Structured Light Plethysmography (SLP) technology is a noninvasive method for collecting accurate representations of

chest The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...

and abdominal wall movement. A checkerboard pattern of light is projected from a light projector onto the chest of an individual. Movements of the grid are viewed by two

digital camera A digital camera, also called a digicam, is a camera that captures photographs in Digital data storage, digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film or film stock. Dig ...

s, digitalised, and processed to form a 3D model and can be interrogated to assess

lung function The lungs are the primary organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the backbone on either side of the heart. Their function in the respiratory system ...

. The system has been tested on over 70 adults (data presented at clinical meetings). SLP is simple to use, accurate and cost effective, is self-calibrating and does not require the use of plastic consumables, reducing cost, risk of cross infection and the device's

carbon footprint A carbon footprint (or greenhouse gas footprint) is a calculated value or index that makes it possible to compare the total amount of greenhouse gases that an activity, product, company or country Greenhouse gas emissions, adds to the atmospher ...

. In conjunction with the Cambridge Veterinary School,

proof of concept A proof of concept (POC or PoC), also known as proof of principle, is an inchoate realization of a certain idea or method in order to demonstrate its feasibility or viability. A proof of concept is usually small and may or may not be complete ...

studies have indicated that the device is sensitive enough to noninvasively pick up respiratory movements in

domestic animal This page gives a list of domesticated animals, also including a list of animals which are or may be currently undergoing the process of domestication and animals that have an extensive relationship with humans beyond simple predation. This includ ...

s (

cat The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the ...

s and

dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the gray wolf. Also called the domestic dog, it was selectively bred from a population of wolves during the Late Pleistocene by hunter-gatherers. ...

s).

A totally “ non-invasive” technique using

structured light upright=1.3, A structured light pattern projected onto a surface (left) Structured light is a method that measures the shape and depth of a three-dimensional object by projecting a pattern of light onto the object's surface. The pattern can be ...

to measure pulmonary function was developed as long ago as the mid-1980s by a

London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...

group at the

Royal Brompton Hospital Royal Brompton Hospital is the largest specialist heart and lung medical centre in the United Kingdom. It is managed by Guy's and St Thomas' NHS Foundation Trust. History Consumption in the 19th century In the 19th century, consumption was a co ...

working in close association with IBM (1-4). The technique used the distortion with movement of a structured pattern of light to calculate a volume or change in volume of a textured surface. At that time structured light pattern was shone on to the anterior chest and

abdominal wall In anatomy, the abdominal wall represents the boundaries of the abdominal cavity. The abdominal wall is split into the anterolateral and posterior walls. There is a common set of layers covering and forming all the walls: the deepest being the vi ...

surfaces, and movie camera film footage was taken and sent to IBM for processing. The digital information was used to compute automatically the volume of the trunk and the position of any point on its surface and its cross-sectional shape at any level. The group found that linear dimensions could be calculated to within 0.5mm and a cross-sectional area within 5% and volume within 3-7%. The group suggested that non-invasive technique measurements were of sufficient accuracy to be tried in

clinical practice ''Clinical Practice'' is a bimonthly peer-reviewed open access medical journal. It covers good clinical practice and health care. The journal was established in 2004 as ''Therapy'' by Future Drugs Ltd, obtaining its current name in 2012 when it wa ...

. However, probably due to

technology Technology is the application of Conceptual model, conceptual knowledge to achieve practical goals, especially in a reproducible way. The word ''technology'' can also mean the products resulting from such efforts, including both tangible too ...

limitations,

data processing Data processing is the collection and manipulation of digital data to produce meaningful information. Data processing is a form of ''information processing'', which is the modification (processing) of information in any manner detectable by an o ...

and storage, the methodology was never commercialised. Male Patient SLP

Independently the Royal Brompton group of the 1980s, a

Cambridge Cambridge ( ) is a List of cities in the United Kingdom, city and non-metropolitan district in the county of Cambridgeshire, England. It is the county town of Cambridgeshire and is located on the River Cam, north of London. As of the 2021 Unit ...

(UK) consortium of clinicians and engineers developed a system in 2009 that has revisited structure light pattern as a noninvasive method for collecting accurate representations of

and abdominal wall movement. The methodology has several advantages: there are no fluorescent markers required to define chest or abdominal surface and the hardware can be minimalized to 2 digital cameras and a digital projector when imaging the anterior surface of the body. The projector shines a grid of black and white squares from superior

iliac crest The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superolateral margin of the greater pelvis. Structure The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the posterio ...

clavicle The clavicle, collarbone, or keybone is a slender, S-shaped long bone approximately long that serves as a strut between the scapula, shoulder blade and the sternum (breastbone). There are two clavicles, one on each side of the body. The clavic ...

; the subject can wear a plain

t-shirt A T-shirt (also spelled tee shirt, or tee for short) is a style of fabric shirt named after the T shape of its body and sleeves. Traditionally, it has short sleeves and a round neckline, known as a '' crew neck'', which lacks a collar. T-shir ...

of any colour. The 2 digital cameras image the grid on chest and

abdomen The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...

and the software extracts 2 sets of 2D image positions of the grid points and stereo vision is used to reconstruct these grid points to form a 3D representation of the chest and abdominal wall surface. The group has tried anything from one grid point to 2000 and is current working on roughly 200 to 300. The thoracic volume is calculated from the volume beneath the reconstructed virtual surface and can be plotted in real time. Calibration is internal: the relative position of cameras and shape of the subject is auto-calibrated at reconstruction time; and externally by placing an object of reference size in front of the cameras. This can be a sheet of paper of known size and potentially has now been transferred to projected points within the grid itself. The group have now collected data on up to 70 adults and 5 children and have also collected data from small

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s. They have compared simultaneous measurements of tidal breathing followed by full inspiration and force expiration by pneumotach and SLP. The pneumotach data was obtained using a laptop based

spirometer A spirometer is an apparatus for measuring the volume of air inspired and expired by the lungs. A spirometer measures ventilation, the movement of air into and out of the lungs. The spirogram will identify two different types of abnormal ventilat ...

and exported for analysis using J-scope software. Extremely good correlations have been obtained from tidal breathing and forced expiration manoeuvres. Tidal breathing correlations have shown to be 0.99 for individual data sets and for n=70 the mean correlation was 0.92 at an SD of 0.04. For forced expiration the correlation was shown to be 0.98, n=70 mean correlation was 0.98 with an SD of 0.12. For forced expirations inspiratory manoeuvres correlation coefficients for

peak flow The peak expiratory flow (PEF), also called peak expiratory flow rate (PEFR) and peak flow measurement, is a person's maximum speed of exhalation, expiration, as measured with a peak flow meter, a small, hand-held device used to monitor a person's ...

were r² 0.84, FEV1 0.95, FEF75 0.76 and FEF50 0.69.

Patient Example Outputs

Healthy Patient SLP Scan

Thoracic Patient SLP Scan

Diseased Patient SLP Scan Being totally non-invasive SLP allows respiratory monitoring without the need for a face mask or mouth piece, allowing for normal respiratory patterns to be recorded. Data output can be configured to allow for the comparisons between selected regions of interest such as chest and abdomen. Further analysis uses

spectral analysis Spectral analysis or spectrum analysis is analysis in terms of a spectrum of frequencies or related quantities such as energies, eigenvalues, etc. In specific areas it may refer to: * Spectroscopy in chemistry and physics, a method of analyzing ...

techniques to monitor trends and changes in respiratory function and alterations in regional chest dynamics. The group has a number of studies on-going . The first application of this technology has been developed to measure spirometry by PneumaCare Ltd, The device - PneumaScan has been developed by PneumaCare in partnership with

Cambridge University The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...

, Addenbrookes NHS Hospital Trust and Plextek Limited. It is capable of recording tidal breathing and spirometry parameters and is self calibrating.

1. Optical mapping of the thoraco-abdominal wall: AJ Peacock, MDL Morgan, S Gourlay, C Turton, DM Dension. Lung Function Unit, Brompton Hospital, London, and UK Science Centre, IBM, Winchester Thorax 1984 39: 93-100 2. Optical measurement of the change in trunk volume with breathing. Peacock A, Gourlay A, Denison D.Bull Eur Physiopathol Respir. 1985 Mar-Apr;21(2):125-9. 3. Measuring the human chest with structured lighting J.R.T. Lewis and T. Sopwith Pattern Recognition Letters Volume 4, Issue 5, October 1986, Pages 359-36 4. J. R. T. Lewis, T. Sopwith: Three-dimensional surface measurement by microcomputer. Image Vision Comput. 4(3): 159-166 (1986) 5. Structured light Plethysmography in infants and Children – a pilot study. Juliet Usher-Smith, Richard Wareham, J Lasenby, J Cameron, P Bridge, R Iles RCPCH York 2009 Arch Dis Child 2009;94(Suppl I):A38–A40 2. Structured light plethysmography (SLP) compared to spirometry: R. Wareham, J. Lasenby, J. Cameron, P. D. Bridge, R. Iles (Cambridge, United Kingdom) E-communication : 350 ERS 2009 3. Spectral analysis of respiratory flow signals from spirometry and a novel structured light imaging system. Peter Bridge1, Richard Iles1, Rich Wareham2, Jonathan Cameron2, Juliet Usher-Smith1, Ward Hills3, Gareth Roberts3, Willem de Boer2,

Joan Lasenby Joan Lasenby is a British applied mathematician whose research interests include 3D reconstruction and motion capture, geometric algebra, inverse kinematics, and the applications of structured light plethysmography in non-invasive medical diagno ...

E-communication : 1858 ERS 2009 4. Comparison of Forced Expiratory Volumes Measured with Structured Light Plethysmography (SLP) and Spirometry Eugene Lau, Douglas Brand, Peter Bridge, Richard Iles, Rich Wareham, Jonathan Cameron, Juliet Usher-Smith, Ward Hills, Gareth Roberts, Willem de Boer,

. BTS 2009 Thorax 2009;64:A51-A54 5. Comparison of Tidal Breathing with Structured Light Plethysmography (SLP) and Spirometry Eugene Lau, Douglas Brand, Peter Bridge, Richard Iles, Rich Wareham, Jonathan Cameron, Juliet Usher-Smith, Ward Hills, Gareth Roberts, Willem de Boer,

. BTS 2009 Thorax 2009;64:A51-A54 6. Spectral analysis of regional respiratory flow signals using structured light plethysmography: S. Ahmed1, P. Bridge2, J. Usher-Smith2, R. Wareham3, J. Cameron3, J. Lasenby, R. Iles2; 1Cambridge University Medical School - Cambridge/UK, 2Addenbrookes NHS Trust, Cambridge University Hospitals - Cambridge/UK, 3Cambridge University - Cambridge/UK. ATS 2010 Am J Respir Crit Care Med 181;2010:A2170 7. Tidal breathing parameters measured by structured light plethysmography (slp) and spirometry: D. Brand1, E. Lau1, J. Cameron2, R. Wareham2, J. Usher-Smith3, P. Bridge3, J. Lasenby, R. Iles3; 1University of Cambridge School of Clinical Medicine - Cambridge/UK, 2Cambridge University, Department of Engineering - Cambridge/UK, 3Addenbrookes NHS Trust, Cambridge University Hospitals - Cambridge/UK Am J Respir Crit Care Med 181;2010:A2171 ATS 2010 8. SLP: A Zero-Contact Non-Invasive Method for Pulmonary Function Testing Richard Iles, Rich Wareham, Jonathan Cameron, Juliet Usher-Smith, Ward Hills, Gareth Roberts, Willem de Boer,

BMVC 2010 9. Structured light plethysmography with pneumotachography. Symposium : Physiological plasters and visiology: the visionary future for lung function? ERS 2010 10. Measurement of lung volumes in real time, using optical plethysmography: Postgraduate Course: WS1 Educational Workshop: Noninvasive assessment of respiratory function in children. ERS 2010 {{DEFAULTSORT:Structured Light Plethysmography Respiratory system imaging Medical tests

Patient Example Outputs

Further reading