Extravasation of radiopharmaceuticals: Why report?

In this essay, I wish to discuss extravasation in the context of medical imaging and therapy with radiopharmaceuticals. Central to this discussion are two facts. First, they are easily identified, but the frequency of significant extravasations is unclear because there is no generally accepted definition of such an event. And second, there appears to be few reports of injuries from these events. The central thesis of this essay is that these events should be reported and followed so that agreement can be reached on the definition of a "significant" event which should be classified as a medical event in accordance with US Nuclear Regulatory Commission (NRC) regulations. I will also outline steps that can be taken to reduce the risk of extravasations.

VADER: a variable dose-rate external 137Cs irradiator for internal emitter and low dose rate studies.

In the long term, 137Cs is probably the most biologically important agent released in many accidental (or malicious) radiation disasters. It can enter the food chain, and be consumed, or, if present in the environment (e.g. from fallout), can provide external irradiation over prolonged times. In either case, due to the high penetration of the energetic γ rays emitted by 137Cs, the individual will be exposed to a low dose rate, uniform, whole body, irradiation. The VADER (VAriable Dose-rate External 137Cs irradiatoR) allows modeling these exposures, bypassing many of the problems inherent in internal emitter studies. Making use of discarded 137Cs brachytherapy seeds, the VADER can provide varying low dose rate irradiations at dose rates of 0.1 to 1.2 Gy/day. The VADER includes a mouse "hotel", designed to allow long term simultaneous residency of up to 15 mice. Two source platters containing ~ 250 mCi each of 137Cs brachytherapy seeds are mounted above and below the "hotel" and can be moved under computer control to provide constant low dose rate or a varying dose rate mimicking 137Cs biokinetics in mouse or man. We present the VADER design and characterization of its performance over 18 months of use.

The Radiation Safety Officer as an Advocate for Patient Safety.

The role of the radiation safety officer is to maintain radiation exposures as low as reasonably achievable. Traditionally, the focus has been on reducing or eliminating unnecessary occupational exposure to employees and ensuring exposure of visitors and members of the public is maintained below regulatory limits. Over the last three decades there has been increasing concern expressed in the medical literature on the potential risks of radiation exposure to patients undergoing diagnostic medical imaging procedures. This paper will discuss the need for advocacy and processes by which the radiation safety officer can expand the focus of a medical radiation safety program to include advocacy for applying the principles and practices of maintaining exposures as low as reasonably achievable to patients.

Cervical spine imaging using mini--C-arm fluoroscopy: patient and surgeon exposure to direct and scatter radiation.

STUDY DESIGN: Direct and scatter radiation was measured during cadaveric cervical spine imaging with a mini-C-arm fluoroscope. OBJECTIVE: The purpose of this study was to evaluate radiation exposure to the patient and surgeon when using a mini-C-arm fluoroscope to image the cervical spine. SUMMARY OF BACKGROUND DATA: Prior studies have quantified radiation exposure using large C-arm fluoroscopy during procedures involving the cervical, thoracic, and lumbar spine. To our knowledge, no studies have quantified radiation exposure during mini-C-arm fluoroscopy of the cervical spine. METHODS: A calibrated OEC MINI 6800 C-arm was used to image a prepared cadaveric cervical spine specimen, which included the skull. The specimen was suspended on an adjustable polycarbonate platform. Thirteen film badge dosimeters were mounted at various positions and angles to detect direct and scatter radiation. Recorded exposure levels were collected and analyzed. RESULTS: Surgeon exposures from the mini-C-arm were considerably lower than previously reported with the standard C-arm, but nonetheless concerning. Patient exposures were considerable and not always reduced compared with values from the standard C-arm. The kVp generated by the mini-C-arm was similar to the standard C-arm. Dosimeters mounted in the same plane recorded dissimilar amounts of radiation during the same test, which underscores the influence of shape on the amount of reflected scatter. CONCLUSIONS: Although using a mini-C-arm unit may reduce exposure levels, substantial exposure to both patient and staff is still achievable. Use of a mini-C-arm for cervical spine imaging reduces exposure to the surgeon more effectively than to the patient. To lower the risk of radiation exposure in the cadaver laboratory, a mini-C-arm should be used in each instance that offers appropriate visualization. In the operating room, all appropriate radiation dose-reducing measures should be strictly enforced by supervising physicians to minimize risk to patients, medical staff, and themselves.

Patient and surgeon radiation exposure: comparison of standard and mini-C-arm fluoroscopy.

BACKGROUND: Use of c-arm fluoroscopy is common in the operating room, outpatient clinic, and emergency department. Consequently, there is a concern regarding radiation exposure. Mini-c-arm fluoroscopes have gained popularity; however, few studies have quantified exposure during mini-c-arm imaging of a body part larger than a hand or wrist. The purpose of this study was to measure radiation exposure sustained by the patient and surgeon during the use of large and mini-c-arm fluoroscopy of an ankle specimen. METHODS: Standard and mini-c-arm fluoroscopes were used to image a cadaver ankle specimen, which was suspended on an adjustable platform. Dosimeters were mounted at specific positions and angulations to detect direct and scatter radiation. Testing was conducted under various scenarios that altered the proximity of the specimen and the radiation source. We attempted to capture a range of exposure data under conditions ranging from a best to a worst-case scenario, as one may encounter in a procedural setting. RESULTS: With all configurations tested, measurable exposure during use of the large-c-arm fluoroscope was considerably higher than that during use of the mini-c-arm fluoroscope. Patient and surgeon exposure was notably amplified when the specimen was positioned closer to the x-ray source. The exposure values that we measured during ankle fluoroscopy were consistently higher than the exposure values that have been recorded previously during hand or wrist imaging. CONCLUSIONS: Exposure of the patient and surgeon to radiation depends on the tissue density and the shape of the imaged extremity. Elevated exposure levels can be expected when larger body parts are imaged or when the extremity is positioned closer to the x-ray source. When it is possible to satisfactorily image an extremity with use of the mini c-arm, it should be chosen over its larger counterpart.

Cervical spine imaging using standard C-arm fluoroscopy: patient and surgeon exposure to ionizing radiation.

STUDY DESIGN: A cadaveric cervical spine specimen is imaged with a standard C-arm fluoroscope during a simulated procedure. Patient and surgeon exposure to radiation is estimated by placing dosimeters at various locations in 3-dimensional space. OBJECTIVE: The purpose of this study was to evaluate radiation exposure to patient and surgeon when using C-arm fluoroscopy during a simulated cadaveric surgical procedure involving the cervical spine. SUMMARY OF THE BACKGROUND DATA: The use of mobile fluoroscopy has become commonplace in orthopaedics. With the current trend towards minimal access techniques, fluoroscopy has become requisite to achieving satisfactory outcomes. Studies have shown that spine surgeons may be at elevated risk for radiation exposure compared to other orthopaedists. Exposure while using C-arm fluoroscopy for procedures involving the pelvis, as well as thoracic and lumbar spine has been documented. However, there are no equivalent studies that evaluate exposure during cervical spine imaging. METHODS: A standard OEC 9800 C-arm was used to image a prepared cadaveric cervical spine specimen, which was suspended on an adjustable platform. Film badge dosimeters were mounted at various positions and angles to detect direct and scatter radiation. Testing was conducted in various radiation dose mapping "scenarios." The configurations tested altered the proximity of the specimen and jig relative to the radiation source. We attempted to capture radiation exposure in various locations, from a best-case to a worst-case scenario, as may be realistically encountered in a procedural setting. RESULTS.: Potential exposure to the patient and surgeon were consistently measurable, and of concern. As the imaged specimen was positioned closer to the radiation source, exposure to the patient was markedly amplified. Exposure to the surgeon did not increase as dramatically. There was a great degree of variability in the exposure doses recorded by the peripheral dosimeters. Even dosimeters that were placed in the same plane diverged widely in their measured exposure. This highlights the influence of the shape of the imaged specimen on reflected scatter. Scatter radiation doses on both sides of the specimen were similar. CONCLUSION: Care should be taken when working on both sides of the imaged subject. Considerable radiation exposure can be encountered when working with a C-arm fluoroscope if appropriate precautions are not observed. All appropriate radiation dose-reducing measures should be strictly enforced by the supervising physician to minimize risk to the patient and the medical team.