Dose Mapping Systems for 3D Conformal Radiation Therapy and Intensity Modulated Radiation Therapy

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MPD Completed on March 19, 2014

Objective for MPD A.3.4

  • Establish standards for 3D dosimetry, quality assurance and treatment verification for conformal radiation therapy.

Background: Recent rapid advances of three dimensional (3D) Conformal Radiation Therapy (3D CRT) and Intensity Modulated Radiation Therapy (IMRT) have created an urgent need for the introduction of high-resolution three-dimensional methods of dosimetry, quality assurance and treatment verification. Conformal treatment techniques can deliver escalated doses to the lesion while minimizing the dose to the surrounding tissues, thereby potentially increasing the so-called therapeutic ratio, which is a measure of the likelihood that the disease will be controlled while minimizing radiation-induced complications. Tissue equivalent gels which either undergo color-body formation or an inter-polymer phase change have been found to be effective in indicating conformal dose mapping.

Needs: A single most important objective for new measurement protocols that are needed should be the development of a reliable system of data correlation between the 3D treatment plan and the 3D phantom measurement. The new system should be readily accessible to medical physicists in hospitals, as these measurements would be used on a routine basis to confirm the quality and safety of conformal radiation therapy equipment, typical treatment protocols and possibly even individual treatment plans. These new measurement protocols would have to be standardized and traceable to measurements performed periodically at NIST or at Accredited Dosimetry Calibration Laboratories (ADCLs).

To meet these needs, standards are needed for phantom design and composition and for their calibration to national reference sources. Software capable of easily translating phantom response via instrumental analyses to absorbed dose is needed. This also involves the development of appropriate measurement protocols and their correlation with patient treatment results.

Despite having been noted in previous CIRMS “National Needs Reports,” activities in the areas addressed by this MPD have been limited to a few research and development projects funded by the National Institutes of Health (NIH), mostly through its Small Business Innovative Research (SBIR) awards.

Action Items:

1 – Establish a system for gathering data and correlating data between 3D treatment plans and 3D phantom measurements. (ongoing efforts at MD Anderson)

2 – Improve 3D phantoms through the use of fiducial markers so that dosimetry can better correlate with treatment plans.

3 – Develop user-friendly computer software for handling data generated by radiation treatment plan (RTP) and 3D dosimetry.

4 – Establish 3D dosimeter calibration protocols such that the absorbed dose response varies <2% in inter-laboratory comparisons.

5 – Develop quality assurance, acceptance testing and commissioning measurement protocols that lead to patient treatment verification.

6 – Conduct workshops and seminars to bring together diverse organizations needed to accomplish the desired goals, including participation from universities, government agencies, e.g. NIH, FDA, NIST, and ADCLs and interested private companies.

Resource Requirements:

1 – A firm commitment to a minimum of 5 person-years, preferably at least 10, over the next four year time period is required to make substantive progress in this area. Resource commitments are needed from government agencies and laboratories, from universities and from private companies working in collaboration with each other.

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