Palliative treatment of advanced cancer using multiple nonconfluent pencil beam radiation: a pilot study

Historically, one of the main problems with radiotherapy has been delivering a dose sufficient to kill a tumor while avoiding excessive destruction of normal tissues. This is particularly true of deep tumors, which can only be irradiated through the overlying structures. In an attempt to solve this problem, the GRID technique has been given the somewhat ponderous nomenclature of multiple nonconfluent pencil beam radiation. The technique gets the name GRID simply from the fact that the radiation is passed through a metallic grid full of holes. The principle is straightforward; skin tolerates radiation better in small patches than in a large area. Therefore, delivering a lot of radiation in a number of narrow beams is more sparing of the skin than a larger beam would be. The technique has largely fallen by the wayside due to the development of new irradiation equipment with better tissue penetration and improved skin-sparing characteristics. However, the GRID technique may still have some advantageous uses. A study was conducted on 22 patients with large tumors, which had resisted all forms of treatment. While a cure of such patients would be extremely unlikely, massive irradiation may provide relief from painful symptoms. Using the GRID technique, doses of radiation were administered; 20 of 22 patients achieved some relief of their more severe symptoms. There were no acute side effects, and no unusual skin damage was observed. (Consumer Summary produced by Reliance Medical Information, Inc.)