An inorganic scintillating material plastic optical fiber (POF) dosimeter for measuring ionizing radiation during radiotherapy applications is reported. It is necessary that an ideal dosimeter exhibits many desirable qualities, including water equivalence, energy independence, reproducibility, dose linearity. There has been much recent research concerning inorganic dosimeters. However, little reference has been made to date of the depth-dose characteristics of dosimeter materials. In the case of inorganic scintillating materials, they are predominantly non water-equivalent, with their effective atomic weight (Zeff) being typically much greater than that of water. This has been a barrier in preventing inorganic scintillating material dosimeter from being used in actual clinical applications. In this paper, we propose a parallel-paired fiber light guide structure to solve this problem. Two different inorganic scintillating materials are embedded separately in the parallel-paired fiber. It is shown that the information of water depth and absorbed dose at the point of measurement can be extracted by utilizing their different depth-dose properties.
The small-field radiotherapy is a developing technique because it can reduce the damage to normal tissues. However measurement of the dose distributions of small radiation fields in radiotherapy is a challenge. In this work, we designed and produced an optic fiber X-ray sensor array with high spatial resolution. The sensing array includes 7 sensing probes connecting to an 8-channel optical switch and a photon counting detector (PCD). To verify the practicality of the system, these sensors were measured under a 10×10 cm2 field of a medical linear accelerator. For the small-field application, the dose distribution of radiotherapy fields 1×1 cm2 and 0.8×0.8 cm2 were measured. The distribution of these small radiotherapy fields were given based on the experimental results.
In radiation measurement, optical fiber sensors (OFS) have many advantages compared to commercial dosimeters, including high spatial resolution. Due to the OFS measurement principle (fluorescence), the recorded measurement results differ from the standard dose value, such as that obtained using an ionization chamber. In this study, a physical correction function is established to considerably reduce the difference. This function quantifies the over-response of OFS to low-energy scattered photons and low-energy electrons. The specific expression of the function is derived from experimental measurement results obtained using the OFS and a commercial standard dosimeter when subject to two different radiation field sizes irradiated using a clinical linac. Following the application of the correction of the function, the measurement difference between the OFS and the standard dosimeter is greatly reduced for a range of radiation fields, in which case the maximum difference decreased from 42.2% to 1.5%. The dose correction method is based on existing quality assurance (QA) protocols used in radiotherapy and is simple and convenient to apply. This research has further promoted the application of OFSs in radiation dose measurement, including radiotherapy QA and in-patient use.
Bladder cancer displays multiple biological features aided in drug resistance; therefore, single therapy fails to induce complete tumor regression. To address this issue, various kinds of cell death of cancer cells as well as restoring tumor immune microenvironment need to be taken into consideration. Here, we introduce a gel system termed AuNRs&IONs@Gel, which target-delivers a combination of photothermal, ferroptotic, and immune therapy through intravesical instillation. AuNRs&IONs@Gel consists of a gel delivery platform, embedded gold nanorods (AuNRs), and iron oxide nanoparticles (IONs). The targeted delivery gel platform provides dextran aldehyde-selective adhesion with cancer collagen. In this condition, photothermal therapy can be performed by gold nanorods (AuNRs) under imaging-guided near-infrared radiation. Local high concentrations of IONs can be absorbed by cancer cell to induce ferroptosis. Moreover, tumor-associated macrophages which often display an immune-suppressive M2-like phenotype will be repolarized by IONs into the antitumor M1-like phenotype, exerting a direct antitumor effect and professional antigen presentation of dead cancer cells. This process triggers a potent immune response of innate and adapt immunities to protect tumor rechallenge in long terms. Our triple-therapy strategy employs FDA-approved nanoparticles to inhibit bladder cancer which may possess great potential for clinical translation.
This paper investigates the trajectory tracking control problem of a dynamic positioning vessel (DPV) subject to tracking performance, time-varying sea loads and inertia uncertainties. Firstly, a novel cascade model of the DPV is built to describe the dynamics. Then, in order to guarantee the performance constraints of the trajectory tracking, a new-type fixed-time performance function is proposed, which can not only guarantee the transient and steady-state performance during task execution, but also achieve convergence at a fixed time. In addition, an adaptive neural network is introduced to handle the problem of parameter uncertainty and unknown sea loads in the system. Furthermore, it is proved by the Lyapunov stability theory that all signals in the closed-loop system are bounded . Finally, numerical simulation results verified the effectiveness of the proposed method and ensure that the tracking error is stable in the interval of 2 m or less within a given time.
Abstract Bladder cancer is the fifth most common malignancy in humans. Cystoscopy under white light imaging is the gold standard for bladder cancer diagnosis, but these tumors are difficult to visualize and can be overlooked, resulting in high recurrence rates. We previously developed a phage display-derived peptide-based near-infrared imaging probe, PLSWT7-DMI, which binds specifically to bladder cancer cells and is nontoxic to animals. Here, we report the first-in-human application of this probe for near-infrared fluorescence endoscopic detection of bladder cancer. The purity, efficacy, safety, and nontoxicity of the probe were confirmed prior to its clinical application. Twenty-two patients diagnosed with suspected non-muscle invasive bladder cancer were enrolled in the present study. Following intravesical administration of the probe, the entire mucosa was imaged under white and near-infrared imaging using an in-house developed endoscope that could switch between these two modes. The illuminated lesions under near-infrared light were biopsied and sent for histopathological examination. We observed a 5.1-fold increase in the fluorescence intensity in the tumor samples compared to normal tissue, and the probe demonstrated a sensitivity and specificity of 91.2% and 90%, respectively. Common diagnostic challenges, such as small satellite tumors, carcinoma in situ , and benign suspicious mucosa, were visualized and could be distinguished from cancer. Further, no adverse effects were observed in humans. These first-in-human results indicate that PLSWT7-DMI-based near-infrared fluorescence endoscopy is a safe and effective approach for the improved detection of bladder cancer, and may enable thorough resection to prevent recurrence.
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