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Medical and Biological Applications of Low Energy Accelerators
Published in Vlado Valković, Low Energy Particle Accelerator-Based Technologies and Their Applications, 2022
They produce three types of high definition (HD) digital accelerators:Elekta Synergy HD is a digital accelerator for advanced IGRT, shown in Fig. 2.12. A trusted solution around the world. Close to 2,000 systems in clinical use in over 70 countries both mature and emerging markets, and about 1 million cancer patients helped annually through Synergy treatments. The unparalleled 50 cm × 26 cm largest IGRT field-of-view enables complete visualization of critical anatomical information to support clinical decisions at the time of treatment. Synergy's advanced MLC provides excellent beam shaping capabilities for dynamic delivery techniques and low leaf transmission protects organ-at-risk (OAR).Remote 24/7 support: Elekta IntelliMax proactive support and predictive maintenance help you avoid unplanned downtime to ensure departmental efficiency to boost your bottom line.Elekta Infinity HD based on Elekta Infinity™ linear accelerator, as shown in Fig. 2.13.Elekta Versa HD Advanced 4D image guidance for Lung SBRT with Symmetry, Optimized DCAT for Lung and Liver SBRT. Single isocenter high definition dynamic radiosurgery (HDRS) for multiple brain metastases. Lung SBRT treatment in less than 2 minutes with Versa HD (see Fig. 2.14).
Reconstructing the Exposure Geometry in X-ray Angiography and Interventional Radiology
Published in Johan Helmenkamp, Robert Bujila, Gavin Poludniowski, Diagnostic Radiology Physics with MATLAB®, 2020
Hence, in order to locate the target organ, the location of the (x-ray beam/system) isocenter relative to the end of the patient table is formulated as a function of (irradiation) time, where and are, respectively, the beam isocenter position and the table head-end position in the x-ray system coordinate system. Then, given that the majority of the x-ray exposures aim to visualize the target organ and adjacent anatomy, the position of the target organ can be approximated as the median position of the isocenter , as, where the set excludes time periods (i.e., exposure series) when the exposure is presumably not aimed at the visualization of the target region. This may for instance be the exclusion of time periods when the isocenter is located outside of the limitations imposed by a head fixation apparatus used for neurovascular procedures.
Image-Guided Radiation Therapy (IGRT) and Motion Management
Published in Eric Ford, Primer on Radiation Oncology Physics, 2020
IGRT starts with a volumetric image acquired during CT simulation (Figure 21.1.2). This reference image is used during the treatment planning to define beams and calculate dose. During this process a treatment isocenter is defined on the reference image, which is the point where one intends to line up the patient during treatment. The second image set for IGRT is the “localization” image, i.e. the CBCT image acquired on the treatment unit with the patient in the treatment position. This image also has an associated isocenter which is the actual isocenter of the treatment unit and is the center of the CBCT image.
3D high resolution clonogenic survival measurement of xrs-5 cells in low-dose region of carbon ion plans
Published in International Journal of Radiation Biology, 2023
Dea Kartini, Olga Sokol, Chutima Talabnin, Chinorat Kobdaj, Marco Durante, Michael Krämer, Martina Fuss
The treatment plan in this study was optimized for a uniform RBE-weighted dose for CHO cells, thus making the absorbed dose in the target vary. Figure 8(a) presents the measured absorbed dose depth profile in a water phantom. With respect to the irradiation plan, absorbed dose was here recalculated with the isocenter placed in the actual experiment position at the entrance window of the phantom. All data points represent the average between the two central pinpoint chambers of each row in the array at a given depth z. The agreement between them was 0.9% on average, and measurement results were within 3% of the TRiP98 prediction in the entrance channel and target. The lateral distribution of measured dose at different depths, close to those where biological samples were placed, is given in Figure 8(b). Across several lateral profiles analyzed from the center of the target to the depth of the bio-samples, dosimetry results were within 6% of the TRiP98 calculation. However, in the very distal part from 140 mm on (≥ 50 mm behind target with doses ≤ 0.2 Gy), larger dose discrepancies were found.
Microspheres Encapsulating Immunotherapy Agents Target the Tumor-Draining Lymph Node in Pancreatic Ductal Adenocarcinoma
Published in Immunological Investigations, 2020
Booyeon J. Han, Joseph D. Murphy, Shuyang Qin, Jian Ye, Taylor P. Uccello, Jesse Garrett-Larsen, Brian A. Belt, Peter A. Prieto, Nejat K. Egilmez, Edith M. Lord, David C. Linehan, Bradley N. Mills, Scott A. Gerber
All radiation was delivered using the Small Animal Radiation Research Platform (SARRP, XStrahl) using a 5-mm collimator. Mice were anesthetized with vaporized isoflurane for the duration of all radiation treatments. Stereotactic body radiation therapy (SBRT) was administered to tumor-bearing mice following a schedule of 4 fractions of 6 Gy radiation each on days 6–9 posttumor implantation, yielding a BED of 38.4 for tumor and 72 for normal tissue (assuming an α/β ratio of 10 for tumor and 3 for normal). Localized delivery was performed using visualization of previously mentioned titanium fiducial markers via computed tomography (CT) scans. The dosing isocenter was positioned using a beam angle designed to avoid major organs. In each case, a dose volume histogram (DVH) was generated to confirm full dose deposition to the tumor and negligible amounts to surrounding organs (e.g., liver and TDLN).
Robust treatment planning of dose painting for prostate cancer based on ADC-to-Gleason score mappings – what is the potential to increase the tumor control probability?
Published in Acta Oncologica, 2021
Eric Grönlund, Erik Almhagen, Silvia Johansson, Erik Traneus, Tufve Nyholm, Camilla Thellenberg, Anders Ahnesjö
For each patient we created a total of 12 DPBN volumetric-modulated arc therapy (VMAT) plans with 2 arcs completing a full rotation for a Versa HDTM linear accelerator and the dose grid set with 3.0 × 3.0 × 3.0 mm3 voxels. See Table 1 for a summary of the tested conditions for the 12 different plans. To test whether variations in lateral dose resolution due to different photon energies would affect the DPBN optimization we optimized six plans with 6 MV photons and six plans with 15 MV photons. Out of the six plans per photon energy, three were optimized with a low precision (LP) conditional probability map, i.e., the original conditional probability map from our earlier study [24], which was constructed from the Gleason-to-ADC correlations given by Turkbey et al. [17]. The other three plans were optimized with a high precision (HP) conditional probability map, which were constructed by compressing the interquartile range data from Turkbey et al. [17] to instead be contained in the range from 12.5 to 87.5%. Furthermore, we chose to optimize with robust minimax optimization for three levels of isocenter positioning errors for the set of plans optimized with the LP and the HP conditional probability map, respectively. The isocenter positioning errors were tested by three different settings: 0.6 cm corresponding to the conventional CTV-to-PTV margin used in the PARAPLY study; 0.2 cm to simulate a very high precision treatment that only take into account the uncertainty of intra-fractional movement of the prostate (based on the recommended margin from Kotte et al. [29]); and finally without any isocenter positioning errors for use as a reference.