scholarly journals Proton Minibeam Radiation Therapy and Arc Therapy: Proof of Concept of a Winning Alliance

Cancers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 116
Author(s):  
Ramon Ortiz ◽  
Ludovic De Marzi ◽  
Yolanda Prezado
Keyword(s):  
Radiation Therapy ◽  
Normal Tissue Complication Probability ◽  
Therapeutic Window ◽  
High Dose ◽  
Proof Of Concept ◽  
Normal Tissues ◽  
Arc Therapy ◽  
High Let ◽  
The Individual ◽  
First Time

(1) Background: Proton Arc Therapy and Proton Minibeam Radiation Therapy are two novel therapeutic approaches with the potential to lower the normal tissue complication probability, widening the therapeutic window for radioresistant tumors. While the benefits of both modalities have been individually evaluated, their combination and its potential advantages are being assessed in this proof-of-concept study for the first time. (2) Methods: Monte Carlo simulations were employed to evaluate the dose and LET distributions in brain tumor irradiations. (3) Results: a net reduction in the dose to normal tissues (up to 90%), and the preservation of the spatial fractionation of the dose were achieved for all configurations evaluated. Additionally, Proton Minibeam Arc Therapy (pMBAT) reduces the volumes exposed to high-dose and high-LET values at expense of increased low-dose and intermediate-LET values. (4) Conclusions: pMBAT enhances the individual benefits of proton minibeams while keeping those of conventional proton arc therapy. These results might facilitate the path towards patients’ treatments since lower peak doses in normal tissues would be needed than in the case of a single array of proton minibeams.

Linear energy transfer dependence of transient yields in water irradiated by 150 keV – 500 MeV protons in the limit of low dose rates

2020 ◽  
Vol 98 (8) ◽  
pp. 427-433
Author(s):  
Ahmed Alanazi ◽  
Jintana Meesungnoen ◽  
Jean-Paul Jay-Gerin
Keyword(s):  
Energy Transfer ◽  
Linear Energy Transfer ◽  
Low Dose ◽  
High Dose ◽  
Dose Rates ◽  
Normal Tissues ◽  
High Let ◽  
Proton Track ◽  
Electron And Photon ◽  
Anti Tumor Activity

FLASH radiotherapy is a new irradiation method in which large doses of ionizing radiation are delivered to tumors almost instantly (a few milliseconds), paradoxically sparing healthy tissue while preserving anti-tumor activity. Although this technique is primarily studied in the context of electron and photon therapies, proton delivery at high dose rates can also reduce the adverse side effects on normal cells. So far, no definitive mechanism has been proposed to explain the differences in the responses to radiation between tumor and normal tissues. Given that living cells and tissues consist mainly of water, we set out to study the effects of high dose rates on the radiolysis of water by protons in the energy range of 150 keV – 500 MeV (i.e., for linear energy transfer (LET) values between ∼72.2 and 0.23 keV/μm, respectively) using Monte Carlo simulations. To validate our methodology, however, we, first, report here the results of our calculations of the yields (G values) of the radiolytically produced species, namely the hydrated electron ([Formula: see text]), •OH, H•, H2, and H2O2, for low dose rates. Overall, our simulations agree very well with the experiment. In the presence of oxygen, [Formula: see text] and H• atoms are rapidly converted into superoxide anion or hydroperoxyl radicals, with a well-defined maximum of [Formula: see text] at ∼1 μs. This maximum decreases substantially when going from low-LET 500 MeV to high-LET 150 keV irradiating protons. Differences in the geometry of the proton track structure with increasing LET readily explain this diminution in [Formula: see text] radicals.

scholarly journals Emergence of Stereotactic Body Radiation Therapy and Its Impact on Current and Future Clinical Practice

2014 ◽  
Vol 32 (26) ◽  
pp. 2847-2854 ◽  
Author(s):  
Robert D. Timmerman ◽  
Joseph Herman ◽  
L. Chinsoo Cho
Keyword(s):  
Radiation Therapy ◽  
Stereotactic Body Radiation Therapy ◽  
Metastatic Cancer ◽  
Local Therapy ◽  
High Dose ◽  
Fractionated Radiotherapy ◽  
Stereotactic Body Radiation ◽  
Normal Tissues ◽  
Future Clinical Practice ◽  
Great Hope

Stereotactic body radiation therapy (SBRT) is generally a tumor-ablative radiation modality using essential technologies capable of accurately and precisely damaging the target with a high dose while geometrically sparing innocent normal tissues. The intent, conduct, and tissue biology are all dramatically distinct from conventionally fractionated radiotherapy such that new understanding is required for its optimization. It is most practical, tolerable, and tumoricidal in its most potent form treating tumors in the lung and liver. However, it is increasingly being used for tumors adjacent to bowels and nervous tissue, albeit with somewhat less ablative potency. Its strengths include high rates of tumor eradication via a noninvasive, convenient outpatient treatment. Its weakness relates to the possibility of causing difficult-to-manage toxicity (eg, ulceration, stenosis, fibrosis, and even necrosis) that may occur considerably later after treatment, particularly in the vicinity of the body's many tubular structures (eg, organ hila, bowel). However, clinical trials in a variety of organs and sites have shown SBRT to result in good outcomes in properly selected patients. Given its short course, lack of need for recovery, and favorable overall toxicity profile, there is great hope that SBRT will find a prominent place in the treatment of metastatic cancer as a consolidative partner with systemic therapy. With considerable published experience, available required technologies and training, and many patients in need of local therapy, SBRT has found a place in the routine cancer-fighting arsenal.

scholarly journals Using the Biology of Chronic Lymphocytic Leukemia to Choose Treatment

Hematology ◽  
2011 ◽  
Vol 2011 (1) ◽  
pp. 104-109 ◽  
Author(s):  
Peter Hillmen
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Intracellular Signaling ◽  
Residual Disease ◽  
Lymphocytic Leukemia ◽  
High Dose ◽  
Signaling Mechanisms ◽  
The Individual ◽  
First Time ◽  
Targeted Approach

AbstractIn recent years, our understanding of the pathophysiology of chronic lymphocytic leukemia (CLL) has advanced significantly. It is now clear that CLL is a relatively proliferative disorder that requires the help of its microenvironment to be maintained and to progress. The stimulation of the CLL cell occurs in most, if not all, patients through antigen stimulation via the BCR. In addition, there is now a clearer appreciation of the role of the p53 pathway leading to chemoresistance. These insights are allowing a more targeted approach with the use of p53-independent drugs such as mAbs and high-dose steroids to overcome genetically poor-risk CLL. The elucidation of the molecular and intracellular signaling mechanisms of disease is just beginning to facilitate the development of several targeted small molecules that promise to revolutionize the treatment of CLL. The measurement of the level of minimal residual disease (MRD) in CLL is becoming more available, facilitating approaches in which the aim of therapy is the eradication of detectable MRD. This also promises to improve personalization of therapy to the individual. Recently, the addition of rituximab to fludarabine plus cyclophosphamide (FCR) has improved overall survival in CLL for the first time, and it appears that this will only be the first small step on the path to much more effective therapies and, hopefully, less toxic targeted therapies.

Dosimetric comparison of helical tomotherapy, volume-modulated arc therapy, and fixed-field intensity-modulated radiation therapy in nasopharyngeal and cervical cancers

2020 ◽  
Author(s):  
Deyang Yu ◽  
Shan Lu ◽  
Lei Wang ◽  
Xueyuan Hu ◽  
Xin Li ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Field Intensity ◽  
Helical Tomotherapy ◽  
Intensity Modulated Radiation Therapy ◽  
Conformity Index ◽  
High Dose ◽  
Fixed Field ◽  
Intensity Modulated ◽  
Radiation Delivery ◽  
Arc Therapy

Abstract Background: To compare the dosimetric parameters of different radiotherapy plans, helical tomotherapy(HT), volume-modulated arc therapy (VMAT), and fixed-field intensity-modulated radiation therapy (FF-IMRT) for nasopharyngeal carcinoma (NPC) and cervical cancer (CC).Methods: A total of 15 patients with NPC and 15 patients with CC were chosen for retrospective analysis and replanned for HT, VMAT, and FF-IMRT. The prescribed doses of the planning target were 2.12/69.96 Gy, 1.8/59.4 Gy for NPC and 1.8/45 Gy for CC, respectively. The dosimetric parameters of the planning target, organs at risk (OARs), and the efficiency of radiation delivery were assessed and compared using the paired-samples t-test.Results: Compared with VMAT and FF-IMRT, HT plans significantly improved the mean conformity index (CI) and homogeneity index (HI). For the OARs, the HT plans reduced the maximum doses of most organs, such as brainstem, spinal cord, and optic nerves in NPC, and significantly reduced the volume of the high-dose region in NPC and the V30 and V40 of small bowel, rectum, and bladder in CC. However, VMAT evidently reduced the treatment time and improved the efficiency of radiation delivery than HT.Conclusions: For NPC and CC, results showed that HT and VMAT possessed better homogeneity and conformity of the target and better sparing of OARs compared with the conventional FF-IMRT, and HT achieved the best effect. VMAT had the shortest radiation delivery time. The results of this study can provide guidance for the selection of appropriate radiation technologies for patients with NPC and CC who are undergoing concurrent chemoradiotherapy.

scholarly journals Requirements for Designing an Effective Metallic Nanoparticle (NP)-Boosted Radiation Therapy (RT)

Cancers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 3185
Author(s):  
Ioanna Tremi ◽  
Ellas Spyratou ◽  
Maria Souli ◽  
Efstathios P. Efstathopoulos ◽  
Mersini Makropoulou ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Metallic Nanoparticles ◽  
Biological Effects ◽  
Ion Beam ◽  
High Energy ◽  
Normal Tissue Complication Probability ◽  
X Rays ◽  
Beam Radiation ◽  
Particle Radiotherapy ◽  
High Let

Many different tumor-targeted strategies are under development worldwide to limit the side effects and improve the effectiveness of cancer therapies. One promising method is to enhance the radiosensitization of the cancer cells while reducing or maintaining the normal tissue complication probability during radiation therapy using metallic nanoparticles (NPs). Radiotherapy with MV photons is more commonly available and applied in cancer clinics than high LET particle radiotherapy, so the addition of high-Z NPs has the potential to further increase the efficacy of photon radiotherapy in terms of NP radiosensitization. Generally, when using X-rays, mainly the inner electron shells are ionized, which creates cascades of both low and high energy Auger electrons. When using high LET particles, mainly the outer shells are ionized, which give electrons with lower energies than when using X-rays. The amount of the produced low energy electrons is higher when exposing NPs to heavy charged particles than when exposing them to X-rays. Since ions traverse the material along tracks, and therefore give rise to a much more inhomogeneous dose distributions than X-rays, there might be a need to introduce a higher number of NPs when using ions compared to when using X-rays to create enough primary and secondary electrons to get the desired dose escalations. This raises the questions of toxicity. This paper provides a review of the fundamental processes controlling the outcome of metallic NP-boosted photon beam and ion beam radiation therapy and presents some experimental procedures to study the biological effects of NPs’ radiosensitization. The overview shows the need for more systematic studies of the behavior of NPs when exposed to different kinds of ionizing radiation before applying metallic-based NPs in clinical practice to improve the effect of IR therapy.

scholarly journals Remote Radiotherapy in the Treatment of Patients with Perivascular Epithelial Cell Tumors

2020 ◽  
Vol 3 (1) ◽  
pp. 11-20
Author(s):  
A. V. Nazarenko ◽  
E. R. Musaev ◽  
S. V. Medvedev ◽  
S. I. Tkachev ◽  
S. B. Aliyeva ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
External Beam Radiation Therapy ◽  
External Beam Radiation ◽  
Definitive Treatment ◽  
Surgical Removal ◽  
High Dose ◽  
Mesenchymal Tumors ◽  
Beam Radiation ◽  
Main Method ◽  
The Individual

The main method of treating rare mesenchymal tumors PEComas is surgical removal of the tumor and external-beam radiation therapy has historically been considered ineffective. However, the individual cases in the foreign literature as well as this article authors’ experience in the form of the clinical case provided in it shows the possibility of achieving some anti-tumor effect due to the use of aggressive variants of radiation therapy. The use of variations of stereotactic radiotherapy with high dose per fraction and sum dose as an neoadjuvant and definitive treatment looks promising.

scholarly journals Dosimetric comparison between helical tomotherapy, volume modulated arc-therapy and Fixed-Field intensity modulated radiation therapy in postoperative adjuvant radiotherapy for cervical cancer

2020 ◽  
Author(s):  
Deyang Yu ◽  
Lei Wang ◽  
Xueyuan Hu ◽  
Xin Li ◽  
Yanling Bai ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Radiation Therapy ◽  
Helical Tomotherapy ◽  
Treatment Time ◽  
Intensity Modulated Radiation Therapy ◽  
High Dose ◽  
Intensity Modulated ◽  
Radiation Delivery ◽  
Arc Therapy ◽  
Dose Volumes

Abstract Background: To evaluate the dosimetric parameters among three different radiotherapy techniques in patients with postoperative cervical cancer, including the Helical Tomotherapy (HT), the Volume Modulated Arc-Therapy (VMAT), and the Fixed-Field intensity modulated radiation therapy (FF-IMRT). Methods: Fifteen cervical cancer patients treated with postoperative radiotherapy were re-planning with HT, VMAT and FF-IMRT. The prescribed target dose of the patients was 1.8/45Gy. The paired-samples t-test was used to compare the dosimetric parameters of the planning target and OARs (Organs at risk), and the efficiency of radiation delivery. Results: Compared with the VMAT and FF-IMRT, the HT plans showed significant improvement in the conformity index (CI) and the homogeneity index (HI). In addition, the HT plans also significantly reduced the volume of high-dose region of the OARS, especially in the V30, V40 of small bowel, rectum and bladder. Meantime, the advantage of VMAT is that it reduced the treatment time and improved the efficiency of radiation delivery obviously, compared with the HT (293.8 ± 12.8s Vs. 557.6 ± 51.9s, P < 0.001) and FF-IMRT (293.8 ± 12.8s Vs. 581.8 ± 26.1s, P < 0.001). Conclusion: Our result reveals that HT showed better CI and HI for the target and reduced high dose volumes to OARs compared with VMAT and FF-IMRT, but the lower dose volumes to OARs increased slightly. As for the benefit of VMAT, it demonstrated the shortest treatment time. Our results could provide guidance for selecting the appropriate radiation technologies for cervical cancer patients who undergoing postoperative adjuvant pelvic radiotherapy.

Victorian Pain

2017 ◽  
Author(s):  
Rachel Ablow
Keyword(s):  
Nineteenth Century ◽  
Victorian Literature ◽  
Social Life ◽  
Charles Darwin ◽  
Harriet Martineau ◽  
The Status ◽  
History Of ◽  
The Individual ◽  
Natural Philosophers ◽  
First Time

The nineteenth century introduced developments in science and medicine that made the eradication of pain conceivable for the first time. This new understanding of pain brought with it a complex set of moral and philosophical dilemmas. If pain serves no obvious purpose, how do we reconcile its existence with a well-ordered universe? Examining how writers of the day engaged with such questions, this book offers a compelling new literary and philosophical history of modern pain. The book provides close readings of novelists Charlotte Brontë and Thomas Hardy and political and natural philosophers John Stuart Mill, Harriet Martineau, and Charles Darwin, as well as a variety of medical, scientific, and popular writers of the Victorian age. The book explores how discussions of pain served as investigations into the status of persons and the nature and parameters of social life. No longer conceivable as divine trial or punishment, pain in the nineteenth century came to seem instead like a historical accident suggesting little or nothing about the individual who suffers. A landmark study of Victorian literature and the history of pain, the book shows how these writers came to see pain as a social as well as a personal problem. Rather than simply self-evident to the sufferer and unknowable to anyone else, pain was also understood to be produced between persons—and even, perhaps, by the fictions they read.

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