Real-time light dosimetry for intra-cavity photodynamic therapy: Application for pleural mesothelioma treatment

Our plain-English summary of Real-time light dosimetry for intra-cavity photodynamic therapy: Application for pleural mesothelioma treatment, by N. Betrouni, C. Munck, W. Bensoltana, et al (Photodiagnosis and Photodynamic Therapy, 2017).

The study

• Authors: N. Betrouni, C. Munck, W. Bensoltana, G. Baert, A.S. Dewalle-Vignion, A. Scherpereel, S. Mordon
• Journal: Photodiagnosis and Photodynamic Therapy
• Published: 2017;18:155-161
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Complete and homogeneous illumination of the target is necessary for the success of a photodynamic therapy (PDT) procedure. In most applications, light dosimetry is done using detectors placed at strategic locations of the target. In this study we propose a novel approach based on the combination of light distribution modeling with spatial localization of the light applicator for real time estimation and display of the applied dose on medical images. The feasibility approach is demonstrated for intrapleural PDT of malignant pleural mesothelioma.

Copyright © 2017 Elsevier B.V. All rights reserved.

In plain English

This article described a new way to estimate light dose in real time during photodynamic therapy (PDT) inside a body cavity, designed for intrapleural PDT of malignant pleural mesothelioma. No patients or asbestos exposure were studied. The method combined a model of how light spreads from the applicator with an electromagnetic tracker following the applicator's position, and displayed the accumulated dose on CT images. The authors tested it on a plaster, 3D-printed, human-sized model of a right-side chest cavity after tumor removal. They compared it with the standard method, which uses 7 light probes. Across six experiments, the new method underestimated the dose, with a mean error of about 10%. After a correction factor of 1.1, the difference between the two methods fell below 1% for the light dose at one position. The authors noted that their model does not account for multiple scattering of light in the intralipid liquid. They described the approach as a new trend in dosimetry for intrapleural PDT. They stated it would shorten procedures by avoiding probe placement, which takes about 15 minutes.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Technical development and laboratory feasibility study of a light dosimetry method, tested on a physical phantom (no patients)
• Who was studied: No human subjects. The method was tested on one anatomically realistic phantom: a human-sized hemithorax made of plaster and 3D printed as a right-side pleural cavity after tumor resection. The authors are from INSERM U1189 and Lille University Hospital, France.
• Exposure: No asbestos exposure was studied. The 'exposure' was laser light from a 635 nm medical diode laser, delivered through a cylindrical diffuser light applicator whose position was followed by an electromagnetic tracking device.
• Main results:
  • Six independent experiments were done, each with different movements of the light applicator inside the phantom cavity.
  • At the 7 probe locations, the new model-based method underestimated the light dose compared with the reference probe measurements, with a mean error of about 10%.
  • Because the underestimation was constant across the six experiments, a correction factor of 1.1 was set. One new experiment was then run with the corrected model values.
  • The corrected comparison was reported for the mean light dose calculated at one position.
  • For that one position after correction, the difference between the two methods' measurements fell below 1%.
  • The reference probe measurements rose steadily over time. The authors explained this by the probes collecting light through the intralipid liquid even when the applicator was far away.
• The authors' conclusion: The authors described their approach as a new trend in dosimetry for intrapleural PDT. They stated that it would reduce intervention time by avoiding placement of measurement probes in the thorax, which they said takes about 15 minutes. This time saving was stated, not measured in the study.
• Limitations the authors state:
  • The light model accounts for absorption and diffusion around the applicator but not for multiple scattering within the intralipid solution. The authors said this may explain the systematic underestimation.
  • The model covers only a limited volume around the applicator. It therefore does not capture light reaching a point when the applicator is far from it.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma.

Related studies

• Illumination profile characterization of a light device for the dosimetry of intra-pleural photodynamic therapy for mesothelioma — C. Munck, S. Mordon, et al. (2016)
• Response of Photofrin-sensitised mesothelioma xenografts to photodynamic therapy with 514 nm light — T.H. Foster, S.L. Gibson, et al. (1996)
• Intrapleural Photodynamic Therapy for Mesothelioma: What Place and Which Future? — C. Munck, S.R. Mordon, et al. (2015)
• Photodynamic therapy for lung cancer and malignant pleural mesothelioma — C.B. Simone, K.A. Cengel (2014)
• A Novel Prospective Study Assessing the Combination of Photodynamic Therapy and Proton Radiation Therapy: Safety and Outcomes When Treating Malignant Pleural Mesothelioma — S.R. Rice, Y.R. Li, et al. (2019)
• Photodynamic therapy for malignant pleural mesothelioma: the future of treatment? — J.S. Friedberg (2011)

Browse return to medical research.