NEW YORK (AP) ¿ Shares of TomoTherapy Inc. slumped Wednesday after the radiation therapy device maker posted disappointing first-quarter results and cut its sales forecast for the year.

TomoTherapy reported a deeper loss and less revenue than analysts expected, and also said its backlog of orders decreased compared with the first quarter of 2008. In afternoon trading, its shares fell 22 cents, or 8.4 percent, to $2.41.

The Madison, Wis., company sells a therapy system called Hi-Art, which can spiral around a patient to deliver more direct doses of radiation to a tumor. Like many hospital equipment makers, TomoTherapy said its results are being hurt as its customers delay or cancel orders due to the U.S. recession.

The company posted a loss of $13 million, or 26 cents per share, from a loss of $6.2 million, or 12 cents per share, a year earlier. Revenue fell 21 percent to $30.6 million from $38.9 million.

Analysts were expecting a loss of 25 cents per share on $31.7 million in revenue, according to Thomson Reuters.

TomoTherapy said its backlog, or orders for shipments it expects to make within the next two years, fell 11 percent, to $157 million, and it added $4 million in equipment orders.

Analyst Junaid Husain, of Soleil Securities, said that total was "abysmal," and suggests that TomoTherapy may be losing customers to Varian Medical Systems Inc. in addition to struggling with the weak economy. He said net orders fell 90 percent from a year earlier.

The company cut its annual revenue outlook to a range of $170 million to $190 million, down from $180 million to $210 million, but maintained its projection for a loss between 60 cents and 85 cents per share. Analysts already expected $180.4 million in revenue, and a loss of 70 cents per share.

Copyright 2009 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.