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External Beam Therapy Equipment
Published in Kwan Hoong Ng, Ngie Min Ung, Robin Hill, Problems and Solutions in Medical Physics, 2023
Kwan Hoong Ng, Ngie Min Ung, Robin Hill
Solution:Advantages: Linear accelerator can provide either megavoltage electron or X-ray therapy with a wide range of energies, allowing radiation oncologists to tailor treatment to the required depth.Most modern linear accelerator features such as high dose rate modes, MLC, electron arcs therapy, dynamic wedges and dynamic MLC operation during treatment.No radioactive source contamination.Higher dose rate (1–10 Gy min−1) allowing shorter treatment time.Have a sharp dose fall-off at the beam edge than Co-60 beam.The trimmer consists of heavy metal bars used to attenuate the beam in the penumbra region, thus ‘sharpening’ the field edges.
Radiotherapy Physics
Published in Debbie Peet, Emma Chung, Practical Medical Physics, 2021
Andrea Wynn-Jones, Caroline Reddy, John Gittins, Philip Baker, Anna Mason, Greg Jolliffe
A linear accelerator comprises a source of electrons, which are accelerated to the required energy using high powered microwaves. To produce a photon beam, the accelerated electrons are made to collide with a heavy metal target, typically tungsten. The resulting photon beam is shaped and directed towards the tumour in the patient. Figure 6.3 shows a schematic of a typical medical linear accelerator. The accelerator is designed so that the couch, collimator and gantry can all rotate around a single point in space, termed the isocentre. This allows the beam to be directed towards the patient from any angle. The distance from the photon source to the surface of the patient is called the Focus to Surface Distance (FSD). A light field is used to show the position of the beam on the surface and a projection of a crosswire is used to indicate the position of the beam central axis.
Linac-Based SRS/SBRT Dosimetry
Published in Arash Darafsheh, Radiation Therapy Dosimetry: A Practical Handbook, 2021
Karen Chin Snyder, Ning Wen, Manju Liu
Linear accelerators (linacs) have been used in radiation oncology as medical treatment devices since 1953, when the first patient was treated at the Hammersmith Hospital in London with a stationary linac and a treatment head that could swivel. The original system was simple, allowing for delivery of treatment of open fields, or field blocked to shield normal tissues with devices that were manufactured out of Cerrobend. Linac-based stereotactic surgery occurred in 1980s after Leksell Gamma Knife had been used for several decades. Its implementation was hindered by the mechanical uncertainty and stability of the multiple moving components.
Technological advancements and future perspectives in breast cancer radiation therapy
Published in Expert Review of Anticancer Therapy, 2023
Alessandra Fozza, Fiorenza De Rose, Maria Carmen De Santis, Icro Meattini, Bruno Meduri, Elisa D’angelo, Damiano Dei, Vanessa Figlia, Eliana La Rocca, Piero Fregatti, Camilla Satragno, Liliana Belgioia, Niccolò Giaj-Levra
Additionally, image-guided radiation therapy (IGRT) seems to be crucial for appropriate target definition, especially in the preoperative BC approach, and it represents an excellent tool in the set-up treatment control. The recent introduction in clinical practice of hybrid linear accelerator with an integrated magnetic resonance can also support radiation oncologists in the target volume delineation and adaptive treatment planning phases. Magnetic resonance imaging can be also used as a new oncological frontier applicable in radiomics. Finally, artificial intelligence and radiomic are progressively entering the modern medicine, with the aim to help the automatic target volume definition, patient selection, treatment planning and to improve tumor phenotype classification and genomic profile achieving a prognostic power. The aim of this review is to describe these technological opportunities, exploring the current literature, and the future prospective.
A model of radiation-induced temporomandibular joint damage in mice
Published in International Journal of Radiation Biology, 2022
Peng Zhang, Lejing Yao, Guoping Shan, Yuanyuan Chen
The task of the SARRP coordinate positioning robot is to perform target movement on the axis from the planning system. Due to restrictions of relative spatial position of the gantry and image detection board, the robot coordinate movement range is only 38 mm in the Z-axis (Matinfar et al. 2007). Moreover, the maximum field size is 145 × 145 mm at the source-heelbase of 350 mm. Therefore, it is not possible to use large animals (body length over 10 cm) with the SARRP. This is one of the reasons why we employed C3H and C57BL/6 mice as the object of these experiments. Similarly, Sønstevold et al. (2015) used an adult male Sprague Dawley mouse, with an average body length of 18 centimeter, in mandibular radiation damage experiments. Obviously, the Sprague Dawley mouse is not compatible with SARRP. However, clinical linear accelerator treatment machines were used to perform dose delivery in their experiments. No evidence for dose delivery with this device has been reported in their literature, and the effects of changes in other organs and internal microenvironments after radiotherapy remain unknown.
The role of small GTPase Rac1 in ionizing radiation-induced testicular damage
Published in International Journal of Radiation Biology, 2022
Yasar Aysun Manisaligil, Mukaddes Gumustekin, Serap Cilaker Micili, Cemre Ural, Zahide Cavdar, Gizem Sisman, Aysegul Yurt
Rats were exposed to low, medium and high doses of radiation corresponding to 0.02 Gy, 0.1 Gy and 5 Gy respectively. A digital Roentgen device (Philips Tele Diagnost, Amsterdam, Netherlands) operating in Department of Radiology, Dokuz Eylul University, was used for low dose exposures. A linear accelerator (Siemens Primus, Erlangen, Germany) available in Dokuz Eylul University Radiation Oncology Department was used for medium and high dose exposures. Following a series of measurements taken with an ionization chamber (RTI, Model R100, Mölndal, Sweden), low dose set up was achieved with a tube potential of 133 kV, tube current of 300 mA and exposure time of 0.5 s to give 0.02 Gy. Medium and high dose exposures were achieved by using 6 MV photon beams with a dose rate of 300 Monitor Units (MU)/min. Irradiation setups with 10 MU and 500 MU were used to provide 0.1 Gy and 5 Gy radiation doses, respectively. Each rat was kept in a 13x18x10 cm plastic container through which X-rays can penetrate easily. The irradiation field was set to 13 × 18 cm2 at a skin to source distance (SSD) of 83 cm for all exposures (Said et al. 2019; Zhang et al. 2020).