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| Liu
Consistency Phantom (LCP) - Catalog # 0312 |
Consistency
Output Check
Photon Beam QA • Electron Beam QA
Field Symmetry and Flatness Measurements |
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"
Your Daily Quality Assurance performed with
Ease and Confidence! "
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| Features: |
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Water
based system, |
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Chamber placement
is consistent from week to week, |
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Set-up is quick
and easy, |
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Built to customer’s
specifications. The chamber holder is made for
your particular chamber, |
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Perform the laser
alignment check at the same time, |
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For physicists
that cover more than one facility, the phantom
can be transported without water, thus lightweight, |
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Economical. Multi-treatment
rooms facility can easily afford to keep one phantom
in each treatment room, so the phantom is always
in temperature equilibrium,
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No assembly required, |
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Sturdy construction. |
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| Description: |
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small portable Liu Consistency Phantom (LCP) is an acrylic
cube with three custom-made ionization chamber holders
for your particular chamber. The phantom is 15cm3 (outside
dimension). Thin, 5.0cm x 5.0cm windows are milled at
the center of four walls. The probe holders are at depths
of 1.0, 2.0, 5.0 and 10cm from the four windowed surfaces
respectively. There are two small filler holes to facilitate
the filling and emptying of the phantom with water.
Cross hair and the outline of a 10cm x 10cm field are
inscribed on the four windowed walls. |
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Technical Specifications:
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Overall Size:
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15cm3 (outside dimension) |
Field Size:
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10.0cm x 10.0cm |
Window Size:
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5.0cm x 5.0cm |
Window Thickness:
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1.0mm |
Chamber Distance “A”
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1.0cm |
Chamber Distance “B”
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2.0cm |
Chamber Distance “C”
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5.0cm |
Chamber Distance “D”
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10.0cm |
Overall Weight: (empty)
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0.8Kg (1.8lbs) |
Overall weight: (full)
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3.6Kg (7.9lbs) |
Materials used:
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Clear Acrylic |
| (Ionization Chambers are not included) |
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| LCP
- Instructions For Use |
| Photon Beam QA |
Electron Beam QA |
Field Symmetry QA |
| 1. |
;Fill the phantom with water, take care
not to have any air pockets inside the phantom. |
| 2. |
Let the phantom stay in the room until it
is at temperature equilibrium. (Normally,
you would just leave the water filled phantom
in the treatment room). |
| 3. |
Place the phantom on the treatment couch;
insert the ionization chamber into the 5.0
cm depth holder. |
| 4. |
With the mechanical distance indicator in
place, raise the treatment couch until the
top of the phantom is at 100cm SSD or whatever
SSD you used during the initial set-up procedure.
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| 5. |
Line up the projected cross hair with the
inscribed cross hair of the phantom. |
| 6. |
The side lasers should project at the centers
of the two inscribed cross hairs on the sides
of the phantom, if the 100 SAD technique was
used. (Laser alignment check). |
| 7. |
Set the collimator to 10cm x 10cm or whatever
collimator setting you used during the initial
set up. Align the field light with the inscribed
10cm x 10cm field of the phantom. |
| 8. |
Connect the ionization chamber to your electrometer. |
| 9. |
Expose the phantom with 200MU of the beam
that you are testing. Repeat this step until
you are satisfied with the readings. |
| 10. |
Take the temperature and pressure readings. |
| 11. |
The average reading (R5.0cm) multiplied
by the temperature pressure correction factor
should be compared with your established reading.
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| 12. |
Now, turn the phantom upside down and repeat
step 5, 6 and 9. |
| 13. |
The average reading (R10cm) divided by (R5cm)
should be the energy ratio. This ratio can
be compared with the one you established earlier.
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| 1. |
Fill the phantom with water, take care not
to have any air pockets inside the phantom. |
| 2. |
Let the phantom stay in the room until it
is at temperature equilibrium. (Normally,
you would just leave the water filled phantom
in the treatment room). |
| 3. |
Place the phantom on the treatment couch;
insert the ionization chamber into the 2.0
cm depth holder. |
| 4. |
With the mechanical distance indicator in
place, raise the treatment couch until the
top of the phantom is at 100cm SSD or whatever
SSD you used during the initial set-up procedure.
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| 5. |
Line up the projected cross hair with the
inscribed cross hair of the phantom. |
| 6. |
The side lasers should be projected at the
centers of the two inscribed cross hairs on
the sides of the phantom, if the 100 SAD technique
was used. (Laser alignment check). |
| 7. |
Insert the appropriate electron cone and
/ or set the collimator to the appropriate
size. |
| 8. |
Connect the ionization chamber to your electrometer.
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| 9. |
Expose the phantom with 200 MU of the beam
that you are testing. Repeat this step until
you are satisfied with the
readings. |
| 10. |
Take the temperature and pressure
readings. |
| 11. |
The average reading (R2.0a) multiplied by
the temperature pressure correction factor
should be compared with your established reading. |
| 12. |
Now, add the pre-determined amount of build-up
material onto the top of the phantom. Lower
the couch until the top of the added material
is at 100cm SSD or the established SSD. |
| 13. |
Repeat steps 5 and 9. |
| 14. |
The average reading (R2.0b) divided by (R2.0a)
should be your energy ratio for the beam. |
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| 1. |
After the completion of the output and energy
ratio measurements of the beam, move the couch
perpendicular to the axis of the chamber until
the cross hair is projected on the edge of
the phantom. |
| 2. |
Open the collimator to 20cm x20cm. |
| 3. |
Expose the ionization chamber to 200MU;
record the reading. (Rleft) |
| 4. |
Move the phantom to the opposite side until
the cross hair is projected on the other edge
of the phantom. |
| 5. |
Expose the ionization chamber to 200 MU;
record the reading. (Rright) |
| 6. |
Turn the phantom 90 degrees. Align the center
with the projected cross hair. |
| 7. |
Move the couch perpendicular to the axis
of the chamber until the cross hair is projected
on the edge of the phantom. |
| 8. |
Expose the ionization chamber to 200MU;
record the reading. (Rin) |
| 9. |
Move the phantom to the opposite side until
the cross hair is projected on the other edge
of the phantom. |
| 10. |
Expose the ionization chamber to 200 MU;
record the reading. (Rout) |
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The ratio of (Rleft) / (Rright) and (Rin)
/ (Rout) are representative of the transverse
and radial symmetry and flatness of the field.
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This phantom was developed by
James Liu, Ph.D.FACR Providence St. Joseph
Medical Center Burbank, CA |
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