Gamma Knife Radiation and Imaging Techniques at Hoag
Advanced Imaging Technique
The evolution and success of Gamma Knife Radiosurgery is directly dependent
on the imaging modalities available to determine the location of the tumor
or AVM. A Gamma Knife (GK) treatment center must have the accompanying
state-of-the-art imaging modalities and neuro-oncologic radiology specialists
in order to maximize the efficacy of the GK treatment unit and team. Hoag
is fortunate to have both the technology and the staffing to collaborate
on neurological and Gamma Knife patients.
Learn more about the advanced
Neuro Imaging available at Hoag.
Gamma Knife Radiation
The leading edge technique is an innovative process developed to treat
one of the most common types of glioma, glioblastoma multiforme. This
treatment combines the functionality of the Gamma Knife with the advances
in diagnostic radiology technology, which include Multivoxel MR-Spectroscopy
scans. This unique combination targets the radiation beyond the local
tumor volume to include the potential malignant tumor path. Prior to this
technological spectroscopy breakthrough, it was impossible to detect where
the tumor would or might spread.
Glioblastoma multiforme (GBM) is among the most common and devastating
brain tumors affecting adults. The most successful treatment regimens
for GBMs include surgical resection, radiation therapy and chemotherapy,
followed by stereotactic radiosurgical boost (Gamma Knife radiosurgery)
and immunotherapy. Despite aggressive therapies, the malignant nature
of GBMs often results in tumor recurrence. Ninety percent of GBMs recur
at the site of the original tumor. In addition to local recurrence, malignant
gliomas frequently spread in predictable patterns along the white matter
pathways in the brain. It is via this mechanism that long-fought battles
against GBMs are often lost.
Predictable Patterns of Spread in Malignant Gliomas
Traditional radiosurgical techniques have focused solely on local tumor
margins, as determined by gadolinium enhancement on MRI. However, recent
data suggests that by targeting the "leading edge" of these
tumors, their spread along white matter pathways can be more effectively
halted. FLAIR sequences and Multivoxel MR-Spect scans can be utilized
to define positive areas outside of the gadolinium T1-weighted enhancing
zones. Targeting these zones with gamma knife is proving to be a successful
method of blocking the path of malignant gliomas.
Gamma Knife Treatment Process
- The patient is admitted to the hospital on the morning of the procedure
and started on intravenous fluids. A stereotactic frame is painlessly
secured to the patient's head. This head frame is a guiding device,
which ensures the Gamma Knife beams are focused exactly where the treatment
is needed. Mild sedation and a local anesthetic are administered prior
to head frame placement. Head frame placement usually takes fewer than
- Imaging studies, such as MRI, CT scan and/or angiography are performed.
The stereotactic frame is displayed on the imaging studies allowing the
physicians to precisely localize the target.
- The team of Gamma Knife physicians utilizes three-dimensional computer
imaging to develop the patient's radiosurgical treatment plan.
- When the treatment plan is complete, the patient is placed on the Gamma
Knife bed. The stereotactic head frame is attached to the helmet containing
192 portals through which radiation beams are focused. The frame and the
helmet prevent movement, ensuring accurate alignment during treatment.
- The Gamma Knife team monitors the patient throughout the procedure. Actual
treatment may last as little as 10 minutes or as long as two hours. During
the procedure, the patient does not hear or feel the Gamma Knife delivering
the radiation treatment.
- The head frame is removed upon completion of the treatment and bandages
are applied to the pin site areas. The patient is observed for approximately
one hour, then discharged from the hospital.
- The patient is contacted by the Gamma Knife nurse the next day for follow-up
and then periodically to monitor the patient's status.
Gamma Knife Patient Instructions.