Determination of a clinical value for the repair half-time (T1/2) of the trigeminal nerve based on outcome data from gamma knife radiosurgery for facial pain.
Stereotactic radiosurgery (GKRS) using the Leksell Gamma Knife is a treatment option for patients with trigeminal pain. We analyzed a database of 326 GKRS procedures performed over 4.6 years at three discrete dose levels commonly described in the published literature. Logistic regression was used to model the logit of response as a function of treatment time. The resulting coefficient was converted to an estimated probability of response for the shortest and longest treatment times in clinical practice. The two estimated probabilities were then compared to yield the estimated difference in the biologically effective dose (BED) between the two doses, using a modified linear-quadratic model for stereotactic radiosurgery. This difference was used to back-calculate a clinical value for T(1/2), resulting in a range of 1.28-1.77 h for T(1/2). The biological model appeared to accurately predict that, given the doses and treatment times used in general clinical practice, there would be no significant difference in clinical outcome.
Stieber
Volker
V
Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1030, USA. vstieber@wfubmc.edu
Robbins
Michael
M
Balamucki
Christopher
C
deGuzman
Allan
A
Tatter
Stephen
S
Ekstrand
Kenneth
K
McMullen
Kevin
K
Branch
Charles
C
Shaw
Edward
E
Bourland
J Daniel
JD
Lovato
James
J
Munley
Michael
M
Ellis
Thomas
T
D005157:Facial Pain / Q000601:surgery*; D006801:Humans; D016015:Logistic Models; D011829:Radiation Dosage; D016634:Radiosurgery; D014276:Trigeminal Nerve / Q000601:surgery*