Thomas L. Morgan

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.

Metastatic squamous cell carcinoma of the neck from an unknown primary: Management options and patterns of relapse†

Management of squamous cell carcinoma of undetermined primary tumors in the head and neck region is controversial. Here we report the Southern California Kaiser Permanente experience with these patients.

Radiation Exposure Issues in Orthopaedics

The topic of radiation exposure for patients, physicians, and staff has become prominent in the lay press. It seems that every week another story about radiation safety makes the evening news. For physicians and surgeons, the largest radiation exposures involve fluoroscopy use with either fixed or mobile units. For patients, fluoroscopy (c-arm), computed tomography (CT), and nuclear medicine studies constitute the vast majority of exposures. The use of each of these modalities has grown dramatically with changes in the practice of medicine. C-arm use in orthopaedic surgery is increasing rapidly as surgery transitions to minimal-access surgery. With less direct visualization, surgery is being conducted with fluoroscopic guidance. When fluoroscopy is combined with a computer for navigation systems, radiation exposure sustained by surgeons can be reduced dramatically. This transition does not decrease the patients radiation dose, and in some instances it can increase it substantially1. CT scans have become accepted as commonplace. The rate of CT use is thirty times greater than it was twenty years ago, and the radiation exposure sustained by a patient can be dramatic2,3. Less than one-sixth of physicians receive any training in radiation safety4. One questionnaire study of physicians showed that 4% did not know that ultrasound did not involve ionizing radiation and 27% did not know that magnetic resonance imaging (MRI) did not involve radiation at all5. Approximately 90% of physicians underestimated the radiation exposure and risks from pediatric radiographs and CT scans4. A single pediatric abdominal CT scan exposes the patient to more radiation than the seventy-year exposure from living in the vicinity of the Chernobyl accident2. For a five-year-old patient who weighs 19 kg, a chest CT is the equivalent of 600 chest radiographs and a CT of the …

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.

Radiation protection during percutaneous nephrolithotomy: a new urologic surgery radiation shield.

BACKGROUND AND PURPOSE As endourology becomes an important part of the practice of urology, the use of fluoroscopic guidance has increased the exposure of urologists to the possibly deleterious effects of radiation. There is a need for a method of radiation protection for percutaneous nephrolithotomy (PCNL), as the exposure from radiation scatter may be significant, depending on the difficulty of establishing access. PATIENTS AND METHODS We ascertained the effectiveness of a newly modified radiation shield during PCNL. Exposure readings were taken using a thermoluminescent dose monitor placed different distances from the radiation source during six PCNLs. We compared the exposure readings with and without the shield. RESULTS The shield was able to reduce the radiation by an average of 96.1% at a distance of 25 cm and 71.2% at a distance of 50 cm from the source. CONCLUSION The shield can be used as one step toward the goal of reducing surgeon radiation exposure. Other methods, such as dose-minimizing imaging protocols and adaptation of equipment optimized to reduce exposure, are also important measures in creating a safe environment for both the urologist and the patient.

A comparison of single-dose and fractionted total-body irradiation on the development of pneumonitis following bone marrow transplantation

PURPOSE A review of 132 consecutive patients who received bone marrow transplant for various malignancies was conducted to determine factors associated with increased risk in developing interstitial pneumonitis (IP) as the result of total body irradiation (TBI). Twenty-four patients were excluded because 22 did not receive TBI and two had insufficient records. METHODS AND MATERIALS Patients were conditioned with TBI and various drug regimens. Eighteen patients received a single 6.0 Gy dose of x-rays. The remaining 90 were treated with three doses of 3.33 Gy separated by 24 h. All patients were followed for at least 18 months for the purposes of determining the IP incidence. RESULTS Twenty-seven of these 108 (25%) patients developed IP; 19 (17.6%) died. The 2-year estimated incidence of IP was 24 and 18.6% for fatal IP. The etiology was determined to be idiopathic in 12 patients, the result of cytomegalovirus in 6 patients, and caused by a variety of other infectious organisms in 9 patients. We were unable to demonstrate a statistically significant increase in IP with age (adults vs. children), dose regimen, use of methotrexate for graft-vs.-host disease prophylaxis, the presence of acute graft-vs.-host disease, time from diagnosis to transplant, or transplant type (allogeneic vs. autologous). CONCLUSIONS The incidence of fatal IP reported here is similar to that reported by other institutions utilizing hyperfractionated TBI protocols. Our data do not support the need for hyperfractionation to reduce the risk of IP.

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.

Radiation therapy port films: a quality assurance study

PURPOSE The purpose of this study was to assess the port film acceptance rate in a large community practice setting and to catalog the reasons for rejection. METHODS Between December 1993 and July 1996, a quality assurance monitor log was maintained on 4,150 patients who underwent a total of 4,450 treatment courses. Port films were taken at the beginning and at the half way point in the treatment course. A total of 20,735 port films were compared with the matching simulation films. We recorded the site being treated, the radiation oncologist who reviewed the films and the reason for rejection. RESULTS The monthly acceptance rate varied from a low of 67% to a high of 83%, with a gradual upward trend. The single most common reason for rejecting films was a centering problem-12% of all films taken were rejected for this reason. The next most common problems were block placement or body setup errors that caused 3.4% and 2.7% of the films to be rejected, respectively. Average acceptance rates between 10 different sites (abdomen, brain, breast, chest, extremities, head and neck, pelvis, prostate, rectum and spine) varied from 68% to 80%. Individual differences between 12 radiation oncologists reviewing the films varied from 67% to 87%. CONCLUSIONS A detailed analysis of field localization errors allowed us to identify areas where improvement was needed and suggested that specific guidelines for acceptance would help reduce the variability noted in the acceptance rate between sites and physicians.

Uninterrupted moderately accelerated radiotherapy in the treatment of unresectable/advanced head and neck cancer: one institution's experience and a comparative review.

Conventional radiotherapy alone in treatment of unresectable or locally advanced head and neck cancer has poor results. To improve outcome without significant increase in acute and late morbidity, we began a moderately accelerated hyperfractionation radiation therapy protocol without breaks for treatment of unresectable/advanced head and neck malignancies. From August 1984 to June 1995, 48 patients with unresectable or advanced carcinoma of the head and neck were treated using a protocol of accelerated hyperfractionation radiation therapy at Kaiser Permanente Medical Center, Los Angeles. Patients were treated twice a day using 150 cGy per fraction, 4 days per week, to a final dose of 60 Gy. Two patients were excluded from this analysis because they did not complete treatment. With a median follow-up of 33 months, 31 (67%) patients have had disease recurrence, 30 (65%) of whom had a locoregional component to their failures. At the last follow-up, 12 patients (26%) were alive with no evidence of disease, 30 patients had died of disease, and 4 had died of intercurrent disease without recurrence. Nine (19%) patients required treatment interruptions averaging 8 days in duration. This accelerated regimen resulted in outcomes similar to those with conventional radiotherapy, most likely because of a conservative total dose. Further refinement of fractionation schedules with potential incorporation of chemotherapy must be investigated.