Abstract
Purpose It is well known that interstitial photodynamic therapy (iPDT) of large tumors requires effective planning to ensure efficient delivery of therapeutic dose to the target tumors. This should be achieved in parallel with minimal damage to the nearby intact tissues. To that end, clinical iPDT can be attained using cylindrical diffusing optical fibers (CDFs) as light sources. In this work, we optimize output CDF powers in order to deliver a prescribed light dose to a spherical volume such as a tumor node. Methods Four CDFs are placed vertically inside the tumor node. The fluence rate is calculated using the diffusion equation. Therapeutic target dose is (20-50) J·cm−2. The optical properties (μa = 0.085 cm−1, μs′ = 16 cm−1) of a breast tumor and the treatment time of 150 sec are used to calculate the fluence rate. Results For four CDFs, the therapeutic target dose (20-50) J·cm−2 is delivered to more than 90%. This is the ratio of the total points that receive the target dose in proportion to the total points in the volume of the node of 3 cm in diameter, whereas, in larger nodes, the ratio is decreased to approximately 67%. Five CDFs are required to improve this ratio by more than 10%. Conclusion Optimizing delivered powers enables the distribution of the therapeutic dose uniformly in the medium. In addition, this simulation study represents an essential part of a development dosimetry system for measuring and controlling the optical dose in the breast tumors.
Highlights
Photodynamic therapy (PDT), as a minimally invasive technique, is a widely and clinically accepted method for treating a wide range of cancers, such as brain and prostate, to name but a few.It comprises a light source and a photosensitizer in order to produce toxic singlet oxygen which, in turn, leads to cancerous tissue destruction [1].Practically, optical fibers in interstitial photodynamic therapy (iPDT) can be inserted inside bulky tumors to ensure efficient illumination of the whole volume of tumors
Owing to the undesired side effects which resulted from conventional techniques used for treating cancers such as X-ray based instrumentation and iPDT is commonly recognized as a viable alternative for treatment of prostate cancer [2]
The Cimmino algorithm has been commonly used for prostate iPDT and proved to be effective when applied to other cancers [2, 3]
Summary
Photodynamic therapy (PDT), as a minimally invasive technique, is a widely and clinically accepted method for treating a wide range of cancers, such as brain and prostate, to name but a few.It comprises a light source and a photosensitizer in order to produce toxic singlet oxygen which, in turn, leads to cancerous tissue destruction [1].Practically, optical fibers in iPDT can be inserted inside bulky tumors to ensure efficient illumination of the whole volume of tumors. Photodynamic therapy (PDT), as a minimally invasive technique, is a widely and clinically accepted method for treating a wide range of cancers, such as brain and prostate, to name but a few. It comprises a light source and a photosensitizer in order to produce toxic singlet oxygen which, in turn, leads to cancerous tissue destruction [1]. Owing to the undesired side effects which resulted from conventional techniques used for treating cancers such as X-ray based instrumentation and iPDT is commonly recognized as a viable alternative for treatment of prostate cancer [2]. Altschuler et al and Davidson et al demonstrated a combination of ultrasound imaging
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