Program Information
Y-90 Microspheres (SIR Spheres) for Treatment of Liver Metastasis : Technique
M Nair1*, (1) ,
Presentations
SU-E-T-402 Sunday 3:00PM - 6:00PM Room: Exhibit HallPurpose:The purpose of this presentation is to discuss the radiation safety and dosimetric technique used for the therapeutic procedure using Y-90 microspheres through intra -arterial administration on patients with liver metastasis
Methods:The radiation dosimetry, technique and safety aspects of 14 patients with primary and metastatic liver cancer, treated with Y-90 microsphere (SIR spheres) are discussed. The liver and tumor volumes were determined using the CT and MR scans . The images were imported into the treatment planning system and the liver and tumor volumes and the volume of the liver affected were outlined and the volume calculation was performed using the software. The lung shunt fraction (LSF) and tumor to liver uptake ratio (TLR) were determined using the nuclear medicine SPECT imaging with Tc-99m MAA. The absorbed dose to the target volume in liver was calculated using the following equation:
Dose β (Gy) = C x Eβ x 5.92 x 10-6 (Gy/s) x T(1/2)(days) x 1.44 x 8.64 x 104 (s)
The distribution of activity in the tumor bed was confirmed by post Y-90 administration imaging using the Bremsstrahlung peak at 30% window. The patient and the procedure room were surveyed and radiation safety instructions were given to the patient
Results:The tumor volume ranged from 77 cc to 700 cc, tumor to liver uptake ranged from 3 to 12. The lung shunt fraction varied from 1.08% to 9.0%. The activity administered ranged from 1.0GBq to 2.5 GBq, . The radiation survey in contact with the patient ranged from 1.8 mR/hr to 2.5 mR/hr and reading at 1 meter was less than 0.2 mR/hr
Conclusion:The technique for radiation dosimetry and radiation safety for Y-90 microsphere therapy is established. The post treatment imaging helped to confirm the distribution of Y-90 microspheres inside the tumor bed.
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