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Patenting Issues in the Development of Nanodrugs
Published in Chetan Keswani, Intellectual Property Issues in Nanotechnology, 2020
Theivasanthi Thirugnanasambandan
The utilization of charged particle beams for cancer radiation therapy is known as particle therapy. It is a recent cancer therapy that has more advantages than conventional radiotherapy. It reduces the radiation dose and supports ion radiation effects at the target only (without damaging the healthy tissues before reaching the tumor). Figure 13.7 explains the particle therapy and nanomedicines that are applied to brain tumors as well as their effects [43]. The ion beams can be tuned by modulating the energy. Hence, during this radiation therapy, with the support of NPs, the radiation effect can be delivered at the target only. It also avoids the undesirable effects on the healthy tissues that are present near and around the tumor.
An Invitation: Acceleration!
Published in Rob Appleby, Graeme Burt, James Clarke, Hywel Owen, The Science and Technology of Particle Accelerators, 2020
Rob Appleby, Graeme Burt, James Clarke, Hywel Owen
The primary particles produced by accelerators are often used directly: for example, the LHC collides very high-energy protons upon each other after accelerating them, whilst a low-energy (several MeV) electron linac can be used to irradiate and sterilise food products and medical equipment. Very often we encounter targets onto which these particles are directed. Some of these targets are used to generate secondary radiation; an important example is to produce neutrons, where heavy-metal spallation targets taking very intense proton beam powers ∼1 MW are commonly used. Those neutrons are enormously important for studies of chemistry, physics and engineering studies of novel materials. Particle physics experiments increasingly also call for high-intensity beams to generate such things as muons and neutrinos, the former for future muon colliders and the latter to see signatures of physics beyond the standard model. At lower particle energies around 10 MeV, electron linacs are used to generate bremsstrahlung photons for use in radiotherapy or for scanning cargo; in fact, this is the most likely situation someone will encounter a particle accelerator and there are around 30,000 such accelerators around the world – the majority, in fact. Another medical application is the use of proton cyclotrons to generate radioisotopes; fluorine-18 is the most commonly-produced isotope, made by directing ~10 MeV protons onto an enriched water target. Higher-energy protons and other species such as carbon-12 ions are directed into patients to perform particle therapy, another form of radiotherapy. We will not describe these applications in detail, but will discuss the basics for the operation of the types of accelerator they employ.
Why Particle Therapy Rather than Photon Therapy or How to Integrate the Decision into Multimodal Management
Published in Manjit Dosanjh, Jacques Bernier, Advances in Particle Therapy, 2018
Joachim Widder, Richard Pötter
This certainly applies for any particle therapy as it has been utilised for decennia using technology that is arguably not optimal (especially, passive scattering; no on-board soft-tissue imaging; no beam flexibility using gantries). Therefore, ‘proton therapy’ or ‘carbon ion therapy’ are insufficiently described entities; more technical details need to be known before either therapy can be compared with photon therapy: for example, image guidance, intensity modulation and beam flexibility (Widder et al., 2015). This has important consequences for the methodology to gain or increase evidence using any health technology (McCulloch et al., 2009). First and typically, technology is developed while being used, and thus it comes in versions. Improvements may happen as small gradual changes, very rarely as quantum leaps. Second, when increasing precision or accuracy (or both) is the aim of using health technology, in general terms this means that collateral damage caused by therapeutic interventions will be reduced proportionally with attaining this aim. Minimally invasive and organ-sparing surgery, both crucial developments in contemporary surgery, are typical examples. Particle therapy fits nicely into this line, its main purpose being reduction of radiation toxicity by reducing dose to tissues surrounding malignant tumours. Employing particle therapy, in particular proton therapy, thus encounters comparable issues as surgery when having to demonstrate its added value in terms of superiority regarding toxic effects of radiation, or its non-inferiority or equivalence regarding tumour outcome. However, in sharp contrast to surgery, side effects of radiotherapy critically depend on dose and dose distributions – dose–volume parameters – delivered to critical tissues and organs. These parameters are quantifiable and in turn lend themselves to modelling. Toxic outcomes after radiotherapy are a function of dose–volume parameters that are modulated more or less by clinical, genetic, molecular or other patient- and tumour-related factors. Any dose-planning of curative radiotherapy has to navigate between delivering sufficient dose at the tumour and dose-limits, dose-constraints and dose-objectives at unaffected organs and tissues surrounding the tumour in order to limit toxicity as much as possible.
Progresses towards laser-driven hadron cancer radiotherapy
Published in Radiation Effects and Defects in Solids, 2018
It has mentioned that particle therapy is potentially a more effective therapeutic procedure than photon therapy. However, the cost of a laboratory using high-intensity laser for proton acceleration and therapy application is very high. It has been estimated that the capital costs for (a) combined proton/carbon facility; (b) proton only facility; and (c) photon facility to be: (a) 139 million €; (b) 95 million €; and (c) 23 million €, respectively.
Utilize empirical models of measured relative dose output factor (rDOF) and transverse penumbra (TP) to evaluate dosimetric uncertainties of in-air spot modelling for spot-scanning carbon-ion and proton radiotherapy
Published in Journal of Nuclear Science and Technology, 2023
Yongqiang Li, Wenchien Hsi, Wenbo Xie
We utilized the Siemens Syngo PT (particle therapy) TPS to construct our treatment plans for both carbon-ion and proton beams. The Syngo TPS was based on the research TRiP98 code, developed in a clinic pilot project. The Syngo TPS used a pencil-beam dose algorithm with the convolution of lateral scattering to calculate the three-dimensional (3D) physical doses of each field in a plan. We constructed each plan with multiple fields through a biological optimization to achieve the clinical goals in term of biological doses required for target and each organ-at-risk. The biological optimization of the Syngo TPS used the first version of the local effect model (LEM I) for carbon-ions to achieve the biological doses of each field, while a constant 1.1 biological factor is used for protons. Details of biological model can be found in publications [2]. To convert the physical dose of each spot for its corresponded MU of delivery, we obtained the D/MU scaling factor as a function of beam energy during the commissioning of our Syngo TPS. The D/MU factor determines the total MU for a 10 cm x 10 cm square uniform scanning field [3] in a single energy layer to have 1.0 Gy of physics dose at a 2.7 mm depth. The depth of 2.7 mm water-equivalent-thickness includes the material of the front-end of plastic phantom and the thickness of farmer chamber. The 10 cm uniform field in Syngo TPS used a symmetric Gaussian-like distribution of in-air spot [4] to model the incident particle flux of each spot at 2.7 mm depth with a treatment iso-center at 2.7 mm depth. The modelled particle flux did not consider the effect of scattering through any materials. The variation of in-air spot-size at different locations to the isocenter for each energy was obtained according to the fit of in-air spot-size measurements at locations of ±20 cm, ±10 cm, and 0 cm to the isocenter. Measurements were performed over 33 and 35 energies for carbon-ion and proton, respectively. We used a multi-wire parallel chamber (MWPC) with a 2-mm spatial resolution for the in-air spot-size measurements. The MWPC could provide reasonable resolution to extract the Gaussian width over a series of energy. Obtained Gaussian width was stored as the table of list of ion beam characteristics (LIBC) in Syngo TPS.