Andrew S. Kennedy

Patrick McNeillie

William Dezarn

 244  Background: 90Y-microsphere brachytherapy for unresectable hepatic cancers is an increasingly popular therapy. The beta radiation dosimetry involved is not well understood and there is lack of pre and post treatment planning capabilities.  Methods: A phantom was developed with tissue equivalent electron density, accurate anthropomorphic size, shape and volume to an adult human liver, with similar properties in response to heat, cold, radiation and diagnostic imaging as human liver tissue. Space-occupying masses were created to accommodate implantation of microspheres to simulate a human treatment. Imaging included MRI, CT and SPECT gamma scans pre and post implantation of 90Y-microspheres.  Results: A phantom was produced that was shaped from a mold of an adult human liver. A mass with a different density than the liver was created in the right lobe that had a 3mm – 6mm rim for microsphere implantation. A known quantity of 99mTc was implanted into the left lobe. 90Y-microspheres of known activity were implanted in the periphery of the right lobe tumor. CT contrast was mixed with the microspheres to improve localization on subsequent CT scans. The electron density of the phantom was identical to human liver. Microsphere implantation was limited to the outer 6 mm of the right lobe tumor and 99mTc limited to the left lobe. Spatial resolution in 3D was excellent on all three modalities (MRI, CT and SPECT gamma).  Conclusions: A human liver phantom as described will be a useful tool in future studies of beta radiation dosimetry, cross sectional and nuclear imaging and tissue responses. The next generation phantom is being developed with blood vessel-like branching channels to allow fluids to pass into and through the phantom similar in scale and diameter to hepatic vessels and tumors. </jats:p

Development of a tissue-equivalent human liver phantom for 90

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