Medical History Vignette: Image Intensification

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Wilhelm Conrad Roentgen’s discovery of x-rays in November 1895 significantly changed the practice of medicine by providing a way of looking inside a living body without cutting it open1. The first medical x-rays were made in February 18962. These early practitioners of what would soon be called radiology had two methods of demonstrating their work. The first was to use photographic plates and the second was to use fluorescent viewers2 (Fig. 1). X-ray photographs, as they were first called, provided static images, while fluoroscopy permitted real-time viewing.

continued up into the 1960’s, when a major development—image intensification—occurred3 .

Fluoroscopic images were always difficult to see, requiring a pitch-black examining room. Furthermore, the radiologist was required to “dark-adapt” his/her eyes by wearing red-tinted goggles for a minimum of 20 minutes before entering the fluoroscopy suite (Fig. 2) The goggles allowed the radiologist to work in a brightly lit room while the cones in their eyes adjusted to “darkness”.

the x-ray room that was pitch-black. The radiologist, Dr. George Alker, (who later convinced me to become a radiologist4), started the exam and was pointing out the various findings to the members of my clinical team. “You see this?” he said, and my fellow team members answered affirmatively. “How about you, Dr. Daffner?”

I replied, “Dr. Alker, I can’t see s—t.”

He looked at me and said, “Good God, son, take off your goggles!” I thought they were needed to see the fluoroscopy screen.

Fig. 1.

(1910)2. The “radiologist” is holding a fluoroscopic screen. Note the exposed x-ray tube behind the patient.

Improvements in radiologic equipment, including safety shielding

I only experienced red goggle fluoroscopy twice (fortunately). The first time was in 1965, when I was a third-year medical student. My colleagues and I went down to the radiology department to watch one of our patients undergo chest fluoroscopy. We were given heavy lead aprons and red goggles. I remember going into

Seven years later, while still a resident, I was doing locum tenens in a small community hospital in eastern North Carolina. The hospital radiology department had new fluoroscopic equipment with image intensification (as did the department at Duke, where I was doing my residency). However, the solo radiologist for whom I was covering also had a private office next to the hospital. I learned that he had scheduled upper GI exams at the office every day. And so, I went next door, where I discovered he had old fashioned fluoroscopy equipment that would require me to put on the red goggles. After “dark-adapting” for 20 minutes, I went into the fluoroscopy suite and stepped on the pedal (after removing my goggles). All I could see was a faint green glow. So, I put the goggles back on and went out to wait another half hour. When I returned, I had the same result. Dr. Alker had told me that in radiology we only did things with three tries. So, after another half-hour with the goggles on, I went back for round three. This time, I could see! To improve the image, I manually turned up the milliamperage as high as it would go. I had the patient swallow some barium and, Hallelujah, watched it descend his esophagus. Then, I lost the barium. After moving the fluoroscopy screen around I saw a dark curvilinear structure on the right and thought, “Ah, that’s the duodenal bulb.” I quickly took four spot films and told the technologist to give the patient more barium and get overhead films. Twenty minutes later the tech came and said, “Here’s your spot film, doctor.” I had four beautiful pictures of the patient’s right femoral head! Fortunately, the overhead films salvaged the study. I told the technologist to either send the other scheduled patients to the hospital or to reschedule the studies when the radiologist returned. So much for old-fashioned fluoroscopy.

My experiences with “red goggle fluoroscopy” gave me a greater degree of respect for the early practitioners of my chosen specialty. I was amazed that they were able to make the diagnoses they did using the existing equipment. Or were they really relying on the overhead radiographs? Image intensification, on the other hand, allowed us to see clear fluoroscopic images without having to “dark-adapt” our eyes, and without increasing the milliamperage (and hence the radiation dose to the patient) to see anything on the screen.

There is an interesting series on the History Channel entitled “Tactical to Practical” that describes how technology that was developed for the military was adapted for everyday uses. Image Intensification, developed in the 1930’s, was one such effort. The original purpose was to provide night-vision equipment for the military. An Image intensifier is a device that converts low level light or x-ray photons of various wavelengths into electrons, amplifies their numbers and then converts those electrons back into light photons of a single wavelength. Image intensification for night-vision equipment as well as medical imaging devices are variants of the devices illustrated in figures 3 and 4. Nightvision equipment is, of course, a miniature version. Early medical enhancement devices displayed the images on a mirror, limiting the number of viewers; later devices used a TV camera instead to project the images onto a CRT (TV) monitor (fig. 4).

Fig. 3. Image Intensifier. X-rays or faint light strikes the input phosphor, producing electrons that are multiplied by the photocathode, and then accelerated and focused on the output phosphor, which converts the electrons back into visible light.

Today, fluoroscopic examinations are performed in a room in which the lighting is only slightly dimmed. Image intensifiers not only permit the images to be seen without the necessity to “dark-adapt” one’s eyes, but also allows significantly lower levels of radiation to be used to obtain those images. The digital images are stored on the Radiology and Hospital Information Systems for display throughout the institution. Image intensification was one of the truly transformative developments in diagnostic radiology, ranking alongside of CT and MRI, for how they changed our way of diagnosing diseases.

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References:

1. Daffner, RH: Roentgen and the discovery that changed medicine. ACMS Bulletin, Nov 2020, pp 331 – 334.

2. American College of Radiology Photographic Archive. Reston, VA.

3. Kevles, BH: Naked to the Bone: Medical Imaging in the Twentieth Century. New Brunswick, NJ, Rutgers University Press, 1997.

4. Daffner, RH: Finding my niche: Diagnostic radiology. ACMS Bulletin, Mar 2020, pp 78 – 80.

Dr. Daffner is a retired radiologist, who practiced at Allegheny General Hospital for over 30 years. He is Emeritus Clinical Professor of Radiology at Temple University School of Medicine and is an amateur historian.

as part of the ACMS membership. We are grateful for residents, exists within our membership community and we want to help you share that expertise with the community! expertise

OPEN LETTER TO THE EDITOR BRuCe WilDeR mD, jD, mPh

After reading Dr. Lamb’s Perspective article “In the Battle,” I read the cited 2020 article by Ashley Andreou, “Unpacking Toxic Masculinity in the Medical Field,”1 that is referred to several times, and then had to go back and reread his article to see if there was anything I had missed.

Ms. Andreou is concerned about physician “burnout,” its causes, and its impact on quality of care and on the quality of life of physicians, and properly brings her perspective to the table. The significance of burnout among physicians (not to forget about nurses and other health care workers), including evidence-based study of its causes and efforts toward prevention, has only relatively recently gained the attention of organized medicine,2 and its science is still evolving.3

1 Ashley Andreou, Unpacking Toxic masculinity in the Medical Field, Women's Media Center, 10/23/20, https://womensmediacenter.com/fbomb/unpacking-toxic-masculinity-in-the-medical-field

2 Measuring and addressing physician burnout, 10/20/22, https://www.ama-assn.org/practice-management/physicianhealth/measuring-and-addressing-physician-burnout

3 Elizabeth Harry, MD, et al, Physician Task Load and the Risk of Burnout Among US Physicians in a National Survey, The Joint Commission Journal of Quality and Patient Safety, 2021;47(2): 2/1/2021, available at https://www.jointcommissionjournal.com/article/S1553-7250(20)30246-4/fulltext (published 10/4/20, d.o.i. https://doi.org/10.1016/j.jcjq.2020.09.011