Intrabeam
The recent development of a new technology has made possible the delivery of
radiation directly to the tissues at the site of the primary tumour. The INTRABEAM
manufactured by Carl Zeiss Surgical GmbH,
is a simple but ingenious device,
in essence a miniature electron beam-driven X-ray source, which provides a point source
of low energy X-rays (50kV max) at the tip of a 3.2mm diameter tube. The radiation source
can be inserted into the area of interest immediately after excision of the tumour and
switched on for 25-30 minutes to provide intra-operative radiotherapy (IORT),
accurately targeted to the tissues that are at highest risk of local recurrence. The
physics, dosimetry and early clinical applications of this soft x-ray device
have been well studied and the probe has already been used for treatment of
human malignant brain tumours. The TARGIT trial is a collaborative international
effort to test the hypothesis that the strategy of delivering IORT in patients
with low risk early stage breast cancer is equivalent in local recurrence rate
to a 6 week course of whole breast radiotherapy.
The System Components for IORT of Breast Tumors:
The Intrabeam Miniature X-ray Source
The radiation dose is provided by a miniature X-ray source PRS 400 that can
deliver X-ray energies up to 50kV. The X-ray point-source is ideal for treating
from within the tumour or tumour bed. Low energy, high dose rate X-rays are
emitted from the source in an isotropic pattern, uniformly irradiating the
target tissue.
The Intrabeam Control Console
The Control Console provides the operator interface and delivers low-voltage
power to the miniature X-ray source, eliminating high-voltage risks. The
miniature X-ray source is verified prior to use, and parameters are then set up
within the control console software for treatment delivery. During the
procedure, the control console monitors the system for safe and accurate dose
delivery.
The Intrabeam Surgical Support System
Mobile and flexible. Functions in any operating room and can easily be
transported from one room to another in minutes. The stand offers perfect
balancing and six degrees of freedom. Electromagnetic clutches lock the
radiation source in the treatment position with millimetre precision.
Reliability and performance in a surgical support system.
The Intrabeam Applicators
A complete set of spherical applicators from 1.5 to 5.0 cm in diameter enable
accurate placement into the tumour bed, ensuring contact with all surfaces of
the treatment area, and uniform dose delivery. The reusable spherical
applicators offer convenience and accuracy.
How does it work?
The electrons are generated and accelerated in the main unit and travel via the electron
beam drift tube which is surrounded by the conical applicator
sheath such that its tip lies at the epicentre of the applicator
sphere. Once the electrons hit the inner surface of the
hemisphere at the tip, x-rays are generated. Thus a uniform
radiation dose rate is available at the surface of the
applicator sphere.
The miniature X-ray source delivers up to 50kV of energy to the target tissue, and the steep dose fall-off ensures that most of the dose stays in the target tissue.
The x-ray source is delivered to the tumour bed utilizing a surgical support
stand. The sterile applicator is joined with a sterile drape
that is used to cover the stand during treatment delivery.
Note that the operating room does not need to be adapted or modifed in any way.