Online dosimetry for temoporfin-mediated interstitial photodynamic therapy using the canine prostate as model

Abstract

Online dosimetry for temoporfin-mediated interstitial photodynamic therapy using the canine prostate as model. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Online dosimetry for temoporfinmediated interstitial photodynamic therapy using the canine prostate as model Abstract. Online light dosimetry with real-time feedback was applied for temoporfin-mediated interstitial photodynamic therapy (PDT) of dog prostate. The aim was to investigate the performance of online dosimetry by studying the correlation between light dose plans and the tissue response, i.e., extent of induced tissue necrosis and damage to surrounding organs at risk. Light-dose planning software provided dose plans, including light source positions and light doses, based on ultrasound images. A laser instrument provided therapeutic light and dosimetric measurements. The procedure was designed to closely emulate the procedure for wholeprostate PDT in humans with prostate cancer. Nine healthy dogs were subjected to the procedure according to a light-dose escalation plan. About 0.15 mg∕kg temoporfin was administered 72 h before the procedure. The results of the procedure were assessed by magnetic resonance imaging, and gross pathology and histopathology of excised tissue. Light dose planning and online dosimetry clearly resulted in more focused effect and less damage to surrounding tissue than interstitial PDT without dosimetry. IntroductionProstate cancer is one of the most common cancer forms in men.1 Current radical treatments, which include surgery and radiotherapy, are associated with side effects primarily in the form of impotence and incontinence. Interstitial photodynamic therapy (PDT) is one alternative technique to treat prostate cancer. 3 The method relies on the use of a light activated drug, photosensitizer, and provides a minimally invasive treatment by the use of needles to insert optical fibers that guide the light to the target tissue. In addition, interstitial PDT potentially offers several other advantages: few side effects, rapid recovery, repeatable treatment if needed, and the method does not exclude other treatment options. Interstitial light delivery, in contrast to traditional PDT which utilizes surface illumination, allows treatment of voluminous tumors with complex structure inside the body...

Interstitial Photodynamic Therapy—A Focused Review

“…Following I-PDT, the PSA level was higher than expected for complete treatment and it was concluded that the light dose of 5 J/cm 2 was insufficient. In a later pre-clinical study in male canines, this group suggested that the threshold light dose should be in the range of 20–30 J/cm 2 for effective I-PDT with mTHPC in the treatment of prostate cancer [ 31 ].…”

Irradiance controls photodynamic efficacy and tissue heating in experimental tumours: implication for interstitial PDT of locally advanced cancer

“…21 For I-PDT of the prostate, multiple investigators have suggested that intratumoural light dose (i.e., light fluence, J/cm 2 ) is the key parameter to achieve an effective tumour control. 22–25 To the best of our knowledge, the impact of intratumoural light irradiance (thereafter referred to as irradiance) on response and local control has not been reported for Photofrin ® -mediated I-PDT.…”

Photodynamic Diagnosis and Therapy for Peritoneal Carcinomatosis from Gastrointestinal Cancers: Status, Opportunities, and Challenges

“…For example, there could be more extensive use of multiple distributed light sources for the simultaneous illumination of different intraperitoneal surfaces, and by continuous imaging and multiple point measurements of the light distribution, with automatic feedback control to dynamically adjust the power from each light source. This type of on-line monitoring and control system has been used for other complex anatomical sites, such as whole-prostate PDT [110], guided by pre-treatment planning based on volumetric CT or MRI.…”