P&CP has implemented programs at several sites that are now using IGRT routinely. Clinically, the P&CP staff has developed IGRT policies and procedures, QA implementation and RTT staff education.
The introduction of Intensity Modulated Radiation Therapy (IMRT), with its inherent capability of close conformity of the dose around a treatment target, led to the introduction of Image Guided Radiation Therapy (IGRT). Forms of IGRT have been utilized for years as part of Stereotactic Radiation Surgery (SRS) as well as in Respiratory Gating; however, it was the introduction of IMRT which expanded the techniques and available technology necessary to make IMRT feasible in the community clinic.
The tighter treatment margins inherent in IMRT demand an accurate isocenter placement for every fraction of a patient’s treatment. Additionally, this accuracy may be documented both for legal and billing purposes.
Currently, there is a wide array of products under the IGRT banner. They can be broadly classified into one of two groups.
1) Products utilizing non-ionization techniques (such as ultrasound or video cameras)
2) Products utilizing ionization methods (such as MV or kV imaging).
Both groups follow similar steps – the patient is positioned, imaged and then, if necessary, shifted to position the treatment area precisely.
The ionization techniques in general are more integrated and more dependent on the accelerator at your center. Techniques range from (a)orthogonal images taken with an Electronic Imaging Portal Device (EPID) with manual registration of bony landmarks to (b)orthogonal images with an On-Board Imager (OBI) with automatic registration of implanted fiducial markers (i.e. seeds) to (c)Cone Beam CT (CBCT). Implementation of this group begins with an evaluation of the capabilities of the current accelerator and, if needed, possible upgrade paths available.
The non-ionization techniques are more independent of the accelerator but usually have vault specific installation requirements. Techniques range from (a)acquired ultrasound images are manually registered with planning CT-based structures with a mechanical attachment to the accelerator couch to (b)ultrasound images acquired with automatic registration of CT-based structures with infrared cameras to monitor table shifts to (c)rigid video cameras used to identify external fiducial markers and monitor any shifts needed. Normally, centers utilize this group if significant upgrades or replacement of accelerator is needed to implement the ionization group.
Other, less popular systems use small implanted fiducial radio-transponders. This allows for tracking movement during treatment.
We have extensive experience with both ionization and non-ionization IGRT products from multiple vendors, utilizing multiple platforms. We can assist in IGRT product evaluations and recommend the most effective options based on both clinical feasibility and cost. After the decision has been made, we can provide acceptance testing services and assist in clinical implementation of your installed IGRT choice.
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An independent, confidential radiation therapy physics auditing program
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Why should your clinic have an independent medical physics audit?
P&CP offers you a safe and efficient auditing system to ensure a sustainable safeguard of your QA program.
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“P&CP has performed exceptionally well in commissioning our new equipment and technology efficiently through experienced physicists with varied backgrounds and resources.”
Karen Johnson
Radiation Oncology Manager Presbyterian Cancer Services/Charlotte, NC |
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