Chin Med J (Taipei) 1998;61:S61.

Comparison of 3D Conformal Radiation Therapy Techniques used for Treatment of Intracranial Lesions : Stereotactic Radiosurgery, Imaging-Guided Robotic Radiosurgery and Intensity Modulated Radiation Therapy

Ping S. Wong, Ph.D., Chung Y. Lin, M.S.

Department of Radiation Oncology, Southwest Cancer Center, Texas Tech University Medical Center, Lubbock, Texas

Abstract

Conformal Radiation Therapy (CRT) techniques make use of the entire three dimensional aspect of the anatomy in the treatment planning process, and the employment of more complex beam geometries, beam-shaping and beam-modulating techniques that reduce the dose to normal tissues. The improved technology has the potential to deliver a 10 to 20 % higher dose to the tumor target with no increase in radiation-induced complications.

Conventional frame-based stereotactic radiosurgery (SRS) technique is compared with two newly developed CRT methods, (a) Imaged-Guided Robotic Radiosurgery and (b) Intensity Modulated Radiation Therapy, for the treatment of intracranial lesions:

(a) Imaged-guided (frameless) Robotic Radiosurgery : The system¹ has a compact 9.3 GHz x-band linear accelerator (285 Ibs) which is maneuvered by a 6 degree-of-fteedom robotic arm. The unit is also equipped with a frameless imaging system to provide a realtime, non-collinear x-ray image of patient to verify the accuracy of the treatment position, and it provides information suitable for dynamically positioning and pointing the linear accelerator.

(b) Intensity Modulated Radiation Therapy : The system² capable of moving each of the 40 (1 x 1 cm²) leaves in and out of the beam during the gantry rotation. It consists of two main components, an inverse treatment planning system and a multileaf intensity modulating collimator that allow conventional 3.1 Ghz linear accelerator to deliver intensity modulated plans.

The physical and clinical aspects of these systems will be discussed. A comparison of these two techniques to that of the conventional stereotactic radiosurgery will also be addressed.

1. Neurotron-1000, ACCURAY, Inc. Sunnyvales, California
2. Peacock, NOMOS Corp. Sewickley, Pennsylvania

[Chin Med J (Taipei) 1998;61:S61.]