation
To effectively plan and verify radiation therapy, many hospital facilities use radiotherapy simulators to analyze images of patients, verify that the planned treatment can be performed as intended, and match the anatomical positioning to the treatment plan. During radiation, x-rays are passed through the patient and are then converted to a video signal by an image intensifier. These images are then displayed on a video monitor to verify and document the planned treatment.
In the past, video monitors provided a full-screen real-time display of the image from the image intensifier and provided contrast and brightness adjustments. Now, with the increasing computational power of Pentium-based PCs and add-in image processor boards, medical-imaging vendors are looking to replace existing monitors with workstations based on PC technology (Pentium/ Pentium-II, PCI, Windows NT) and to increase functionality.
At Precitron AB (Uppsala, Sweden), a PC-based system dubbed the Imcon/Orion workstation has been developed to replace the conventional fluoroscopic monitors found in radiation-therapy simulators. In operation, images from the x-ray image intensifier are digitized, processed, and displayed using the PCI-based Genesis vision processor from Matrox (Dorval, Quebec, Canada).
"Using the functionality of the Genesis, including on-board DSP," says Kjell Westerlund, president of Precitron AB, "allows the PC-based system to digitize and enhance the signal, make geometrical corrections, and display the resultant images from the x-ray intensifier at 25 frames/s."
Using the board`s nondestructive overlay mode, the physician can draw target-volume and beam-block contours on the image. These contours also can be projected onto the patient using a modified monochrome LCD panel from Sharp Electronics (Mahwah, NJ) and are controlled by the host PC over an RS-232 link. In this way, they can be marked on the patient`s skin together with other reference points for visual verification of treatment set-up at the radiation-therapy system.
In developing the image-processing algorithms for the Imcon/Orion, Westerlund and his colleagues used image-processing functions found in the high-level C-library for the Genesis board. To provide physicians with an easy-to-use graphical user interface, Westerlund employed Delphi software from Borland--now Inprise (Scotts Valley, CA)--a Windows application tool that is designed to develop, deploy, and manage distributed is applications.