Observer Performance Evaluation of a Digital Camera for Acquiring

Radiographic Images for Teleradiology

Elizabeth A. Krupinski, PhD

University of Arizona

Goal Conduct a feasibility study to

determine if a commercially available digital camera can be used to acquire photographs of radiologic images to transmit them via store-forward technology over a telemedicine network.

Arizona Telemedicine Program (ATP)Sites

Tuba City

Kingman

Cottonwood

Ganado

PaysonSpringerville

Whiteriver

DOC - Phoenix

DOC - Yuma

NogalesPatagonia

Douglas

AHSCKinoTucson VA

AHSC Hub

Telemedicine

Telepathology

TeleradiologyDOC - Florence

DOC - Buckeye

DOC - Douglas

Study Rationale Teleradiology is an important part of an

increasing number of Radiology & Telemedicine programs

Saves time and feedback to referring clinician is faster than with other methods (e.g., courier) - 85% of our teleradiology cases have a “wet read” report generated within 6 hours

Rationale Continued

It can, however, be expensive! For digital modalities a merge box is

needed For plain film a digitizer or video capture

system is required Some sites just cannot afford these options A low-cost alternative had to be explored

The Test Site The Patagonia Family Health Center in rural

Arizona needed consults, especially in orthopedics & bone radiology

The clinic has no x-ray facilities so sends patients to Nogales’ Mariposa Clinic, the report & films are then sent over either with the patients or later

Problem - Mariposa only has a general radiologist so sub-specialty consults are often required

The Camera

Canon PowerShot600CCD image sensor832 x 608 pixels24-bit color resolutionf/2.5 lensBuilt-in flash150 kB file size

The Cases 40 bone trauma cases (e.g., fracture,

subluxation, soft tissue damage) from the Patagonia Family Health Clinic

Cases that required a consult in the past & were representative of the types of cases they would be sending for teleconsults in the future - typically subtle lesions

The Photographs Film images were placed on standard

viewbox with extraneous light blocked out The physician identified region(s) of

interest based on clinical history and nature of problem

At least one global and one close up shot were acquired for each image using the Canon PowerShot camera

The Displays

Images sent over ARTN to the MedVision workstation

Color monitor, 1024 x 768 pixels Window/level, zoom/pan available for use

during viewing Film images displayed on standard viewbox

Example of a Close-Up Shot

Example of an Original Film Image

Photographed Image on the Monitor

Protocol 2 orthopedic surgeons & 2 bone radiologists

reviewed the 40 cases on film & using the digital photographs displayed on the monitor

Film reading 6 months after monitor reading Reported:

• Diagnosis

• Decision confidence using 6-level scale

• Image quality using 4-level scale

Results - Image Quality

0

1020

3040

50P

ER

CE

NT

Film Photo

ExcellentGoodFairPoor

Results - Image Quality 2 = 20.32, df = 9, p = 0.02 9 of the photo cases were rated poor

4 film cases were rated poor Of the 9 photo cases, 4 (45%) were rated as poor

because the region-of-interest was not captured sufficiently

Some views (film & photo) were not what the readers were used to - different technologists

Results - Diagnoses* Reader Agreement (Kappa)*

1 0.89

2 0.92

3 0.94

4 0.88

* Agreement with truth. Truth was determined from the film images by 2 radiologists not participating in the study.

Results - Confidence

0

20

40

60PE

RC

ENT

FILM vs PHOTOCONFIDENCE

Same*

One*

Two*

* How many categories film & monitor confidences differ by - a difference of two is considered significant

Conclusions A digital still camera can be used effectively to

capture images of bone trauma radiographs for store-forward telemedicine consults

Well-framed close-up shots of the region-of-interest are essential

Good quality original films are essential

Other Applications? Other non-screening applications where a

specific suspicious region-of-interest can be identified for close-up photographs

Unless the lesion is fairly gross, the global shots are not adequate for consultation - close-up shots are required in the majority of cases