Rationale and Objectives
In recent years, there has been increasing interest in the impact of environmental factors such as ambient light on radiologist performance. One commonly encountered distractor found within all clinical departments that has received little or no attention is acoustic noise.
Materials and Methods
The present work records the level of noises encountered within environments where radiologic images are viewed and establishes the impact of a clinically relevant level of noise on the ability of radiologists to perform a typical diagnostic task. Noise levels were recorded 10 times within each of 14 environments, 11 of which were locations where radiologic images are judged. Thirty chest images were then presented to 26 senior radiologists, who were asked to detect up to three nodular lesions within 30 posteroanterior chest x-ray images in the absence and presence of noise at an amplitude demonstrated in the clinical environment. Jackknife free-response receiver-operating characteristic analyses was performed on the free-response data.
Results
The results demonstrated that noise amplitudes rarely exceeded that encountered with normal conversation with the maximum mean value for an image-viewing environment being 56.1 dB. This level of noise had no impact on the ability of radiologists to identify chest lesions with figure of merits of 0.68, 0.69, and 0.68 with noise and 0.65, 0.68, and 0.67 without noise for chest radiologists, nonchest radiologists, and all radiologists, respectively. Equally, no differences were seen for false-positive and false-negative scores or on the time required to judge the images.
Conclusion
These findings suggest that noise at levels encountered within areas where radiologic images are viewed is not a major distractor within the reporting environment, but the need for further work has been identified.
Much emphasis is placed on the adherence of standards and quality control protocols to promote the production of high-quality images within diagnostic imaging departments ( ). In particular, a plethora of data is available to encourage optimum acquisition ( ), transfer, and display ( ) of patient anatomic and pathologic features so that images of appropriate levels of spatial and brightness resolution are presented to the viewer. Although the presentation of a diagnostically efficacious image is clearly necessary, the production of an accurate interpretation is equally important, which has been shown to be dependent on the viewing environment in which the observer finds himself or herself ( ). Until recently, little guidance has ben available for this latter part of the imaging chain.
One component of the viewing environment that has gained increasing scientific attention is the level of ambient lighting ( ). Consequently, detailed guidance has become available on lighting levels based on monitor diffuse and specular reflection coefficients ( ), and whereas more data are required particularly relating to human visual adaptation ( ), work is being done to address this deficiency ( ). In contrast, a potential distraction that has gained little or no attention in the radiologic world is acoustic noise, and although it has an impact on almost every observer, there is little understanding of its effect on correct interpretation of medical images.
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Materials and methods
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Establishing the Amplitude of Acoustic Noise in Clinical Environments
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Impact of the noise recording
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Results
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Table 1
Amplitudes of Sound Recorded in Various Reporting Environments
Location Average Amplitude dB(A) Amplitude Range dB(A) Consultant radiologist office 1 43.9 42.6–45.5 Consultant radiologist office 2 42.2 40.9–43.1 Radiology registrar office 42.7 40.5–46.2 General radiology exam room 47.7 46.3–49.5 Radiology conference room 42.7 41.2–45.1 Emergency radiology exam room 48.1 46.5–54.2 Emergency reporting station 1 56.1 48.2–68.8 Emergency reporting station 2 46.7 40.1–54.1 Emergency reporting station 3 53.4 42.8–59.3 Intensive care reporting station 1 49.9 47.2–53.9 Intensive care reporting station 2 50.7 43.7–59.6 Radiology waiting area 47.9 39.9–54.4 Emergency waiting area 58.8 55.5–65 Outpatients waiting area 57.3 53.7–62
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Table 2
Numbers and Details of Participating Radiologists
Radiology Group No. Male/Female (n) Mean No. of Years of Postregistration Experience Chest specialists 11 5/6 18 (10) Nonchest specialists 15 9/6 21 (5) All radiologists 26 14/12 20 (7)
Standard deviations are shown in parentheses.
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Table 3
Mean Values for Figures of Merit, False Positives, and False Negatives Across All Radiologists within Each Subgroup
Experimental Group Figure of Merit False Positives False Negatives Chest radiologists Sound pattern 0.68 (0.04) 3.3 (0.5) 1.2 (0.4) No sound pattern 0.65 (0.1) 3.4 (0.8) 0.9 (0.3) Nonchest radiologists Sound pattern 0.69 (0.06) 4.6 (0.6) 0.4 (0.1) No sound pattern 0.68 (0.06) 6.2 (0.7) 1.5 (0.7) All radiologists Sound pattern 0.68 (0.05) 4.1 (0.4) 0.7 (0.2) No sound pattern 0.67 (0.07) 5.0 (0.6) 1.2 (0.5)
False-positive and false-negative values represent the mean total amount across all images. Standard deviations are shown in parentheses.
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Discussion
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Table 4
Average Time in Seconds Taken to Assess Each Image
Radiology Group Exposure to Sound Pattern No Sound Pattern Chest specialists 12.9 (2.6) 13.7 (2.9) Nonchest specialists 15.4 (5.6) 16.7 (5.6) All radiologists 14.3 (4.7) 15.4 (4.9)
Standard deviations are shown in parentheses.
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