title: Killing two birds with one stone: a dosimetric study of dual target radiosurgery using a single isocenter.
abstract: The treatment of hematogenous brain metastases is a frequent indication for stereotactic radiosurgery (SRS). It is common for more than one metastasis to be treated during the same SRS session. We retrospectively identified four cases where our m3 micro multileaf collimator (mMLC) was used to create two distinct apertures and treat adjacent lesions using a single isocenter. For these four cases, single isocenter plans with static conformal beams were dosimetrically compared to plans utilizing two isocenters with static conformal beams or conformal arcs. The effects on dose homogeneity, dose conformity, and the minimum isodose separating the two targets are minor and variable. On the other hand, the use of a single isocenter technique consistently halves delivery time and decreases the integral dose to normal tissue. For small adjacent metastases, which can simultaneously be encompassed within the high-resolution portion of the m3/Novalis mMLC collimator, the use of a single rather than a dual isocenter technique is feasible and generally advantageous.
authors.affiliation: Department of Oncology, Division of Radiation Oncology, McGill University, Montreal, Quebec, H3G 1A4, Canada. david.roberge@muhc.mcgill.ca
authors.forename: David
authors.initials: D
authors.lastname: Roberge
authors.forename: Russell
authors.initials: R
authors.lastname: Ruo
authors.forename: Luis
authors.initials: L
authors.lastname: Souhami
mesh_terms: D001932:Brain Neoplasms / Q000556:secondary / Q000601:surgery*; D001943:Breast Neoplasms / Q000473:pathology / Q000601:surgery*; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000601:surgery*; D011829:Radiation Dosage; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies