Investigation of a measurement-based dosimetry approach to beta particle-emitting radiopharmaceutical therapy nuclides across tissue interfaces.

In this work, we present and evaluate a technique for performing interface 
measurements of beta particle-emitting radiopharmaceutical therapy agents in solution.
APPROACH: Unlaminated EBT3 film was calibrated for absorbed dose to water using a NIST 
matched x-ray beam. Custom acrylic source phantoms were constructed and placed above 
interfaces comprised of bone, lung, and water equivalent materials. The film was placed 
perpendicular to these interfaces and measurements for absorbed dose to water using solutions of 
90Y and 177Lu were performed and compared to Monte Carlo absorbed dose to water estimates 
simulated with EGSnrc. Surface and depth dose profile measurements were also performed.
MAIN RESULTS: Surface absorbed dose to water measurements agreed with predicted results 
within 3.6 % for 177Lu and 2.2 % for 90Y. The agreement between predicted and measured absorbed 
dose to water was better for 90Y than 177Lu for depth dose and interface profiles. In general, 
agreement within k = 1 uncertainty bounds was observed for both radionuclides and all interfaces. 
An exception to this was found for the bone to water interface for 177Lu due to the increased 
sensitivity of the measurements to imperfections in the material surfaces.
SIGNIFICANCE: This work demonstrates the feasibility of using radiochromic film for 
performing absorbed dose to water measurements on beta-emitting radiopharmaceutical therapy 
agents across material interfaces.