Towards personalized dosimetry with 32P microparticle therapy for advanced pancreatic cancer

Publication date: Available online 1 August 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Yaser Hadi Gholami, Nicole Wilson, David James, Zdenka Kuncic
PurposeThe aim of this study was to develop a Monte Carlo model for patient-specific dosimetry of ³²P microparticle Localized Internal Radionuclide Therapy (LIRT) for advanced pancreatic cancer.Methods and MaterialsSpherical tumor geometries and a pancreatic phantom were modeled, as well as different 3D non-uniform clinical pancreatic geometries based on patient-specific ultrasound images. The dosimetry simulations modeled the dose distribution due to the energy spectrum of emitted beta particles.ResultsThe average dose for small (3 cm diameter) and large (6 cm diameter) spherical tumors was 111 Gy (for 7.6 MBq administered activity) and 128 Gy (for 58 MBq), respectively. For the clinical 3D geometries, based on patient data, the mean doses delivered to the tumor were calculated to be in the range 102-113 Gy, with negligible dose to the pancreas for the smallest tumor volumes. The calculated dose distributions are highly non-uniform. For the largest tumor studied, the pancreas received ≈6% of the tumor dose (5.7 Gy). Importantly, we found that as the smallest tumor studied exhibited the most dynamic changes in volume in response to the treatment, the dose to tumor and pancreas is significantly underestimated if a static tumor volume is assumed.ConclusionThese results demonstrate the dosimetry of ³²P microparticle LIRT for pancreatic cancer and the possibility of developing personalized treatment strategies. The results also highlight the importance of considering the effects of non-uniform dose distributions and dynamic change of tumor mass during treatment on the dosimetry of the tumor and critical organs.

Teaser

A Monte Carlo particle simulation platform was developed to model the dosimetry of ³²P microparticle internal radionuclide treatment for advanced pancreatic cancer. Patient-specific dosimetry simulations based on data from previous ³²P microparticle clinical studies demonstrated the importance of considering non-uniform dose distributions as well as relative dynamic changes in tumor volume and dose rate during treatment. These results will be valuable in designing future personalized treatment strategies.


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