- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Comparison of treatment plans for a?high-field MRI-linac and a?conventional linac for esophageal cancer; Vergleich der Behandlungspl?ne von einem Hochfeld-MRT-Linac und einem konventionellen Linac beim ?sophaguskarzinom;
摘要： Purpose To compare radiotherapy treatments plans in esophageal cancer calculated for a high-?eld magnetic resonance imaging (MRI)-linac with plans for a conventional linac. Materials and methods Ten patients with esophageal squamous cell carcinomas were re-planned retrospectively using the research version of Monaco (V 5.19.03, Elekta AB, Stockholm, Sweden). Intensity modulated radiotherapy (IMRT) plans with a nine-?eld step-and-shoot technique and two-arc volumetric modulated arc therapy (VMAT) plans were created for the Elekta MRI-linac and a conventional linac, respectively. The prescribed dose was 60 Gy to the primary tumor (PTV60) and 50 Gy to elective volumes (PTV50). Plans were optimized for optimal coverage of the 60 Gy volume and compared using dose–volume histogram parameters. Results All calculated treatment plans met prede?ned criteria for target volume coverage and organs at risk dose both for MRI-linac and conventional linac. Plans for the MRI-linac had a lower number of segments and monitor units. No signi?cant differences between both plans were seen in terms of V20Gy of the lungs and V40Gy of the heart with slightly higher mean doses to the heart (14.0 Gy vs. 12.5 Gy) and lungs (12.8 Gy vs. 12.2 Gy). Conclusion Applying conventional target volume and margin concepts as well as dose-fractionation prescription re- veals clinically acceptable dose distributions using hybrid MRI-linac in its current con?guration compared to standard IMRT/VMAT. This represents an important prerequisite for future studies to investigate the clinical bene?t of MRI-guided radiotherapy exploiting the conceptional advantages such as reduced margins, plan adaptation and biological individual- ization and hypofractionation.
关键词： Intensity-modulated radiotherapy,Volumetric modulated arc therapy,Organs at risk,Squamous cell carcinomas,Magnetic resonance imaging
更新于2025-09-10 09:29:36
-
Cherenkov imaging for linac beam shape analysis as a remote electronic quality assessment verification tool
摘要： Purpose: A remote imaging system tracking Cherenkov emission was analyzed to verify that the linear accelerator (linac) beam shape could be quantitatively measured at the irradiation surface for Quality Audit (QA). Methods: The Cherenkov camera recorded 2D dose images delivered on a solid acrylonitrile butadiene styrene (ABS) plastic phantom surface for a range of square beam sizes, and 6 MV photons. Imaging was done at source to surface distance (SSD) of 100cm and compared to GaF film images and linac light fields of the same beam sizes, ranging over 5×5cm2 up to 20×20cm2. Line profiles of each field were compared in both X and Y jaw directions. Each measurement was repeated on 2 different Clinac2100 machines. An inter-reader comparison of the beam width interpretation was completed using procedures commonly employed for beam to light field coincidence verification. Cherenkov measurements are also done for beams of complex treatment plan and isocenter QA. Results: The Cherenkov image widths matched with the measured GaF images and light field images, with accuracy in the range of +/-1mm standard deviation. The differences between the measurements were minor and within tolerance of geometrical requirement of standard linac QA procedures conducted by human set up verification, which had a similar error range. The measurement made by the remote imaging system allowed for beam shape extraction of radiation fields at the SSD location of the beam. Conclusions: The proposed Cherenkov image acquisition system provides a valid way to remotely confirm radiation field sizes and provides similar information to that obtained from the linac light field or GaF film estimates of the beam size. The major benefit of this approach is that with a fixed installation of the camera, testing could be done completely under software control with automated image analysis, potentially simplifying conventional QA procedures with appropriate calibration of boundary definitions, and the natural extension to capturing dynamic treatment beamlets at SSD could have future value, such as verification of beam plans with complex beam shapes, like IMRT or “star-shot” QA for the isocenter.
关键词： linear accelerator,light field,dosimetry,QA,radiotherapy,Cerenkov
更新于2025-09-10 09:29:36
-
A multi-institutional retrospective study of carbon-ion radiotherapy for non-squamous cell malignant tumors of the nasopharynx: Subanalysis of Japan Carbon-Ion Radiation Oncology Study Group study 1402 HN
摘要： Background: This multi‐institutional retrospective study focused on the clinical outcome of carbon‐ion radiotherapy (C‐ion RT) for non‐squamous cell malignant tumors of the nasopharynx. Methods: The Japan Carbon‐ion Radiation Oncology Study Group collected and analyzed data for 43 patients with non‐squamous cell malignant tumors of the nasopharynx treated with C‐ion RT at four institutions in Japan. Results: Twenty‐nine patients had adenoid cystic carcinomas, seven had malignant melanomas, three had adenocarcinomas, two had mucoepidermoid carcinomas, and two had other pathologies. Twenty‐six of the 43 patients (61%) had T4 tumors. The most common dose‐fractionation schedule was 64 Gy (relative biological effectiveness) in 16 fractions. The median follow‐up period was 30 months. The 2‐year local control (LC) and overall survival (OS) rates were 88% and 84%, respectively. For late toxicity, one patient developed grade 4 optic nerve disorder and two developed grade 5 pharyngeal hemorrhage. Actual incidence of grade 3 or higher late adverse events was 19%, and included cranial nerve dysfunction, jaw bone necrosis, central nervous system necrosis, and ear inflammation. Conclusions: C‐ion RT provided good LC and OS rates with acceptable toxicity for treatment of non‐squamous cell malignant tumors of the nasopharynx.
关键词： overall survival,carbon‐ion radiotherapy,non‐squamous cell malignant tumors of the nasopharynx,local control,toxicity
更新于2025-09-10 09:29:36
-
Percentage depth dose fragmentation for investigating and assessing the photon beam dosimetry quality
摘要： Aim: The purpose of this study is to introduce a new approach to assess the dosimetry quality of photon beam with energy and irradiation field size. This approach is based on percentage depth dose (PDD) fragmentation for investigating the dosimetry quality. Materials and methods: For the investigation of the dosimetry quality of 6 and 18 MV photon beams, we have proceeded to fragment the PDD at different field sizes. This approach checks the overall PDD and is not restricted to the exponential decay regions, as per the International Atomic Energy Agency Technical Reports Series No 398 and the American Association of Physicist in Medicine Task Group 51 recommendations. Results and discussion: The 6 MV photon beam deposited more energy in the target volume than the 18 MV photon beam. The dose delivered by the 6 MV beam is greater by a factor of 1·5 than that delivered by the 18 MV beam in the build-up region and the dose delivered by the 6 MV beam is greater by a factor of 2·6 than that delivered by the 18 MV beam in the electronic equilibrium and the exponential decay regions. Conclusion: The dose measured at different points of the beam is higher for 6 MV than for 18 MV photon beam. Therefore, the 6 MV beam is more dosimetrically efficient than the 18 MV beam. Using the proposed approach, we can assess the dosimetry quality by taking into account overall PDD not only in the exponential decay region but also in the field.
关键词： radiotherapy efficiency,fragmentation,photon beam energy,quality index,dosimetry quality
更新于2025-09-10 09:29:36
-
Cancer Theranostics || Multimodality Image-Guided Treatment
摘要： Recent advances in molecular biology and imaging technology with precision engineering have allowed in vivo imaging of anatomic structures at submillimeter ranges and pathologic processes at subnanomolar concentrations. Multimodality imaging is exemplified by the current practice of single photon emission computed tomography (SPECT-CT) and positron emission tomography computed tomography (PET-CT) [1]. Subcentimeter lesions on computed tomotraphy (CT) can be characterized by functional abnormalities identified on SPECT to enhance sensitivity of detecting radio-isotopes or PET, which routinely assess lesion glucose metabolism using F-18 FDG (fluorine-18 fluoro-2-fluorodeoxyglucose). Conversely, subcentimeter hypermetabolic lesions on SPECT or PET can be identified on CT to allow exact localization to guide various types of therapy including surgery, radiotherapy, and experimental therapies. Guided therapies target abnormal tissues, which often refer to, but are not limited to, neoplasms. For instance, drainage of an abdominal bacterial abcess may require scintigraphic confirmation of infection to determine the need of intervention and anatomic guidance from CT or magnetic resonance imaging (MRI) to access the lesion.
关键词： Cancer treatment,Radiotherapy,Multimodality imaging,PET-CT,SPECT-CT,Surgery,Image-guided therapy,Molecular imaging
更新于2025-09-10 09:29:36
-
Dynamic 3D measurement of modulated radiotherapy: a scintillator-based approach
摘要： With the rise of high-conformity dynamic radiotherapy, such as volumetric modulated arc therapy and robotic radiosurgery, the temporal dimension of dose measurement is becoming increasingly important. It must be possible to tell both ‘where’ and ‘when’ a discrepancy occurs between the plan and its delivery. A 3D scintillation-based dosimetry system could be ideal for such a thorough, end-to-end verification; however, the challenge lies in retrieving the volumetric information of the light-emitting volume. This paper discusses the motivation, from an optics point of view, of using the images acquired with a plenoptic camera, or light field imager, of an irradiated plastic scintillator volume to reconstruct the delivered 3D dose distribution. Current work focuses on the optimization of the optical design as well as the data processing that is involved in the ongoing development of a clinically viable, second generation dosimetry system.
关键词： dynamic radiotherapy,volumetric modulated arc therapy,plenoptic camera,robotic radiosurgery,3D scintillation-based dosimetry
更新于2025-09-09 09:28:46
-
Selecting noncoplanar beam directions in a patient coordinate system for radiotherapy planning
摘要： To introduce a beam angle selection method based on the patient coordinate system for treatment planning of noncoplanar intensity-modulated radiation therapy (IMRT). Traditionally, in radiotherapy planning, beam directions are selected in the machine coordinate system. A noncoplanar beam direction is established through a treatment table rotation followed by a gantry rotation. However, visualizing the beam direction relative to the patient is di?cult. The suggestion here is to describe the beam direction in the patient coordinate system. First, a coplanar beam direction is selected in the transverse plane of the patient coordinate system. The noncoplanar beam direction is then obtained by adjusting the coplanar beam toward the foot or head in the patient coordinate system. Finally, the noncoplanar beam direction is expressed in terms of gantry and table angles in the machine coordinate system via formulae developed in this study. A 3D computer-aided design model of the linear accelerator (linac) is established with Solidworks and used to validate the feasibility of the proposed method. A clinical case was chosen to demonstrate the effectiveness of this method. Treatment plans with the conventional coplanar and noncoplanar beam settings were made. Compared with the conventional coplanar IMRT plan, improved normal tissue sparing of the organs at risk using the noncoplanar IMRT plan is evident. The proposed method for noncoplanar treatment planning makes beam direction selection simpler and straightforward.
关键词： Noncoplanar intensity-modulated radiation therapy,Radiotherapy planning,Noncoplanar planning,Patient coordinate system,Noncoplanar beam direction
更新于2025-09-09 09:28:46
-
Nanoscale Metal–Organic Layers for Radiotherapy–Radiodynamic Therapy
摘要： Nanoscale metal?organic layers (nMOLs) are an emerging class of 2D crystalline materials formed by reducing the dimensionality of nanoscale metal?organic frameworks (nMOFs). nMOLs hold significant potential in biomedical applications by combining the structural and compositional tunability of nMOFs and anisotropic properties of 2D nanomaterials. Here we report two novel nMOLs, Hf12-Ir and Hf6-Ir, based on Hf12 and Hf6 secondary building units (SBUs) and photosensitizing Ir(bpy)[dF(CF3)ppy]2+ derived ligands [bpy = 2,2′-bipyridine; dF(CF3)ppy = 2-(2,4-difluorophenyl)-5-(trifluoromethyl)pyridine] for radiotherapy (RT) and radiodynamic therapy (RDT). Upon X-ray irradiation, the Hf12 or Hf6 SBUs in the nMOLs efficiently absorb X-rays to enhance RT by producing hydroxyl radicals and to elicit RDT through the excitation of Ir(bpy)[dF(CF3)ppy]2+ to generate singlet oxygen and superoxide anions. Hf12-Ir and Hf6-Ir promoted effective cell instant death through RDT and reproductive death through RT to elicit superb cell anticancer efficacy, resulting in >99% tumor regression at low X-ray doses of 0.5 × 5 Gy.
关键词： Nanoscale metal?organic layers,Radiodynamic therapy,Radiotherapy,Hf12-Ir,Hf6-Ir
更新于2025-09-09 09:28:46
-
Chemical analysis of in vivo–irradiated dentine of head and neck cancer patients by ATR-FTIR and Raman spectroscopy
摘要： Objectives To evaluate the effect of in vivo radiotherapy on the chemical properties of human dentine by Fourier-transform infrared spectroscopy (FTIR) and Raman analysis. Materials and methods Chemical composition was evaluated comparing control and irradiated group (n = 8). Irradiated teeth were obtained from radiotherapy patients subjected to fractionated X-ray radiation of 1.8 Gy daily totaling 72 Gy. The teeth were sectioned according to the type of dentine (crown or root dentine), obtaining 3-mm dentine cervical slices. The analyzed parameters by FTIR and Raman spectroscopies were mineral/matrix ratio (M:M), carbonate/mineral ratio (C:M), amide I/amide III ratio, and amide I/CH2 ratio. Raman also calculated the phosphate and carbonate crystallinity. Results FTIR revealed that M:M had a decrease in both factors (p = 0.008; p = 0.043, respectively) and root dentine showed a lower C:M in the irradiated group (p = 0.003). Raman revealed a higher phosphate crystallinity and a lower carbonate crystallinity in crown dentine of irradiated group (p = 0.021; p = 0.039). For amide I/amide III, the irradiated showed a lower ratio when compared to the control group (FTIR p = 0.002; Raman p = 0.017). For amide I/CH2, the root dentine showed a higher ratio than the crown dentine in both methods (p < 0.001). Conclusions Radiotherapy altered the chemical composition of human dentine. The exchange of phosphate-carbonate ions in the hydroxyapatite and higher concentration of organic components was found after radiotherapy. Clinical relevance The increased risk of radiation-related caries in patients undergoing head and neck radiotherapy is due not only to salivary, dietary, and microbiological changes but also to changes in tooth chemical composition.
关键词： Radiotherapy,Raman spectroscopy,Head and neck cancer,Fourier-transform infrared spectroscopy,Dentine
更新于2025-09-09 09:28:46
-
Proton versus photon radiation-induced cell death in head and neck cancer cells
摘要： Background: Photon (X-ray) radiotherapy (XRT) kills cells via DNA damage, however, how proton radiotherapy (PRT) causes cell death in head and neck squamous cell carcinoma (HNSCC) is unclear. We investigated mechanisms of HNSCC cell death after XRT versus PRT. Methods: We assessed type of death in 2 human papillomavirus (HPV)-positive and two HPV-negative cell lines: necrosis and apoptosis (Annexin-V fluorescein isothiocyanate [FITC]); senescence (β-galactosidase); and mitotic catastrophe (γ-tubulin and diamidino-phenylindole [DAPI]). Results: The XRT-induced or PRT-induced cellular senescence and mitotic catastrophe in all cell lines studied suggested that PRT caused cell death to a greater extent than XRT. After PRT, mitotic catastrophe peaked in HPV-negative and HPV-positive cells at 48 and 72 hours, respectively. No obvious differences were noted in the extent of cell necrosis or apoptosis after XRT versus PRT. Conclusion: Under the conditions and in the cell lines reported here, mitotic catastrophe and senescence were the major types of cell death induced by XRT and PRT, and PRT may be more effective.
关键词： photon radiotherapy,radiation-induced cell death,head and neck cancer,cell death mechanisms,proton radiotherapy
更新于2025-09-04 15:30:14