Program Information
90Y Microspheres Dosimetry Calculation with Voxel-S-Value Method: A Simple Use in the Clinic
F Maneru1*, A Otal2 , M Gracia3 , N Gallardo4 , J Olasolo5 , N Fuentemilla6 , L Bragado7 , M Martin-Albina8 , S Lozares9 , S Pellejero10 , S Miquelez11 , A Rubio12 , (1) Complejo Hospitalario de Navarra, Pamplona, Navarra, (2) Hospital Clinica Benidorm, Benidorm, Alicante, (3) Complejo Hospitalario de Navarra, Pamplona, Navarra, (4) Complejo Hospitalario de Navarra, Pamplona, Navarra, (5) Complejo Hospitalario de Navarra, Pamplona, Navarra, (6) Complejo Hospitalario de Navarra, Pamplona, Navarra, (7) Complejo Hospitalario de Navarra, Pamplona, Navarra, (8) ,,,(9) Complejo Hospitalario de Navarra, Pamplona, Navarra, (10) Complejo Hospitalario de Navarra, Pamplona, Navarra, (11) Complejo Hospitalario de Navarra, Pamplona, Navarra, (12) Complejo Hospitalario de Navarra, Pamplona, Navarra
Presentations
SU-E-T-2 (Sunday, July 12, 2015) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose:To present a simple and feasible method of voxel-S-value (VSV) dosimetry calculation for daily clinical use in radioembolization (RE) with ⁹⁰Y microspheres. Dose distributions are obtained and visualized over CT images.
Methods:Spatial dose distributions and dose in liver and tumor are calculated for RE patients treated with Sirtex Medical miscrospheres at our center. Data obtained from the previous simulation of treatment were the basis for calculations: Tc-99m maggregated albumin SPECT-CT study in a gammacamera (Infinia, General Electric Healthcare.). Attenuation correction and ordered-subsets expectation maximization (OSEM) algorithm were applied.
For VSV calculations, both SPECT and CT were exported from the gammacamera workstation and registered with the radiotherapy treatment planning system (Eclipse, Varian Medical systems). Convolution of activity matrix and local dose deposition kernel (S values) was implemented with an in-house developed software based on Python code. The kernel was downloaded from www.medphys.it. Final dose distribution was evaluated with the free software Dicompyler.
Results:Liver mean dose is consistent with Partition method calculations (accepted as a good standard). Tumor dose has not been evaluated due to the high dependence on its contouring. Small lesion size, hot spots in health tissue and blurred limits can affect a lot the dose distribution in tumors. Extra work includes: export and import of images and other dicom files, create and calculate a dummy plan of external radiotherapy, convolution calculation and evaluation of the dose distribution with dicompyler. Total time spent is less than 2 hours.
Conclusion:VSV calculations do not require any extra appointment or any uncomfortable process for patient. The total process is short enough to carry it out the same day of simulation and to contribute to prescription decisions prior to treatment. Three-dimensional dose knowledge provides much more information than other methods of dose calculation usually applied in the clinic.
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