3. APPLICATIONS AREAS FOR MEDICAL
MEASUREMENT
Photogrammetry has, over the years, been proposed as a
viable measurement technique for a range of areas of the
human body, from the eye to the entire trunk, using a full
range of techniques, now expanded via digital processing
and newer technologies in medical imaging. Evidence of
the quantity of papers is provided in the lists of references
in chapters on the subject in monographs: Newton (1980)
refers to 68; Sheffer and Herron (1989) list 72. Many other
relevant papers are to be found beyond the circle of
photogrammetric publications. Medical photogrammetry is
also encountered at various congresses with a medical
affinity, especially the proceedings of the Biostereometrics
meetings which have of course considerable
photogrammetric content.
The following broad areas of application for medical
photogrammetry have been identified, and are discussed
more closely in the associated full report. The main points
from that report are as follows.
i) There is a real demand for motion analysis but with many
participants already and with complex image processing
and data analysis needed, small photogrammetric groups
may find it difficult to make inroads into this field.
ii) Extensive conference series on back surface
measurement purposes imply a significant level of demand.
However, a number of sophisticated commercial products
already exist. In addition, photogrammetric back shape
measurement can now be done by commercial software for
general photogrammetry. Furthermore, alternative optical
methods, many automated, are currently more popular than
photogrammetry. Moire methods are simple but appear to
be favoured less than the various structured light
techniques. The Working Group survey shows that while
photogrammetrists were involved in back measurement,
few of the medical responses reported an interest in back
measurement. Although back surface measurement can
be perceived as an field of fruitful photogrammetric
research, it would from all the evidence that this would not
seem to be so.
iii) The limited number and the expense of existing facial
measurement systems suggests that there are
opportunities for more development. However, demands
for detail and specialised output make this work demanding
- and probably not justified in general, unless stimulated by
contact with a individual medical specialist.
iv) For measurement of many body surfaces, structured
light techniques are currently more popular than
photogrammetry.
v) Opportunities are to be found in dental research, with
little competition from other techniques or from commercial
organisations. Interesting challenges occur in this
worthwhile work, in which the experienced
photogrammetrists can be indispensable.
vi) Among all the applications, repetition does not appear
to be common, and there is only a limited amount of
wastage through re-development by photogrammetrists and
by non-photogrammetrists.
4. DISCUSSION
There is of course no simple solution to the general
unproductive state of routine medical photogrammetry.
There are many issues which have not been raised in the
discussion so far but which are frequently raised in
discussions on the question, at the ISPRS Commission V
Symposium in 1994 in particular, but more generally
whenever medical photogrammetrists meet and
communicate. The discussion below puts some of the
arguments concerning the challenges of medical
photogrammetry and offers some solutions which interested
and concerned photogrammetrists in general and the
Working Group in particular may contemplate.
Medical photogrammetry has always faced its own special
problems, which derive especially from the involvement of
living patients, but which also derive from involvement with
practitioners from a distinctly different discipline. Live
patients mean coping with movement, and their comfort,
convenience and safety. The challenge of having to relate
to and interact with other health professionals involved in a
wide range of medical and health matters requires that
photogrammetrists understand their wants and needs and
supply medically important information in a useable form.
But some specific issues relating to photogrammetry's
implementation are as follows.
i) Although medical photogrammetry suffers from the
difficulty that it measures externally rather than the internal
circumstances which typically affect health and medicine,
it must be recognised that a role exists for external
measurement when internal measurement techniques have
dangerous side-effects or high cost. All applications,
whether for routine clinical measurement or for medical
research, for recording high-speed human motion, deducing
the shape of the spine from the back, recording all-round
shapes of the torso, limbs, or feet, measuring the intricate
detail of the face, measuring the cornea and the retina, and
inside the mouth, are very beneficial and can make
valuable contributions to the community. There may be
rewards, even financial, to the photogrammetric community.
ii) Many medical photogrammetric developments are carried
out by academic institutions and are intended for unique
projects, and not for reproduction, yet alone commercial
use. Such development should not be seen as
unproductive, but rather as worthwhile areas in which
commercially-driven organisations cannot be expected to
contribute. Perhaps commercial success is not always
pertinent, especially to photogrammetrists interested in
making a useful contribution to medicine.
ii) There is evidence that there are many useful
applications which do not need sophisticated measurement,
but sometimes no more than a tape measure perhaps with
clever analysis of its output. In this vein, it is notable that
the one of the prime considerations in the highly valuable
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996
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