Grenz ray therapy

Author: Vanessa Ngan, Staff Writer, 2005.

Grenz ray therapy — codes and concepts

What are Grenz rays?

Grenz rays are a form of radiation, similar to ultraviolet radiation, x-rays and gamma rays. The difference is that Grenz rays are produced at low kilovoltages giving them a very low penetration power. They are absorbed within the first 2 mm of skin, which means they do not penetrate beneath the dermis of the skin. Grenz rays appear to reduce Langerhans cell numbers, hence producing an anti-inflammatory effect. It is said to “calm down” inflammation of the skin.

Grenz rays are also referred to as “border” rays and Bucky rays. They are classified as “ultrasoft” or “soft” radiation. They should not be confused with “superficial radiation therapy” which is used in the treatment of malignant skin cancers.

What is Grenz ray therapy used for?

Grenz ray therapy is seldom used nowadays as more recent medical advances in the treatment of skin diseases have made radiation treatments less necessary. However, Grenz ray therapy is occasionally very helpful for conditions that fail to respond to the usual therapeutic modalities.

Grenz rays can be used in combination with other therapies in the treatment of many skin conditions including:

What does the Grenz ray procedure involve?

Grenz ray therapy usually consists of 200 Roentgens, given weekly or twice weekly for a total of 800–1000 Roentgens (ie, over 3 or 4 sessions). If necessary, further treatment with Grenz rays can be repeated at 4–6 month intervals.

The radiation dose is delivered from the tube of a Grenz machine at a target skin distance of 10–15 cm.

What are the side effects and complications of Grenz ray therapy?

Very few side effects are associated with Grenz ray therapy. Doses over 200 Roentgens cause a mild sunburn reaction at the site. A persistent dark tan may linger for several months afterwards.

It is essential that proper radiation safety measures are followed when using Grenz ray therapy. It has been found that Grenz rays, given alone, are capable of causing nonmelanoma skin cancers in patients that are abnormally sensitive to radiation exposure.

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Related information



  • Grenz Rays – Dermatologic Disease Database, American Osteopathic College of Dermatology
  • Frentz G. Grenz ray-induced nonmelanoma skin cancer. J AM Acad Dermatol. 1989 Sep;21 (3 Pt 1):457-8

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