Causes behind Radiation overdose at Cedar-Sinai (2008)
School of engineering
Newcastle Upon Tyne, England
Abstract Given the rapid improvements in technology and machinery that are used in health centers across the world, companies face huge pressures to develop and engineer new and more innovative products, with the aim of aiding hospitals and professionals to be more efficient when examining and diagnosing patients. However, it should not come as a huge surprise for the technology being used to fail. In this article, I will be investigating the main causes that lead to 206 patients at Cedar-Sinai health center being examined for potential stroke, where new CT machines were used that exposed these patients to a dangerous dose of radiation eight times the prescribed limit, also I will be outlining the measures which are now in place to reduce such incidents happening in the future.
Introduction Clinical medicine has without doubt been revolutionized with the aid of medical imaging. Modern-day imaging continues to provide detail and accuracy beyond believe, reflected in reduced hospital stays, more effective surgical treatments, improved treatment of cancer, elimination of exploratory surgery and treatment of stroke patients just to list a few.
The first Computed tomography scanner developed by Godfrey Hounsfield backed by EMI Central Research Laboratories based in Hayes, West London, produced its first image on the 1st October 1971 at Atkinson Morley’s Hospital, located in London, England. The image produced was an 80 x 80 matrix, taking roughly 5 minutes to generate by the prototype scanner, however in today’s technology, CT scanners are able to produce images with a 1024 x 1024 matrix from a few million data points, in a few seconds, making it a crucial and valuable asset to the medical centers around the world.
5 A computed tomography fires narrow beams of x-rays at a patient, while rotating around the body, this results in signals which can be detected by the x-ray detectors located directly opposite the x-ray beams and is processed by the computer to generate a cross-sectional “slices ” of the body part, given the term tomographic images, these images contain a greater amount of detail than that found in x-ray images making them very useful tools to physicians, the slices produced are then “stacked” in the order produced by the machines computer to produce a three dimensional image showing the inner structures as you would see if you were to physically perform a surgical operation, so the doctors can identify and locate any abnormalities or damage to the patient’s internal organs.
Overtime CT scanners have become far more advanced the first clinical CT scanner was dedicated to only producing head images only, as the effectiveness of these machines became more recognized around the world, in less than 6 years and there are about 6000 Computed tomography scanners installed worldwide, and were able to take whole body images.
During its 45-year history, Computed tomography functions at a far greater speed, and improvement in resolution and patient comfort. As Computed tomography are able to produce images faster, more anatomy can be scanned in far less time than before this is important as it helps to eliminate any artefacts
that can arise from the patient motion.
The CT machines used to produce these images require the technicians to be fully trained in operating them and understand the safe limits of radiation to which patients can be exposed to, because of the dangerously high dosage of radiation these machines are capable and could be programmed to emit. But during an eighteen-month period at Cedars-Sinai Medical center, where 206 patients were exposed to eight times the normal radiation dose, and 20% directly to their eye.
reports by IMV (Medical information division) in figure 2 shows the rapid increase in the use of CT imaging in the United states, the radiation exposure associated with them over the last decade outline the dangers which could arise, clearly shown in the radiation overdose incident that took place at Cedar-Sinai beginning February 2008 and after 18 months, for such a major incident to occur indicates there are multiple causes which can be classified in two very different categories being the Medical Centre and the manufactures.
Many sources such as the ‘New York Times’ related the main cause to mainly human ‘error’, this came about as a result of the hospital started to use a new protocol for a specialized form of scan which was believed to provide doctors with more useful information in their effort to treat stroke patients. So that meant resetting the CT machines to be able to override the pre-programmed instructions which accompanied the scanner when it was first installed.
Once these new instructions were programmed into the machines, they were essentially locked in. The machine was used for other types of scans which the ‘error’ did not effect.
The ‘Swiss cheese’ model of organizational accidents, is an excellent procedure which can be used to reduce the likelihood of accidents occurring in large organizations, the model is built on the idea of having barriers at each step in a process to eliminate any potential error before the final outcome, so in an event of a major error to occur all the holes will have to line up this would be the case in a flawed system that would allow an error or mistake at the beginning to reach and affect the outcome. So, to reduce the chances of an error effecting the outcome the more cheese slices used the smaller the chances of errors and also the smaller the holes the better as smaller holes could imply a more detailed analysis at each stage of the process that would ultimately catch or even stop the error becoming an accident.
The incident at Cedar-Sinai could be linked to the system failing, because of the difficulty in detecting errors during the process of CT imaging, unlike errors that lead to physically visible outcomes, that can easily be found, an example being a plane engine failing due to internal faults causing it to explode during the testing period, can be investigated quicker and instantaneous safe guarding actions could be taken to prevent any casualties, however with CT scanners the accidents could take years before they are detected, so it’s crucial the system in place has virtually no flaws and any human errors don’t become accidents. This is where the problem starts, 9 ‘INSIDE SCIENCE’ reported that Medical Centre Cedar Sinai were not accredited by American College of Radiology, who offers guidelines for standards and protocols, and obviously the process used for CT scans at Cedar-Sinai was not effective in preventing errors progressing through its successive layers of defense.
The system as a whole failed because individual parts that make it did not carry out their roles effectively and this could be linked to the team, management, individuals.
individual technologist has responsibility to ensure patients under their care are not exposed to dangerous levels of radiation (ARRT Code of Ethics). This implies practicing with integrity, only using equipment that is serviced properly and maintained locally or by vendor.
Although in the investigation carried out by the FDA and GE healthcare the product manufacturers, they did not find any faults with the machines itself, but recommendations included there could have been an improvement in safety features built in the scanners, one of the obvious features the GE scanners had is a feature called automatic exposure control. The feature automatically adjusts the radiation dose according to a person’s body part and their size so smaller children receive less radiation, because their body is growing and radiation is more likely to cause cancer, rather than using a pre-determined radiation level, the aim of the feature being to reduce the doses. But when the feature is used with certain machine settings which governed image clarity, the effect was to drastically increase the radiation dose delivered to the patients.
GE scanners have a feature called automatic exposure control. It automatically adjusts the radiation dose according to a person’s size and the body part being scanned, rather than using a fixed, predetermined radiation level. Its intent is to lower radiation doses. But when used in combination with certain machine settings that govern image clarity, its effect was to significantly raise the dose of radiation delivered to a patient.
According to Cedar-Sinai the GE manual as part of the CT scanner failed to state the feature was not designed to be used in brain scans. And the GE trainers failed to fully explain the feature.
After many high-profile incidents of radiation overdose leading to patient harm during CT imaging, it’s not a secret that ionizing radiation used by medical imaging have many harmful effects associated to them, but their benefits to medical centers far outweigh the risks posed. However due to the heavily reported incident, at cedar-Sinai. National organizations such as the Medical Imaging and Technology Alliance, American College of Radiology and the joint Commission have devised various standards linked to radiation safety.
One of the changes coming in the form of a SB 1237 in 2010 to ensure radiation dose are monitored better for CT scans. The law going into effect from July 1st, 2012 involve a number of components:
Hospitals and clinics are required by law to record dose of every procedure performed using a CT scanner, Especially volume of volume of CT dose index. And the dose length product.
The dose information has to be sent to the Picture Archiving and Communication System (PAC) when possible also the information must be part of the patient’s report helping to determine their radiation dose received over their lifetime.
In an event where patents receive excessive dose of radiation must be reported to the California Department of Public Health (CDPH); and radiation physicist to annually verify dose levels annually.
Conclusion during an 18-month period 206 suspected stroke patients underwent CT scans, as a result of resetting the default settings on the machine, physicians being under the assumption that increasing the radiation dosage to supply eight times the recommended for the specific scan on the machines, believing it could provide highly detailed images, as the settings on the CT scanner was changed to reflect their theory, lead to the machine being locked in with the new settings. Both the manufactures and Cedar-Sinai could have taken steps to help prevent the accident occurring as ‘human error’ is essentially unavoidable, in such high pressure and complexity situations.
After patients started reporting hair loss, the Health care center began their own investigation which found the incident was caused by the CT machine and therefore investigation carried by the Food and Drug Administration (FDA) concluded the error was due to operator error, and the FDA issued recommendations to both the manufactures and Cedar-Sinai to help tackle such incidents developing in the future.
In my opinion, the main cause for the incident came about because there were not enough safety features that could have prevented the incident and the lack of regular machine checks and failure to record the radiation dose patients were being scanned with as one of the primary reasons the incident went unnoticed for 18 months, I cannot find a reason to why a product that is capable of providing dangerous levels of radiation directly at specific body parts allows users to make changes, or only allow lead technologists and supervisors access to changing settings on the machine, it’s important that users are not fully locked out of the system as that’s impractical, considering the number of CT scans carried out in health centers users should be allowed to make changes but not any that could pose a risk to the patient, as well as having warnings built in the system to alert users of changes to the protocols that could lead to overexposure.
I believe the changes and new laws which are implemented as a direct result of the incident at cedar Sinai will help reduce the incidents occurring in the future but I believe these laws will only be effective if the medical centers are educated in maintaining the CT machines, and the new technology used in them must be explained to and be part of the manual issued to the medical centers furthermore the manufacturers should perform frequent machine tests to test for any flaws or changes made to the system.