ViewRay Inc. MRIdian® system L-0009 Release 4.5 37
Chapter 2: Safety Information and
2.7.5 Pre-screening Prior to Imaging or Treatment on the
MRIdian
® System
All individuals undergoing imaging or treatment on the MRIdian system must
first be pre-screened in accordance with ACR Guidance Document for Safe MR
Pr
actices: 2007. There are 3 classes of patients who either should not undergo
MR imaging or who must be imaged using particular caution. Those three
classes are:
1. Patients for whom use of the MRIdian system is contraindicated.
This includes patients who have metallic implants or
electrically, magnetically or mechanically
activated implants (e.g., cardiac pacemakers) because the magnetic and electromagnetic
fields may produce strong attraction and/or torque to the implant or may interfere with the
operation of these devices. This applies also to patients who rely on electrically, magnetically
or mechanically activated life support systems. Scanning patients with intracranial aneurysm
clips is also contraindicated unless the physician is certain the clip is not magnetically active.
2. Patients having a higher than normal likelihood of needing emergency medical treatment,
indep
endent of the physical environment of the MRIdian system.
In terms of the need for medical supervision, particular
caution is required in performing
imaging or treatment with the MRIdian system in the following cases: Patients with greater
than normal potential for cardiac arrest, patients who are likely to develop seizures, or
claustrophobic reactions, decompensated cardiac patients, febrile patients, and patients with
impaired ability to perspire, patients who are unconscious, heavily sedated, or confused, and
with whom no reliable communication can be maintained, and examinations which are
carried out at room temperature above 24 degrees C or relative humidity above 60%. See
"Uninterruptible Power Supply” on page 7.
3. Patients having a higher than normal likelihood of needing emergency medical treatment
due
to the elevated values of the applied fields, when the MRIdian® system operates within
the First Level Controlled Operating Mode as described in "Operating Modes” on page 46.
This class includes patients with implanted surgical clips (hemostatic clips) or other
f
erromagnetic material, patients engaged in occupations or activities which may cause
accidental lodging of ferromagnetic materials, or who may have imbedded metal fragments
from military activities, neonates and infants (for whom data establishing safety are lacking),
patients with permanent (tattoo) eye-liner or with facial make-up (severe eye irritation has
been reported), patients with compromised thermoregulatory systems (e.g. neonates, low
birth weight infants, certain cancer patients), patients with metallic implants, because they
may cause artifacts in images due to magnetic field distortion, patients with implanted
prosthetic heart valves, and pregnant patients (the safety of magnetic resonance examination
has not been completely established for embryos and fetuses).
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