Radiation overdoses occur more often than you might think. According to an investigation by The New York Times, they can also be deadly.

The Times article highlights several patients who suffered greatly because of radiation overdoses. In one case, a 43-year-old man died in 2007, following radiation treatments at St. Vincent’s Hospital in Manhattan for tongue cancer. The hospital failed to detect a computer error that directed a linear accelerator to blast his brain stem and neck with errant beams of radiation – on three consecutive days. Prior to his death, the radiation overdoses left the man in severe pain, deaf, struggling to see, nauseated and unable to swallow. He sustained burns, and the radiation caused his teeth to fall out and ulcers his mouth and throat.

That patient wasn’t alone. the Times uncovered 621 mistakes involving radiation treatment errors from 2001 to 2008 at hospitals in New York State. In 133 of the cases, the devices used to shape or modulate radiation beams were left out, wrongly positioned or otherwise misused. In 284 cases, the investigation found radiation missed all or part of its intended target or treated the wrong body part entirely.

According to the Times, radiation errors were most often attributed to “software flaws, faulty programming, poor safety procedures or inadequate staffing or training.”

Unfortunately, the Times found that patients in New York are unable to vet the radiotherapy center where they get treatment because the state does not disclose where or how often medical mistakes occur. What’s more, fines or license revocations are rarely used to enforce safety rules. According to the Times, New York State issued just three fines against radiotherapy centers over the past eight years, the largest of which was $8,000.