Tag Archives: radiation

Patient receives double dose of radiotherapy

By ThinkReliability Staff

The risk associated with medical treatment administration is high. There is a high probability for errors because of the complexity of the process involved in not only choosing a treatment, but ensuring that the amount and rate of treatment is appropriately calculated for the patient. The consequence associated with treatment errors is significant – death can and does result from inappropriately administered treatment.

Medical treatment includes delivery of both medication and radiation. Because of the high risk associated with administering both medication and radiation therapy, independent checks are frequently used to reduce risk.

Independent checks work in the following way: one trained healthcare worker performs the calculation associated with medical treatment delivery. If the treatment is then delivered to the patient, the probability that a patient will receive incorrect treatment is the error rate of that healthcare worker. (For example, a typical error rate for highly trained personnel is 1/1,000. If only one worker is involved with the process, there is a 0.1% chance the patient will receive incorrect treatment.) With an independent check, a second trained worker performs the same calculations, and the results are compared. If the results match, the medication is administered. If they don’t, a secondary process is implemented. The probability of a patient receiving incorrect treatment is then the product of both error rates. (If the second worker also has an error rate of 1/1,000, the probability that both workers will make an error on the same independently performed calculation is 1/1,000 x 1/1,000, or 0.0001%.)

However, in a case last year in Scotland, a patient received a significant radiotherapy overdose despite the use of independent checks, and verification by computer.   In order to better understand how the error occurred, we can visually diagram the cause-and-effect relationships in a Cause Map. The error in this case is an impact to the patient safety goal, as a radiotherapy overdose carries a significant possibility of serious harm. The Cause Map is built by starting at an impacted goal and asking “why” questions. All causes that result in an effect should be included on the Cause Map.

In this case, the radiotherapy overdose occurred because the patient was receiving palliative radiotherapy, the incorrect dose was entered into the treatment plan, and the incorrect dose was not caught by verification methods. Each of these causes is also an effect, and continuing to ask “Why” questions will develop more cause-and-effect relationships. The incorrect dose was entered into the treatment plan because it was calculated incorrectly (but the same) by two different radiographers working independently. Both radiographers made the same error in their manual calculations. This particular radiotherapy program involved two beams (whereas one beam is more common). The dose for each beam then must be divided by two (to ensure the overall dose is as ordered). This division was not performed, leading to a doubled calculated dose. The inquiry into the overdose found that both radiographers used an old procedure which was confusing and not recommended by the manufacturer of the software that controlled the radiotherapy delivery. While a new procedure had been implemented in February 2015, the radiographers had not been trained in the new procedure.

Once the two manual calculations are performed, the treatment plan (including the dose) was entered into the computer (by a third radiographer). If the treatment plan does not match the computer’s calculations, the computer sends an alert and registers an error. The treatment plan cannot be delivered to the patient until this error is cleared. The facility’s process at this point involves bringing in a treatment planner to attempt to match the computer and calculated doses. In this case, the treatment planner was one of the radiographers who had first (incorrectly) performed the dose calculation. The radiographers involved testified that alerts came up frequently, and that any click would remove them from the screen (so sometimes they were missed altogether).

The inquiry found that somehow the computer settings were changed to make the computer agree with the (incorrect) manual calculations, essentially performing an error override. The inquiry found that the radiographers involved in the case believed that the manually calculated dose was correct, likely because they didn’t understand how the computer calculated doses (not having had any training on its use) and held a general belief that the computer didn’t work well for calculating two beams.

As a result of this incident, the inquiry made several recommendations for the treatment plan process to avoid this type of error from recurring. Specifically, the inquiry recommended that the procedure and training for manual calculation be improved, independent verification be performed using a different method, procedures for use of the computer be improved (including required training on its use), and requiring manual calculations to be redone when not in agreement with the computer. All of these solutions will reduce the risk of the error occurring.

There is also a recommended solution that doesn’t reduce the risk of having an error, but increases the probability of it being caught quickly. This is to outfit patients receiving radiotherapy with a dosimeter so their received dose can be compared with the ordered dose. (In this case, the patient received 5 treatments; had a dosimeter been used and checked the error would likely have been noticed after only one.)

To view the Cause Map for this incident, please click on “Download PDF” above.

Study Finds that Fukushima Fallout is Affecting Babies in US

By Kim Smiley

A recent study found that babies born on the West Coast of the United States shortly after the Fukushima nuclear reactor meltdown have a higher rate of congenital hypothyroidism than those born a year earlier.  Thyroid issues have long been known to be associated with exposure to radiation and this finding feeds worries about the long term and long distance impact of the reactor disaster.

This issue can be analyzed by building a Cause Map, a visual root cause analysis, which intuitively lays out all the causes that contributed to an issue.  A Cause Map is built by asking “why” questions and adding the answers to the Cause Map to show the cause-and-effect relationships.

Why has the rate of congenital hypothyroidism increased?  This happened because the infants had radioactive iodine in their thyroids and radioactive iodine may affect the functioning of the thyroid if ingested.  If the thyroid doesn’t function properly, it can’t make the necessary hormones for healthy development and both growth and development can be stunted. The impacts of radioactive iodine are predominantly seen in the thyroid because ingested iodine concentrates in the thyroid where it is used to produce hormones.  The body can’t distinguish between stable and radioactive isotopes of iodine and it will store whatever iodine is available so ingested radioactive iodine can be kept within the body long enough to cause damage.

In the cases of fetuses, the mother passes iodine to her baby.  If pregnant woman ingests radioactive iodine, some of it will likely end up in the thyroid of her baby who needs the iodine to develop properly.  In this example, pregnant women on the West Coast were exposed to significantly higher than normal levels of iodione-131 following the Fukushima meltdown. Iodione-131 is a fission product that is created in a nuclear reactor when atoms are split.  When the reactor containment failed, radioactive isotopes of iodine were released into the environment along with other fission products.  Winds carried some of the radiation across the Pacific Ocean. Iodine-131 concentrations in precipitation in the United States were up to 211 times above normal in the days following the accident.  Some of this radioactive iodine found its way into the food supply and was ingested by people, some of them pregnant women causing the increase in cases of congenital hypothyroidism.

The good news is that congenital hypothyroidism with can be treated if found early.  The bad news is that there may be more health issues from the Fukushima meltdown in places outside of Japan discovered in the future.  The reality is that more than two years after the event we still don’t know what all the impacts of the radiation will be, both in Japan which has obviously suffered the most and in other countries.



Infants Exposed to Unnecessary Radiation

By ThinkReliability Staff

A recent New York Times article, X-Rays and Unshielded Infants, used an example of poor x-ray technique issues to highlight problems with the operation of radiation equipment in the medical industry.

In 2007, a director at a medical center in Brooklyn, New York discovered that premature babies were routinely being over-radiated during x-rays.  Full body x-rays of babies, known as “babygrams” were being done when not medically necessary. When a simple chest x-ray was ordered, as is common for premature babies with lung issues, the entire body was being x-rayed without any shielding.  Additionally, the CT scanners had been set too high for infants in some cases.  There were also issues of poor body positioning that made it difficult for doctors to accurately read the x-rays.

The end result was that many young babies were being habitually exposed to unnecessary radiation at this facility.  This is especially troubling when you consider the fact that children are particularly vulnerable to radiation exposure because their cells divide more quickly because they are still growing.

The causes in this example aren’t well known, but a basic Cause Map can be started and could be expanded if more information becomes available.  Click on “Download PDF” above to view the Cause Map.

What is clear is that this is more than a case where one person made a single error.  The culture and training in the department didn’t recognize the importance of limiting radiation exposure.  The radiation field as a whole is also minimally regulated.  Standards and regulations are decided at the state level and many states choose not to regulate all occupations working with radiation.  In 15 states radiation therapists are unregulated, 11 states don’t regulate imaging technologists and medical physicist are unregulated in 18 states. For the past 12 years, the American Society of Radiologic Technologists has lobbied for a bill to set education and certification requirements for people working in medical imaging and radiation therapy, but as of yet no bill has been passed.

After the improper radiation techniques were discovered, the hospital instituted many changes to their procedures.  No more full body x-rays were performed and shielding was used to minimize radiation exposure for children as well as adult patients. An investigation is also underway by the New York state health department.

Why Potassium Iodide?

By Kim Smiley

In addition to evacuating the people near the nuclear plants in crisis, the Japanese government has distributed potassium iodide.  There has also been a run on potassium iodide on the West Coast of the United States.


Why would pills protect against radiation?  The first part of the answer lies in the thyroid gland.  The thyroid contains some of the only cells in the body that can absorb iodine.  The thyroid needs iodine in order to produce thyroid hormones which are used by nearly every cell in the body and help regulate important functions such as metabolism.  The second part of the answer is that iodine-131 is a common isotope produced by the fission of uranium atoms during the operation of nuclear reactors.  When fission products are released into the environment and consumed by humans, the thyroid can absorb radioactive iodine, just like it absorbs stable iodine.  Exposure from radioactive iodine can lead to thyroid cancer.

When exposure to radiation is possible, potassium iodide is used because the thyroid has a limit to how much iodine it needs.  If the thyroid has been flooded by stable iodine, it decreases the chance that radioactive iodine will be absorbed.  Any unneeded iodine should be passed through the body relatively quickly, limiting the amount of exposure to the radiation emitted by the iodine-131.

History has shown us that the threat of thyroid cancer is very real following a nuclear reactor accident.  There has been an epidemic of thyroid cancer in the area affected by the Chernobyl accident in 1986.  Experts believe that distribution of iodide potassium could have largely prevented this long term health consequence.  Additionally, the majority of iodine exposure came from drinking milk produced by cows living in the area contaminated by the accident.  If people had avoided drinking contaminated milk in the months following the accident, the effects of radioactive iodine would have greatly been diminished.  Another possible solution that could be applied to help prevent thyroid cancer following a reactor accident would be to test all food and drink for contamination.

There are a few other important facts to consider about potassium iodide.  It is not recommend for low levels of radiation.  The U.S. Nuclear Regulatory Committee has stated that very low levels of radiation may reach the United Stations, but that the amount is well below any harmful limit.  Officials have repeatedly stated that there while use of the potassium iodide is an appropriate precaution for individuals near the accident site in Japan, there is no need for people within the US to take potassium iodide to protect against the effects of radiation.  There are also a number of unpleasant side effects associated with potassium iodide and it is recommended that you speak to your doctor before taking the supplement.

Click on the “Download PDF” button above to view a Process Map of how the body absorbs iodine and a high level Cause Map of the thyroid epidemic following Chernobyl.

Therac-25 Radiation Overdoses

By ThinkReliability Staff

The Therac-25 is a radiation therapy machine used during the mid-80s. It delivered two types of radiation beams, a low-power electron beam and a high-power x-ray. This provided the economic advantage of delivering two kinds of therapeutic radiation with one machine. From June 1985 to January 1987, the Therac-25 delivered massive radiation overdoses to 6 people around the country. We can look at the causes of these overdoses in a root cause analysis performed as a Cause Map.

The radiation overdoses were caused by delivery of the high-powered electron beam without attenuation. In order for this to happen, the high-powered beam was delivered, and the attenuation was not present. The lower-powered beam did not require attenuation provided by the beam spreader, so it was possible to operate the machine without it. The machine did register an error when the high-powered beam was turned on without attenuation. However, it was possible to operate the the beam with the error and the warning was overridden by the operators.

The Therac-25 had two different responses to errors. One was to pause the treatment, which allowed the operators to resume without any changes to settings, and another was to reset the machine settings. The error resulting in this case, having the high-power beam without attenuation, resulted only in a treatment pause, allowing the operator to resume treatment with an override, without changing any of the settings. Researchers talking to the operators found that the Therac-25 frequently resulted in errors and so operators were accustomed to overriding them. In this case, the error that resulted (“Malfunction 54”) was ambiguous and not defined in any of the operating manuals. (This code was apparently only to be used for the manufacturing company, not healthcare users.)

The Therac-25 allowed the beam to be turned on without error (minus the overridden warning) in this circumstance. The Therac-25 had no hardware protective circuits and depended solely on software for protection. The safety analysis of the Therac-25 considered only hardware failures, not software errors, and thus did not discover the need for any sort of hardware protection. The reasoning given for not including software errors was the “extensive testing” of the Therac-25, the fact that software, unlike hardware, does not degrade, and the general assumption that software is error-proof. Software errors were assumed to be caused by hardware errors, and residual software errors were not included in the analysis.

Unfortunately the coding used in the Therac-25 was in part borrowed from a previous machine and contained a residual error. This error was not noticed in previous versions because hardware protective circuits prevented a similar error from occurring. The residual error was a software error known as a “race condition”. In short, the output of the coding was dependent on the order the variables were entered. If an operator were to enter the variables for the treatment very quickly and not in the normal order (such as going back to correct a mistake), the machine would accept the settings before the change from the default setting had registered. In some of these cases, it resulted in the error described here. This error was not caught before the overdoses happened because software failures were not considered in the safety analysis (as described above), the code was reused from a previous system that had hardware interlocks (and so had not had these problems) and the review of the software was inadequate. The coding was not independently reviewed, the design of the software did not include failure modes and the software was not tested with the hardware until installation.

This incident can teach us a lot about over-reliance on one part of a system and re-using designs in a new way with inadequate testing and verification (as well as many other issues). If we can learn from the mistakes of others, we are less likely to make those mistakes ourselves. For more detail on this (extremely complicated) issue, please see Nancy Leverson and Clark Turner’s An Investigation of the Therac-25 Incidents.”

Therapy Equipment Delivers Radiation Overdoses for Years

By ThinkReliability Staff

In September of last year, a physicist at a healthcare facility was trained on use of the BrainLAB stereotactic radiation therapy system.  During this training, the physicist realized that the system had been incorrectly calibrated, as the wrong chamber had been inserted into the machine.  The facility realized that the chamber had been incorrectly inserted at installation in 2004, and that patients who used the portion of the machine calibrated by that chamber had received radiation overdoses over those five years.

The facility is working through the impacts of these errors, the causes of the error, and what needs to be done to keep an issue like this from ever happening again.

First let’s examine the impacts to the goals resulting from this error.  There’s an impact to the patient safety goal due to potential for deaths and injuries. (Because these patients  were already sick – sometimes very sick – the facility is still determining what impact the overdoses may have had.)  There has not yet been mention of an employee impact – the physicist who set up the machine is no longer at the facility – so we’ll just put a “?” after Employee Impact.  The event was reported to The Joint Commission (no reports were required by law), which can be considered an impact to the compliance goal.   The organizational goal was impacted due to potential lawsuits against the hospital.   The patient services goal was impacted because 76 patients received an average overdose of 50% (other patients received overdoses that were considered within the acceptable range for treatment).  Because radiation was involved, there is the potential for an environmental impact.  However, there is no evidence that any radiation leaked to the environment, we’ll put a “?” by the environmental goal as well.  Lastly, the property and labor/time goals were impacted because of the additional follow-up exams, testing, support, and treatment, which the facility will provide for all those affected by the issue.

Once we’ve determined the impact of the event, we can begin an analysis of how it happened.  Or, what were the causes?  The goals were impacted due to the overdose to several patients.  The overdose occurred because the radiation therapy machine was miscalibrated and the miscalibration was not discovered for five years.  The machine was miscalibrated because the incorrect chamber was installed and the chamber installation was not verified.  The physicist chose the wrong chamber and the equipment representative (who was on hand for the installation) did not notice the error.  At this point, it’s unclear why the physicist chose the wrong chamber and why the equipment representative did not notice the error.

The miscalibration was not noticed for five years because any re-calibration of the machine depended on the chamber which was incorrectly installed.  So although the machine was not delivering the correct amount of  radiation, the problem was with the calibration itself, resulting in a propagating error.  According to the facility, none of the patients showed any unusual side effects that would indicate they were getting too much radiation. However, some of the symptoms may take years to develop.  Additionally, no other staff members were trained on the equipment for five years.  It was a second staff member who was trained on the equipment who finally noticed the error.

Even though there are some questions still remaining in our Cause Map, we can develop some solutions, as the facility in question (as well as other stakeholders) is doing.   One suggestion is to do an external calibration of the machine – i.e., use a calibration method that is completely separate from the machine to determine if the correct amount of radiation is being delivered.  Also, have an independent verification that each piece of the equipment was installed correctly.   Require the equipment representative to sign off on the installation.  Last but not least, train other staff members to operate the equipment as backup.   The facility is working with the FDA to assist in its efforts to increase the safety of radiation use in healthcare settings.  (See our previous blog about this topic.)

Step 4 to avoid radiation therapy errors: verify HOW MUCH – how much radiation therapy is required, and how much is the patient actually getting.

Wrong Body Part Irradiated

By ThinkReliability Staff

In October of 2005 a therapist was preparing a patient for radiation therapy.  The therapist used a tattoo on the patient’s body to guide the radiation therapy.  Additionally the therapist brought up a photo of the area to be irradiated.  Unfortunately in this instance the tattoo and the photographs both indicated the patient’s esophagus – which was the site of previously delivered radiation therapy – instead of his upper spine, where the new radiation treatments were to be delivered.

Although there was no damage to the patient’s health, this incident impacted the facility’s patient safety goal, because of the potential for injury to a patient when radiation is delivered unnecessarily.  Additionally, it impacted the patient service goal because the radiation treatment was misdirected to the wrong body part.  The organization and compliance goals were impacted because of this reportable error.  Lastly, there are impact to the materials and labor goals due to the additional treatments that were required to deliver radiation to the upper spine.

The situation was complicated by the software error that brought up an old picture, indicating that the therapy should treat the esophagus.  To add to the confusion, there was a tattoo on the esophagus designating it as the site of the therapy.  There was nothing in the set-up notes to indicate that the patient had had a previous round of radiation therapy.  It is unclear whether the therapist had access to the patient’s chart, which would have designated the area to be irradiated and would mention the previous therapy.

The facility involved introduced measures to solve the software problems which resulted in the old photograph being downloaded.  Second therapy sites are now marked with double tattoos.  Information such as the therapy location and any previous radiation therapy sites are now included in the set-up notes.  Additionally, ensuring that the therapist has access to a patient’s medical chart will help allow the therapist to ensure a patient’s therapy is delivered properly.

Step 3 to avoid radiation therapy errors: verify the WHERE – which body part requires the radiation therapy

Wrong Radiation Treatment Delivered to Patient

by ThinkReliability Staff

A cancer patient was scheduled to receive two radiation therapy treatments – radiation to her upper lung every day, and radiation to her mediastinum on alternating days.  However, a mix-up resulted in her receiving the program for her lungs to her mediastinum (which resulted in ten times the prescribed dose) and receiving the program for her mediastinum to her lungs (which resulted in one-tenth the prescribed dose).  The patient died of cancer later in the year.

This incident impacted the facility’s patient safety goal, because the patient died of cancer, possibly because the radiation dose to her lungs was too low to effectively fight the cancer.  Additionally, it impacted the patient service goal because the patient received the wrong radiation treatment.  The organization and compliance goals were also impacted because of this reportable error.

How did this happen?  The patient had a complex radiation therapy program, involving two different treatments to two different parts of her body simultaneously (radiation was delivered to different body parts on alternating days). Obviously some confusion on the part of the staff was involved, and because only one therapist was present for administering the therapy, there was no oversight, or anyone else to catch the error.

Based on the causes of this incident, we can develop action items to be taken by the facility to reduce the risk of this type of incident happening again.  Unless it is medically necessary, avoiding administering two different therapies at one time would reduce the risk of this type of confusion.  The treatment a patient is receiving should always be verified before the treatment is administered.  Also, because of the high level of risk to patients, more than one therapist should be present.  (The facility involved in this particular incident has implemented a rule that more than one therapist be present for complex treatments.  Although it’s not clear exactly what’s meant by complex, surely this would qualify.)   Hopefully these steps, when taken by facilities who deliver radiation therapy to patients, will reduce the risk of radiation errors.

Step 2 to avoid radiation therapy errors: verify the WHAT – the type of treatment the patient is receiving.

Radiation Therapy Delivered to Wrong Patient

By ThinkReliability Staff

In March 2006 a patient (who we’ll call Patient A) reached an exciting milestone. She had just completed radiation treatment for a brain tumor.  However, she was not told that her radiation therapy was complete.  Instead, the therapist opened the medical chart of another patient (Patient B) and left.  Another therapist came in, saw the chart for Patient B, and noticed that Patient B required radiation treatment for breast cancer.  The therapist then delivered that radiation to Patient A.

This incident impacted the facility’s patient safety goal, because of the risk of injury to Patient A.  Additionally, it  impacted the patient service goal, because Patient A received unnecessary radiation.  The organization and compliance goals were also impacted because of this reportable error.

How did this happen?  Patient A was at risk for injury because of the delivery of unnecessary radiation.  She was given radiation meant for another patient because the therapist delivered the radiation and Patient A, not knowing that her own treatment was complete, didn’t know to stop it.  The therapist did not effectively verify the identity of Patient A, instead going off the chart that had been opened by the previous therapist, for unknown reasons.  Had the first therapist told Patient A that her therapy was complete, or had the first therapist not opened another patient’s chart, or had the second therapist verified the identity of Patient A, this error would probably not have occurred.

Based on the causes of this incident, we can develop action items to be taken by the facility to reduce the risk of this type of incident happening again.  Therapists should not open charts until they have verified the identity of a patient.  They should verify a patient’s identity before treatment, and they should review the outcome of a treatment with the patient.  After all, had any of these steps occurred, Patient A would have been able to properly celebrate the end of her radiation therapy, rather than worry about a risk to her health.

Step 1 to avoid radiation therapy errors: verify the WHO – the identity of the patient.

Applying the Proposed FDA Initiatives to Fatal Radiation Overdose

By ThinkReliability Staff

Recently, we posted two blogs about medical radiation overdoses resulting from cancer overdoses –  a patient who overdosed on radiation therapy for breast cancer, and a second patient who overdosed on intensity modulated radiation therapy for tongue cancer.  Because of the risk of these types of incidents, proper control of radiation in medical settings has become a high priority for several investigations.  Recently, the U.S. Food and Drug Administration (FDA) released an initiative to control unnecessary radiation exposure from medical imaging.  Many of the initiatives to reduce exposure from medical imaging can also be applied to reduce exposure from
radiation therapy.

We will look at one of our previous blogs – the intensity modulated radiation therapy overdose – and discuss how the initiatives proposed by the FDA may have prevented the death of Scott Jerome-Parks.  There are two radiation protection concepts for the initiatives – justification for use of radiation-related procedures, and optimization of the dose during the procedures.

The justification portion of the initiative aims to ensure medical justification and informed decision-making by patients and their doctors.  In order for the decisions to be informed, the FDA notes that patients must have comprehensive understanding of both the risks and benefits of the use of radiation.  If patients were more aware of the risks of the use of radiation, it’s possible that Jerome-Parks and others would have chosen alternative approaches or would have selected facilities based on their experience or safety rating.  Currently, because reporting requirements for errors involving radiation are inconsistent (or there are none at all), it’s nearly impossible for patients to make these sorts of comparisons.

Another issue raised by the Jerome-Parks case is the lack of safeguards on the radiation equipment itself.  Jerome-Parks received seven times the radiation dose on three occasions, and nobody noticed.  The FDA proposes that equipment designed to deliver radiation be equipped with safeguards that optimize radiation doses and/or provide alerts when radiation exceeds a reference level or range.  These safeguards would alert providers when radiation doses are higher than expected, giving them another chance to verify that the settings are correct.  Hopefully this will prevent many occurrences of radiation overdose.

The FDA has also noted the lack of training and quality assurance practices for some radiation delivery practitioners.  Several medical organizations are attempting to create standardized training and quality assurance methods to provide practitioners with the information they need to properly use radiation delivery equipment.  The FDA is also planning to partner with the Center for Medicare and Medicaid Services (CMS) to incorporate appropriate quality assurance practices into accreditation and participation criteria for medical facilities, further
supporting the safe use of radiation delivery equipment.

Looking at the two previous radiation overdose cases, we can see the detrimental effect of radiation therapy when not used properly.  Because of the great potential impact to patient safety, all involved parties MUST work together to ensure less patient risk from radiation therapy.