This page contains answers to common questions handled by our support staff, along with some tips that we have found useful and presented here as questions. Please click on one of the following:
A. Please contact SeeDOS Ltd and we will help you through all of the stages.
A. Please contact SeeDOS Ltd and go to training on this web site for venues.
A. SeeDOS Ltd can advise on seed supply, please contact us using the Enquiry Form.
A. Customers have increasingly asked us for a list of items they need when starting a prostate implant program. Here is an outline of the categories of products to consider. Most of these items are available through SeeDOS Ltd. This list will be filled in with more detail in the future so check it when you visit again.
A. The next course is shown under training courses on this web site. Please contact SeeDOS for confirmation.
A. The 91230, IMRT Dose Verification Phantom was designed for TPS verification by 3D evaluation of:
C. Both other available phantoms allow measurement of the three bullet points above. However, the SeeDOS IMRT Dose Verification Phantom allows these measurements to be done in nearly any three dimensional position throughout the phantom whereas users are restricted to limited positions for other available phantoms due to their modular design.
C. One of the key benefits and features of the 91230 is the speed in which it allows you to accomplish these steps. Using the 91230 you can measure ion chamber, film and diodes in the same measurement. You must do 2-3 additional steps when trying to do this with other available phantoms.
A. This must be determined by the medical facility.
C. Both the 91230 and one of the other available phantoms are anthropomorphic which should help in both set up and comparison accuracy between the planned dose and measured dose. With multiple locations placement of chambers, film, and diodes at nearly any position within the 91230 you will have added assurance that the treatment will go as planned when delivered to the patient.
A. Film size is limited only by the size of the phantom (30 cm x 45 cm). Either ready pack or radiochromic film can be used. The Kodak® EDR2 film, 10” x 12”, is a commonly used ready pack film with a wide response range. GAFCHROMIC® MD-55 and HD-810 are commonly used radiochromic films.
C. All IMRT Phantoms can accept the same size films, however the 91230 can accommodate a larger area of usable film that can be used than any other phantom.
Q. How do I eliminate air gaps using ready pack film with the SeeDOS Code 91230 IMRT phantom?
A. The weight of the 91230 IMRT Dose Verification Phantom slabs completely prevent air gaps on film positioned in phantom. With over 100 users, there have been no reported cases of air gaps when customers have been surveyed.
C. Both other available phantoms use cumbersome clamps to squeeze their phantom pieces together to eliminate air gaps. This adds to the many pieces of both of their modular systems and increases time and effort in set up.
A. Yes. Coronal film placement provides the advantage of easy irradiation of reference marker points outside of the treated area for accurate comparison with the treatment plan dose. This allows fast comparison of film image with TPS since the reference marker points facilitate orientation of the film. The TPS can reconstruct an image in sagital or transverse planes. Coronal film views provide the best beam’s eye view since the patient is positioned A/P or P/A. As noted IMRT speaker Dr. Jack Yang states “We set up the 91230 IMRT Dose Verification Phantom in coronal view for film measurements specifically these measurements are relative. The coronal film view is the simplest way to view general comparisons to the treatment plan and to check for hot spots, isodose curve lines and to check the relative agreement between calculated vs. measured dose distribution. The coronal film view will not only show hot spots but will show the length of the hot spot over the critical viewing area rather than a slice that would be seen in a vertical plane.
C. Both other available phantoms have film placement in the vertical plane for sagital and transverse views. This is in the same view as the treatment plan default view and people then think this is the most beneficial. However, a single slice view is not as useful as an overall view when comparing the treatment plan dose to the measured dose as your comparison is designed to be a relative measurement with film. Both horizontal and vertical planes are acceptable methods of viewing. One of the other available phantoms has irradiation reference marker points as does the SeeDOS 91230. The other available phantom does not offer this feature.
In the 91230 IMRT Phantom, coronal film placement also offers the advantage of simultaneous ion chamber and film use since the planes are parallel. The use of ion chambers in the coronal plane, while film is in the transverse plane, is problematic because the planes are perpendicular.
A. No. Acrylic delivers the same accuracy as water equivalent materials using the established correction factors published in AAPM Task Group 21. We have simplified the conversion by combining all corrections into one straightforward correction factor that is included with each IMRT Phantom purchased. Acrylic is characterized in this publication for acrylic to water conversion for high-energy photon and electron beams.
C. One of the other available water equivalent phantoms is not characterized for each energy, other than for cobalt. Since acrylic is fully known and has published data for its conversion to water, there will be absolutely no inaccuracies of its equivalence once the conversion is applied. Some water equivalent phantoms may only be characterized for cobalt to ascertain their equivalence to liquid water. Since exacting measurements are essential when dealing with the small field sizes in IMRT, it is important to know the true equivalent properties to liquid water that the published acrylic to water conversion provides. Also, the transparency of the acrylic offers exceptional visualization, leading to more accurate placement of film, chambers, and diodes.
C. Both alternative phantoms available offer six different measuring devices as well. The benefit of the SeeDOS 91230 is that all measuring devices can be measured simultaneously whereas the other phantoms require separate measurements to be used depending on which module you have in place.
A. Yes, the Chamber Phantom Slabs and the Acrylic Phantom Slabs have radiused corners and edges that are designed to eliminate CT imaging artifacts. Its anthropomorphic shape also allows additional benefits to this end.
C. One of the alternative IMRT phantoms available has no CT imaging artifacts the other has CT imaging artifacts.
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