Safety First

Greater precision and targeted radiotherapy techniques address error rates

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(©istockphoto.com/Mark Kostich)

Todd Pawlicki, PhD, (right) is a professor in the radiation oncology department and Dan Scanderbeg is a medical physicist at the University of California, San Diego. (University of California, San Diego)

Going the Extra Mile

Vendors in radiotherapy are concerned with quality and safety. Some are also bringing innovative solutions to aspects of their products. 

In brachytherapy, Cianna Medical Inc. (Aliso Viejo, Calif.) has developed a novel breast brachytherapy device. The SAVI® breast brachytherapy applicator delivers radiation through an array of catheters. The single-entry system allows physicians to sculpt the dose to the patient’s

anatomy and tumor cavity. This device can lead to less skin toxicity, lower persistent seroma rates, and reduce the risk of infection.

As with any radiotherapy method, SAVI can only achieve its full safety potential if it is administered correctly. To that end, Cianna Medical takes the following measures: employs three full-time medical physicists; provides in-class training to new physicists and radiation oncologists using the  technology; assigns a physicist to oversee a facility’s first cases; provides remote treatment planning support; and delivers a clinical and safety orientation for support staff.

In the external beam radiation therapy world, .decimal Inc.® (Sanford, Fla.) takes a unique approach to maximize performance of its systems. Most EBRT vendors install their product at a client site and then train them how to use it. But that’s where the implementation ends.

As a medical device manufacturer of patient-specific devices, .decimal provides missing tissue compensators, modulators for advanced IMRT delivery, BolusECT compensators for bolus electron conformal therapy, and apertures and range compensators used in proton therapy. In addition, .decimal has developed q.d™, a system for IMRT physics that serves as a comprehensive compensator-based IMRT commissioning program, IMRT delivery capability assessment, and an IMRT delivery benchmarking tool. With this approach, .decimal works with clients to measure the accuracy of IMRT planning and delivery, and produce metrics of dose delivery. Customers can compare results with their own baseline standards or with other institutions. 

The q.d step-by-step process helps users diagnose sources of error and fix them before treating patients. A .decimal medical physicist oversees the process until the equipment and procedures have performed satisfactorily in clinical tests and are being used successfully with patients.

– Todd Pawlicki, PhD

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Unlocking the Power

The ability to provide highly targeted, localized treatment is one of the most important goals of radiation therapy. And the key to realizing that goal is imaging. Solutions make it possible to
perform efficient daily imaging, which helps ensure proper dosage and accurate delivery of intensity-modulated radiation therapy (IMRT) to treat common and complex cancers.

The 3-D volumetric imaging capabilities from the TomoTherapy®

system allow positioning adjustments based on day-to-day changes to a patient’s anatomy. In addition, it provides a comprehensive picture of the dose that the tumor has already received, so future fractions can complete treatment according to the planned dose description.

Another trend in localized treatment is using short courses of high-dose radiation, also known as hypofractionation. Daily 3-D image guidance is important with hypofractionated dosing because when delivering fewer, high-dose fractions, they must be accurately targeted and extremely precise to spare surrounding healthy tissues.

Hypofractionation is being used more frequently for localized head, neck, lung, and prostate cancers. Tumors in the head, neck, and lungs can grow fast and repopulate within a few weeks. Therefore a higher dose and faster treatment cycle can result in a more effective treatment. There is a growing belief that fewer, higher doses are more effective to treat prostate cancer. Oncologists now find that shorter treatment of 25 fractions or fewer are preferable, instead of the previous 35 or more fractions of lower doses.

Hypofractionated radiation delivery is also creating a new opportunity to treat patients with widespread metastatic disease. The accuracy and image documentation associated with newer radiation therapy technologies provides clinicians with a reliable account of the dosage delivered over the course of an initial treatment to safely handle isolated metastases.

The TomoTherapy system with daily 3-D volumetric imaging capabilities and helical IMRT delivery also supports “dose painting,” which delivers boosts of high doses of radiation to small volumes of a tumor while minimizing exposure of areas in close proximity. Precision associated with this type of radiation delivery may enhance control of resistant parts of the tumor, and not increase risk to healthy organs.

Daily 3-D volumetric image guidance has the power to unlock significant opportunities for precise, localized radiation therapy treatment. The best radiation therapy treatment plan has little value to patients if they are not assured that the planned dose distribution will hit the target.

– Sue Warren is a radiation therapist and dosimetrist with Madison, Wis.-based TomoTherapy Inc.

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A recent series of articles in the New York Times has alerted the public to some important issues concerning the safety of radiation therapy. However, those of us who deliver radiotherapy have always been aware of these issues and the ongoing efforts to address them.

These articles, which were published earlier this year, related several stories of therapeutic errors that harmed patients, sometimes fatally. Yet the author was careful to assure readers that “radiation saves countless lives, and serious accidents are rare.” But the articles also called attention to areas where greater precautions and oversight are necessary. Clearly, there is a need for similar quality and safety controls that govern other endeavors where lives depend on the expert operation of
sophisticated technology.
     
The Precision Dilemma

Radiation treatments are routinely delivered in a safe manner. There’s a strong emphasis on quality assurance among equipment manufacturers that develop new technology and clinical staffs who deliver treatments. Yet one of the most vexing issues in radiotherapy stems from the emphasis on using that new technology. Ironically, many of the problems that lead to errors result from efforts to make radiation therapy better.

Take linear accelerators, for instance. These machines, which have been used to deliver radiation therapy since the 1960s, originally directed rectangular or block-shaped radiation beams at the tumor area. Because these shapes bore no relation to the actual shape of the tumor, large margins of healthy tissue were included in the area targeted by the beam, exposing tissues to radiation damage.

To overcome this problem, researchers and vendors attempted to make radiation therapy more precise. Advances enabled the development of successively more targeted radiotherapy techniques, from 3-D conformal to intensity-modulated radiation therapy (IMRT) to image-guided radiation therapy (IGRT). Greater precision has the potential to reduce the severity of side effects and improve treatment outcomes.

But greater precision brings its own challenges in the form of computerized treatment planning and radiation delivery by computerized machines. These challenges, in turn, create greater complexity, more opportunities for errors, and new error pathways. In addition, the impact of an error can be multiplied. For instance, an incorrect treatment plan could result in ill-targeted or poorly modulated dosing that could be repeated over several radiation sessions. Similarly, a typing error at a keyboard or other simple mistakes can turn an intended precise treatment into one that is delivered incorrectly.

So-called “gating” techniques in IGRT are an example of how safety and efficiency are sometimes at war with itself in radiotherapy. The need for gating is based on the fact that some tumors move in concert with the patient’s breathing cycle. Radiation oncologists take this into account when targeting the radiation by correlating the patient’s breathing motion (using additional hardware and software) to the tumor’s motion. But the computer and human operators must accomplish many complex steps to get this right.

The issue of brachytherapy versus external beam radiation therapy (EBRT) is another area where precision is usually an advantage – but where the mistake potential is theoretically greater when delivered using high dose-rate (HDR) brachytherapy. In this case, the problem is not that there is greater opportunity for mistakes with brachytherapy, but that mistakes may have greater impact on the patient.

Brachytherapy normally delivers radiation in a more localized fashion than EBRT, but it is delivered with fewer treatments at higher doses. Because the higher dosage is delivered quickly, a mistake that results in an overdose could have more impact in a single treatment of brachytherapy than a single EBRT treatment. The same is true of hypofractionated EBRT approaches, namely stereotactic body radiotherapy (SBRT), in which therapy is delivered in fewer sessions with greater doses per session.

Regulators have responded to the HDR issue by establishing protective rules, and brachytherapy now has additional safety regulations. Some of the tighter regulations stem from an unfortunate incident in 1992 in which a brachytherapy patient was accidentally overdosed when the radiation source broke off from the HDR device and was inadvertently left in the patient’s body.

The medical staff compounded the problem by failing to take ordinary measures that might have detected the problem. The federal Nuclear Regulatory Commission (NRC) investigated the incident and responded with several mandates. For example, a physician and physicist are now required to be present for all HDR treatments. This stipulation is not required for EBRT.

Examining Quality and Safety Issues

Beyond the complexity problem, there are other areas in radiotherapy safety where improvements are needed. The regulatory environment is a good place to start. At the federal level, the NRC regulates radioactive materials. Machine-generated radiation, which is used more frequently, is largely unregulated at the federal level.

Accident reporting is also a regulatory mishmash. Because no single federal agency oversees radiotherapy, there is no one clearinghouse that receives and investigates reports.

States have not picked up the slack. In states where reporting is required, enforcement may be lackadaisical or inconsistent. This is a missed opportunity to improve safety by sharing information on best practices. Reporting would give a clearer picture of the scope, dimensions, and solutions to safety problems.

Licensing critical personnel is also inconsistently regulated. Medical physicists have primary responsibility for the technical quality and safety in a radiotherapy department. They perform a variety of safety roles, including ensuring that machines are properly calibrated and deliver the correct dose. But these clinicians are currently required to be licensed in only 4 states.

The Times investigated numerous accident reports from New York hospitals (a licensure state) and discovered that, among other safety issues, several hospitals had performed inadequate quality assurance and had insufficient staffing to support the complexity of treatments they performed. But this shows a failure on the regulatory side because in many states, quality assurance is voluntary, the Times noted. Certification of radiotherapy departments may also help ensure consistently safe practices. 

Developing New Solutions

The good news on the safety front is that the radiotherapy field is well aware of the issues and is moving to address them in novel ways. In particular, there are efforts to adopt safety mechanisms that have been used effectively in other fields.

One of these mechanisms is called failure mode and effects analysis (FMEA) – an approach that applies to product development and operations management. FMEA is a technique to determine the opportunity for error in a given process, the likelihood the error can be detected, and the potential severity of the error. It has been used successfully in other industries, including the armed forces, aerospace, the food industry, and other healthcare fields. It can be applied to any form of radiotherapy.

Once FMEA is applied, other tools such as process mapping, root cause analysis, and fault tree analysis can help the radiotherapy industry identify the part or aspect of a machine or process that could have the largest impact on patients. These approaches can help the radiology field focus safety efforts where they can do the most good.

Professionals in the field are also discussing the use of statistical process control (SPC). SPC uses techniques that analyze devices and processes to make sure they are performing within clinical tolerances. The goal is to provide a quantitative method to identify and then remove unusual sources of variability before they have the opportunity to harm a patient.

The radiology field is being proactive addressing these crucial safety issues. In fact, American Physician Partners Inc. and the American Society for Therapeutic Radiology and Oncology will be holding a conference in June with the sole topic of safety in radiation therapy. It is no coincidence that the conference is coming so soon after the Times articles were published. The radiology industry was already on the case, but now there’s more focus and collaboration among professional societies.

– Todd Pawlicki, PhD, is associate professor and director of the division of medical physics, department of radiation oncology, and Arno J. Mundt, MD, is professor and chair of the department of radiation oncology at the University of California, San Diego in La Jolla, Calif. They are also co-editors of Quality and Safety in Radiotherapy, a new book that comprehensively covers quality techniques and quality assurance methods for radiotherapy. Direct comments and questions to editorial@rt-image.com.