Optical Coherence Tomography for Monitoring Late Oral Radiation Toxicity After Radiotherapy of Head and Neck Cancer Patients
At the imaging session, the patient will be asked to sit on the chair and put her/his chin
on the chin-rest and the height of the chair will be adjusted accordingly. Before turning on
the light source, the patient will be asked to wear the safety goggles and open her/his
mouth while the probe is slowly moved inside the oral cavity. At this point, by looking at
the superficial oral tissue, we will find regions in the oral cavity with superficial
changes. When such regions are found, OCT images of these regions will be taken. Imaging of
each location is expected to take about 3 to 4 minutes (including the time required to find
the region of interest, acquisition of structural, Doppler and speckle variance images, and
the time between each of these processes). After this, the patient can close her/his mouth
and rest for couple of minutes. The same procedure will be performed on another site of
complication. The 3-4 minute imaging procedure is repeated 3 to 5 times (depending on the
patients' ability to keep the mouth open), after which the patient is dismissed and the
sterile probe cover will be disposed. All the acquired data will be stored in a computer
which is kept in a locked office. The data will be processed within the week after the
imaging session so that structural, Doppler and speckle variance images of the imaged sites
of complication can be compared.
During imaging, structural OCT real-time images are shown on the monitor to facilitate the
task of finding the region of interest and keeping track of the patient's movements and move
the probe accordingly. During the Doppler or speckle variance imaging (approximately 7
seconds each within the 3-4 minutes interval mentioned before), the patient is asked to keep
as still as possible, in order to avoid any motion artifact in the OCT images.
Note that time frame for this study is 1 day, since subjects are only imaged once with no
Imaging healthy volunteers
The imaging session of the volunteers takes between 30 to 60 minutes. The imaging procedure
of these healthy volunteers is very similar to that explained for the patients; however, all
the acquired OCT images of this group would be of healthy oral tissue.
Note that time frame for this study is 1 day, since the volunteers are only imaged once with
no follow-up assessments.
**Important note: The aim of this study is to compare the images from patients with those of
healthy volunteers and show that there are specific changes in the structural and vascular
features of the patients (due to radiation toxicity) when compared to the volunteers. So,
the comparison is done between the two cohorts of the study.
For the healthy volunteers, the gathered OCT data will be processed to form structural,
Doppler and speckle variance images of healthy oral tissue to serve as a reference. The same
procedure will be performed on late oral radiation toxicity patients to reconstruct
structural, Doppler and speckle variance images of the site of oral complications. Then, the
images of healthy volunteers and patients will be compared in terms of the layer thickness,
the back-reflection properties of each layer, and the size and profile of blood flow of the
microvasculature. In order to compare these two sets of images quantitatively, certain
metrics will be defined based on the images of the healthy volunteers. All these
quantitative comparisons of healthy oral tissue and tissue with radiation complication will
be used to form an OCT atlas of oral radiation toxicity. Moreover, white-light images of the
regions of OCT study will be taken in order to serve as a reference for the superficial
complications caused by radiation.
Observational Model: Case Control, Time Perspective: Cross-Sectional
Comparison between the oral layer structure of radiation toxicity patients and healthy volunteers as shown in the OCT structural images
Structural OCT images of the oral tissue of the late radiation toxicity patients will be taken and will be processed to highlight any differences between them and the healthy human oral tissue. An example of the expected differences (in the patients compared to healthy volunteers) is total loss of basal layer and thus loss of differentiation between epithelium and lamina propria in the patients.
at the imaging time point [comparison between cohorts]
Alex I Vitkin, PhD
University of Toronto/UHNToronto
Canada: Ethics Review Committee