Treating Cancer With Precision
Technology
The Alpha DaRT Technology
As known in the medical community, Alpha particles are highly lethal to cancerous cells, creating complex double-strand DNA breaks. Only a few hits to the cell nucleus are required to kill the cancer cell. However, as a result of their short range in tissue, Alpha particles had been unsuitable for the treatment of cancer.
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Alpha DaRT overcomes this range limitation and enables Alpha radiation for the treatment of solid tumors. The treatment is delivered by intratumoral insertion of the Alpha DaRT seed that contains Radium-224 atoms embedded below its surface. In the process of decay, Radium-224 releases its short-lived Alpha-emitting atoms into the tumor. By diffusion and convection, these atoms disperse to a therapeutically significant range of several millimeters, delivering a high dose of radiation inside the tumor.
The Radium-224 Decay Chain
The Alpha DaRT Technology was developed in 2003 at Tel Aviv University. Since then, numerous preclinical studies have found the technology to be effective and safe for various indications, including tumors that are considered to be resistant to standard radiotherapy.
The findings were published in 12 papers in peer-reviewed scientific journals.
Developed by Leading Scientists at Tel Aviv University
The Difference Between Alpha, Beta and Gamma Radiation
Radiation Therapy for Cancer?
Radiation therapy, the use of high-energy particles or waves, such as x-rays, gamma rays, electron beams, or protons, has long been used to treat cancer. From as early as the 20th Century, physicians have given regular doses of radiation to greatly improve the patient’s chance for cure. From physicists Wilhelm Roentgen
Marietta Blau, Nuclear Physicist 1925 who first discovered the X-ray, to Marietta Blau, who contributed significantly to the fast development of medical and industrial applications of radiation, especially alpha radiation.
Image 1 - Marietta Blau, Jewish Nuclear Physicist 1925
Alpha DaRT Technology​
Benefits of Alpha Radiation for Cancer Treatment
At its basic form, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. Alpha, beta and gamma radiation are all types of ionizing radiation – a type of radiation that carries enough energy to detach electrons from atoms or molecules.
Dependent on the radiation type, its source, speed, and size provide a good indicator for understanding how far each type of radiation can travel and the associated damage it can cause to cells. For this reason, it is highly important that methods of cancer treatment are adapted to utilize the advantageous properties of different radiation types.
Image 2 - Range of Alpha, Beta and Gamma Radiation
For example, gamma radiation has a very long range that can penetrate the human body unhindered and can travel several hundred meters in the air. In contrast, alpha radiation has a very short range traveling only a few centimeters in air. In fact, alpha particles are stopped by a thin sheet of paper or by the skin, see Image 2.
The long range of gamma radiation to penetrate through tissue makes it highly suitable for external beam radiation therapy, that directs high-energy rays from outside the body into the tumor, without the need for surgery.
However, when using external-beam radiation healthy tissues are unavoidably exposed to radiation. For this reason, advances in cancer radiation therapy have aimed to provide new ways to both lower the dose to produce the same therapeutic response, while providing a more targeted and localized activity for improved patient outcomes and reduced cost.
The unique properties of alpha radiation compared to beta and gamma radiation, are making it a highly effective treatment approach for localized and targeted radiation therapy. See Table 1 to understand the characteristics of the different radiation types.
Table 1 - Comparative characteristics between alpha, beta and gamma radiation
LET
When considering radiation effectiveness, a good measurement is to look at the radiation’s linear energy transfer (LET). LET is defined as the average amount of energy that is lost (and deposited) per unit path-length as a charged particle travels through a given material; in other words, in cancer treatment, the capability of the radiation to efficiently kill the tumor cells and its range inside the tissue.
Low LET radiation types such as X-rays, gamma rays and beta particles deposit a relatively small quantity of energy. On the other hand, high-LET particles, including protons and alpha particles, deposit more energy on the targeted areas and therefore are significantly more effective in killing cancer cells.
The Difference Between Alpha, Beta and Gamma Radiation
Radiation Therapy for Cancer?
Radiation therapy, the use of high-energy particles or waves, such as x-rays, gamma rays, electron beams, or protons, has long been used to treat cancer. From as early as the 20th Century, physicians have given regular doses of radiation to greatly improve the patient’s chance for cure. From physicists Wilhelm Roentgen
Marietta Blau, Nuclear Physicist 1925 who first discovered the X-ray, to Marietta Blau, who contributed significantly to the fast development of medical and industrial applications of radiation, especially alpha radiation.
Image 1 - Marietta Blau, Jewish Nuclear Physicist 1925
Alpha DaRT Technology​
Benefits of Alpha Radiation for Cancer Treatment
At its basic form, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. Alpha, beta and gamma radiation are all types of ionizing radiation – a type of radiation that carries enough energy to detach electrons from atoms or molecules.
Dependent on the radiation type, its source, speed, and size provide a good indicator for understanding how far each type of radiation can travel and the associated damage it can cause to cells. For this reason, it is highly important that methods of cancer treatment are adapted to utilize the advantageous properties of different radiation types.
Image 2 - Range of Alpha, Beta and Gamma Radiation
For example, gamma radiation has a very long range that can penetrate the human body unhindered and can travel several hundred meters in the air. In contrast, alpha radiation has a very short range traveling only a few centimeters in air. In fact, alpha particles are stopped by a thin sheet of paper or by the skin, see Image 2.
The long range of gamma radiation to penetrate through tissue makes it highly suitable for external beam radiation therapy, that directs high-energy rays from outside the body into the tumor, without the need for surgery.
However, when using external-beam radiation healthy tissues are unavoidably exposed to radiation. For this reason, advances in cancer radiation therapy have aimed to provide new ways to both lower the dose to produce the same therapeutic response, while providing a more targeted and localized activity for improved patient outcomes and reduced cost.
The unique properties of alpha radiation compared to beta and gamma radiation, are making it a highly effective treatment approach for localized and targeted radiation therapy. See Table 1 to understand the characteristics of the different radiation types.
Table 1 - Comparative characteristics between alpha, beta and gamma radiation
LET
When considering radiation effectiveness, a good measurement is to look at the radiation’s linear energy transfer (LET). LET is defined as the average amount of energy that is lost (and deposited) per unit path-length as a charged particle travels through a given material; in other words, in cancer treatment, the capability of the radiation to efficiently kill the tumor cells and its range inside the tissue.
Low LET radiation types such as X-rays, gamma rays and beta particles deposit a relatively small quantity of energy. On the other hand, high-LET particles, including protons and alpha particles, deposit more energy on the targeted areas and therefore are significantly more effective in killing cancer cells.
The Difference Between Alpha, Beta and Gamma Radiation
Alpha Radiation
Physical Origin
Alpha radiation is released when an atom undergoes radioactive decay, giving off a particle (called an alpha particle) consisting of two protons and two neutrons (essentially the nucleus of a Helium-4 atom).
Image 3 - The alpha particle consists of 2 neutrons and 2 protons
It transforms the originating atom to a different element with an atomic number 2 less and atomic weight 4 less than it started with.
Process of Decay
Image 4 - Alpha decay and recoil
Size, speed and range
Due to their positive electric charge and heavy mass, alpha particles interact strongly with matter and travel slowly. Alpha particles have an extremely short range reaching only a few centimeters in air and are unable to penetrate the natural protective barriers of our skin (clothing can stop alpha particles). Inside cell tissue, alpha particles have a range of only 50-90 μm (equivalent to a few cell diameters).[i]
Effect on cells
Typically, alpha particles have a LET that is about 100 to 1000 times greater than the average of beta particles. This provides a much greater potential for biological damage. As a result of alpha particles higher Relative Biological Effectiveness (RBE), a significantly lower dose of alpha radiation is needed to achieve the same amount of biological damage compared to other radiation forms.​[ii]
When alpha particles hit a cell nucleus, they cause DNA double-strand breaks. These breaks result in changes in the normal structure of chromosomes, that carry our genetic information and prevent cells from replicating. The DNA double-strand breaks created by alpha particles have been found to be highly complex, more concentrated and more resistant to cell repair mechanisms, and thus more destructive than double-strand breaks caused by other modalities. [iii]
However, thanks to the alpha particles’ short range in tissue, there is a very low risk of healthy cells being affected by an alpha-radiation based treatment.
Image 5 - Alpha particles destroy cancer by causing DNA double-strand breaks
Shielding
Shielding is the placement of an “absorber” between you and the radiation source – as ionizing radiation passes through matter, the intensity of the radiation is diminished. Alpha, beta, and gamma radiation can all be stopped by different thicknesses of absorbers.
Alpha particles are stopped after traveling through only a few centimeters in air. Due to its short range, no shielding is required. For example, a thin piece of paper, or even the dead cells in the outer layer of human skin, provides adequate shielding.
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Image 6 - The range of alpha particles, alpha particles can be stopped by a sheet of paper
Moreover, as a result of its high potency to cause biological damage, a much lower dose of alpha radiation is required, reducing the risk from radiation exposure and the need for shielding.