Radiosurgery target selection in post embolization avm patients

Proceedings of the 33rd Annual ASTRO Meeting

209

1030 RADIOSURGERY

TARGET

SELECTION

IN POST EMBOLIZATION

C. Young, M. Schwartz, P. 0’13rien, K. TerBrugge, Toronto-Bayview

Regional

Cancer

Centre;

AVM PATIENTS

R. WiIIinsky, F. Gentili, M.C. Wallace.

University

of Toronto

Brain Vascular

Malformation

Study Group

Purpose: Whereas many AVMs are approximately shape affecting target selection for radiosurgery.

spherical,

when embolization

has been used, the residual lesion may have an irregular

Material

and Methods: Our multidisciplinary group, comprised of one radiation oncologist, two interventional radiologists and three neurosurgeons, can offer radiosurgery, embolization and surgery either singly or in combination. All referrals are discussed by the group and the most appropriate therapy recomme:lded. Although radiosurgery can be the initial treatment modality, circumstances may dictate the use of surgery and/or embolization first, with radiosurgery in reserve to deal with the residual. Factors include lesions exceeding the 3 cm. maximum diameter for radiosurgery, and patients requiring moreimmediateprotection fromhemorrhagethanthe 1 to Zyearlatencyperiod associatedwith radiosurgery. Thus of 14 patients radiated over21 months,4 had radiosurgery only,1 had surgery and radiosurgery, 6 had embolization and radiosurgery, and 3 had alI 3 modalities. A total of 9 had embolization prior to radiosurgery.

Results: In two post-embolization cases, thecentre of thelesion selected atthetimeof radiosurgery on thelateral viewdidnot correspond tothecentre ofthelesion chosenon theAP view. All other possible causes including movement of either the frame, or the AVM between

injections,

were considered

and ruled out.

Conclusions: From careful examination of the radiographs, we concluded that the long axes of the two compartments of the lesion were orthogonal, making one part more obvious on one view, the other on the alternate view. We advise that radiosurgery be planned to encompass both parts of the lesion when this phenomenon is noted.

1031 EVALUf.rION FOR CLINICAL USEFULNESS OF CT SIMULATION SYSTEM IN RADIOTHERAPY PLANNING FOR LUNG CANCER PATIENTS Toshiya Sakaguchi, M.D., Kazuyuki Takeyuki Kushima, M.D., Soejima. M.D., Kazufumi Imanaka. M.D., Michio Kono,M.D. Department

of Radiology,

Yonezawa.M.D.,

Toshinori

Kobe University School of Medicine

Purpose: We have been developing the radiotherapy planning system using CT,which is named CT diseases. We have already Simulation Sys tern (CBS) and applied to various malignant the outline of this system at 32nd meeting of ASTRO. This time we assessed the presented clinical usefulness of CTSS in radiotherapy planning of lung cancer patients compared with conventional X-ray simulator. Methods and Materials: This study was evaluated in terms of irradiated volume, the effect of radiotherapy and the occurrence of radiation fibrosis. 1)Irradiated volume was figured out by calculation of field size and iso-center depth. 2)Effect of radiotherapy was evaluated by CT and MRI after the completion of treatment. 3)The degree of re.diation fibrosis was judged utilizing chest X- rays on 1,3,6 months after irradiaion according to Kono's classification( 75 th RSNA). Results: subject of 50 cases in CTSS, and 40 cases in conventional X- ray simulation were the this research. Results were as follows. 1)Using CTSS, irradia.ted volume decreased. no apparent difference was revealed between 2)Concerning to the effect of radiotherapy, both methods. of irthe occurrence of radiation fibrosis was alleviated with decrease 3)Using CTSS, radiated volume. Conclusion: As CTSS was applied in the radiotherapy planning of lung cancer patients, it was considered to contribute the alleviation of the side effect of radiation by reducing irradiated volume.