Users Manual Part 6

IBA | 48-2 |
Clinical User’s Guide
Volume 1 - Treatment Session
|Part XI
- Patient Positioning and Alignment Using the Universal Beam Triggering Interface
|
The Triggering Solution
To overcome this problem, the radiation beam, be it the proton beam or X-rays
emitted by the X-ray tube, can be subjected to a triggering technique, whereby the
beam may be interrupted at given points in time (i.e., beam not authorized), and
triggered again when the position of the patient returns to a given state (i.e., beam
authorized).
Detection of the patient's movements may be done by various techniques, and each
technique may have its own patient monitoring equipment. The information supplied
by the gating equipment can then be used for commanding a beam triggering
scheme.
The PTS caters to a variety of gating devices, using the UBTI.
Triggering is only applicable between the start and the end of the irradiation. No
triggering is needed during beam tuning and preparation.
Triggering Requirements
The PTS operates within the following beam triggering timing constraints:
The PTS shall accept a beam triggering frequency going from 1 cycle per minute
to 30 cycles per minute. A cycle assumes one start and one stop of the beam.
The minimal time between two requests of beam triggering (Request "Beam
Off" to request "Beam On") will never be smaller than 1 sec.
Important Only use gating sources that are compliant with the Universal Beam
Triggering Interface (UBTI) specification, and certified for intent of use
for X-rays and with proton and/or particle therapy.
CAUTION As a Radiation Therapy Technologist, when planning a treatment with
automatic beam gating, choose the treatment delivery settings (such as
beam delivery technique, dose rate, number of repaintings) and patient
monitoring settings (such as duty cycle, acquisition frequency) in
function of the clinical goals to be achieved and safety criteria to be
met, taking into account the global latency of the system (latency of the
patient monitoring system combined with the latency of the treatment
machine and the latency to detect and process a system failure).