AuntMinnie 2010: Agreement reached in the case of CT radiation on children in Mad River

Editor's Note: As part of AuntMinnie.com's upcoming 25th anniversary celebration, we're presenting 25 for 25 – a series featuring our most popular content from the past 25 years. New articles will be published every Monday until our official anniversary at RSNA 2024. Our top article in 2010 was a follow-up to our most viewed article from 2009.

SACRAMENTO, CA – A California X-ray technician accused of giving a 23-month-old boy a severe overdose of radiation was required to testify this week about her role in the incident. Witnesses who testified at a hearing to revoke the technician's license said they still don't understand how the boy could have endured 151 CT scans in just over an hour.

In January 2008, 23-month-old Jacoby Roth fell out of bed and, when he could barely move his head, his worried parents took him to the emergency room at Mad River Community Hospital in Arcata, a small town 290 miles north of San Francisco.

There, a doctor ordered X-rays and CT scans to check for damage to the child's cervical spine. He was taken to the scanning room, where X-ray technician Raven Knickerbocker performed CT scans at the C1 through C4 levels of the cervical spine, in the same area of ​​the middle maxillary sinuses, middle clivus, and posterior cranial fossa.

Over the next 68 minutes, the toddler was subjected to 151 scans.

Radiation overdose

The incident was raised again this week during two days of hearings by the California Department of Public Health (CDPH) on whether Knickerbocker should be stripped of his license as a radiologic technologist.

In testimony before an administrative law judge, the boy's father, who stood at the foot of the CT table during the scans to calm his son, recalled his growing anxiety as the scans dragged on. “I said, 'Stop it!'” Father Roth recalled, noting that Knickerbocker only stopped the scans when he became angry.

Jacoby Roth several hours after receiving 151 CT scans in 68 minutes. Image courtesy of Don Stockett, the Roth family attorney.

Within hours, the child had a bright red ring around his head from the massive radiation overdose. Photographs of the left side of the boy's face show a clear line running from the infraorbital ridge back through the ear and neck; a similar line runs from the infraorbital ridge through the ear on the right side.

In confidential comments, some state officials called it the worst case of a child radiation overdose in the United States.

The boy's mother, Carrie Roth, recalled questioning the need for the scans and worrying about radiation since her son had already had a CT scan at a young age. “Is this safe?” she asked doctors when she was told her son needed another CT scan because he had moved around during Knickerbocker's scans.

Father Roth asked how this could be, pointing out that his son was secured in a baby carrier and had been asleep for most of the first examination.

“I had a bad feeling,” he testified. “I knew something was wrong. There's no way a CT scan can take an hour and 20 minutes. I should have stopped earlier.”

“I started crying,” the boy's mother recalled. “What happened the first time?” she asked the doctor, referring to the first long ultrasound.

Carrie Roth described how Knickerbockers “the [scanner] button several times, approximately every 30 seconds.”

Scan records show an average interval of 25 seconds between the 151 scans that began at 8:29 a.m. on Jan. 23, 2008, and ended at 9:37 a.m. The CT scanner used was a 1998 Picker PQ-5000 single-slice scanner, whose tubes took about 25 seconds to cool between scans. It was replaced a month after the incident, but hospital officials said the replacement had been planned long before and was unrelated.

A second CT scan, by X-ray technician Susan Sampson, took just two minutes and included 25 axial sections. Sampson recalled being “a little shocked” to learn that Knickerbocker had performed 151 scans of the same area at the base of the boy's skull. “That's a lot longer than an exam normally takes,” she testified, estimating that it should have taken less than 10 minutes.

Knickerbocker showed little emotion during the hearing, but was moved to tears when a former supervisor said she had been a good employee before the incident. She did not testify during the hearing.

Bruce Fleck, the hospital's former radiology chief, testified that Knickerbocker later offered many explanations for the incident, such as the boy's parents distracting her, the scanning table not moving in increments and the boy's father leaning on the table. But he noted that an experienced operator like Knickerbocker should have known to stop after a few images if the scanner wasn't working properly.

When asked if the scanner had any way of automatically taking pictures, he said the images showed the machine was in manual axial mode. “She had to press the button every time,” Fleck noted.

He also noted that Sampson had no problems when she used the device. It was later checked and no malfunctions were found.

Knickerbocker could not provide a “valid explanation” for why she took 151 pictures of the same place, Fleck said. “I think it was simply an act of insanity,” he told a stunned court.

“I think it was just an act of insanity.”— Bruce Fleck, former head of radiology at Mad River Community Hospital

Dave Laumann, the chief technician at the time, said Knickerbocker told him she didn't know 151 scans had been taken. “It just seemed to me like she wasn't going to deal with it,” he testified.

Fleck was so upset by Knickerbocker's “flagrant ethical violation” that he wrote the incident to the American Registry of Radiologic Technologists (AART). Many radiology staff at the hospital said Knickerbocker violated ALARA (as low as reasonably achievable) standards by performing such a lengthy scan.

A report by the hospital's medical physicist calculated that the boy's absorbed radiation dose was 2.8 Gy (2,800 mSv) and may have been as high as 11 Gy (11,000 mSv). The dose the boy was exposed to is comparable to a standard pediatric CT scan of the whole spine, in the range of 1.5 to 4.0 mSv, pediatric imaging experts say.

Using relevant material from the article “Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric CT”, published in the American Journal of Radiology (February 2001, Vol. 176:2, pp. 289–296) a report by the hospital's medical physicist concluded that the child had a 39% increased risk of developing a fatal cancer during his lifetime.

State investigators who interviewed Knickerbocker said she told them she only pressed the scan button two or three times and could not explain why the machine made so many scans.

Mindy Malone, a CDPH health physicist who investigated the incident, said Knickerbocker called for help during the scanning session but never received help. However, Laumann said he came into the room shortly after the scan began to check on the procedure, contradicting Knickerbocker's claims.

Wesley Root, MD, the hospital's radiology chief, said a review of the scanner showed that Knickerbocker had only recorded the initial shift for the exam, meaning the machine would automatically stop after one shift, Malone testified.

“Only one scan was done at a time,” Malone testified. “She had to manually set the exposure each time.”

Root also noted that the red light above the scanner's tripod flashes each time a scan is performed, casting doubt on Knickerbocker's claim that she was unaware that 151 scans were performed.

Driving license revocation

Mad River fired Knickerbocker two weeks after the incident; the CDPH revoked her license nine months later. The CDPH concluded that “operator error” by Knickerbocker was the cause of the overdose and fined Mad River $25,000. The hospital had failed to follow its radiation safety policies and procedures. Knickerbocker's explanations of the incident were inconsistent, state officials found.

The Roth family's attorney, Don Stockett of Folsom, California, has filed a lawsuit against the hospital and Knickerbocker, alleging negligence and medical malpractice. Stockett said he sent a blood sample from Jacoby Roth for analysis to Dr. David Lloyd, a DNA specialist and senior researcher in the Molecular Design Group of the School of Biochemistry and Immunology at Trinity College in Dublin, Ireland. The analysis showed that Roth suffered significant chromosomal damage, Stockett said.

Knickerbocker was expected to testify at the hearing in Sacramento, but because the testimony took a long time, the hearing was postponed to a later date to be determined.

Father Roth said Knickerbocker should lose her driver's license forever. “We are still concerned about the long-term impact on our son,” he said. “She should never be allowed to be near other people's children again.”