China
Africa
Explore chapters and articles related to this topic
Medical and Biological Applications of Low Energy Accelerators
Published in Vlado Valković, Low Energy Particle Accelerator-Based Technologies and Their Applications, 2022
Particle therapy is the expanding radiotherapy treatment option of choice for cancer. Its cost, however, is currently hindering its worldwide expansion. In addition, the ideal application of particle therapy is restricted by a series of unsolved technical challenges. Both the cost and technical limitations are directly traceable to dependence on the legacy of accelerators and their associated treatment possibilities. This chapter is written to address these needs. First, a technical overview is presented of photon and particle therapy for cancer tumors. Second, the underlying limitations of the existing legacy systems are identified, especially those related to accelerators, and suggestions are made for current and future developments to address these shortcomings. The legacy systems referred to here are of the slow scanning variety using large circular accelerators.
Linear energy transfer and relative biological effectiveness
Published in Michael C. Joiner, Albert J. van der Kogel, Basic Clinical Radiobiology, 2018
Michael C. Joiner, Jay W. Burmeister, Wolfgang Dörr
X-rays and γ-rays are uncharged electromagnetic radiations, physically similar in nature to radio waves or visible light except that their wavelength is less than 10 picometers (10−12 m) so that the individual photons (‘packets’ of energy) are energetic enough to ionize molecules in tissues that they penetrate. This ionization results in the biological effects seen in radiotherapy. These X- and γ-rays all have roughly the same biological effect per unit dose, although there is a small dependence on the energy with lower energies being slightly more effective. The biological damage produced by high-energy photon beams is the result of ionizations by energetic electrons set in motion by photon interactions. Accordingly, the biological effects from beams of energetic electrons are similar to that from high-energy photon beams. While one could therefore refer to conventional radiotherapy as ‘particle therapy’, this terminology generally refers to another class of radiotherapy which is being increasingly adopted. The term particle therapy typically refers to radiotherapy using protons, neutrons, α-particles, fully stripped carbon ions or even heavier ions.
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.
A systematic review of the role of carbon ion radiation therapy in recurrent rectal cancer
Published in Acta Oncologica, 2020
Bhanu Prasad Venkatesulu, Prashanth Giridhar, Timothy D. Malouf, Daniel M. Trifletti, Sunil Krishnan
In the subset of the patients who develop a recurrence, the outcomes are very poor with a 3-year survival rate of <30%. This is largely due to the complex anatomical location of these recurrences in relatively inaccessible and heavily pretreated tissues. Dense radiation-induced fibrosis and altered lymphovascular planes that complicate surgery following primary radiation therapy, and fibrosis and associated hypoxia also confer relative radioresistance to these recurrent tumors [6]. Multiple institutional studies have shown that a combination of re-irradiation with photon-based radiotherapy followed by surgery offers the best oncological outcomes with 3-year overall survival (OS) rates of 50% [7]. Multiple reports have shown that re-irradiation of LRRC tends to enhance R0 resection and palliation of symptoms. Strategies to perform re-irradiation have included different techniques such as 3-dimensional conformal radiation therapy (3 D-CRT), intensity-modulated radiation therapy (IMRT), stereotactic body radiation therapy (SBRT) and/or intra-operative radiation therapy (IORT). Additionally, different fractionation schedules, such as once-daily and twice-daily, in conjunction with other modalities, such as chemotherapy and hyperthermia, have been investigated. Currently, there is interest in investigating particle therapy, including proton and carbon ion radiotherapy, as novel radiation modalities [8].
A Nordic-Baltic perspective on indications for proton therapy with strategies for identification of proper patients
Published in Acta Oncologica, 2020
Petter Brandal, Kjell Bergfeldt, Ninna Aggerholm-Pedersen, Gloria Bäckström, Irina Kerna, Michael Gubanski, Kirsten Björnlinger, Morten E. Evensen, Maire Kuddu, Erik Pettersson, Marianne Brydøy, Taran P. Hellebust, Einar Dale, Alexander Valdman, Lars Weber, Morten Høyer
Amongst different heavier particle therapy modalities, proton therapy (PT) is hitherto the most clinically used [1]. The beneficial effects of protons are primarily based on reduction of low to intermediate radiation dose bath to normal tissue surrounding the radiotherapy target volume [2]. The advantageous dose distribution is supplemented by altered biological mechanisms of action leading to a higher radiobiological effect and increased tumour cell kill, clinically accounted for as 10% in protons and indeed much higher for heavier ions such as carbons [3,4]. Although some uncertainty remains, the relative biological effectiveness (RBE) of protons relative to photons or 60C is estimated to 1.1. With the superior dose deposition compared to photon-based radiotherapy, protons offer two major advantages; reduced dose to organs at risk adjacent to the target and potentially dose escalation in treatment of radio-resistant tumours. There is therefore a worldwide belief that PT can improve outcomes for a proportion of cancer patients for whom radiotherapy is indicated, and so far more than 200.000 patients have been treated with this modality [1].
Bringing Europe together in building clinical evidence for proton therapy – the EPTN–ESTRO–EORTC endeavor
Published in Acta Oncologica, 2019
Damien C. Weber, Cai Grau, Pei S. Lim, Dietmar Georg, Yolande Lievens
Approximately one out of two cancer patients should receive radiotherapy at least once in the course of their disease in Europe [1] and elsewhere [2]. Particle therapy is an expensive anti-cancer treatment, with a cost factor of approximately 2.5, for protons when compared to modern RT techniques [3]. The costs associated with particle therapy is consequential to the considerable investment costs but also due to the high operation and maintenance costs of operating a proton therapy (PT) facility. Ongoing technical developments or alternative fractionation schemes (i.e., hypo-fractionation) [4,5] may lead to cost reduction but it is not expected that a dramatic decrease in costs will be reached in the near future [6]. As a result, there is an ongoing debate on the ‘value’ of PT and its cost-effectiveness [7,8].