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TH‐AB‐BRA‐11: Fear Not the Y‐90 Surgical Staff Dose
Author(s) -
Vanderhoek M,
McKenney S,
Huang S,
Harkness B
Publication year - 2015
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4926154
Subject(s) - medicine , liver transplantation , nuclear medicine , radiation dose , bremsstrahlung , brachytherapy , dose rate , dosimetry , radiation therapy , radiation transport , absorbed dose , monte carlo method , transplantation , radiology , medical physics , physics , photon , quantum mechanics , statistics , mathematics
Purpose: Patients with hepatic malignancies treated with ⁹⁰Y‐microsphere brachytherapy are often precluded from liver transplantation for 4‐weeks (∼10 half‐lives) following therapy. This delay protects surgical staff from potential radiation dose but negatively impacts patients who could benefit from early transplantation post‐therapy. We investigated the potential radiation dose to surgical staff performing early liver transplantation. Methods: Measured data from 30 treated patients were used to determine an average liver ⁹⁰Y‐radioactivity concentration (C avg = 60 µCi/cm 3 ) and average maximum patient surface exposure rate (R avg_max = 5.9 mR/h). Beta and bremsstrahlung dose rates at the liver surface were calculated from C avg and R avg_max respectively. These surface dose rates were compared with Monte Carlo (Geant4) simulated dose rates for a voxelized 1600 cm 3 liver (C liver = C avg ) containing a 5 cm diameter tumor (C tumor = 3C avg ). The radiation dose to the hands of a transplant surgeon (Dhand) handling a radioactive liver for 2‐hours was estimated using the calculated and Monte Carlo derived liver surface dose rates. D hand was determined at different time‐points post ⁹⁰Y‐therapy. Results: Transplantation performed at 1‐day and at 1‐week post ⁹⁰Y‐therapy resulted in D hand <100 mSv and D hand <20 mSv, respectively. At 1‐week post‐therapy, D hand was less than 5% of the annual occupational dose limit to the hand (500 mSv). Calculated D hand and Monte Carlo derived D hand agreed within 20%. At the liver surface, bremsstrahlung dose rates were less than 1% of beta dose rates. Location of the liver tumor did not have a significant effect on D hand . Conclusion: Potential radiation dose to surgical staff is low (<5% of annual limit) when performing liver transplantation in patients as early as 1‐week after ⁹⁰Y microsphere brachytherapy. Future work aims to improve dosimetry by incorporating patient specific imaging data of the ⁹⁰Y radioactivity distribution and by measuring dose to surgical staff via ring and body dosimeters.