In the name of God

Brachytherapy for Malignant Gliomasz.Mansouri

Shahid Beheshti university medical of science

Introduction

Primary 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 BT

Anatomy

Indications

the eligibility criteria for BT: Unifocal Supratentorial Not larger than 5cm(in largest

diameter) Without ventricular,corpus callosum

or brain stem infiltration Good performance status (kps>60)

Physics of brachytherapy

Most commen source for brachytherapy of brain is I-125.

Implants are 1.temporary high activity or 2. permanent low activity

Temporary implant

1.CT or MRI for tumor localization 2. 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 location

4.preplanning;countoring TV(tumor+/-5mm margin)Determination of suitable&length of catheters

Temporary implant

5. 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 implant

source:Low activity I-125 seeds For patients with recurrent GBM Can be done after debulking of the

tumor, sources are placed along the walls of the resection cavity at 0.5- to 1.0-cm intervals

CT 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 implant

After 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dose delivery (40-60GY) at 0.5 cm to 1 cm from the balloon surface At the end of this period, the Iotrex and saline are withdrawn and the balloon catheter is then removed during a brief surgical procedure.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 techniques 2.booklet of overview of brachytherapy 3.principles and practice of brachytherapy ,using

afterloading systems.