Brachytherapy of gbm

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In the name of God

In the name of GodBrachytherapy for Malignant Gliomasz.MansouriShahid Beheshti university medical of science

IntroductionPrimary malignant brain tumors are among the most aggressive of all human neoplasms.

Astrocytoma represent about 40% of all brain tumors & 75% of astrocytomas are anaplastic(grade III) and GBM(grade IV).

Why Brachytherapy?most patients with GBM fail locally within close proximity to the original tumor. Given this pattern of failure, there has been much interest in radiation dose escalation in improving clinical outcomes of this patient population. One way for this, is BTAnatomy

4Indicationsthe eligibility criteria for BT:UnifocalSupratentorialNot larger than 5cm(in largest diameter)Without ventricular,corpus callosum or brain stem infiltrationGood performance status (kps>60)

Physics of brachytherapyMost commen source for brachytherapy of brain is I-125.Implants are 1.temporary high activity or 2. permanent low activityTemporary implant1.CT or MRI for tumor localization2. fixation of a stereotactic frame at 4 points to the patients skull under local or general anesthesia.3.CECT (cuts: 3-5mm) to ensure of frame location4.preplanning;countoring TV(tumor+/-5mm margin)Determination of suitable&length of cathetersTemporary implant5. Neurosurgeon placing catheter precutaneously and parallel to each other at the calculated positions.6.CECT for analysis of the catheter configuration (24h after implantation) and treatment planning.7.loading the source with afterloading system.8.After 6 days and delivery 50 GY to tumor and its margin,the cathters are dislodged.

Permanent implantsource:Low activity I-125 seedsFor patients with recurrent GBMCan be done after debulking of the tumor, sources are placed along the walls of the resection cavity at 0.5- to 1.0-cm intervalsCT scan for dosimetric calculation Removal of the catheters can be done without anesthesia

Gliasite catheter

During the tumor resection, the balloon portion of the GliaSite catheter is placed within the resection cavity ,The other end of the catheter serves as the injection port and is fixed on top of the skull and concealed underneath the skin

Treatment planning

Gliasite implantAfter 3-7 days and dose delivery (40-60GY) at 0.5 cm to 1 cm from the balloon surface At the end of this period, the Iotrex and saline are withdrawn and the balloon catheter is then removed during a brief surgical procedure.

Thank you !References:1.brachy therapy,application and techniques2.booklet of overview of brachytherapy3.principles and practice of brachytherapy ,using afterloading systems.