Stereotactic noninvasive volume measurement compared with geometric measurement for indications and evaluation of gamma knife treatment.

Object: Volume estimation is one of the most important criteria in the evaluation and follow up of radiosurgical treatments and outcomes; however, several limitations are involved in the calculation estimation of target volumes.
Methods: Retrospective and prospective studies were conducted to evaluate the efficacy of a new noninvasive stereotactic method when it is compared with geometric volume calculation of intracranial tumors for planning stereotactic radiosurgery treatment as well as for follow up and outcome evaluation. Two equations were created that permit comparison of the calculated and measured volumes. These equations took linear and quadratic forms, respectively. Volume estimation using the stereotactic approach compared with traditional volume calculation gave more accurate results regardless of the shape and size of the lesion.
Conclusions: The use of stereotactic volume calculation is highly recommended in planning, follow up, and determination of the outcome in patients participating in radiosurgical treatment and should lead to more uniform reports of the response to treatment.