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Part 7:
The Simulation
Three months have now gone by since I began my Androgen Ablation
therapy. To date I have had no serious adverse reactions to this
treatment. It will continue concurrently with the IMRT for another 3 months. My literary research has indicated that the
treatment has probably shrunk my prostate to half of its original
size by this time. In addition to starving the androgen dependent
cancer cells, the smaller prostate will be beneficial during the
radiation phase. This is due to the fact that it presents a more
concentrated target and that the spacing between it and other organs,
better kept from radiation, has increased. The normal distance
between the end of the rectum and the prostate is about 1/2".
Anything which permits better concentration on the prostate to the
exclusion of the rectum, the bladder etc. would be highly beneficial.
As I would learn today, 1/2" or 12.7mm, would seem like a mile to the
precisely focused radiation beam.
This is my second visit to Memorial Sloan Kettering and, as I sit in the
small, third floor secluded waiting, area I am struck by an
observation I first observed on my initial visit. That observation
being that this does not seem like a hospital. There is not an
endless stream of hospital personnel hurrying through the halls,
there are no bells, chimes or calls for medical personnel. I seldom
see another patient on this floor.
During both visits to MSK my path has never crossed with
more than two other patients at any given time. I will learn today
how remarkable this is. Considering the IMRT therapy alone, and there
are other forms of treatment in progress, there are 5 3-D machines in
use. Each machine has a total of thirty patients signed up for its
use at 15 minute intervals. This continues all day long on a five day
per week basis.
Combined with this are many patients undergoing initial testing
and both men and women undergoing treatment for various types of
cancer. I am told today that this facility has treated 11,412
patients with the 3-D equipment since 1990 and that I will be patient
#11,413. This is a massive backlog of experience of course and one which spins off great masses of data which was used to develop the advanced procedure of IMRT to ultimate perfection.
The atmosphere one senses, while waiting in the pleasant waiting
area, is one of scientific research facility. Along the corridors are
various rooms, each neatly identified with small lettering and all
with closed doors. Passing quietly down the corridors or working with
their scientific specialty in each of the rooms, is a staff of young
and vibrant medical and scientific personnel. This is a staff of the
best and the brightest drawn from medical schools all over the
nation. I would guess that the average age is in the range of
midthirties to midforties. I have never seen any one person whom I
would estimate was older than 55 although they must exist in some
region of this facility I have yet to explore.
My thoughts touch upon the aspect that here are the children of my
generation practicing the latest technology which will now save the
generation of their parents.
I had an initial meeting with Dr. Zelefsky, my radiation oncologist, who wanted a
report on my experience with the Hormonal Androgen Ablation treatment
to date. I reported that I have had virtually no adverse side effects
except perhaps some slight experience with hot flashes for 15 minutes
or so shortly after I retire. I have been taking the Casodex at about
7PM each night - the Lupron shot continues to work its magic through
the previous injection.
Dr. Zelefsky indicates that "You are lucky!". Some men report more
severe response to the treatment with longer and more prominent hot
flash episodes. I wonder if this is truly a side effect of the
treatment or a personal response by individuals who are likely to
cringe at any change in normal body chemistry or pain.
The objective of today's visit is to undergo the "simulation"
which will provide data for the 3-D machine to do its work properly.
I am led down one of the quiet hallways and behind one of the closed
doors into a room which more resembles a room for advanced and
specialized physics research. In the middle of the room sets a huge,
black, machine which seems to be resulting from the marriage between
a CT Scanner and an X-Ray machine. In front of the machine is a long
sliding table which can be positioned to give infinite adjustments in
body position to within millimeters. The identification tag on the
machine reads simply "Simulator".
The lights dim in the room and an two women begin their well
choreographed dance. As the room darkens I now see red beams of laser
energy shooting from the walls and ceiling to converge on the table
upon which I now lie. I am positioned into exactly the same position
I will assume upon the IMRT machine eventually. Lying face down I have
my legs raised about 4" and placed on foam blocks. A wedge template
is temporarily placed between my upper legs to produce an angle of
about thirty degrees.
Small marks are made on my body - one behind each knee one by the
outside if the right and left thigh, one on each side of my upper
inside buttocks at the base of the spine and one in midback. Each of
these benchmarks is now the target for one of the laser beams
crisscrossing across the room in the darkness. Using these reference
points, the position of my body is recorded with the precision of one
millimeter in any direction - the thickness of the laser beam.
Through all of this absolute stillness on my part is vital.
The two women then prepare to make a mold of my body. They take a
sheet of thermoplastic about 3 feet square to which is attached a
firm non thermoreactive edge on two sides. The sheet is then placed
in hot water and becomes soft. The softened sheet is then placed over
my back to cover an area between my lower back and upper thigh. The
calibrating wedge between my legs remains in place. The softened
plastic is then placed over my body by the two women feeling like a
hot turkish towel. It is worked into place and conforms to the exact
shape of my body. The two side edges, which contain about 8 - 1/2"
holes are then formed into flanges and bolted down to the table. This
will be the exact position my body will assume when I finally begin
the 3-D treatment and it can be duplicated exactly in another room
where the treatment will take place.
The mold is now removed but my body remains motionless with the
red lasers assuring that all of the benchmark targets are still being
hit perfectly. Each of the reference points on my body is then
tattooed with a small permanent dot about the size of a pin head. A
35mm flash camera is then used to record the exact location of the
tattooed marks in addition to the similar information recorded
elsewhere. My body is now essentially calibrated so that it can be
positioned to the EXACT same position during each of my subsequent
visits.
While I am positioned on the "Simulator" Dr. Zelefsky
makes an appearance. He advises me of something which gives further
credence to the wisdom of having this type of treatment done by a
facility which has thousands of prior patients - not simply hundreds
- certainly NOT a facility just beginning the treatment. Remember,
Memorial Sloan Kettering has done over 11,000 of these
treatments over 6 years. Yet the doctor has something to tell me
which is the product of the ever changing base of knowledge being
provided by the virtually endless stream of data accumulation being
generated by case studies.
The normal treatment is 42 sessions. In my case that would amount
to 75.6 Gray of radiation (7,560 Rads). It is well known that higher
radiation levels lead to better cure rates but this must be tempered
with great experience and precision to prevent collateral damage to
nearby organs.
Dr. Zelefsky now reports that, within the last week,
they have enough data to indicate that they can boost the radiation
to 45 treatments or 81.0 gray (8,100 Rads) without increasing
collateral damage. With patients having a PSA over 10 this assures
even a higher cure rate. I give him the O.K. to proceed in accordance
with the latest findings. My treatment will be on the cutting edge!
Having completed the calibration procedure, and mold making, on
the simulator, I now am taken to another "laboratory" containing a
Cat Scan and put under the supervision of two different young medical
personnel.
The lights dim and I find that I am once again reclining in the
same position as I had assumed with the simulator. The now familiar
red lasers crisscross the room from the walls and the ceiling, the
mold is refastened to my body and clamped down to the movable table
which feeds into the CT Scan machine. My position is exactly
identical to that I had taken earlier on the Simulator. It is
absolutely imperative that I remain absolutely motionless during the
20 minutes that the CT Scan takes cross sectional pictures of my
abdominal area. Following the session on the CT Scan I have an
opportunity to discuss some of the technical background with the
medical personnel - specifically, how this data is transferred into
the IMRT machine.
First, I am advised that MSK will soon be combining the
Simulator and the CT Scan in a single room. The patient will remain
in position, on the table, after the Simulator and will be rolled to
the CT Scan on a rail system so that repositioning will no longer be
necessary. At present there exists no satisfactory way to transmit
the data from the CT Scan into the IMRT machine which is a computer
controlled Linear Accelerator. This is done by making photographs of
the CT Scan data and then scanning them into the computer which
controls the IMRT machine.
Once programmed into the IMRT computer, this visual presentation of
my internal organs and prostate are studied by a physicist and my
radiation oncologist. A consultation is then held between my doctor,
the physicist, a computer programmer, and other pertinent staff
members to plan a specific treatment program custom designed to my
anatomy and my exact cancer geometry. The objective is to design a
program which focuses the high radiation beam exactly where it is
needed and to have it miss the areas where it could do damage.
Five planes of radiation will be oriented as follows:
While I am lying on my stomach the Zero Degree reference is a
plane perpendicular to my back. My right side will be 90 degrees. My
feet will be 180 degrees and my left side will be 270 degrees. The
procedure being used in my case is called "Multiplanal". A more exact
description might be "Pentaplanal Radiation".
The beam emits from a small rectangular shaped slot in the eye of
the collimator which focuses the radiation. As the beam travels
toward the patient it expands into an ever enlarging rectangular
shape as the distance increases - much the same as a rectangular
opening in the lens of a 35mm projector is seen on a screen.
Hence, the distance between the collimator and the patient becomes
another critical variable. Surrounding the slot in the collimator are
a number of shaping fingers which are computer controlled and which
both shape and block radiation from undesired areas near the primary
target.
So it is that the radiation filling the rectangular area, as it
strikes the patient, can be shaped into any configuration, including
cylindrical, and effectively blocked from striking organs which
should be protected from the radiation. As I learned last week the
radiation decreases in a gradient from the central target. It is
therefore impossible to have a high dosage immediately adjacent to a
very low dosage, but rather to reduce the damage to areas needing
protection as much as possible.
The gantry, containing the collimator, swings in an arc to allow
the radiation planes to enter the top, the sides, and the bottom of
my body. Specifically, the angles of the radiation planes are: 225 -
285 - 0 - 75 - and 135 degrees. The amount of radiation along each
plane may vary slightly but each plane delivers about the same
radiation dose of 36 RAD (Radiation Absorbed Dose) for a total of
180 RAD per session (1.8 Gray). The computer has calculated the
amount of radiation necessary to penetrate my body mass and to enter
the prostate adequately from planes along all of the selected angles
and still minimize exposure to other organs as much as possible. The
radiation planes focus on the prostate as a common target and stops
there.
Based on the data from the MRI, and various scans by the particle
accelerator and x-rays, the computer has generated a hard copy color
image of my prostate and has also overlaid all of the radiation
fields from the particle accelerator. To view the printed image is
the same as being able to see the combined effects of all five planes
of radiation simultaneously and to see a cross sectional view of the
prostate with all of the various segments of the radiation beams
broken into sub fields which are quantified by the percentage of
total radiation to be applied. All of this is presented in seven
colors for easy interpretation.
Moving outward from the prostate in nongeometric shapes are wave
forms which indicate radiation in five more decreasing levels down to
10%. The lower levels impinge upon organs for which minimal radiation
is desired. So it is that you can actually see the well defined
fields that the particle accelerator saturates with each treatment.
Once a week a series of "films" or negatives is taken of the prostate
using the same planes of radiation as the treatment itself to monitor
that the desired pattern is being maintained. In a precision
treatment like this great care is employed every step of the way to
insure perfection.
Hence, the prostate itself is surrounded by a tight yellow circle
which signifies that everything within that circle will receive the
full 8,100 RADS or 100% radiation. Several small "islands" within the
prostate itself are a darker orange which means they receive 107% or
8,670 RADS.
Now, the 12.5 mm between the top of the rectum and the prostate
seems like a mile when compared to a precise and calibrated energy
beam. Once the treatment procedure has been defined, it is placed
before a review panel and approved. This custom designed procedure is
then placed on a computer disk and will become the memory of the
computer's brain as it controls the IMRT machine during my treatment.
I will meet with my. radiation oncologist once a week to verbally
discuss my treatment as it proceeds.
About two weeks will be required to formulate a treatment program
for me. My next visit will be on April 10th 1997.
The specific program being designed for me is based upon a
technological innovation within the existing technology of 3-D
Conformal Radiotherapy. It is called Intensity Modulated Radiation
and employs the delivery of different intensity levels within the
intended target at which it is aimed.
During the next visit a computer program will be used to control a
machine similar to the IMRT machine but one which uses low energy
x-rays rather than high energy accelerated energy beams. With the
completion of this "dry run" the computer program will be confirmed
as will the other variables in the operation. Successful completion
of the "dry run" will lead to finally beginning treatment on the IMRT
machine within a day or two.
That treatment will proceed 5 days a week for 45 sessions which
will end in mid-June 1997. I had remarked to one of the medical
personnel in the CT Scan room that it was important to select the
best treatment facility available as well as the best possible form
of treatment. "Salvage Operations" after an unsuccessful treatment by
any method are either difficult or not particularly profitable. He
assured me that after this procedure there would be no "Salvage
Operation" since the success rate has been very high with over 11,000
treated at this facility and with still ever greater experience,
gained along, the way the success rate should improve.
I am pleased that I chose this method of treatment and I am VERY
impressed with the skill and precision of all the personnel I have
dealt with so far at this facility. My personal respect for Dr. Zelefsky
has been enhanced along the way on two fronts. (1) He is obviously a
dedicated and brilliant young man (2) He has been able to maintain an
excellent "common touch" with me - always treating me as an equal
with respect and dignity. Our rapport grows at every meeting. Along
the way I had met far too many doctors who thought they were special
creatures, and that the patient was something less than an equal
human being.
While riding back to my home on the train I reflected on an
overview of what has transpired so far and my reactions to events of
the past seven months since my last PSA test produced results of 15
- subsequently reduced to 10 by additional testing . Still - much too
high.
It had been a long road to reach this point in my adventure. I had
studied and had become very knowledgeable about prostate cancer and
all the various forms of treatment. I had chosen the IMRT technique
because it appealed to me as the best form of treatment for my case
while having the potential for the least negative side effects. My
path had led me through two hospitals, several Radiologists, four
different Urologists, and countless tests. There was the ever present
digital rectal exam (D.R.E) which seemed to almost take the place of
a handshake whenever I encountered a new doctor. There was the
repetitive blood testing. There was the Bone Scan and the MRI which
was like riding in a steel drum with someone pounding on the outside
with a hammer. Finally there was the "Simulation" and the CT Scan.
I am sure that patients look at all of this from different points
of view depending upon their own background. To some it is little
more than one unpleasant experience after another. To someone with
technical, scientific, or engineering training, it is nothing short
of fascinating. My personal training and experience, not to mention
scientific curiosity is making this a most fascinating adventure. I
have had training or experience in most of the disciplines I am now
encountering including: engineering, physics, mathematics, computer
technology, radiation, and plastics technology. So it is that I see
each of these experiences as a dance of scientific precision and
fascination. I see the laser beams tracing specific angles throughout
the air in a darkened room as a three dimensional problem in
trigonometry or analytic geometry reminiscent of two dimensional
problems I have solved before. I understand the photography and
imaging required. As well, I appreciate the computer technology
involved. At the base of all of this is the biochemistry involved
with the hormonal therapy and the biology of the cancer itself.
Combining all of these in an adventure in which YOU are involved
and are literally betting your life, is a fascinating experience.
As the train rumbled along toward home another vision appeared in
my mind. On this visit to Memorial Sloan Kettering I had gained entrance
to some of the inner sanctum. I had experienced things behind some of
those closed doors. However, I had yet to see the greatest machine of
them all - the IMRT machine.
While the Linear Accelerator is a fascinating piece of machinery,
it is the carefully crafted computer program, assembled by skilled
doctors, engineers, physicists, and scientists, and based on data
input from the patient's work up, that works the wonder of treatment
here. This program gives the Linear Accelerator the ability to send
out precise beams of radiation in an infinite number of different
directions, to focus these beams, to modulate them, and to control
them precisely through undulating and masking fingers which are
computer controlled in the eye or collimator of this amazing machine.
The simulation will provide information to the computer detailing
the exact position of the prostate, seminal vesicles, rectum, and
bladder. This information will be used to determine how the radiation
beams should enter the body, as well as the shape of the beams. The
radiation will be given from a rotating gantry which transverses an
arc of 180 degrees. The program is designed in such a way as to
permit the beams to bypass the critical organs, as much as possible,
but yet converge on the prostate to form a high dose region. As many
as 16 distinct and separate beams will be controlled by the computer
during this operation.
On April 10, 1997 the "Dry Run" took place. By this time, the
results of the Simulation had been evaluated by a team of
Radiologists, Medical Oncologists, and Physicists. The x-rays from
the Simulation plus the previous MRI studies were used to devise a
computer program which would be custom designed to treat my specific
prostate cancer. The treatment which will be based on exact
quantitative, targeted radiation and the determination of proper
angles for the radiation beams to strike the prostate while
minimizing damage to the adjacent organs.
This program is then copied to a 3 1/4" floppy disk which controls
the operation of the particle accelerator, the collimator which
focuses the particle beam, and the gantry which controls the angle at
which the radiation beams enter the body.
During the dry run all the systems are in place and I am
positioned on the table, face down, under my custom built mold. The
computer program operates the system, but only low powered x-rays are
used to check out the accuracy of the computer program.
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