Object. The use of radiosurgery in the treatment of acoustic neuromas has increased substantially during the last decade. Most published experience relates to the use of the gamma knife. In this report, the authors review the methods and results of linear accelerator (LINAC) radiosurgery in 44 patients with acoustic neuromas who were treated between 1993 and 1997.Methods. Computerized tomography scanning was selected as the stereotactic imaging modality for target definition. A single, conformally shaped isocenter was used in the treatment of 40 patients; two or three isocenters were used in four patients who harbored very irregular tumors. The radiation dose directed to the tumor border was the only parameter that changed during the study period in the first 24 patients who were treated the dose was 15 to 20 Gy, whereas in the last 20 patients the dose was reduced to 11 to 14 Gy. After a mean follow-up period of 32 months (range 12-60 months), 98% of the tumors were controlled. The actuarial hearing preservation rate was 71%. New transient facial neuropathy developed in 24% of the patients and persisted to a mild degree in 8%. Radiation dose correlated significantly with the incidence of cranial neuropathy, particularly in large tumors (greater than or equal to 4 cm(3)).Conclusions. Single-isocenter LINAC radiosurgery proved to be an effective treatment for acoustic neuromas in this series, with results that were comparable with those reported for gamma knife radiosurgery and multiple isocenters.

Background: Radiosurgery is a therapeutic technique characterized by the delivery of a single high dose of ionizing radiation from an external source to a precisely defined intracranial target. The application of radiosurgery to the treatment of acoustic neurinomas has increased substantially in the last decade. Most of the published experience pertains to the use of the gamma knife.Objectives: To report the experience at the first Israeli Linear Accelerator Radiosurgery Unit in the management of 44 patients with acoustic neurinomas.Methods: We analyzed the clinical records and imaging studies of all patients undergoing radiosurgery for acoustic neurinomas between 1993 and 1997, and quanitified the changes in tumor volume, hearing status, and facial and trigeminal nerve function. The contribution of radiation dose and original tumor volume upon those variables was also studied.Results: At a mean follow-up of 32 months (range 12-60), 98% of the tumors were controlled (75% had shrunk; 23% had stable volume). The actuarial hearing preservation rate was 71%. New transient facial neuropathy developed in 24% of the patients, persisting in mild degrees in 8%. Neuropathy correlated primarily with tumor volume. Tumors with volumes >4 mi were at high risk when marginal radiation doses were >1,400 cGy. Dose reduction to a maximum of 1,400 cGy produced no neuropathies in the last 20 patients, still preserving tumor control rates.Conclusions: Radiosurgery is an effective and cost-efficient therapeutic modality for newly diagnosed acoustic neurinomas in the elderly or medically infirm population, and for all residual or recurrent tumors after conventional surgery.

Purpose/Objective: To assess the feasibility and toxicity of loco-regional radiotherapy for high risk stage II or III breast cancer, following high dose chemotherapy and stem cell support.Other groups have experienced an increased toxicity of radiotherapy after high dose chemotherapy with stem cell support reporting a 35-45% incidence of clinical pneumonitis following high dose chemotherapy with BCNU containing regimens. Materials & Methods:Between February 1994 and February 1998, 171 consecutive patients with high risk stage II (103 pts) or III (68 pts) breast cancer, median age 45 (range 25-63) years, were treated in our institution with Adriamycin-based induction chemotherapy followed by high dose chemotherapy (cyclophosphamide 6gr/M 2, carboplatin 800mg/M 2 and thiotepa 500mg/M 2 as a 96-hour continuous infusion [STAMP V]) and peripheral stem cell support We present the results of treatment of 95 of these patients (59 stage II, 36 stage III) who received radiotherapy in our institution (76 patients received radiotherapy at the referring hospital).Radiotherapy was begun within 90 days from admission to transplant (less than 60 days from transplant discharge).All patients underwent simulation and were treated with a linear accelerator (6-8 MeV photons).The breast was irradiated via two tangential fields to a dose of 5040cGy (180 x 5/W), the axilla and supraclavicular area were treated with an anterior field to a dose of 5040cGy (180 x 5/W) (6-8 MeV photons).We endeavored to minimize the lung tissue in the tangential field to a strip of less than 1.5 cm.Forty three patients were treated to the internal mammary nodes by a direct electron field to a dose of 5040cGy (180 x 5/W).Patients who underwent breast conserving surgery received an electron boost to the tumor bed (200 x 7cGy).Median follow up is 23 months.Results: Twelve patients relapsed (5 stage 1I, 7 stage III), two relapsed in the irradiated breast and 10 developed systemic disease.The treatment was well tolerated.Three patients had treatment delay due to skin toxicity.Hematological toxicity was greater than normally seen during breast irradiation, but no patient required a break for hematological toxicity.Three patients developed clinical pneumonitis and recovered completely after a course of steroids.There was no treatment related mortality.Conclusions: Early administration of radiotherapy to the chest wall/breast, axilla, supraclavicular and internal mammary areas following high dose chemotherapy using the STAMP V protocol is well tolerated.In our experience this treatment is safe with a low incidence of clinical pneumonitis and no mortality.The choice of transplant protocol (without BCNU) and strict quality control of treatment planning, radiation fields and doses are important factors in assuring the safety of this protocol.257

Stereotactic targeting of the postero-ventral pallidum (PVP) presents special challenges to the surgeon 1) The target is in intimate relation to the optic tract and the internal capsule. 2) Proper angulation of the trajectory is crucial to achieve optimal effects given the long craniocaudal extension of the PVP. 3) The PVP is difficult to identify on computerized tomography (CT): the border between the internal capsule and the pallidum is usually not apparent. Potential sources of error in target determination include: - angulation of the scanning plane in relation to the intercommissural plane; - projection of the reference points (anterior commissure/posterior commissure [AC/PC]) results in the foreshortened intercommissural line, affecting the Y co-ordinate; - small tilts between the CT gantry and the stereotactic frame affect determination of the X and Z co-ordinates. Correction of these sources of error is done with basic trigonometric algorithms. The authors have developed a rapid method of stereotactic co-ordinate calculation which avoids the need to perform error-prone calculations under the pressure of operating room conditions. 1) The frame is applied with its basal plane corresponding roughly to the orbito-meatal line. 2) Thin CT slices (2 mm increments) are obtained through the area of interest and the slices are printed. 3) The major reference points (Foramen of Monro, AC, PC) are identified and marked. The PC point is projected onto the film containing AC (or viceversa if the PC slice is caudal to AC). 4) The intercommissural distance is measured, and the true length is obtained from a correction graph. The Y co-ordinate is then calculated as 1/2 ICL + 2 mm [towards AC]. 5) The slice corresponding to the target [Z co-ordinate] is obtained from a correction graph that takes into consideration the gap [number of slices] between AC and PC. 6) The X co-ordinate is placed 20 to 22 mm from midline. A graph that takes into consideration the coronal tilt of the stereotactic frame in relation to the CT gantry allows for final corrections of the X and Z co-ordinates. This step-by-step simple method of co-ordinate calculation can be used with any CT-compatible stereotactic frame.