Radiology – Imaging

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Radiology – Imaging2017-07-11T22:01:51+00:00

Radiology and Imaging

radiology and imaging image from New Medical Terms

Röntgen’s wife’s hand

Unlike most diagnostic and therapeutic specialties, historians have pinpointed when and where the field of radiology was born and who its father was. Wilhelm Conrad Röntgen (1845-1923), whilst a professor at the University of Würzburg, was investigating the external effects of various types of vacuum tubes from Heinrich Hertz, Nikola Tesla, Philip von Lenard and others, when an electrical discharge passed through them (on 8 November 1895). Long story short, he noticed a shimmering fluorescence from a barium platinocyanide screen, which he speculated might be a new type of electromagnetic rays, which he called X-rays (X is the mathematical designation for “unknown) and much of the world for a time called Röntgen rays. 

Röntgen piddled around in his lab with the X-rays for another two weeks, deathly afraid of his professional reputation were he to report results that later proved wrong. During that time, he tried different ways to block the X-rays, first using lead, then his wife’s hand (top image). At that precise moment, diagnostic radiology was born. Everything after that was anticlimactic: Röntgen’s honorary Doctor of Medicine degree (1897), his chair of physics at the University of Munich (1900), his Nobel Prize in Physics (1901), his appointment at Columbia University (NYC—he stayed in Germany because of WW1) and an element, roentgenium, named after him (2004). 

Röntgen died before learning that there was an even greater reason to be deathly afraid of X-rays than the risk to his professional reputation. In 2011, workers at the Maastricht University Medical Center in the Netherlands examined an X-ray machine from 1896. The good news was that the century-old device was surprisingly accurate. The bad news was that because the image took 90 minutes to develop (as opposed to 21 milliseconds for a modern X-ray), the patients were exposed to 1,500 times (!) more radiation than they are today. The literature of the early 20th century is awash with death and disease in radiologists, radium workers–including Marie Curie herself, and other individuals exposed to high levels of radiation before the dangers of X-rays were fully known.  

MRI soft tissue image from New Medical Terms

MRI showing tendinitis of hip

From its primitive and unregulated origins, radiology has evolved in successive waves to become the modern field of imaging. Whilst exposure to X-rays is no longer a sine qua non for obtaining a picture of a body region or vascular bed, radiation drives the bulk of imaging procedures. It is required for fluoroscopy, a procedure that allows real-time imaging of structures in motion and angiography–which is most commonly used to identify sites of arterial stenosis and occlusion. 

Where endoscopy has been inconclusive, radiocontrast in the form of barium swallows and enemas help identify hiatal hernias at one end and polyps and precancerous lesions at the other end of the GI tract. Other X-ray based studies include mammography and DXA (dual-energy X-ray absorptiometry), both of which are forms of low-energy projectional radiography, the former to identify early breast cancer and the latter osteoporosis. In nuclear medicine imaging, a radiopharmaceutical–e.g., 99mTc, 123I, 131I, 67Ga, 68Ga, 111In, 201Tl, and 18F-fludeoxyglucose, with a tissue-centric affinity is injected and its distribution assessed, to identify a malignancy–e.g., in a whole body scan, or a regional alteration in function–e.g., hyperthyroidism or alteration in flow–e.g., a V/Q scan in suspected pulmonary embolism. Positron emission tomography (PET) can be combined with CT or MRI to stack anatomic information atop the pathological changes present in the tissue. One wonders how radiologists from the first half of the 20th century would react to seeing “sliced” CT images routinely generated in the second half.   

Non-radiologic techniques–e.g, MR imaging, were naturally absorbed into the field of radiology, given that the 3D sectioning produced by MRI is visually similar and functionally complementary to the data provided by computed tomography. MRI is preferred for evaluating soft tissue–e.g., ligament and tendon injury (image, bottom, coronal T2 fat-saturated MR image of hip, arrows indicate trochanteric bursitis), spinal cord injury and brain tumors. While ultrasound (Doppler technique) generally falls under the imaging umbrella, it has been commandeered in part by other specialties, to wit, in obstetrics to assess fetal growth and health, by vascular surgeons to weigh stenosis of distal peripheral and carotid arteries, and by cardiologists to dynamically evaluate the heart, cardiac valves and status of the great vessels. 

Radiology is a desirable specialty in most countries, as it provides a comfortable income and a 9-to-5 schedule. In the US, radiologists have 5 years (1 year internship, 4 years of residency) of post medical school training, in the UK, they have 7 years (2 years of Foundation training, 5 years as registrars/residents).  

References 

https://en.wikipedia.org/wiki/Wilhelm_R%C3%B6ntgen

http://abcnews.go.com/Health/Wellness/century-ray-machine-shows-radiation-risks-yore/story?id=13140857

https://en.wikipedia.org/wiki/Radiology

http://www.diffen.com/difference/CT_Scan_vs_MRI