Patient exposure to ionising radiation in the intensive care unit due to portable chest radiography

Risk of Radiation Exposure to Emergency Department Personnel From Portable Radiographs

BACKGROUND

There are concerns that emergency health care workers are exposed to ionizing radiation as the result of frequent portable radiographs obtained in the emergency department (ED) during active patient care.

OBJECTIVE

Our aim was to investigate whether ED staff are exposed to significant radiation due to scatter from portable radiography at a busy trauma center and whether exposure was related to factors such as location or distance.

METHODS

This was a prospective cohort study performed during 3 consecutive months in the ED at a large, academic trauma center. Volunteer attendings, nurses, and resident physicians were asked to wear dosimeter badges during their shifts throughout the study period. Twelve stationary dosimeters were placed in selected locations in the ED, particularly in the resuscitation rooms, where most of the portable radiographs were obtained.

RESULTS

During the 3-month study period, 1464 portable radiographs were obtained in the resuscitation rooms in the ED, mostly chest and pelvic radiographs. Analysis from stationary dosimeters placed in the ED showed a median of 0.18 mSv (95% CI 0.16-0.22 mSv) for the main resuscitation room and 0 mSv for other critical care patient rooms. Analysis of dosimeters worn by staff showed no measurable radiation exposure (0.00 mSv).

CONCLUSIONS

The level of radiation exposure to ED staff found in this study was well below the recommended allowable occupational exposure of 50 mSv/y. Radiation exposure is not a significant occupational hazard in a busy ED level I trauma center. Existing precautions should adequately protect staff from occupational exposure, and use of further protective gear, or the need for individual monitoring using dosimeters, appears unwarranted.

Cumulative total effective whole-body radiation dose in critically ill patients

BACKGROUND

Uncertainty exists about a safe dose limit to minimize radiation-induced cancer. Maximum occupational exposure is 20 mSv/y averaged over 5 years with no more than 50 mSv in any single year. Radiation exposure to the general population is less, but the average dose in the United States has doubled in the past 30 years, largely from medical radiation exposure. We hypothesized that patients in a mixed-use surgical ICU (SICU) approach or exceed this limit and that trauma patients were more likely to exceed 50 mSv because of frequent diagnostic imaging.

METHODS

Patients admitted into 15 predesignated SICU beds in a level I trauma center during a 30-day consecutive period were prospectively observed. Effective dose was determined using Huda's method for all radiography, CT imaging, and fluoroscopic examinations. Univariate and multivariable linear regressions were used to analyze the relationships between observed values and outcomes.

RESULTS

Five of 74 patients (6.8%) exceeded exposures of 50 mSv. Univariate analysis showed trauma designation, length of stay, number of CT scans, fluoroscopy minutes, and number of general radiographs were all associated with increased doses, leading to exceeding occupational exposure limits. In a multivariable analysis, only the number of CT scans and fluoroscopy minutes remained significantly associated with increased whole-body radiation dose.

CONCLUSIONS

Radiation levels frequently exceeded occupational exposure standards. CT imaging contributed the most exposure. Health-care providers must practice efficient stewardship of radiologic imaging in all critically ill and injured patients. Diagnostic benefit must always be weighed against the risk of cumulative radiation dose.

Accuracy of low-dose chest CT in intensive care patients

In this prospective study, we set out to determine the accuracy of low-dose computerized tomography (LDCT) of the chest in intensive care patients. Fifteen adult intensive care patients were examined with a standard-dose CT protocol (average radiation dose = 6.7 mSv), chosen as the reference standard, followed by a non-contrast-enhanced LDCT protocol (average radiation dose = 0.59 mSv). Each examination was then read by two separate groups of radiologists blinded to both the purpose and the protocol of the study. In the small group examined, the results showed 100% accuracy in the diagnosis of pneumomediastinum, pericardial effusion, and pleural effusion, and 90% accuracy in the diagnosis of pneumothorax and consolidation. There were no false-positive findings, and the few false-negative findings were unlikely to lead to any clinical interventions. Our examination protocol, while providing a tenfold reduction of the radiation dose, nevertheless remained accurate enough for resolving certain clinical questions common in the intensive care patient. Thus, we suggest that protocols aimed at reducing the radiation dose in chest CT could be applied to the intensive care patient for resolving some specific questions, without compromising the diagnostic yield of the examinations.

Portable chest radiographs in the intensive care units: referral patterns and estimated cumulative radiation exposures

The objective of this article was to determine the frequency of referrals for portable chest radiographs from medical and (noncardiac) surgical intensive care units (NICU and SICU) and their respective stepdown units (NICA and SICA). Additionally, the cumulative entrance skin exposure (ESE) using an ion chamber was determined. We retrospectively reviewed the medical records of all adult patients admitted to the MICU, SICU, MICA, and SICA at a tertiary referral center during a 6-month interval. The duration of stay and the number of portable chest radiographs were determined for each patient. The measured ESEs from all portable radiography units ranged from 5 to15 mR (average: 10mR). The cumulative radiation exposure for each patient was calculated. There were 567 patients admitted to the units: 146 surgical and 421 medical. Their ages ranged from 15 to 87 years. The duration of stay varied from 1 to 68 days. A total of 3,794 portable chest radiographs were obtained. The number of radiographs per patient varied from 1 to 94. The number of radiographs and the corresponding cumulative radiation doses were as follows: 406 patients (72%) had fewer than five radiographs (<50 mR); 76 (13%) had five to 10 radiographs (<100 mR); 35 (6%) had 11 to 20 (<200 mR); and 50 (9%) had more than 20 chest radiographs (>200 mR). The cumulative ESE ranged from 10 to 940 mR. It exceeded 450 mR in only nine (1.5%) patients. Most (73%) patients undergoing intensive care undergo fewer than five radiographs during their stay in the units. Patient exposure from portable chest radiographs in this population is less than the average annual exposure from background radiation in the USA (450-500 mR), and is much less than the average annual exposure from teratogenic radiation.

The utility of routine postoperative chest radiography in the postanesthesia care unit

STUDY OBJECTIVE

To evaluate the clinical significance and cost effectiveness of routine chest radiographs in the postanesthesia care unit (PACU).

DESIGN

Prospective study.

SETTING

University hospital.

PATIENTS

100 patients who were admitted to the PACU following various surgical procedures, and in whom a postoperative chest radiograph was routinely performed.

INTERVENTIONS

Chest radiograph was taken in each study patient soon after admission to the PACU. The indications for postoperative chest radiograph were: thoracotomy (30 patients), thoracoscopy (7), central vein catheterization (CVC) (75), pulmonary artery catheterization (3), and mechanical ventilation (36). A staff anesthesiologist examined each patient, evaluated each chest radiograph, and decided if a treatment action was to be taken. A chest radiologist later evaluated each chest radiograph, and her interpretation was compared with the anesthesiologist's interpretation to assess if this may affect patient management.

MEASUREMENTS AND MAIN RESULTS

The anesthesiologist found eight abnormal chest radiographs (8%): three with pulmonary congestion, four in whom the CVC was in the right atrium, and one with malpositioned CVC. In four patients (4%), the chest radiographic findings directly affected patient management. The radiologist confirmed the anesthesiologist's interpretation and found four additional abnormalities: one pulmonary congestion, one malpositioned CVC, and two chest radiographs, each with a small pneumothorax.

CONCLUSIONS

Abnormal chest radiographic findings resulted in a change in the management of only 4% of the patients. Therefore, the yield of a routine postoperative chest radiograph in the PACU is low. Performing a chest radiograph for a specific indication rather than on a routine basis, may decrease work load and save expenses. Postoperative chest radiography can be safely evaluated by a staff anesthesiologist.