1. This is a radiotherapy treatment for primary liver cancer specific ally for hepatocellular carcinoma (HCC)
   1. Therapeutic approach
      
      1. TheraSpheres Millions of tiny glass beads that are between 20 to 30 µm in diameter contain ⁹⁰Y or
      2. SIR-Spheres Millions of tiny resin spheres are between 22 to 42 µm labeled with ⁹⁰Y
      
      3. Administered directly to a vascular tumor
      4. Most of the particles go to the liver tumor because blood flow to the tumor is between 3 to 7 times greater when compared to the surrounding tissue
      5. Results in a crossfire of beta radiation directly to the tumor site
      6. This is a tumor down-staging agent and may lead to other therapeutic options
         1. Transplantation
         2. Resection
         3. Radio-frequency ablation
         4. Video on TheraSpheres - https://youtu.be/l3ZhcI20VhQ
         5. Video on SIR-Spheres -https://www.youtube.com/watch?v=1mWhQtD2cyc
   2. Procedure
      1. This type of procedure is called transarterial radioembolization (TARE)
      2. Catheter is inserted into the patient at the hepatic artery
      3. Contrast and fluoroscopy is applied to find the specific area of the tumor
      
      4. Application of ^99mTcMAA is to assess the biodistribution of particles prior to the TheraSpheres injection
         1. Hepatic shunting to other areas of the body must be assessed to assure that the beta charged spheres will mostly go to the tumor
         2. A small catheter is placed into the hepatic artery and coil emboization is applied to non hepatic arterial blood flow areas
         3. MAA is then injected and spot views of the lung and liver are taken ANT and POST. In addition whole body image can be squired. This is done to assess the biodistribution of the particles and determine the therapeutic dose of TheraSpheres
      5. Biodistribution of the particles
         1. Normal activity would indicate the area of the liver tumor with only a small amount of activity in the lungs
         2. Abnormal would show activity in the lungs and GI tract
         
         3. Given the ROIs drawn above a Lung Shunting Fraction (LSF) is applied to determine the shunting effect so that a therapeutic dose is assessed
      6. Calculation of the therapeutic dose
         1. Method 1 - determined by assessing the mass of the liver with the use of CT and/or ultrasound
            1. Average kg for a female is 1200 to 1400
            2. Average kg a male 1400 to 1500
         2. Method 2 - looks at the amount of MAA distributed in the liver and the lungs
         
         3. The above formula is applied to determine the amount to give to the patient
         4. Dose calculator for SIR-Spheres - https://smac.sirtex.com/
      
      7. Administration
         1. An acrylic box is used to assist in shielding the beta radiation
         2. The technologist is required to monitor all individuals leaving the room to assure that there is no contamination
         3. One the dose is administered the tubing and syringe should be measured in order to determine the exact dose be given to the patient
         4. TheraSphere Infusion training - https://youtu.be/WmRn-BkjiMU (23 minutes)
         5. SIR-Spheres basic administration - https://www.youtube.com/watch?v=1mWhQtD2cyc (6 minutes)
            
      8. Contraindication
         1. Vascular abnormalities and/or bleeding
         2. Liver dysfunction and pulmonary insufficiency
         3. Complete portal vein obstruction or altered MAA distribution
      9. Side effects
         1. Fatigue, pain, nausea, and loss of appetite
         2. Minor changes in liver enzymes
   3. Two types of TheraSpheres
   1. Resin based - SIR-Sphere
   2. Glass based - TheraSphere (MCV uses this)
   
   3. Is one better than the other? According to Boston Scientific TheraSpheres is preferred, based on the diagram above. Note - Boston Scientific owns this product

TheraSpheres video: https://btgplc.com/en-US/Home

SIR-Spheres video: https://www.sirtex.com/us/clinicians/about-sir-spheres-microspheres/mode-of-action/

More information can be found at the TheraSpheres website: http://www.nordion.com/therasphere/patients_us/about_therasphere.asp

Package Insert for TheraSpheres Link

Package Insert for SIR-Spheres (draft) Link