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Small-field Therapy Dosimetry Studies Using Alanine/EPR


NIST has an ongoing program in small-field therapy dosimetry studies using alanine/EPR.


An international protocol is under development by the IAEA and the AAPM to address the difficult problems of small-field dosimetry in radiation therapy (e.g., GammaKnife, IMRT, Cyber Knife, TomoTherapy), encountered when going from national standards in large reference fields to small fields, through the use of alanine/EPR dosimetry. The NIST currently provides measurement support for an ongoing survey of approximately 100 Leksell Gamma Knife (LGK) units worldwide in collaboration with the University of Pittsburgh Cancer Center, and is planning (1) the use of smaller alanine pellets to address smaller fields, and (2) the increase in sensitivity by appropriate use of EPR signal-generating reference material and more complex signal-analysis software. If successful, the use of small alanine pellets to characterize radiation treatment fields would significantly improve both the spatial resolution and accuracy of clinical dosimetry.

Author: Marc Desrosiers

Lead Organizational Unit: