Yttrium-90 is a radioisotope used in the medical industry for the Radioembolisationof malignant tumors in the liver such as hepatocellular carcinoma, HCC.
HOW IS YTTRIUM-90 PRODUCED? Yttrium-90 is produced through Beta Decay/high-purity separation of Strontium-90, which is a fission product of Uranium in a nuclear reactor (PNNL, 2013). When Yttrium-90 decay, it forms stable Zirconium-90. Yttrium-90 has a Half-Life: 64hrs and purely beta-emitter.
HOW IS IT DETECTED? Geiger-Mueller detector, NaI(Tl) detector or liquid scintillation counter are used in detection in the environment and labs (PerkinElmer, 2010). SPECT scans, of the abdomen, are used after the procedure to detect the Bremsstrahlung radiation from the yttrium-90 and to confirm the placement of the beads (Sirtex, 2014)
HOW IS IT USED? Yttrium-90 is used in the treatment of Liver Cancer's, by killing the cancer cells and shrinking the tumour. The Liver has two main blood supplies, the Hepatic Artery and the Portal Vein (75%). When a tumor grows it can receive all of its blood supply from the artery. By using Radioembolisation, tiny resin or glass microsphere’s filled with the radioisotopes are injected directly into the artery. These beads stay in the blood vessels around the timor and it receives strong radiation directly. Before the procedure a mapping angiogram, which takes 2-4, is undertaken and during this an anaesthetic is administered. A catheter is threaded through the artery in the groin and guided into the liver and a tracer is injected. The Angiogram picture help guide the catheter and help the doctors calculate how much Y-90 is needed specifically. If the body reacts well, 2 weeks later another catheter will be threaded to the liver and the beads will be injected and it takes 1 hour to complete (UW Medicine, 2012).
94% of the radiation is delivered in 11 days
Selective Internal Radiation Therapy
PROPERTIES THAT MAKE IT SUITED TO TREAT LIVER CANCER?
It is very useful because of it's relatively short half life, meaning it won't cause damage to the patient after treatment.
It's Beta radiation only travels through 11mm of liver.
Beta emitter
Because of these Properties, it is ideal to be used for selective internal radiation like Radioembolisation. Yttrium-90 ply has a short half life, which means it targets the cancer and doesn't linger in the body and therefore leaving extra radiation leading to radiation poisoning. The radiation waves can only penetrate 11mm, therefore kills the cancer and surrounding cells and not damaging healthy tissue.
BENEFITS / RISKS The benefits of Radioembolisation are:
Less invasive - not being cut open
Fewer side effects than traditional radiation therapy
Higher dose is given than external beam therapy
Patients with inoperable tumours can have their lives extended by months or years
Less external radiation released
The risks associated with Radioembolisation are:
Infection (1/1000)
Allergic reaction to the Y-90
Risks associated with the use of Catheter's
MIcrosphere's can lodge in the incorrect place
(RSNA, 2013) The risks associated with Radioembolisation are the same as any medical procedure. The benefit that it could extend a terminal patients life by months or even years out way the general risks.
SAFETY PRECAUTIONS
It is stored behind lead shielding. When in transport it is placed in Acrylic v-vial holder inside another acrylic
box. Yttrium-90 has two inbuilt safety features: minimal penetration depth and
it’s short half-life.
Only trained staff are allowed to use and handle the Y-90
Avoid it touching your skin by using proper PPE
Any waste products are properly disposed of outside of the hospital, but they are disposed of in radioactive purple bags