Complex Dosimetry Check
A Complex Dosimetry Check (CDC) is required for each new protocol involving IMRT / SBRT / VMAT / TomoTherapy. It can be performed by two means:
- either a site orders a specific IMRT phantom (carrying films and TLDs), scans it, plans it, irradiates it and then sends it back for evaluation (end-to-end check), or
- the site irradiates its own in-house IMRT phantom, based on a provided plan, and sends the measurements and TPS dose files for evaluation.
CDC credentialing ensures that the institution has correctly implemented the advanced technique within their practice. This increases the likelihood that the quality of radiation treatment provided to EORTC trial patients is at the highest standard.
CDC Credentialing is granted for the combination of treatment planning system and algorithm, treatment unit and technique. Currently, treatment units are distinguished as: Linac and Rotational. IMRT techniques are distinguished as Static (step and shoot), dynamic and rotational. These IMRT techniques are further subdivided into flattening filter free and flattened beams.
A successful CDC is valid for IMRT accreditation in a trial.
A repeat credentialing exercise for a new trial is required when either:
- any of the combination parameters change
- the gamma index criteria for a specific trial to which the institution wants to participate is not met
- the disease site credentialed for is not deemed comparable (complexity of treatment) to that of the trial to which the institution wants to participate
Mailed Phantom Procedure
Third party phantoms for CDC accreditation may be necessary for specific studies. When necessary, sites wishing to participate in a trial will directly contact the provider of the service to arrange for delivery and re-sending of the irradiated phantom. Results provided by the third party will be forwarded to the EORTC and serve as the basis for credentialing.
Virtual Phantom Procedure
This procedure uses a “Virtual” phantom as opposed to a “real” phantom. The Virtual Phantom Procedure is very similar to patient QC procedures carried out for the treatment of complex techniques where a patient’s plan is transferred onto an IMRT QA phantom, recalculated and then irradiated according to plan. The delivered dose is then compared to the calculated dose to assess metrics such as DtA or the gamma index. In the context of an EORTC clinical trial, the plan transferred and recalculated is usually the same plan submitted for the Benchmark Case.
The measured and planned data are sent to EORTC for processing with acceptance criteria depending on the study characteristics, disease site and technique; a frequent criterion for acceptance is a 3 mm / 3 % gamma analysis with 95% compliance.