Electron therapy or electron beam therapy (EBT) is a kind of external beam radiotherapy where

electrons The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no ...

are directed to a

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

site for medical treatment of cancer.

Equipment

Electron beam therapy is performed using a medical

linear accelerator A linear particle accelerator (often shortened to linac) is a type of particle accelerator that accelerates charged subatomic particles or ions to a high speed by subjecting them to a series of oscillating electric potentials along a linear ...

. The same device can also be used to produce high energy photon beams. When electrons are required, the x-ray target is retracted out of the beam and the electron beam is

collimated A collimated beam of light or other electromagnetic radiation has parallel rays, and therefore will spread minimally as it propagates. A perfectly collimated light beam, with no divergence, would not disperse with distance. However, diffraction p ...

with a piece of apparatus known as an applicator or an additional collimating insert, constructed from a low melting point alloy.

Properties

Electron beams have a finite range, after which dose falls off rapidly. Therefore, they spare deeper healthy tissue. The depth of the treatment is selected by the appropriate energy. Unlike photon beams there is no surface sparing effect, so electron therapy is used when the target extends to the patient's

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different de ...

Indications

Electron beam therapy is used in the treatment of superficial tumors like cancer of skin regions, or total skin (e.g.

mycosis fungoides Mycosis fungoides, also known as Alibert-Bazin syndrome or granuloma fungoides, is the most common form of cutaneous T-cell lymphoma. It generally affects the skin, but may progress internally over time. Symptoms include rash, tumors, skin lesion ...

), diseases of the limbs (e.g. melanoma and

lymphoma Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). In current usage the name usually refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enla ...

), nodal irradiation, and it may also be used to boost the radiation dose to the surgical bed after

mastectomy Mastectomy is the medical term for the surgical removal of one or both breasts, partially or completely. A mastectomy is usually carried out to treat breast cancer. In some cases, women believed to be at high risk of breast cancer have the operat ...

lumpectomy Lumpectomy (sometimes known as a tylectomy, partial mastectomy, breast segmental resection or breast wide local excision) is a surgical removal of a discrete portion or "lump" of breast tissue, usually in the treatment of a malignant tumor or brea ...

. For deeper regions intraoperative electron radiation therapy might be applied.

References

* Eric E. Klein: "Electron-Beam Therapy: Dosimetry, Planning, and Techniques" in: Edward C. Halperin, Carlos A. Perez, Luther W. Brady (ed.): ''Perez and Brady's Principles and Practice of Radiation Oncology'', 5th. edition, 2008 {{Radiation oncology Electron beams in medical applications Medical physics Radiation therapy

Equipment

Properties

Indications

See also

References