This article is intended as an introduction to photographing a patient’s head using the Frankfort Horizontal as a method of alignment. Discussions from peer reviewed journals and results from a preliminary study for my dissertation on the same subject have informed, what is intended to be introductory reading for people interested in clinical photography of the head.
Patients should always be asked to remove any jewellery that is visible on their head or face and hair should be tied back so that a clear outline of the head and neck can be seen. Ideally the patient should be asked to wear a hospital top so that the neckline can be seen clearly and the images can be repeated in the same manner for any following photographic sessions (see fig 1).
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Fig 1. Anterior Posterior. |
Clinical photographs provide clinicians in hospitals with images that are used to help evaluate the condition of their patients and inform decisions for treatment planning. Hansell and Ollerenshaw (1969) state that in order for the images to maintain accuracy, repeatability and consistency, clinical photographers must use Standardised Representational Photography (SRP), a component of which is patient positioning.
Alignment of the head in clinical photography is carried out using the Frankfort Horizontal (FH). In 1877 a Craniometric conference was held in Munich for German anthropologists, specifically for the purpose of reaching an agreement on a method to measure skulls. After another meeting, three years later in Berlin, Professors Kollmann, Virchow and Bank outlined a scheme submitted to the 13th General Congress of the German Anthropological Society in Frankfort – on – Maine in 1882 which was adopted and named the, ‘Frankfort Agreement’ (archive.org, n.d).
This accepted horizontal plane was defined in Gaeson’s critical review of the Frankfort Agreement as,
“that plane which is determined by two straight lines (one on either side of the skull), connecting the lowest points on the inferior margins of the orbits with the points of the upper margins of the bony auditory meatus situated vertically above their centres” (archive.org, n.d).
It is given as the standard reference plane in guidelines produced by the Institute of Medical Illustrators (IMI) when detailing methods for head alignment.
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Fig 2. Position of the Frankfort Horizontal (Vetter, 1992). |
Clinical photographs of a patient must be able to be reproduced repeatedly using the same method.
For pictures taken in the clinical photography studio, and where possible, on location, this is achieved using consistent magnification ratios, background, patient positioning and lighting.
The anatomical landmarks on a patient’s face should be clearly identifiable whether photographed against a black or a white background (in some cases a green or blue background is used. For the purposes of this article black and white will be referred to). A short survey that asked a cross section of clinicians and clinical photographers found there was roughly a 50/50 split in preference of white or black backgrounds being used. This difference in opinion highlights the subjective nature of the human perception of how an image is viewed.
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Fig. 3a Head photographed against white background |
Fig. 3b Head photographed against black background |
The focal length of the lens used for photography of the head is 105mm as it produces the least amount of distortion in the features of the face. The IMI Guidelines (2007) state a magnification ratio of 1:8, although clinicians requesting photos of craniofacial patients will specify a ratio of 1:10 as is illustrated in the West Midlands Handbook of Clinical Photography, Shrewsbury Group (2009) so that the back of the head can be clearly seen.
There is approximately 0.5m difference in focal length between the two ratios shown in figures 4a and b. The patient positioning should always stay the same regardless of the magnification ratio being used.
The patients head is positioned using the Frankfort Horizontal which provides a standard reference plane that can be used for every patient and can be aligned along the true horizontal of the grid in the cameras viewfinder.
This method of alignment was regarded as the most effective, by 77% of respondents asked in the survey for this study, for aligning the head in clinical photography.
The methods of alignment given for comparison were the Reid Horizontal (RH), a horizontal reference plane that passes through the outer canthi of the eyes and is parallel to the Frankfort Horizontal, and the Natural Head Position (NHP) which is the position of a person’s head when focused on a point directly in front of them, such as their reflection in the mirror.
There have been arguments put forward by some, such as Farhad (2013) who highlights the individual variance in facial anatomy and the impact this has on aligning the head using the Frankfort Horizontal. The images in figures 5a and b show the difference in inclination of the FH in patients with marked jaw disfigurements.
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Fig 5a Inclination of FH of patient with significant class III jaw relationship |
5b Inclination of FH of patient with class ll jaw relationship (Farhad, 2013). |
Vegter and Hage (2000) share the same opinion as Farhad and suggest using the Natural Head Position to align the patient. They argue, that in the case of cleft patients an individually adjusted technique produces more comparable results that don’t distort the features of the patient.
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(Vegter and Hage, 2000). |
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The images in figures 6 a-c illustrate the argument that Vegter and Hage make, however it should be noted that their lateral photograph of the patient has not aligned the Frankfort Horizontal accurately as the patients head is tilted down too far so that the rim of the orbital arch is not horizontal with the top of the tragus, meaning that a comparison for the purposes of this study is insufficient.
Figures 7 a and b show the results of two lateral photographs taken of the head of someone with no facial deformities, one aligned using the Frankfort Horizontal and one using the Natural Head Position.
A horizontal line has been drawn in fig 6a with the FH drawn below it. This persons FH slopes downwards when their head is positioned in the Natural Head Position. When asked to move the chin up so that the FH is horizontal, the shape of the persons head looks different in that the jaw line is more prominent. To the requesting clinician the slightest movement of the head, away from the standard set by their institution will have an impact on how the patient is assesed. The Frankfort Horizontal is the standard method of alignment set by the IMI and so should be used unless otherwise specified by the consultants reviewing the pictures.
References.
Farhad,B.N., (2013).The Frankfort Plane and Head Positioning in Facial Aesthetic Analysis-The Perpetuation of a Myth. JAMA Facial Plastic Surgery 15 (5).
Hansell, P. and Ollerenshaw, R., (1969). Longmore’s Medical Photography. 8th ed. Bath. The Focal Press.
Institute of Medical Illustrators, (2006). Rhinoplasty and Septorhinoplasty Photography. [online]. Available from:< http://www.imi.org.uk/document/rhinoplasty-photography> [Accessed 4th July 2015].
Rowe, S., (2013), Creation and Implementation of Standardised Craniofacial Views for the Institute of Medical Illustrators National Guidelines. Journal of visual communication. 36 (3-4), 121-127.
Vegter, F. and Hage, J,J., (2000). Standardized Facial Photography of Cleft Patients: Just Fit the Grid?.Cleft Palate–Craniofacial Journal. September. 37 (5).
Vetter, J.P, (1992). Biomedical Photography. London. Focal Press.
Shrewsbury Group,. (2009). West Midlands Handbook of Clinical Photography.