This study is a continuation of the phantom study discussed in section4.8. The
experiment setup was similar to that of section 4.8.1, with the human torso submerged in a tub of a liquid solution with optical properties similar to that of tissue.
treatment is collected from the IR navigation system while concurrently light distribution measurements were made using t isotropic d
fluence calculations made using data from the IR navigation sys distribution theory (using eqn.
5.3.2 Results: Human Torso Cavity
The human torso phantom picture in
optical properties, and the fluence experienced at the cavity was measured using two isotropic detectors. Figure 5.3 displays th
fluence, treating the torso cavity as a sphere of the same volume. Unlike the spherical cavity, there appears to be greater agreement between theory and observation for a water cavity as
149 (b)
: Schematics for treatment procedure and optimization algorithm
(a) Schematics for the treatment procedure for image guided treatment. (b) Schematics for the optimization algorithm to determine iteratively the position of the laser source relative to the wand tip (λm).
5.3 IR Camera Study for Human Torso Cavity
is a continuation of the phantom study discussed in section4.8. The
experiment setup was similar to that of section 4.8.1, with the human torso submerged in a tub of a liquid solution with optical properties similar to that of tissue. Position data of the
treatment is collected from the IR navigation system while concurrently light distribution made using t isotropic detectors. These measurements were
fluence calculations made using data from the IR navigation system to verify our light (using eqn. ( 5.1 )) is correct and applicable in patient-like settings.
Results: Human Torso Cavity
phantom picture in Figure 5.1c was submerged in a solution of varying optical properties, and the fluence experienced at the cavity was measured using two isotropic
displays the results of these measurements compared to the calculated fluence, treating the torso cavity as a sphere of the same volume. Unlike the spherical cavity, there appears to be greater agreement between theory and observation for a water cavity as
algorithm
(a) Schematics for the treatment procedure for image guided treatment. (b) Schematics for the optimization
is a continuation of the phantom study discussed in section4.8. The
experiment setup was similar to that of section 4.8.1, with the human torso submerged in a tub n data of the
treatment is collected from the IR navigation system while concurrently light distribution etectors. These measurements were compared to
tem to verify our light like settings.
was submerged in a solution of varying optical properties, and the fluence experienced at the cavity was measured using two isotropic
e results of these measurements compared to the calculated fluence, treating the torso cavity as a sphere of the same volume. Unlike the spherical cavity, there appears to be greater agreement between theory and observation for a water cavity as
150 compared to the air cavity.
(a)
(c) Figure 5.3: Averaged measured fluence averaged fluence measured (circles) compared
cavity, (b) water cavity, and (c) attenuating medium cavity.
151
(b)
(c)
: Averaged measured fluence per source power for human torso phantom compared to analytic solution averaged fluence measured (circles) compared the fluence calculated (dashed line) for the human torso cavity for an (a) air cavity, (b) water cavity, and (c) attenuating medium cavity.
for human torso phantom compared to analytic solution. The the fluence calculated (dashed line) for the human torso cavity for an (a) air
5.3.3 Navigation System Application to human torso phantom
Using the procedure presented in
cavity. Using the position tracking data coupled with
source and the cavity wall (the location of which is determined using the contour displayed in
5.5a), a comparison is made between measured and observed fluence. By including the scattered light in the calculation, greater agreement is achieved between observation and theory, as seen in
Figure 5
The walls of the phantom are represented by blue,
isotropic detectors measuring fluence are represented by green squares.
152
Navigation System Application to human torso phantom
Using the procedure presented in [145], two treatments were conducted using the human torso cavity. Using the position tracking data coupled with Eqn.( 5.2 ) where r is the distance between the light
ource and the cavity wall (the location of which is determined using the contour displayed in
, a comparison is made between measured and observed fluence. By including the scattered light in the calculation, greater agreement is achieved between observation and theory, as seen in
5.4: Contour of human torso taken with IR camera
The walls of the phantom are represented by blue, the movement of the light source is represented by pink, and the two isotropic detectors measuring fluence are represented by green squares.
, two treatments were conducted using the human torso is the distance between the light ource and the cavity wall (the location of which is determined using the contour displayed in Figure
, a comparison is made between measured and observed fluence. By including the scattered light in the calculation, greater agreement is achieved between observation and theory, as seen in Figure 5.5.
(a)
(b)
Figure 5.5: Results for IR system applied
function of time (red) compared to the direct light calculation (blue) and the direct plus scattered light calculation (green).
153
: Results for IR system applied to torso phantom. (a-b) the overall fluence rate measured as a function of time (red) compared to the direct light calculation (blue) and the direct plus scattered light ) the overall fluence rate measured as a function of time (red) compared to the direct light calculation (blue) and the direct plus scattered light
154
The results for a spherical air cavity are in good agreement with the theory presented in Eqn. ( 5.2 ). Upon the introduction a medium within the cavity, however, this agreement begins to break down and the theory consistently overestimates the amount of fluence experienced by the cavity wall. Further investigation is needed to determine the cause of this disagreement. When considering a cavity of arbitrary geometry such as an empty human torso, the geometry can effectively be approximated as a sphere of the same volume and still achieve good
agreement between fluence observations and calculated fluence. Again, with the introduction of an attenuating medium in the cavity, our theory overestimates the fluence at the cavity wall.