July was a tough month and I haven't posted because I just did not want to post bad news. I started this blog to help others in the same situation as Roxy and I, so here I am. I am also posting the MRI report below.
There seems to be a late effect side effect that has injured a part of her brain that was healthy in the previous MRI.
I have since found this article that talks about late effects of Cyberknife that can occur months after the treatment, it states these late effects are rare, but Roxy has a few: brain changes and and a mass in her spleen. She is also having gallblader and liver changes, but that may be due to the steroids she has been on. I have also found another dog, Farrah, who had Cyberknife and developed another cancer as well. While Cyberknife gave Roxy 4 fabulous months that she would not have had, it is not an easy transition going through the brain changes. She fails the knuckle test on 3 of her 4 paws. Her brain has almost no knowledge of her left rear leg, her left front leg is getting pretty bad, and now the right rear seems to be having problems. Having a 65 lb dog with neurological issues is physically demanding, although my body can now fully lift her when necessary. She cannot balance herself to urinate, and needs support on her left side or she will fall down. Most days I can still entice her to walk some with
Plato Duck Treats, but some days her legs just wont work. When this happens she either falls to the side or drops down onto her belly. I have a fabulous wagon to take her out in, and there is a lot of love from people that we meet. It also seems that her tongue doesn't always work properly.
So how do I feel about Cyberknife? From what I can tell from the blogs of others, dogs seem to have these late effects pretty frequently. I believed in the science that we could shrink the tumor with little damage to surrounding tissue. I figured that with the brain tumor gone Roxy would likely have other health issues, but I never imagined that there would be brain changes that were not there before that would cause a new set of problems for Roxy. Cyberknife was Feb 24, so we are a little over 5 months out. I believe the Cyberknife caused these brain changes. Immediately after the Cyberknife was when Roxy first started dragging one of her toes on her rear left leg. This was a new symptom that was not present previously.
I also found a couple of stories of dogs who chose the Dr. Pluhar' canine brain tumor clinical trials. Riley seems to be doing great years later, Jake only made it two months.
I guess we never know what we are going to get, I have left the heartache behind and am focusing on the time we still have.
In health to you all.
Anne & Roxy
Roxy's MRI Report
www.avmi.net
Magnetic Resonance Imaging Report
History: Previous cyberknife radiation therapy for suspected meningioma in the left caudal fossa with good initial response. Recent recurrence of symptoms, R/O recurrence vs. other.
Study Parameters: The brain was imaged using the following sequences: Sagittal T1 - 3 mm Sagittal T2 - 3 mm Transverse T2 - 4 mm
Transverse T1 - 4 mm Transverse FLAIR - 4 mm Transverse GRE T2* - 4 mm Transverse T1 post contrast - 4 mm Sagittal T1 post contrast - 3 mm Dorsal T1 post contrast - 4 mm
Comment: This study is compared to the study performed on 02/13/2012.
Findings: There is a single, 1.0 cm x 0.6 cm x 0.6 cm, markedly enhancing, T2 hypointense to isointense extramedullary mass within the left cerebellopontine angle. This mass is smaller on the current study than on the previous study on 02/13/12. The previous detected compression of the adjacent brain stem is reduced and the previously detected vasogenic edema within the adjacent brain stem is resolved on the current study. On the current study, there is a poorly marginated area of mild to moderate somewhat patchy contrast enhancement within the rostral left cerebellar hemisphere surrounded by a larger region of nonenhancing, T2 hyperintense edema. No other areas of abnormal intracranial contrast enhancement are noted. No other intracranial mass effects are appreciated.
Interpretation: This study is consistent with partial response of the presumptive meningioma to the previous radiation therapy with roughly 50% reduction in tumor diameter. Patchy contrast enhancement within the overlying rostral left cerebellar hemisphere and surrounding nonenhancing T2 hyperintensity are most consistent with radiation induced brain injury. Alternative differentials for the new cerebellar lesion including intra parenchymal extension of the previously identified neoplasia vs. infectious/inflammatory etiologies are considered unlikely.
Michael R. Broome, DVM, MS, Dipl. ABVP Jim Hoskinson, DVM, DACVR
3047 Edinger Ave • Tustin • CA • 92780 • Tel: 949-559-7289 • Fax: 949-559-6727 2340 S. Sepulveda Blvd • Los Angeles • CA • 90064 • Tel: 310-477-4453 • Fax: 949-559-6727
Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiotherapy (SBRT)
What is stereotactic radiosurgery and how is it used?
Stereotactic radiosurgery (SRS) is a highly precise form of radiation therapy initially developed to treat small brain
tumors
and functional abnormalities of the brain. The principles of cranial
SRS, namely high precision radiation where delivery is accurate to
within one to two millimeters, are now being applied to the treatment of
body tumors with a procedure known as stereotactic body radiotherapy
(SBRT).
Despite its name, SRS is a non-surgical procedure that delivers
precisely-targeted radiation at much higher doses, in only a single or
few treatments, as compared to traditional
radiation therapy.
This treatment is only possible due to the development of highly
advanced radiation technologies that permit maximum dose delivery within
the target while minimizing dose to the surrounding healthy tissue. The
goal is to deliver doses that will destroy the tumor and achieve
permanent local control.
SRS and SBRT rely on several technologies:
- three-dimensional imaging and localization techniques that determine the exact coordinates of the target within the body
- systems to immobilize and carefully position the patient and maintain the patient position during therapy
- highly focused gamma-ray or x-ray beams that converge on a tumor or abnormality
- image-guided radiation therapy (IGRT) which uses medical imaging to
confirm the location of a tumor immediately before, and in some cases,
during the delivery of radiation. IGRT improves the precision and
accuracy of the treatment
Three-dimensional imaging, such as
CT,
MRI,
and PET/CT is used to locate the tumor or abnormality within the body
and define its exact size and shape. These images also guide the
treatment planning—in which beams of radiation are designed to converge
on the target area from different angles and planes—as well as the
careful positioning of the patient for therapy sessions.
Although SRS commonly refers to a one-day treatment, physicians
sometimes recommend multiple stereotactic delivered treatments. This is
important for tumors larger than one inch in diameter as the surrounding
normal tissue exposed to the single high dose of radiation must be
respected and limited, and the volume of normal tissue treated increases
proportionally to the tumor size. Delivering the radiation in a few
sessions as opposed to one, can improve safety and allow the normal
tissue to heal in between treatments. Therefore, fractionating the
treatment allows for high doses to still be delivered within the target,
while maintaining an acceptable safety profile. This procedure is
usually referred to as fractionated stereotactic radiotherapy (SRT), and
typically refers to the delivery of two to five treatments of focused
radiation.
SRS and SBRT are important alternatives to
invasive surgery, especially for patients who are unable to undergo surgery and for tumors and abnormalities that are:
- hard to reach
- located close to vital organs/anatomic regions
- subject to movement within the body
SRS is used to treat:
- many types of brain tumors including:
- benign and malignant
- primary and metastatic
- single and multiple
- residual tumor cells following surgery
- intracranial, orbital and base-of-skull tumors
- arteriovenous
malformations (AVMs), a tangle of expanded blood vessels that disrupts normal blood flow in the brain and sometimes bleeds.
- other neurological conditions like trigeminal neuralgia (a nerve disorder in the face), tremor, etc.
SBRT is currently used and/or being investigated for use in treating
malignant or benign small-to-medium size tumors in the body and common
disease sites, including the:
- lung
- liver
- abdomen
- spine
- prostate
- head and neck
SRS fundamentally works in the same way as other forms of radiation
treatment. It does not actually remove the tumor; rather, it damages the
DNA of tumor cells. As a result, these cells lose their ability to
reproduce. Following treatment, benign tumors usually shrink over a
period of 18 months to two years. Malignant and metastatic tumors may
shrink more rapidly, even within a couple of months. When treated with
SRS, arteriovenous malformations (AVMs) may begin to thicken and close
off slowly over a period of several years following treatment. Many
tumors will remain stable and inactive without any change. Since the aim
is to prevent tumor growth, this is considered a success. In some
tumors, like acoustic neuromas, a temporary enlargement may be observed
following SRS due to an inflammatory response within the tumor tissue
that overtime either stabilizes, or a subsequent tumor regression is
observed called pseudoprogression.
What equipment is used?
There are three basic kinds of equipment, each of which uses different instruments and sources of radiation:
- The Gamma Knife®, which uses 192 or 201 beams of
highly focused gamma rays all aiming at the target region. The Gamma
Knife is ideal for treating small to medium size intracranial lesions. See the Gamma Knife page for more information.
- Linear accelerator (LINAC) machines, prevalent
throughout the world, deliver high-energy x-rays, also known as
photons. The linear accelerator can perform SRS on larger tumors in a
single session or during multiple sessions, which is called
fractionated stereotactic radiotherapy. Multiple manufacturers make
this type of machine, which have brand names such as Novalis Tx™,
XKnife™, Axesse™ and CyberKnife®. See the Linear Accelerator page for more information.
- Proton beam or heavy-charged-particle radiosurgery
is in limited use in North America, though the number of centers
offering proton therapy has increased dramatically in the last several
years. See the Proton Therapy page for more information.
Who will be involved in this procedure and who operates the equipment?
The treatment team is comprised of a number of specialized medical professionals, typically including a
radiation oncologist,
medical radiation physicist,
radiologist,
dosimetrist,
radiation therapist, and
radiation therapy nurse.
- The radiation oncologist and, in some cases, a neurosurgeon head the
treatment team and oversee the treatment; they outline the target(s) to
be treated, decide on the appropriate radiation dose, approve the
treatment plan, and interpret the results of radiosurgical procedures.
- A radiologist interprets imaging that identifies the target(s) to be treated in the brain or body.
- The medical radiation physicist ensures the delivery of the precise dose of radiation.
- The physicist, or a dosimetrist under the supervision of the
physicist, uses special computer software to devise a treatment plan; he
or she calculates the exposures and beam configuration to conformally
treat the target(s) to the prescribed dose.
- A highly trained radiation therapist positions the patient on the
treatment table and operates the machine from an adjacent protected
area. The radiation therapist can observe the patient through a window
or on a closed-circuit television and is able to communicate with the
patient throughout the procedure. In the case of the Gamma Knife, the
neurosurgeon and/or radiation oncologist may help position the patient
for treatment and the radiation oncologist may operate the machine.
- The radiation therapy nurse assesses the patient, provides the
patient with information about the treatment, monitors the patient
during treatment, and helps answer questions after treatment.
- A neurologist or neuro-oncologist may participate with the
radiation oncologist and neurosurgeon in the multidisciplinary team that
considers various treatment options for individual cases and helps
decide who may benefit from radiosurgery for lesions in the brain.
How is the procedure performed?
• Stereotactic Radiosurgery Using the Gamma Knife
Gamma Knife
radiosurgery involves four phases: placement of the head frame, imaging
of the tumor location, computerized dose planning, and radiation
delivery.
In the first phase, a nurse will place a small needle in your hand or
arm to give you medications and contrast, if needed, for imaging. A
neurosurgeon will use local anesthesia to numb two spots on your
forehead and two spots on the back of your head. A box-shaped head frame
will be attached to your skull using specially designed pins to keep
your head from moving within the frame until the treatment session is
finished. This lightweight aluminum head frame is also a guiding device
that makes sure the Gamma Knife beams are focused exactly where the
treatment is needed.
Next, you will be taken to an imaging area where a
magnetic resonance imaging (MRI) scan will be performed to show the exact location of the tumor in relation to the head frame. In some cases, a
computed tomography
(CT) scan may be performed instead of, or in addition to, an MRI scan.
If you are having treatment for an arteriovenous malformation, you may
also have an angiogram. New developments in Gamma Knife software allow
for pre-planning. Therefore, you may have your treatment planning MR
images prior to the day of your treatment to improve the efficiency of
the treatment process.
During the next phase, you will be able to relax for an hour or two
while your treatment team identifies the tumor(s) for treatment and
develops a treatment plan using special computer software to optimally
irradiate the tumor and minimize dose to surrounding normal tissues.
Next, you will lie down on the Gamma Knife bed and your head frame
will be fixed to the machine before beginning treatment. You will be
made comfortable with a pillow or wedge-shaped sponge under your knees
and a blanket over you. The treatment team will then go to the control
area outside the treatment room to begin your treatment. You will be
able to talk to your physician through a microphone in the helmet, and a
camera will allow the team to see you at all times. The bed you are
lying on will move backward into the Gamma Knife machine. You will not
feel the treatment and the machine is very quiet. Depending on the Gamma
Knife model and the treatment plan, the whole treatment may be
performed without interruption or it may be broken up into multiple
smaller parts. The total treatment may last less than one hour or up to
four hours. A chime will sound when the treatment is complete and the
bed will return to its original position. As soon as the treatment is
finished, you will sit up and the head frame will be removed. In most
cases, you should be able to go home soon afterward.
• Radiosurgery Using the Linear Accelerator
Linear accelerator
(LINAC) SRS is similar to the Gamma Knife procedure and its four
phases: head frame placement, imaging, computerized dose planning and
radiation delivery. LINAC technology is much more common than Gamma
Knife technology and has been in practice for a similar length of time.
Unlike the Gamma Knife, which remains motionless during the procedure,
part of the LINAC machine (called a
gantry)
rotates around the patient delivering the radiation beams from
different angles. Obtaining the MRI before frame placement is also a
more routine pre-planning practice with LINAC-based SRS. A CT with the
frame in place is also commonly acquired.
When SRS is delivered using CyberKnife, a robotic arm moves the
compact LINAC around the patient under image-guidance. The CyberKnife is
also based on delivering SRS without an invasive head frame, and a more
simple plastic head mask can be used to keep the head from moving
during delivery which can improve patient comfort. The development of
frameless SRS is possible due to the incorporation of image-guidance in
the delivery of treatment. Now, most LINAC based SRS technology is
moving towards frameless SRS. The Gamma Knife has also developed
frameless technology in order to spare the patient the invasive frame
placement procedure. Frameless SRS also allows for fractionated SRS, or
SBRT, which again may be an advantage for large tumors or those in
particularly critical locations.
• SBRT
SBRT typically consists of one to five treatment sessions delivered over the course of one to two weeks.
For some technologies like the CyberKnife that base image-guidance
according to an x-ray based solution, you may be asked to have a
fiducial marker placed in or near your tumor for selected cases.
However, for most CT based image-guidance technologies, this step is not
needed. If a fiducial is required, depending on the location of your
tumor, your radiation oncologist may work with a pulmonologist,
gastroenterologist or radiologist to have one to four fiducial markers
placed near the tumor. Placement of the fiducial marker is almost always
an outpatient procedure.
Next, your radiation oncologist will determine the method of aligning
your body with the beams from the linear accelerator, which is called a
simulation. Immobilization devices are often used to align patients
very precisely and make sure they remain still during simulation and
treatment. Some of these systems may hold you quite tight; therefore you
should tell your physician if you suffer from claustrophobia. After an
immobilization device is created for you, a CT scan is performed over
the area to be treated. Your physicians may also perform a '4DCT,' where
the CT scan obtains information on how your tumor moves while you
breathe. This is very common for tumors in the lungs or liver. After the
scan is completed, you will be sent home.
The third part of the course is planning. The radiation oncologist
will work with a radiation dosimetrist and medical physicist to plan the
beam arrangement best suited for your tumor. They may incorporate other
imaging techniques, such as MRI or PET/CT. Using specialized software,
the team will go through hundreds of different combinations of beams to
figure out which would be best for your situation.
Radiation delivery of SBRT is done on a linear accelerator. There are
normally no restrictions on eating or drinking, though some patients
may take an anti-inflammatory, anti-nausea or anti-anxiety medication
prior to the treatment. You will be placed in the immobilization device.
X-rays or a CT scan (depending on the mode of image-guidance specific
to the LINAC technology) will be taken to line up the beams of radiation
with the tumor prior to starting the radiation therapy. The radiation
therapist will position you with guidance from the radiation oncologist
based on these x-rays. The radiation therapist will then deliver the
treatment. Sometimes, x-rays or a CT scan will be taken during the
treatment to monitor the position of the tumor. Treatment can take up to
one hour or more.
Is there any special preparation needed for the procedure?
SRS and SBRT are usually performed on an outpatient basis. However,
be prepared to spend up to a half-day or more at the facility. You will
be informed whether you need to have someone accompany you and drive you
home afterward.
You may be asked not to eat or drink anything after midnight on the
night before your treatment. You should ask your physician about taking
any medications on the day of your treatment and bring those medications
with you to the procedure. You should also tell your physician if any
of the following apply to you:
- You are taking medications by mouth or insulin to control diabetes.
- You are allergic to intravenous contrast
material, shellfish, or iodine.
- You have a pacemaker, artificial heart valve, defibrillator,
brain aneurysm clips, implanted pumps or chemotherapy ports, neurostimulators,
eye or ear implants, stents, coils or filters.
- You suffer from claustrophobia.
What will I feel during and after the procedure?
Radiosurgery treatments are similar to having an x-ray. In general
you will not be able to see, feel or hear the x-rays. One exception is
that some patients who are having treatments to the brain may see
flashes of light while the machine is on, even with their eyes closed.
There is no pain or discomfort from the actual treatment.
If you experience pain for other reasons, such as back pain or
discomfort from the head frame or immobilization device, you should let
your doctor or nurse know.
When the head frame is removed, there may be some minor bleeding from
the pin sites that will be bandaged. You may experience a headache and
can ask for medication to help make you feel more comfortable.
In most cases, radiosurgery and SBRT patients can resume all of their normal activities within one or two days.
Side effects of radiation treatment include problems that occur as a
result of the treatment itself as well as from radiation damage to
healthy cells in the treatment area.
The number and severity of side effects you experience will depend on
the type of radiation and dosage you receive and the part of your body
being treated. You should talk to your doctor and nurse about any side
effects you experience so they can help you manage them.
Radiation therapy can cause early side effects during or immediately
after treatment, and are typically gone within a few weeks. Late side
effects can occur months or years later. Common early side effects of
radiation therapy include tiredness or fatigue and skin problems. Skin
in the treatment area may become more sensitive, red, irritated, or
swollen. Other skin changes include dryness, itching, peeling and
blistering.
Depending on the area being treated, other early side effects may include:
- hair loss in the treatment area
- mouth problems and difficulty swallowing
- eating and digestion problems
- diarrhea
- nausea and vomiting
- headaches
- soreness and swelling in the treatment area
- urinary and bladder changes
Late side effects, which are rare, occur months or years following treatment and are often permanent. They include:
- brain changes
- spinal cord changes
- lung changes
- kidney changes
- colon and rectal changes
- infertility
- joint changes
- lymphedema
- mouth changes
- secondary cancer
- fracture of bones
There is a slight risk of developing cancer from radiation therapy.
Following radiation treatment for cancer, you should be checked on a
regular basis by your radiation oncologist for recurring and new
cancers.
Using techniques such as SBRT, the aim is to maximize the
cancer-destroying capabilities of radiation treatment while minimizing
its effect on healthy tissues to limit the side effects of the treatment
itself.
Locate an ACR-accredited provider: To locate a medical imaging or radiation oncology provider in your community, you can search the
ACR-accredited facilities database.
Exam costs: The costs for specific medical
imaging tests and treatments vary widely across geographic regions.
Many—but not all—imaging procedures are covered by insurance. Discuss
the fees associated with your medical imaging procedure with your doctor
and/or the medical facility staff to get a better understanding of the
portions covered by insurance and the possible charges that you will
incur.
Web page review process: This Web page is
reviewed regularly by a physician with expertise in the medical area
presented and is further reviewed by committees from the American
College of Radiology (ACR) and the Radiological Society of North America
(RSNA), comprising physicians with expertise in several radiologic
areas.
Outside links: For the convenience of our users, RadiologyInfo.org provides links to relevant websites. RadiologyInfo.org, ACR and RSNA are not responsible for the content contained on the web pages found at these links.
Images: Images are shown for
illustrative purposes. Do not attempt to draw conclusions or make
diagnoses by comparing these images to other medical images,
particularly your own. Only qualified physicians should
interpret images; the radiologist is the physician expert trained in
medical imaging.
This page was reviewed on July 06, 2012
