Treatment Planning for Stereotactic Radiosurgery with Photon Beams

Abstract

www.tcrt.org .Stereotactic Radiosurgery (SRS) has evolved as a unique discipline that combines aspects of both surgery and radiation oncology. Technological developments in the past few decades have provided a wide array of treatment techniques, including (i) the Gamma KnifeTM; (ii) Linac-based stereotactic techniques using circular collimators or using micro multileaf collimators (mMLCs); (iii) the Cyber KnifeTM. using an x-band Iinac mounted on a robotic arm; and (iv) serial and spiral tomotherapy. This paper provides a review of the treatment planning methods for stereotactic radiosurgery. Because of the differences in planning strategies used for each SRS technique. this paper will provide both a general review of the pre-requisites and common features of SRS treatment planning and the planning techniques specific to each of the SRS techniques.

Review on modern techniques in diagnostic and planning radiology

“…The dose uniformity at the maximal depth in a water equivalent phantom must be at least 80% of the central nominal field area. 33 Contemporary TBI techniques use megavoltage photon beams produced by 60 Co sources or Linacs. The beams could be stationary with field sizes ~70-x200 cm 2 applied to the whole body of the patient, or translationally or rotationally moving to cover the whole body with smaller field sizes.…”

Radiosurgical techniques for the treatment of brain neoplasms: A short review

“…Both CT and MRI are often needed for planning the stereotactic treatment. Additionally, pre-treatment position imaging verification is strongly advised to avoid possible mistreatments during the course of stereotactic radiosurgery, although the stereotactic system itself is extremely accurate[13,17,19]. In the follow-up period, imaging is important to monitor the effects of the stereotactic treatment.…”

“…In these situations, imaging with multiparametric MRI techniques is very useful. In the initial identification of radiation-related changes, it enables assessment of metabolic and physiological characteristics of the tissue and possible tumor recurrence, and thus, may be useful for monitoring treatment changes in intracranial neoplasms[17-19].…”

“…The characteristics of both are: (1) application of a single high dose of radiation; (2) stereotactic localization of the lesion with CT imaging; (3) the use of computerized dose calculation, which can precisely define the amount of radiation that the central nervous system receives; (4) a steep dose-gradient, with the target receiving the highest dose and the dose steeply falling in the area surrounding it, so that these tissues receive a negligible or manageable dose; and (5) an accurate application of radiation, both spatially and in terms of dose. Technical development has allowed more accurate planning and irradiation of intracranial lesions[1,18,19].…”

American College of Radiology (ACR) and American Society for Radiation Oncology (ASTRO) Practice Guideline for the Performance of Stereotactic Radiosurgery (SRS)

“…In addition to the IGRT recommendations given in the Quality control of stereotactic accessories section, it is further recommended that the ACR-ASTRO Practice Guideline for IMRT 46 be followed when IMRT is used and when other techniques that use inverse planning are used. Furthermore, it is recognized that various testing methods may be used, with equal validity, to assure that a system feature or component is performing correctly.…”