TUCSON, Ariz. (AP) - A cancer patient says she was left alone in a CT scanner for hours after a technician apparently forgot about her, and she finally crawled out of the device, only to find herself locked in the closed clinic.

Elvira Tellez of Tucson said she called her son in a panic, and he told her to call 911.

Pima County sheriff's deputies arriving at the oncology office had her unlock the office door to let them in, said Deputy Dawn Hanke, a department spokeswoman. The deputies contacted the office manager, who was not aware of the situation.

Tellez was taken to a hospital as a precaution, then released early the next day.

Tellez said she's had trouble sleeping since last week's incident. She and her family said they want an explanation from the medical office, Arizona Oncology Associates, but have yet to receive one. She said the technician did call to apologize the next day.

"I don't know what to think," Tellez said in Spanish. "I think and think and think, but I can't understand it."

Ted Eazer, practice director for Arizona Oncology Associates, said Friday that the group has revised its closing procedures so no one is ever left behind in an office again. A sweep of the facilities will be done and a written checklist followed.

The executive director of Arizona Oncology Associates, Sonya Hohm, was in a meeting Friday and not immediately available for comment, her assistant said.

Diagnosed with bone cancer, the 67-year-old Tellez had been sent to the clinic for tests to see if her cancer had spread.

A technician placed her inside the large machine at about 4 p.m. on Sept. 19, dimmed the lights so she could relax and told her not to move during the 25-minute procedure.

"At some point, my mom lost track of time and felt like too much time had passed, but she couldn't look at a clock or anything because it was dark," her son Ariel Tellez said.

After calling out, then screaming for help, she said, she spent several hours trying to free herself from the machine. Finally, she wiggled out from under a heavy blanket and out of the machine. By the time deputies found her, it had been five hours since she was placed inside.

A physician who works at the practice and knew of the incident told The Arizona Daily Star it's not the first time such a thing has happened.

"People have been left in the office after hours, when something like that happens - it's the same sort of thing," Dr. Steven Ketchel said. "My guess is she was lying on the table, waiting and waiting and nobody told her she could go home."

Eazer said Ketchel was referring to incidents in other facilities, and that a patient had never before been left behind at Arizona Oncology clinics.

Copyright 2007 The Associated Press.