Selective Internal Radiation Therapy (Clinical Case example using Therasphere™) Dr Richard J Owen – Interventional Radiology Associate Professor University of Alberta Canada

Right lobe tumor, Hepatitis B patient presenting with a mass on ultrasound Confirmed at biopsy to be hepatocellular carcinoma, unusually high activity on PET Ct Prior to the treatment. (only about 15% of HCC’s are PET avid).

Pre procedure angiography Catheter angiography, tip proximal to GDA demonstrating anatomy. Catheter advanced distally in next image. Prior left lobe resection for HCC.

Pre procedure angiography Highly vascularized right lobe tumor is seen. No abnormal vessels supplying outside the liver are seen, Catheter tip is distal to left hepatic and Gastroduodenal. No embolization to redirect flow necessary

CTA with catheter in right hepatic artery Intense tumor blush on the delayed (20 seconds post intra arterial injection) in right posterior lobe (Segment 7)

Nuclear Medicine Shunt study with SPECT CT Demonstrates significant (15%) lung shunt, this will require careful calculation to ensure lung dose does not exceed 30 Gray for a single treatment or 50 Gray for cumulative lung dose

Calculation of Dose The liver volume and corresponding mass determined using CT, either a direct CTA with catheter in situ or good dual phase liver mass CT. Radioactivity required: GBq (1 x 109 decays/sec) [Desired Dose (Gy)][Treatment Vol (L][1.03] 50 Dose to lung (Gy) = [treatment dose GBq][lung shunt %][50] 1 <50 Gy total <30 per rx Delivery of the desired activity is accomplished by using the Yttrium-90 Physical Decay Table to determine the appropriate time of injection.

Decay Chart, activities relate to 10am Standard time

TheraSphere System Ready for Assembly Administration (single use) tubing set located in blister pack acrylic shield to house the dose, tubing and waste various consumables – supplied by hospital radiation meter – supplied by hospital

Post Y90 low dose PET (treatment day) Activity concentrated in the region of the right libe tumor confirming a correct dose delivery, this is carried out after the treatment and takes advantage of the tiny proportion of Y90 decays that result in positron emission.

Follow up CT 2 months after treatment Arterial and venous phase imaging demonstrates complete tumor necrosis, rim enhancement on the arterial phase is likely radiation induced injury to adjacent liver parenchyma

Follow up Ct at 7 months Shrinkage and confirmed necrosis of right lobe tumor. Unfortunately there is tumor recurrence adjacent to the liver resection margin anteriorly. This could not be treated.