title: A formalism for independent checking of Gamma Knife dose calculations.
abstract: For stereotactic radiosurgery using the Leksell Gamma Knife system, it is important to perform a pre-treatment verification of the maximum dose calculated with the Leksell GammaPlan (DLGP) stereotactic radiosurgery system. This verification can be incorporated as part of a routine quality assurance (QA) procedure to minimize the chance of a hazardous overdose. To implement this procedure, a formalism has been developed to calculate the dose DCAL(X,Y,Z,dav,t) using the following parameters: average target depth (dav), coordinates (X,Y,Z) of the maximum dose location or any other dose point(s) to be verified, 3-dimensional (3-dim) beam profiles or off-centerratios (OCR) of the four helmets, helmet size i, output factor Oi, plug factor Pi, each shot j coordinates (x,y,z)i,j, and shot treatment time (ti,j). The average depth of the target dav was obtained either from MRI/CT images or ruler measurements of the Gamma Knife Bubble Head Frame. DCAL and DLGP were then compared to evaluate the accuracy of this independent calculation. The proposed calculation for an independent check of DLGP has been demonstrated to be accurate and reliable, and thus serves as a QA tool for Gamma Knife stereotactic radiosurgery.
authors.affiliation: Department of Radiation Oncology, Boston Gamma Knife Center, Massachusetts 02111, USA. jtsai@lifespan.org
authors.forename: J S
authors.initials: JS
authors.lastname: Tsai
authors.forename: M J
authors.initials: MJ
authors.lastname: Engler
authors.forename: M J
authors.initials: MJ
authors.lastname: Rivard
authors.forename: A
authors.initials: A
authors.lastname: Mahajan
authors.forename: J A
authors.initials: JA
authors.lastname: Borden
authors.forename: Z
authors.initials: Z
authors.lastname: Zheng
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D001932:Brain Neoplasms / Q000601:surgery; D006801:Humans; D011785:Quality Assurance, Health Care; D016634:Radiosurgery / Q000295:instrumentation* / Q000592:standards / Q000706:statistics & numerical data; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods* / Q000706:statistics & numerical data; D013679:Technology, Radiologic