Precision Radiation Oncology最新文献

Beam-matched linear accelerators (linacs) enable flexible patient scheduling and efficient treatment delivery in the event of unexpected machine downtime. The purpose of this study was to test the feasibility of 3D gamma index as an additional metric beyond standard measurement-based comparisons for more efficient evaluation of treatment plans between linacs with nominally matched beam models to ensure safe patient transfer. Seventeen 3D conformal radiotherapy (3DCRT) plans and thirty-six volumetric-modulated radiation therapy (VMAT) plans for different disease sites were selected from the original linac. An in-house script was used to automatically create new plans for the target linac and calculate dose using parameters of the original plans. 3D gamma analysis was performed to compare plan dose distributions between the target and original linacs using PyMedPhys. The 2%/2 mm gamma pass (γ≤1) rate was >99.99% for all 3DCRT plans. The median 1%/1 mm pass rate was 99.86% but two cases failed (< 90%). For VMAT plans, the median and minimum 2%/2 mm gamma pass rates were 99.43% and 93.81%. For 1%/1 mm, the median pass rate was 92.02% but ten cases failed. The results indicated using 3D gamma index can enhance the confidence and add an extra layer for safe patient transfer.

Radiation-induced heart disease (RIHD) is a serious complication but difficult to assess in patients undergoing thoracic radiotherapy (RT). We aim to analyze RIHD using heart ultrasound and elastic modulus, exploring relationships between functional, anatomical or biomechanical changes of the heart and radiation dose. Twenty BALB/c mice were divided into four groups (control, 10 Gy, 20 Gy and 25 Gy) with a single fraction of image-guided volumetric modulated arc radiotherapy (VMAT) to murine heart on a linear accelerator. Transthoracic echocardiography (TTE) was performed on a small-animal ultrasound imaging system with a handheld microscan transducer. E-wave/A-wave ratio (E/A) and myocardial performance index (MPI) for diastolic performance were noninvasively evaluated weekly, as well as ejection fraction (EF%), fractional shortening (FS%), left ventricle (LV) mass and heart wall thickening for systolic performance. At the end of the fifth week, all mice were sacrificed for elastic modulus measurement on a dynamic mechanical analyzer (DMA) and for histopathological staining. All experiments were conducted in accordance with the local institution's animal research committee guideline. Significant difference was observed in E/A ratio between the control and 25 Gy irradiated groups (1.8±0.5 and 0.7±0.9, respectively; p<0.05), indicating reduced diastolic performance and increased stiffness in left ventricle after high-dose heart radiation. Diastolic dysfunction in irradiated groups was also observed with significantly increased MPI. In contrast, posterior wall thickness, aortic peak velocity, heart rate, EF and FS were not significantly different after RT. Heart elasticity was reduced substantially with the increased radiation dose. HE and Masson Trichrome staining confirmed more fibrosis deposition in irradiated hearts. RIHD evaluation with ultrasound imaging noninvasively and biomechanical modulus measurement invasively in the image guided, precision dose-escalated murine heart irradiation is feasible. Increased myocardial stiffness, abnormal diastolic relaxation, more collagen deposition, and reduced tissue elasticity are observed in irradiated heart tissue. This study may facilitate our understanding of RIHD and facilitate improving patients' quality of life in the future.

Purpose: We aim to perform image-guided, dose-escalated, well-controlled liver-irradiated animal studies and subsequently evaluate radiation induced liver injury (RILI) using longitudinal CT.

Methods: Eighteen 6-8 weeks mice were divided into three groups: control, 15Gy and 30Gy irradiated groups. The animal protocol was approved by the animal care ethics committee of our institution. Precision radiotherapy started with CT simulation, followed by treatment planning using volumetric modulated arc therapy (VMAT), image guidance with cone beam CT (CBCT) and radiation delivery on a medical linear accelerator. Weekly CT was conducted on the same CT simulator using same scanning parameters. At the end of fifth week, all mice were sacrificed, and histological staining was performed. Body weight, liver volume, HU values and histogram distributions were analyzed.

Results: Body weight of irradiation groups was significantly reduced compared to that of the control group (p<0.05). Liver volume in irradiated groups was reduced too. The average liver HU was significantly reduced in irradiated groups (HU mean = 62±3, 48±6, and 36±8 for the control, 15Gy and 30Gy respectively; p _{control vs. 15Gy} < 0.05, p control vs. 30Gy < 0.05). A linear relationship between liver HU and radiation dose was found. Furthermore, HU histogram changes with time and dose showed not only density but also structure might be affected by radiation. HE and Masson Trichrome staining confirmed histological change and increased collagen deposition in irradiated liver.

Conclusion: Longitudinal unenhanced CT is a useful imaging tool to evaluate the severity and progression of radiation induced liver injury.

Previously, a synchrotron-based horizontal proton beamline (87.2 MeV) was successfully commissioned to deliver radiation doses in FLASH and conventional dose rate modes to small fields and volumes. In this study, we developed a strategy to increase the effective radiation field size using a custom robotic motion platform to automatically shift the positions of biological samples. The beam was first broadened with a thin tungsten scatterer and shaped by customized brass collimators for irradiating cell/organoid cultures in 96-well plates (a 7-mm-diameter circle) or for irradiating mice (1-cm² square). Motion patterns of the robotic platform were written in G-code, with 9-mm spot spacing used for the 96-well plates and 10.6-mm spacing for the mice. The accuracy of target positioning was verified with a self-leveling laser system. The dose delivered in the experimental conditions was validated with EBT-XD film attached to the 96-well plate or the back of the mouse. Our film-measured dose profiles matched Monte Carlo calculations well (1D gamma pass rate >95% with the criteria of 2%/1 mm/2% dose threshold). The FLASH dose rates were 113.7 Gy/s for cell/organoid irradiation and 191.3 Gy/s for mouse irradiation. These promising results indicate that this robotic platform can be used to effectively increase the field size for preclinical experiments with proton FLASH.

Background: Nanosecond pulsed electric fields (nsPEF)-based electroporation is a new therapy modality potentially synergized with radiation therapy to improve treatment outcomes. To verify its treatment accuracy intraoperatively, electroacoustic tomography (EAT) has been developed to monitor in-vivo electric energy deposition by detecting ultrasound signals generated by nsPEFs in real-time. However, utility of EAT is limited by image distortions due to the limited-angle view of ultrasound transducers.

Methods: This study proposed a supervised learning-based workflow to address the ill-conditioning in EAT reconstruction. Electroacoustic signals were detected by a linear array and initially reconstructed into EAT images, which were then fed into a deep learning model for distortion correction. In this study, 56 distinct electroacoustic data sets from nsPEFs of different intensities and geometries were collected experimentally, avoiding simulation-to-real-world variations. Forty-six data were used for model training and 10 for testing. The model was trained using supervised learning, enabled by a custom rotating platform to acquire paired full-view and single-view signals for the same electric field.

Results: The proposed method considerably improved the image quality of linear array-based EAT, generating pressure maps with accurate and clear structures. Quantitatively, the enhanced single-view images achieved a low-intensity error (RMSE: 0.018), high signal-to-noise ratio (PSNR: 35.15), and high structural similarity (SSIM: 0.942) compared to the reference full-view images.

Conclusions: This study represented a pioneering stride in achieving high-quality EAT using a single linear array in an experimental environment, which improves EAT's utility in real-time monitoring for nsPEF-based electroporation therapy.

Breast cancer has surpassed lung cancer as the most common type of malignancy worldwide. Treatments for breast cancer include surgery, chemotherapy, radiotherapy, targeted therapy, endocrine therapy, immunotherapy, and hyperthermia. Radiotherapy plays an important role in breast cancer treatment. Patients with early breast cancer can have longer survival after combined treatment, but cardiotoxicity caused by radiotherapy may affect long-term prognosis. This article reviews cardiac damage caused by radiotherapy in breast cancer.

Purpose: To facilitate the use of quantitative modeling of biological effects in treatment planning by introducing a simpler function equivalent to the Lyman formula for calculating normal tissue complication probability (NTCP).

Methods: We first provide an approximation of the Lyman-Kutcher-Burman (LKB) formula using three parameters (n, m, TD₅₀) as a function of equivalent uniform dose (EUD). The parameters for the new formula are defined in terms of the Lyman model's m and TD₅₀. Conversely, m and TD₅₀ are expressed in terms of the parameters of the new equation. The role of the Lyman volume-effect parameter n remains unchanged from its role in the Lyman model.

Results: The new formula, which exhibits a sigmoidal shape, demonstrates symmetry about TD₅₀, akin to the LKB model. The difference in NTCP between the two formulas is less than 0.1%. The parameters (n, m, TD₅₀) are preserved through rigorous mathematical deduction and have been recalibrated to the tolerance data of Emani et al. using the proposed formula. This new model provides a better fit to these data than the model by Burman et al., which was fitted "by eye" rather than using statistical methods.

Conclusion: We have developed a formula that represents NTCP as a function of EUD, which proves to be potentially useful. The parameters derived in this study are mathematically robust and offer a superior fit to the data compared to previous efforts. Additionally, the new model fits brain data as well as, if not better than, the LKB model.

Radiopharmaceutical therapy (RPT) is a precision medicine approach that involves the targeted delivery of radioactive atoms to tumor cells, representing a breakthrough strategy for cancer treatment. Radiopharmaceuticals typically consist of a small amount of radioactive material, a radionuclide, paired with a chemical that specifically targets the cell. Some radionuclides naturally target specific cells or biological processes without the need for modification. RPT is a novel cancer treatment method that offers various advantages over current traditional treatment approaches. One of the primary advantages of RPT is its ability to target cancer cells, including those in metastatic areas. Another key advantage of RPT is that radiation can be delivered systemically, locally, or physiologically to specific cells internally rather than being applied externally. Moreover, radiotracer imaging can be utilized to determine radiopharmaceutical absorption in target tissues before providing a therapeutic dose. Compared to all other cancer treatment approaches, RPT has demonstrated high efficacy with minimal toxicity. The recent approval of multiple RPT medicines by the US Food and Drug Administration highlights the tremendous potential of this treatment. This article provides a detailed review of RPT, including insights into manufacturing procedures, safety measures, and its applications in cancer therapy.

Nuclear protein in testis (NUT) carcinoma is a rare and highly aggressive cancer, characterized by rearrangements involving the NUT gene located on chromosome 15q14. In this report, we present the case of a 52-year-old female diagnosed with primary parotid NUT carcinoma. Despite undergoing surgery, adjuvant chemotherapy, and incomplete regional radiotherapy, the patient succumbed to the disease after an overall survival duration of 7 months. We retrospectively discuss patient clinical and pathological features, as well as therapeutic approaches of NUT carcinoma of the head and neck.

Objective: To evaluate the efficacy and safety of definitive radiotherapy in selected patients with local recurrence of Kimura disease of the head and neck after surgery.

Methods: This retrospective study collected the clinical data of 14 patients with postoperative recurrence of Kimura disease of the head and neck who received definitive radiotherapy at the First Affiliated Hospital of Fujian Medical University between 2006 and 2022. The radiation dose ranged from 28 to 40 Gy. Its efficacy and safety were analyzed.

Results: During follow-up, ranging from 17 to 168 months, local control was achieved in 13 (92.9%) of the 14 patients with postoperative recurrence. There were no serious late toxicities except for mild xerostomia in four (28.6%) patients; the patients' peripheral blood eosinophil count dropped from 1.73×10⁹/L before treatment to 0.42×10⁹/L after treatment, and the eosinophil percentage dropped from 20.64% to 9.78%. Both changes were statistically significant (p<0.001).

Conclusions: The findings of the study suggest that definitive radiotherapy is a viable and effective alternative to repeated surgery for managing recurrent Kimura disease of the head and neck, with significant response rates and a good safety profile. Peripheral blood eosinophil counts and percentages serve as simple and reliable biomarkers for monitoring Kimura disease progression and treatment responses.