System for interstitial photodynamic therapy with online dosimetry: first clinical experiences of prostate cancer

Abstract

Abstract. The first results from a clinical study for Temoporfinmediated photodynamic therapy ͑PDT͒ of low-grade ͑T1c͒ primary prostate cancer using online dosimetry are presented. Dosimetric feedback in real time was applied, for the first time to our knowledge, in interstitial photodynamic therapy. The dosimetry software IDOSE provided dose plans, including optical fiber positions and light doses based on 3-D tissue models generated from ultrasound images. Tissue optical property measurements were obtained using the same fibers used for light delivery. Measurements were taken before, during, and after the treatment session. On the basis of these real-time measured optical properties, the light-dose plan was recalculated. The aim of the treatment was to ablate the entire prostate while minimizing exposure to surrounding organs. The results indicate that online dosimetry based on real-time tissue optical property measurements enabled the light dose to be adapted and optimized. However, histopathological analysis of tissue biopsies taken six months post-PDT treatment showed there were still residual viable cancer cells present in the prostate tissue sections. The authors propose that the incomplete treatment of the prostate tissue could be due to a too low light threshold dose, which was set to 5 J/cm 2 .

Determination of the tumor tissue optical properties during and after photodynamic therapy using inverse Monte Carlo method and double integrating sphere between 350 and 1000 nm

“…Swartling et al researched the interstitial PDT with online feedback to deliver a tailored light fluence dose, exceeding a predefined threshold dose, to the whole prostate gland and adapt the dose plan in cases where the optical attenuation changes during the therapy. 30 They have reported that the optical properties of the gland tissue did not markedly vary during the treatment with Foscan R in clinical study. But, Thompson et al reported that light transmission decreased in nodular basal cell carcinomas during 5-amino levulinic acid mediated PDT.…”

Treatment plan evaluation for interstitial photodynamic therapy in a mouse model by Monte Carlo simulation with FullMonte

“…In the practice of interstitial PDT delivery, however, patient optical properties vary widely [33,34]. Development of treatment plans which are robust to a range of optical properties, as well as techniques for in-vivo detection and compensation for such variability (building on prior efforts in the prostate [4,25]), would be important contributions to PDT practice. The first part involving assessment of variability is enabled in a straightforward way by the present work, requiring only simulation of clinicallyderived meshes over a range of properties with analysis of the results.…”

“…Researchers at Lund University and SpectraCure AB [25] have run clinical trials for prostate cancer using the SpectraCure IDOSE platform, which uses multiple treatment fibers and realtime monitoring. Their planning system uses a diffusion-based solver to calculate light fluence, aiming to deliver a minimum threshold dose to the entire prostate gland while minimizing exposure to nearby organs [26].…”

Recovery of optical properties using interstitial cylindrical diffusers as source and detector fibers

“…10 Techniques involving separate spectroscopy instruments require the insertion of additional needles into the target volume, increasing the risk and complexity of the procedure. Investigators at Lund University have replaced the treatment diffusers with flat-cleaved fibers that are also used for optical property determination, 11 reducing the complexity. However, when flat-cleaved fibers are used for treatment, we have previously shown that treatment time and the number of fibers required to adequately cover the tumor volume are both increased.…”