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Realtime light dosimetry software tools for interstitial photodynamic therapy of the human prostate

Johansson, Ann LU ; Axelsson, Johan LU ; Andersson-Engels, Stefan LU and Swartling, Johannes LU (2007) In Medical Physics 34(11). p.4309-4321
Abstract
Photodynamic therapy (PDT) for the treatment of prostate cancer has been demonstrated to be a safe treatment option capable of inducing tissue destruction and decreasing prostate specific antigen (PSA) levels. However, prostate-PDT results in large intra- and interpatient variations in treatment response, possibly due to biological variations in tissue composition and short-term response to the therapeutic irradiation. Within our group, an instrument for interstitial PDT on prostate tissue has been developed that combines therapeutic light delivery and monitoring of light transmission via numerous bare-ended optical fibers. Here, we present algorithms that utilize data on the light distribution within the target tissue to provide realtime... (More)
Photodynamic therapy (PDT) for the treatment of prostate cancer has been demonstrated to be a safe treatment option capable of inducing tissue destruction and decreasing prostate specific antigen (PSA) levels. However, prostate-PDT results in large intra- and interpatient variations in treatment response, possibly due to biological variations in tissue composition and short-term response to the therapeutic irradiation. Within our group, an instrument for interstitial PDT on prostate tissue has been developed that combines therapeutic light delivery and monitoring of light transmission via numerous bare-ended optical fibers. Here, we present algorithms that utilize data on the light distribution within the target tissue to provide realtime treatment feedback based on a light dose threshold model for PDT. This realtime dosimetry module is implemented to individualize the light dose and compensate for any treatment-induced variations in light attenuation. More specifically, based on the light transmission signals between treatment fibers, spatially resolved spectroscopy is utilized to assess the effective attenuation coefficient of the tissue. These data constitute input to a block-Cimmino optimization algorithm, employed to calculate individual fiber irradiation times provided the requirement to deliver a predetermined light dose to the target tissue while sparing surrounding sensitive organs. By repeatedly monitoring the light transmission signals during the entire treatment session, optical properties and individual fiber irradiation times are updated in realtime. The functionality of the algorithms is tested on diffuse light distribution data simulated by means of the finite element method (FEM). The feasibility of utilizing spatially resolved spectroscopy within heterogeneous media such as the prostate gland is discussed. Furthermore, we demonstrate the ability of the block-Cimmino algorithm to discriminate between target tissue and organs at risk (OAR). Finally, the realtime dosimetry module is evaluated for treatment scenarios displaying spatially and temporally varying light attenuation levels within the target tissue. We conclude that the realtime dosimetry module makes it possible to deliver a certain light dose to the target tissue despite spatial and temporal variations of the target tissue optical properties at the therapeutic wavelength. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Radiometry: instrumentation, Prostatic Neoplasms: radiotherapy, Prostatic Neoplasms: pathology, Photochemotherapy: instrumentation, Photochemotherapy: methods, Radiometry: methods, Radiotherapy Planning, Computer-Assisted: methods
in
Medical Physics
volume
34
issue
11
pages
4309 - 4321
publisher
American Association of Physicists in Medicine
external identifiers
  • wos:000251145900024
  • pmid:18072496
  • scopus:35648958149
ISSN
0094-2405
DOI
10.1118/1.2790585
language
English
LU publication?
yes
id
779670f0-00fb-4ee3-a76c-40ee19a39708 (old id 968830)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/18072496?dopt=Abstract
date added to LUP
2008-01-29 15:49:36
date last changed
2017-10-08 04:16:41
@article{779670f0-00fb-4ee3-a76c-40ee19a39708,
  abstract     = {Photodynamic therapy (PDT) for the treatment of prostate cancer has been demonstrated to be a safe treatment option capable of inducing tissue destruction and decreasing prostate specific antigen (PSA) levels. However, prostate-PDT results in large intra- and interpatient variations in treatment response, possibly due to biological variations in tissue composition and short-term response to the therapeutic irradiation. Within our group, an instrument for interstitial PDT on prostate tissue has been developed that combines therapeutic light delivery and monitoring of light transmission via numerous bare-ended optical fibers. Here, we present algorithms that utilize data on the light distribution within the target tissue to provide realtime treatment feedback based on a light dose threshold model for PDT. This realtime dosimetry module is implemented to individualize the light dose and compensate for any treatment-induced variations in light attenuation. More specifically, based on the light transmission signals between treatment fibers, spatially resolved spectroscopy is utilized to assess the effective attenuation coefficient of the tissue. These data constitute input to a block-Cimmino optimization algorithm, employed to calculate individual fiber irradiation times provided the requirement to deliver a predetermined light dose to the target tissue while sparing surrounding sensitive organs. By repeatedly monitoring the light transmission signals during the entire treatment session, optical properties and individual fiber irradiation times are updated in realtime. The functionality of the algorithms is tested on diffuse light distribution data simulated by means of the finite element method (FEM). The feasibility of utilizing spatially resolved spectroscopy within heterogeneous media such as the prostate gland is discussed. Furthermore, we demonstrate the ability of the block-Cimmino algorithm to discriminate between target tissue and organs at risk (OAR). Finally, the realtime dosimetry module is evaluated for treatment scenarios displaying spatially and temporally varying light attenuation levels within the target tissue. We conclude that the realtime dosimetry module makes it possible to deliver a certain light dose to the target tissue despite spatial and temporal variations of the target tissue optical properties at the therapeutic wavelength.},
  author       = {Johansson, Ann and Axelsson, Johan and Andersson-Engels, Stefan and Swartling, Johannes},
  issn         = {0094-2405},
  keyword      = {Radiometry: instrumentation,Prostatic Neoplasms: radiotherapy,Prostatic Neoplasms: pathology,Photochemotherapy: instrumentation,Photochemotherapy: methods,Radiometry: methods,Radiotherapy Planning,Computer-Assisted: methods},
  language     = {eng},
  number       = {11},
  pages        = {4309--4321},
  publisher    = {American Association of Physicists in Medicine},
  series       = {Medical Physics},
  title        = {Realtime light dosimetry software tools for interstitial photodynamic therapy of the human prostate},
  url          = {http://dx.doi.org/10.1118/1.2790585},
  volume       = {34},
  year         = {2007},
}