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A Monte Carlo study of organ and effective doses of cone beam computed tomography (CBCT) scans in radiotherapy

Cone-beam CT (CBCT) scans utilised for image guided radiation therapy (IGRT) procedures have become an essential part of radiotherapy. The aim of this study was to assess organ and effective doses resulting from new CBCT scan protocols (head, thorax, and pelvis) released with a software upgrade of the kV on-board-imager (OBI) system. Organ and effective doses for protocols of the new software (V2.5) and a previous version (V1.6) were assessed using Monte Carlo (MC) simulations for the International Commission on Radiological Protection (ICRP) adult male and female reference computational phantoms. The number of projections and the mAs values were increased and the size of the scan field was extended in the new protocols. Influence of these changes on organ and effective doses of the scans was investigated. The OBI system was modelled in EGSnrc/BEAMnrc, and organ doses were estimated using EGSnrc/DOSXYZnrc. The MC model was benchmarked against experimental measurements. Organ dos...
Source: Journal of Radiological Protection - Category: Physics Authors: Source Type: research

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Authors: Pawlewicz K, Szutkowski Z, Kawecki A Abstract Adenoid cystic carcinoma (ACC) of the trachea is a relatively rare tumor among thoracic diseases. The present study reports the case of a 23-year-old woman with ACC of the trachea who underwent surgical resection of the tumor in The National Institute of Tuberculosis and Lung Diseases (Warsaw, Poland). Histopathological examination revealed that the tumor was not completely resected (R2 resection) and strict observation of the patient was therefore prescribed. After ~9 years of follow-up, clinical and histopathological tumor progression was confirmed and the pa...
Source: Oncology Letters - Category: Cancer & Oncology Tags: Oncol Lett Source Type: research
CONCLUSIONS: Average motion and patient set-up uncertainties during radiotherapy treatment were found to be limited. However, uncertainties were larger for the cranio-caudal direction and outliers were found in all orthogonal directions. When having available 4D-CT and CBCT information, the use of patient-specific and anisotropic safety margin expansions is advised for both target volume and OAR. PMID: 29457751 [PubMed - as supplied by publisher]
Source: Acta Oncologica - Category: Cancer & Oncology Authors: Tags: Acta Oncol Source Type: research
J Neurol Surg B DOI: 10.1055/s-0038-1625967Suprasellar tumors in particular tumors located in the retrochiasmatic area and anterior third ventricle are challenging cases in terms of optimal surgical exposure. Several approaches have been described including transsylvian, translamina terminalis, endoscopic endonasal, and anterior interhemispheric. Each approach has advantages and disadvantages. In this video, we present a case of retrochiasmatic anterior third ventricular tumor that was operated via anterior interhemispheric transcallosal transforaminal approach. The patient is a 42-year-old female who presented with sudden...
Source: Journal of Neurological Surgery Part B: Skull Base - Category: Neurosurgery Authors: Tags: Skull Base: Operative Videos Source Type: research
AbstractRadiation therapy plays an essential role in the treatment of cancer. In radiation therapy, the ideal radiation doses are delivered to the observed tumor while not affecting neighboring normal tissues. In three-dimensional computed tomography (3D-CT) scans, the contours of tumors and organs-at-risk (OARs) are often manually delineated by radiologists. The task is complicated and time-consuming, and the manually delineated results will be variable from different radiologists. We propose a semi-supervised contour detection algorithm, which firstly uses a few points of region of interest (ROI) as an approximate initia...
Source: Journal of Digital Imaging - Category: Radiology Source Type: research
Conclusions This study demonstrates 3D printed bolus in postmastectomy radiation therapy improves fit of the bolus and reduces patient setup time marginally compared with standard vinyl gel sheet bolus. The time savings on patient setup must be weighed against the considerable time needed for the 3D printing process.
Source: Practical Radiation Oncology - Category: Cancer & Oncology Source Type: research
Abstract Four dimensional computed tomography (4DCT) scans are routinely used in radiation therapy to determine the internal treatment volume for targets that are moving (e.g. lung tumors). The use of these studies has allowed clinicians to create target volumes based upon the motion of the tumor during the imaging study. The purpose of this work is to determine if a target volume based on a single 4DCT scan at simulation is sufficient to capture thoracic motion. Phantom studies were performed to determine expected differences between volumes contoured on 4DCT scans and those on the evaluation CT scans (slow scans...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research
Conclusion.R0 resection, the goal of neoadjuvant treatment, can be achieved in 70% of patients presenting with locally advanced pancreatic cancer. The median DFS was 31 months (95% CI: 11. 3–51.1). No relationship was found with tumor size, degree of vascular involvement, carcinoembryonic antigen test (CEA), CA 19‐9, degree of tumor regression on scan, fall in CA 19‐9, or SUV on PET scan and subsequent survival.
Source: The Oncologist - Category: Cancer & Oncology Authors: Tags: Chinese Edition, Clinical Trial Results, Endocrinology Source Type: research
Abstract A 72-year-old man underwent total gastrectomy for gastric cancer (por2, T3, N2, Stage IIIA). Eleven courses of postoperative chemotherapy with TS-1 (tegafur/gimeracil/oteracil) were administered. Five months after surgery, the serum carcinoembryonic antigen value was slightly elevated. However, computed tomography did not reveal any metastatic lesions in other organs. Two years after surgery, the patient felt a mass in the left mammary. A 2-cm tumor was palpable in the central portion of the breast. Ultrasonography revealed a hypoechoic tumor, which was Class 3 on aspiration biopsy cytological examination...
Source: Clinical Breast Cancer - Category: Cancer & Oncology Authors: Tags: Clin J Gastroenterol Source Type: research
Conclusions Both increased tumor size and metabolic activity are associated with increased risk of death. Combining size and metabolic activity together is superior for predicting 2-year survival and identifying patients for whom survival is statistically worse.
Source: Journal of Computer Assisted Tomography - Category: Radiology Tags: Abdominal Imaging Source Type: research
Abstract PURPOSE: The deformable registration of pulmonary computed tomography images before and after radiation therapy is challenging due to anatomic changes from radiation fibrosis. We hypothesize that a line-enhanced registration algorithm can reduce landmark error over the entire lung, including the irradiated regions, when compared to an intensity-based deformable registration algorithm. MATERIALS: Two intensity-based B-spline deformable registration algorithms of pre-radiation therapy and post-radiation therapy images were compared. The first was a control intensity-based algorithm that utilized comput...
Source: Technology in Cancer Research and Treatment - Category: Cancer & Oncology Authors: Tags: Technol Cancer Res Treat Source Type: research
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