Local Alpha Cancer Treatment
Local Alpha Cancer Treatment - How does it work?
The alpha particles’ major benefit is their ability to destroy cancer cells in a highly localized manner. Yet, until the Alpha DaRT, this same short path length of alpha particles in tissue had made them unsuitable for the treatment of larger mass such as solid tumors.
What does "Alpha DaRT" Stand for?
Alpha DaRT stands for Alpha "Diffusing Alpha-emitters Radiation Therapy" and enables local alpha cancer treatment by overcoming the range limitation of alpha particles. Instead of using a radiation source which directly releases alpha particles, the technology uses a source that releases alpha emitters, atoms that emit alpha particles during their radioactive decay.
The Alpha DaRT technology is based on this process, specifically the decay of the atom Radium-224. Radioactive decay transforms the originating atom into a different element. A row of several decays is called a decay chain.
How is the Treatment Delivered?
In order to deliver the alpha radiation, small seeds similar in size to fiducial markers, are impregnated with Radium-224 and inserted directly into the tumor. Once the seeds get in touch with the tumor tissue, the Radium’s alpha-emitting daughter atoms exit the seeds and diffuse and disperse inside the tumor tissue to a therapeutically significant range of several millimeters. The daughter atoms then decay inside the tumor and "shoot out" high-energy alpha particles, providing a high dose of alpha radiation in a targeted, localized area inside the tumor, without harming the healthy tissue.
Alpha DaRT Technology
The Radium-224 Decay Chain
Radium-244’s decay chain, below, explains the process in more detail. The first alpha emitter that enters the tumor, Radon-220 (a short-lived novel gas) shoots out of the seed’s surface by recoil of the Radium’s alpha decay.
Radon-220 enters the tumors tissue and alpha-decays (half-life: 56 s) to Polonium-216. Polonium-216 (half-life: 0.15 s) then alpha-decays and turns into Lead-212. Lead having a longer half-life of 10.64 hours has the time to diffuse inside the tissue of the tumor and release its daughter atoms within a range of a few millimeters around the seed. The Lead’s daughter atoms are Bismuth-212 (60.6 min), Thallium-208 (3.05 min) and Polonium-212 (0.3 µs). Following a beta and alpha decay, Thallium and Polonium, respectively, transform to a stable atom, Lead-208.
Research has shown that the diffusing atoms reach a shorter range in healthy tissue than inside the tumors. This enables the treatment of critical areas that are in proximity to e.g., major blood vessels or vital organs.
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Image 11 - Radium-224 Decay chain