Volume 3, Issue 1
- Editor: Dr Nick Stone
Newsletter distribution: courtesy of
Springer,
publishers of Lasers in Medical Science
Inside this issue
A new editor
This newsletter has been delayed in coming to press thanks
to the change of editors. We will now get up to speed and
provide the BMLA membership with a bi-annual output.
Have you got news or any interesting articles?
Send it to the Editor at:
n.stone@medical-research-centre.com
Any comments on content or style are welcome
and may even be taken on board.
Photodiagnostics for dummies
This short article has been written as a brief
overview of the field of photodiagnostics, with a focus
on cancer detection. There are a number of competing or
complimentary techniques currently being investigated. These
include fluorescence, Raman and infrared spectroscopies,
elastic scattering and diffuse reflectance spectroscopy.
They each have their pros and cons and depending on the
application some may be selected above others.
The primary requirement for successful treatment
of any malignancy is early detection. Although the pathogenesis
of most malignancies is not fully understood, some cancers
are known to develop through a pre-malignant state. Current
methods of detecting early malignancies rely upon surveillance
of at risk populations or diagnostic investigations following
presentation with suspicious symptoms. By the time symptoms
are present tumours are usually of a significant size, and
it is often too late to facilitate a full cure.
Biochemical changes within tissue may either
initiate disease or occur as the result of the disease process.
The qualitative analysis of such changes provides important
clues in the search for a specific diagnosis and the quantitative
analysis of biochemical abnormalities is important in measuring
the extent of the disease process, designing therapy and
evaluating the efficacy of treatment. The conventional method
for detection of malignancy using histopathological examination
of biopsy samples relies upon the subjective assessment
of tissue architecture, which is likely to demonstrate abnormal
changes at a later stage than would analysis of biochemistry.
Furthermore, histopathological analysis requires tissue
to be removed with possibly undesirable consequences. Evidently,
the development of a rapid, non-invasive, qualitative histochemical
analysis technique, enabling objective biochemical analysis
of tissue, would be of great value. This may be possible
with a variety of optical techniques.
Over the past few years a number of groups have been working
towards real-time, non-invasive techniques that utilise
light to study abnormalities in tissue. Recent technological
developments have made it possible to obtain significant
amounts of biochemical or architectural data from extremely
complex biological tissue in very short time scales (milliseconds
to seconds). Optical diagnosis relies upon measurement of
the interaction of light photons with the constituents of
biological tissue. The resultant data can provide an evaluation
of histochemistry or morphology. This information can aid
with the deduction of the pathological state of the tissue,
and hence lead to a diagnosis.
Light can interact with tissue in a number
of ways, including elastic and inelastic scattering; reflection
off boundary layers; and absorption, leading to fluorescence
and phosphorescence. All of these can be utilised in some
way to measure abnormal changes in tissue. Many authors
have used the term ‘Optical Biopsy’ when describing
these techniques. Optical biopsy is a misnomer because no
tissue is removed in the analysis, however it does help
to convey to the lay-person the general principle of using
light to detect cancerous transformations in tissue.
Initial optical biopsy systems, utilising
tissue fluorescence, have been used as an adjunct to current
investigative techniques, mainly to improve targeting of
blind biopsy. Future prospects utilising molecular-specific
techniques may enable complete replacement of biopsy with
objective optical detection providing a real-time, highly
sensitive and specific measurement of the tissue histological
state. However until its efficacy is proven it is most likely
that optical detection will be used as a complimentary technique
to improve targeting of biopsy selection.
The clinical requirements for an objective,
non-invasive real time probe for the accurate and repeatable
measurement of tissue pathological states are overwhelming.
There is a clinical need for optical diagnosis in a number
of important areas:
1. |
Situations where sampling errors severely
restrict the effectiveness of excisional biopsy, such
as the high failure rates associated with blind biopsies,
whereby the clinician has to randomly select sites
for sample collection. This method is used to screen
for pre-malignant conditions such as ulcerative colitis
and Barrett’s oesophagus. |
2. |
Where conventional excisional biopsy is potentially
hazardous, examples of vulnerable regions include
the central nervous system, vascular system and articular
cartilage. |
3. |
An immediate diagnosis during an investigative procedure
would eliminate the need for many secondary procedures
by enabling treatment to take place directly following
diagnosis. This is especially useful with the development
of treatments utilising light energy, such as photo-dynamic
therapy and laser ablation. This is likely to improve
patient outcomes and decrease waiting times by reducing
the number of costly procedures required. |
4. |
Tumour margins could be identified during surgical
resection, thus enabling a more accurately targeted
resection to be performed. |
5. |
A surgeon with any doubt over a diagnosis could
cross-validate a previous diagnosis prior to excision
of an organ or lesion using a non-invasive optical
probe.
Techniques such as Raman spectroscopy (RS) and Fourier-Transform
Infra-red absorption spectroscopy (FTIR) have recently
provided evidence of discrimination between multiple
pathology groups within each organ. Raman spectroscopy,
which can be performed endoscopically at any excitation
wavelength, is most likely to provide in vivo diagnosis.
FTIR currently shows the greatest promise for rapid
in vitro diagnosis and spectral imaging, where water
content of tissues does not prove problematic.
|
Other techniques such as optical coherence
tomography and optoacoustic imaging are demonstrating potential
for high spatial resolution in vivo imaging which may one
day provide similar information to histology, although in
real time. Whereas imaging techniques are always eye-catching,
it should be noted that these techniques still provide information
only about structure and cellular morphology. To provide
real information about early molecular changes and disease
prognosis those techniques that provide extra-value information
on tissue biochemistry associated with disease will be the
way forward.
A number of recent reviews on this area have
been published. These include:
- Barr et al (2004), Photodiagnostics and Photodynamic
Therapy, 1, 75-84.
- Crow et al (2003), British Journal of Urology, 92,
400-407.
- Fulljames et al (1999), Italian Journal of Gastroenterology
and Hepatology, 31, 695-704.
Nick Stone.
Have you got news? Send it to the Editor
at: n.stone@medical-research-centre.com
Recent LMS Highlights
Over the last twelve months Lasers in Medical
Science (the journal of the European Laser Association)
has published 41 articles covering important applications
of light applied to medical diagnostics and therapies. In
addition two LMS supplements have been produced covering
the 18th International Congress in Laser Medicine and the
Joint International Laser Conference.
Lasers in Medical Science has established
itself as the leading international journal publication
in the rapidly expanding field of the medical applications
of lasers and light. It provides a forum for the publication
of papers on the technical, experimental and clinical aspects
of the use of medical lasers, including the use of lasers
in surgery, endoscopy, angioplasty, hyperthermia of tumours,
and photodynamic therapy.
In addition, the journal publishes articles on the medical
application of new lasers, light delivery systems, sensors
to monitor laser effects, basic laser-tissue interactions
and the modelling of laser-tissue interactions.
The journal also welcomes articles relating
to the use of non-laser light-tissue interactions.
Instructions for prospective authors can
be found at
www.springeronline.com/journal/10103/submission
Access to e-mailbase
An e-mailbase has been set up by the BMLA
with the aim of promoting discussion on safe use of lasers
in medicine. This mailbase is intended to promote a focused
forum for clinicians, physicists, engineers, nurses and
others involved in the use of medical lasers. As the quality
of the mailbase is dependant on the number of participants,
anyone involved in this field and in particular non-members
of BMLA are encouraged to join.
To join the BMLA mailbase please
visit the following web page
www.jiscmail.ac.uk/lists/bmla.html
Anyone experiencing difficulties enrolling
on the mailing list, should contact Ian Gillan at the following
address dr.gillan@physics.org
If you have still to enrol on the e-mailbase
you can catch up with those missed discussions and messages
by simply visiting the mailbase archive. All part of the
service.
New face of the BMLA?
 |
Since its inception
circa 1980-something, the BMLA has used a slightly
'laserised' Union Flag. This now looks a bit dated.
Also, since many members are joining from outside
UK, this is a good time to change the face of the
BMLA.
The BMLA will continue to be a UK-based
society for anyone with a genuine interest in the
use of optical radiation in medicine. |
A new competition has been launched to design
a new logo. The treasurer has been persuaded to offer a
bottle of best bubbly to the designer of the best logo,
as judged by the Executive Committee.
To start us off, an amateur designer has
come up with the logo displayed above. If you think you
can do better, engage your creative talents and send the
result to H.Moseley@dundee.ac.uk.
You could win a bottle of bubbly.
Deadline is 20 July 2004.
Forthcoming Meetings
BMLA Annual Scientific Meeting and
AGM
9-10 September 2004 - Eastman Dental Clinic, London
Contact: c.hopper@ucl.ac.uk
British Skin Laser Study Group
11th May 2005 – Epsom
Contact: Christopher.Harland@epsom-sthelier.nhs.uk
Joint BMLA and Lasercare Meeting
10-11 November 2005 – City Hospital, Birmingham
Contact: Sean.Lanigan@swbh.nhs.uk
Photos from First Joint International
Laser Conference
The BMLA hosted the First Joint International
Laser Conference involving the American Society for Lasers
in Medicine & Surgery, the European Laser Association,
and the British Medical Laser Association on 21-23 September,
2003 in Edinburgh. Some of the sites are shown below…
The current BMLA
Executive
President: Harry Mosley
Secretary: Colin Hopper
Treasurer: Vasant Oswal
Officers: Hugh Barr, Sean Lannigan, Nick
Stone, Mark Stringer.
If you would like to nominate yourself for a role in assisting
with the management of this organisation please apply to
the secretary prior to the AGM in September.
Newsletter Archive
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Theo
Maiman demonstrated the first visible light
laser, the ruby laser, in 1960 |
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