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Sunday, August 26, 2012

An Introduction to Medical Photography


I've always been a bit of a photobug.  I blame my grandmother who gave me my first camera when I was just a young kid.  Back in those days, we had this stuff called film.  The pictures were unpredictable and expensive, so I only took pictures of things I felt were important.  Fast forward 20 years, and the technology is incredible.  Digital photography is everywhere!  Cameras, phones, and maybe even glasses soon.

With the explosion in technology, it's very easy to take pictures of clinically relevant cases.  Images are a great teaching tool, but you need to get the right picture.  A few years ago, I attended the SAEM workshop on medical photography taught by Dr. Jason Thurman.  The course is great and if you have the chance to attend, I highly recommend it.  Here are some pearls I gleaned from their teaching as well as some additional hints to improve your skills.

1. It all starts with consent.  Like any procedure, to take a picture for educational purposes, you need to obtain consent.  This is likely to be institution specific.  Check with you institution to determine if you need an additional form.

2. What equipment do you need? These days, the quality of camera phones has improved dramatically.  That being said, dedicated cameras still have more functionality.  Digital SLRs offer the greatest functionality, but also cost a significant amount.  My advice would be to start small and if you think this is for you, move up to a dSLR.

3. Know the basics

Exposure: The amount of light that hits the sensor.  In photography this is controlled by the aperture and shutter speed.  These controls have a reciprocal relationship.

Shutter Speed: Simple; the amount of time that the shutter is open, expressed as a fraction of a second (1/60, 1/90).  Slow shutter speeds mean blurred motion if the subject is active.

Aperture: The opening in the lens that allows light through, expressed as the f-stop number; like gauge: bigger number = smaller opening.  Aperture is REALLY important because it controls the depth of field, which is basically the amount of the scene that is in focus. The smaller the aperture, the greater the depth of field.  This comes into play when taking close up or macro photos (like the eye above).  The closer to an object you are, the narrower the depth of field becomes.  Since you'll have to use a small aperture (f16 or smaller) your shutter speed will likely be slow, hence, you'll need a flash.

Gray World Assumption: All camera light meters try to make the detected scene 18% gray based on some light physics.  Because of this, scenes that are dark or bright end up messing up the exposure. (Think about the last time you tried to take a picture in bright sunlight or snow).  To compensate for this, watch the sensor and adjust the f-stop + or - one stop.  Fortunately with digital photography, we can view the pictures and make the adjustments on the fly (burned up a lot of good film trying to master this technique)

Lighting: There are 3 types of lighting: axial, texture, and flat.


Axial lighting involves holding the flash parallel to the barrel of the lens.  This reduces harsh shadows that might be created if the flash was placed in the shoe.  The image of the eye above was taken using axial light

Textural lighting adds dimension to an image by placed the light source at a 30-45 degree angle off to the side.

Image of a child with chicken pox taken using texture lighting

Flat Lighting produces the most accurate color.  It's accomplished by placing the flash on the side of the barrel or using a special flash called a ring flash.

Image of erythema migrans taken using a ring flash to produce flat lighting

4. Control the background: remove any distractions! (These, incidentally, can be an identifier)  Things like jewelry, tattoos, clothing all take away from image quality.  Place the body part in question onto a solid clean background (leftover surgical towels work AWESOME for this).  If possible, add a ruler to demonstrate scale.

Get Close, control the background, and use a scale

5. Get the right views: Think like a radiologist.  If photographing the face, get an AP, lateral, and oblique.  Think similarly for the rest of the body.  Don't be afraid to get a standard shot and then zoom in to focus on the pathology.

Now get out there, take a camera, take lots of pictures, share them, and Vive le FOAMe
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5 comments:


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  2. Sometime its very difficult for viewing the disease patient photograph...
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  3. totally agree with you, it;s tough to see these picture... Medical Photography

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