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SGRT for Proton Therapy
Published in Jeremy D. P. Hoisak, Adam B. Paxton, Benjamin Waghorn, Todd Pawlicki, Surface Guided Radiation Therapy, 2020
However, there are fundamental differences between linac-based treatments and proton treatments. These include the dose distributions that are achievable. As protons begin traveling through tissue, they gradually lose energy and the absorbed dose is deposited nearly uniformly with depth. However, as protons near the end of their range, there is a sharp increase in energy loss. This results in a sharp increase in dose near the end of the protons’ range known as the Bragg peak. After the Bragg peak, the dose drops essentially to zero. In order to cover a treatment target, the Bragg peak is “spread out” by varying the energy of the incident proton beam. Because protons deposit their dose and stop within tissue, proton treatment beams have no exit dose, whereas a large portion of MV X-ray beams from a linac pass through the patient. These differences, which are illustrated in the Figure 23.1, give proton treatments the advantage of being able to deliver the same therapeutic dose to a target with much less integral dose to the patient. However, proton treatments are more sensitive to changes in the water equivalent thickness (WET) between the incident surface and the target. A clinical scenario where a WET change is possible is weight gain in the patient. This example of patient change is also illustrated in Figure 23.1 by the curves labeled “+1 cm.” These curves have an additional 1 cm of water added to the entrance of the respective beams. The X-ray curve shows a small offset in depth dose with the added water, but the proton curve is shifted by the 1 cm change in WET.
Generation of Bremsstrahlung Radiation from Different Low- to High-Z Targets for Medical Applications: A Simulation Approach
Published in Pandit B. Vidyasagar, Sagar S. Jagtap, Omprakash Yemul, Radiation in Medicine and Biology, 2017
Bhushankumar Jagnnath Patil, Vasant Nagesh Bhoraskar, Sanjay Daga Dhole
Proton beams are also a newer form of particle beam radiation used to treat cancer. They can offer better dose distribution due to its unique absorption profile in tissues, known as the Bragg peak, allowing the deposition of maximum destructive energy at the tumor site, while minimizing the damage to healthy tissues along their path. These have particular clinical use in pediatric tumors and in adults tumors located near critical structures such as spinal cord and skull base tumors, where maximal normal tissue sparing is crucial [15]. Particle radiation has higher LET than photons with higher biological effectiveness. Therefore, these forms of radiations may be more effective to the radio-resistant cancers such as sarcomas, renal cell carcinomas, melanomas, and glioblastoma [16]. However, the equipment for the production of particle radiation therapy is considerably more expensive than for photons. The decreasing costs of cyclotrons are likely to result in a wider use of proton beam therapy in the future [17].
Radiation Therapy and Radiation Safety in Medicine
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
In addition to proton beams, other heavy charged particles can be used to irradiate tumors. One promising development is the use of carbon-12 ions for radiation therapy (it is referred to as heavy-ion therapy). As in the case of protons, the energy transfer to tissues due to carbon-12 ions is characterized by a sharp Bragg peak allowing for more precise targeting of deep-seated tumors. Because their mass is about twelve times larger than the proton mass, carbon ions can deposit even more energy within a target volume. As a result, the RBE of carbon-12 ions is about two to three times larger than for protons. This can decrease the number of required treatment sessions and reduce damage to the healthy tissues.
Research on frequency modulation technology and its verifications of superconducting synchrocyclotron for cancer therapy
Published in Journal of Nuclear Science and Technology, 2022
Pengzhan Li, Tianjue Zhang, Bin Ji, Meng Yin, Ming Li, Juanjuan Guo, Xianlu Jia, Jun Lin, Guofang Song, Shigang Hou, Gaofeng Pan, Zhiguo Yin
In the field of medical radiation, proton therapy [1] has developed greatly due to its Bragg peak effect. Proton therapy is considered as one of the most advanced methods for cancer treatment, and most of the proton therapy is based on cyclotron. Compared with conventional cyclotron, synchrocyclotron is featured with a simple structure, low precision requirement, and low cost [2]. Furthermore, the superconducting technology makes the machine smaller and easier to install in hospital. MSU proposed the first superconducting synchrocyclotron for proton therapy in the 1980s. Some commercial manufacturers provide their superconducting synchrocyclotron solutions later (Table 1).
Everything you wanted to know about space radiation but were afraid to ask
Published in Journal of Environmental Science and Health, Part C, 2021
Jeffery Chancellor, Craig Nowadly, Jacqueline Williams, Serena Aunon-Chancellor, Megan Chesal, Jayme Looper, Wayne Newhauser
The biological effect of the radiation dose depends on physical and biological factors, e.g., multiple particle and energy-specific factors, dose rate per exposure and the frequency of multiple exposures. The (physical) absorbed dose is the energy absorbed per mass (J/Kg, Gy). For a dose-based system of radiation protection and for the determination of occupational dose limits, it is necessary to attempt summing the total risk of radiation from multiple sources (e.g., SPE protons, GCR, etc.).33 At a given ion velocity, LET increases with atomic number. Thus, for ground-based research, it is key to have the correct abundances and energy distributions of each ion present in the space radiation environment. As charged particles lose energy successively through material interactions, each energy loss event can result in damage to the biological tissue. In addition, as charged particles near the end of their track (i.e., as they slow down and are nearly stopped) the LET rises sharply, creating the so-called “Bragg peak”.34 This is demonstrated in Figure 3. The phenomenon of the Bragg peak is exploited in cancer therapy in order to concentrate the dose at the target tumor while minimizing impact to the surrounding tissue. This is demonstrated in Figure 3 where the relative dose deposition in tissue for various radiation types utilized in space radiobiology studies is plotted versus depth in tissue. The gray shaded area is the average width of a mouse model. Also shown are the average diameters of Yucatan mini-pigs and humans. Gamma and X-ray radiations deposit most of the energy at or near the surface, while in contrast, charged particles such as protons, carbon, iron, etc., have distinct Bragg peaks. In each example, the Bragg peak is located outside the body mass of the mouse, indicating the difficulty in replicating the relative organ dose distribution of a GCR exposure incurred by humans during spaceflight.
Physical study of proton therapy at CANAM laboratory on medulloblastoma cell lines DAOY
Published in Radiation Effects and Defects in Solids, 2020
L. Torrisi, M. Davidkova, V. Havranek, M. Cutroneo, A. Torrisi
The proton therapy remains the most advantageous permitting to deposit high energy at the Bragg peak controllable from the incident proton energy and permitting to sweep it inside the tumor minimizing the dose released to the near healthy tissue (10). The electron and nuclear stopping powers at the Bragg peak will be increased by the presence of the high atomic number Au-NPs in the targeted tissue.