THE PRODUCTION OF MUTATIONS BY THE IRRADIATION OF MONTCALM BARLEY

1955 ◽  
Vol 33 (6) ◽  
pp. 515-530 ◽  
Author(s):  
Thomas Lawrence
Keyword(s):  
High Dose Rate ◽  
Mutation Induction ◽  
High Dose ◽  
X Rays ◽  
New Approach ◽  
X Ray ◽  
Dose Rates ◽  
Radiation Sources ◽  
Early Maturing ◽  
New Varieties

Five radiation sources were used to induce mutations in barley. All treatments were given at a dosage of 10,000 r. equivalent. The radiation sources with their respective dose-rates in the region of the irradiated seeds were: a betatron (181.8 r./min.), an X-ray machine (201 r./min.), radium-beryllium (5.3 r./min.), and two Co60 sources (4.5 r./min. and 75.75 r./min.). None of the radiation sources used was more effective than the X-ray treatment in producing mutations. The betatron and the high dose-rate treatments from Co60 appear to be somewhat less effective than X-rays. Over 30 different mutant types were produced, including a number of vital mutants, such as stiff-strawed and early-maturing types. These appear promising as new varieties, but require further agronomic evaluation. It is concluded that mutation induction will become a useful new approach for plant breeders.

scholarly journals Nanomelanin Potentially Protects the Spleen from Radiotherapy-Associated Damage and Enhances Immunoactivity in Tumor-Bearing Mice

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1725 ◽  
Author(s):  
Nguyen Thi Le Na ◽  
Sai Duc Loc ◽  
Nguyen Le Minh Tri ◽  
Nguyen Thi Bich Loan ◽  
Ho Anh Son ◽  
...  
Keyword(s):  
Cancer Treatment ◽  
Interleukin 2 ◽  
High Dose Rate ◽  
High Dose ◽  
X Rays ◽  
Necrosis Factor Alpha ◽  
Oh Groups ◽  
X Ray ◽  
Tumor Bearing ◽  
Tnf Α

Radiotherapy side-effects present serious problems in cancer treatment. Melanin, a natural polymer with low toxicity, is considered as a potential radio-protector; however, its application as an agent against irradiation during cancer treatment has still received little attention. In this study, nanomelanin particles were prepared, characterized and applied in protecting the spleens of tumor-bearing mice irradiated with X-rays. These nanoparticles had sizes varying in the range of 80–200 nm and contained several important functional groups such as carboxyl (-COO), carbonyl (-C=O) and hydroxyl (-OH) groups on the surfaces. Tumor-bearing mice were treated with nanomelanin at a concentration of 40 mg/kg before irradiating with a single dose of 6.0 Gray of X-ray at a high dose rate (1.0 Gray/min). Impressively, X-ray caused mild splenic fibrosis in 40% of nanomelanin-protected mice, whereas severe fibrosis was observed in 100% of mice treated with X-ray alone. Treatment with nanomelanin also partly rescued the volume and weight of mouse spleens from irradiation through promoting the transcription levels of splenic Interleukin-2 (IL-2) and Tumor Necrosis Factor alpha (TNF-α). More interestingly, splenic T cell and dendritic cell populations were 1.91 and 1.64-fold higher in nanomelanin-treated mice than those in mice which received X-ray alone. Consistently, the percentage of lymphocytes was also significantly greater in blood from nanomelanin-treated mice. In addition, nanomelanin might indirectly induce apoptosis in tumor tissues via activation of TNF-α, Bax, and Caspase-3 genes. In summary, our results demonstrate that nanomelanin protects spleens from X-ray irradiation and consequently enhances immunoactivity in tumor-bearing mice; therefore, we present nanomelanin as a potential protector against damage from radiotherapy in cancer treatment.

scholarly journals X-ray Emission Hazards from Ultrashort Pulsed Laser Material Processing in an Industrial Setting

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7163
Author(s):  
Ulf Stolzenberg ◽  
Mayka Schmitt Rahner ◽  
Björn Pullner ◽  
Herbert Legall ◽  
Jörn Bonse ◽  
...  
Keyword(s):  
Material Processing ◽  
High Dose ◽  
Reference Scenario ◽  
X Rays ◽  
Laser Material Processing ◽  
Laser Material ◽  
X Ray ◽  
Dose Rates ◽  
Industrial Setting ◽  
Ambient Dose

Interactions between ultrashort laser pulses with intensities larger than 1013 W/cm2 and solids during material processing can lead to the emission of X-rays with photon energies above 5 keV, causing radiation hazards to operators. A framework for inspecting X-ray emission hazards during laser material processing has yet to be developed. One requirement for conducting radiation protection inspections is using a reference scenario, i.e., laser settings and process parameters that will lead to an almost constant and high level of X-ray emissions. To study the feasibility of setting up a reference scenario in practice, ambient dose rates and photon energies were measured using traceable measurement equipment in an industrial setting at SCHOTT AG. Ultrashort pulsed (USP) lasers with a maximum average power of 220 W provided the opportunity to measure X-ray emissions at laser peak intensities of up to 3.3 × 1015 W/cm2 at pulse durations of ~1 ps. The results indicate that increasing the laser peak intensity is insufficient to generate high dose rates. The investigations were affected by various constraints which prevented measuring high ambient dose rates. In this work, a list of issues which may be encountered when performing measurements at USP-laser machines in industrial settings is identified.

Radiation therapy in the management of gynaecological cancer

2020 ◽  
pp. 832-843
Author(s):  
Anthony Fyles ◽  
Anuja Jhingran ◽  
David Gaffney ◽  
Dustin Boothe ◽  
Marco Carlone ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
World War Ii ◽  
Radiation Treatment ◽  
Uterine Cancer ◽  
High Dose Rate ◽  
Gynaecological Cancer ◽  
High Dose ◽  
External Beam ◽  
X Rays ◽  
Dose Rates

Therapeutic applications for radiation therapy followed quickly from the discovery of X-rays by Roentgen in 1895. The first radiation treatment is credited to Grubbe, who reported the external beam treatment of breast cancer in 1896. Application to gynaecological cancers was almost immediate. However, the limited penetrating ability of the low-energy radiation of early X-ray tubes and isotopes was a major limitation. Consequently, brachytherapy and near-contact external beam therapy were preferred for gynaecological cancer until the advent of cobalt-60—the first source of a penetrating beam of megavoltage photons with a high dose rate, long half-life, and reasonable cost. This led to cobalt-60 machines becoming the most widely utilized treatment machine from the 1950s to 1970s. Radar research during World War II dramatically improved microwave technology. Linear accelerator-based machines (linacs) applied these advances to use microwaves to accelerate electrons onto a tungsten target and emit a fraction of their kinetic energy as mega-electron volt energy X-rays. The emitted X-rays are collimated into a beam and directed towards the patient. Advantages of linacs over cobalt-60 include higher dose rates, sharper beam edges, higher energies, and simplified radiation protection. This chapter describes the basic principles of radiotherapy and the role of radiotherapy in the management of gynaecological cancers, including cervix cancer, uterine cancer, and rarer tumours such as those arising from vaginal, vulvar, and ovarian cancers.

scholarly journals Development of a Portable Hypoxia Chamber for Ultra-high Dose Rate Laser-Driven Proton Radiobiology Applications

2021 ◽  
Author(s):  
Pankaj Chaudhary ◽  
Deborah Caroline Gwynne ◽  
Boris Odlozilik ◽  
Aaron McMurray ◽  
Giuliana Milluzzo ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dose Rate ◽  
Oxygen Concentration ◽  
High Dose Rate ◽  
High Dose ◽  
X Rays ◽  
Enhancement Ratio ◽  
Dose Rates ◽  
Oxygen Enhancement Ratio ◽  
Oxygen Enhancement

Abstract BackgroundThere is currently significant interest in assessing the role of oxygen in the radiobiological effects at ultra-high dose rates. Oxygen modulation is postulated to play a role in the enhanced sparing effect observed in FLASH radiotherapy, where particles are delivered at 40-1000 Gy/s. Furthermore, the development of laser-driven accelerators now enables radiobiology experiments in extreme regimes where dose rates can exceed 10^9 Gy/s, and predicted oxygen depletion effects on cellular response can be tested. Access to appropriate experimental enviroments, allowing measurements under controlled oxygenation conditions, is a key requirement for these studies. We report on the development and application of a bespoke portable hypoxia chamber specifically designed for experiments employing laser-driven sources, but also suitable for comparator studies under FLASH and conventional irradiation conditions.Materials and MethodsWe used oxygen concentration measurements to test the induction of hypoxia and the maintenance capacity of the chambers. Cellular hypoxia induction was verified using hypoxia inducible factor-1α immunostaining. Calibrated radiochromic films and GEANT-4 simulations verified the dosimetry variations inside and outside the chambers. We irradiated hypoxic human skin fibroblasts (AG01522B) and patient-derived glioblastoma (E2) cancer stem cells with laser-driven protons, conventional protons and reference 225 kVp X-rays to quantify DNA DSB damage and repair under hypoxia. We further measured the oxygen enhancement ratio for cell survival exposed to cyclotron-accelerated protons and X-rays in the normal fibroblast and radioresistant GBM stem cells. ResultsOxygen measurements showed that our chambers maintained a radiobiological hypoxic environment for at least 45 minutes and pathological hypoxia for up to 24 hrs after disconnecting the chambers from the gas supply. We observed a significant reduction in the 53BP1 foci induced by laser-driven protons, conventional protons and X-rays in the hypoxic cells compared to normoxic cells at 30 minutes post-irradiation. Under hypoxic irradiations, the Laser-driven protons induced significant residual DNA DSB damage in hypoxic AG01522 cells compared to the conventional dose rate protons suggesting an important impact of these extreme high dose-rate exposures. We obtained an oxygen enhancement ratio (OER) of 2.1 ± 0.108 and 2.501 ±0.125 respectively for the AG01522 and patient derived GBM stem cells for the X-rays using our hypoxia chambers for irradiation. ConclusionWe demonstrated the design and application of portable hypoxia chambers for studying cellular radiobiological endpoints after laser-driven protons at ultra-high dose, conventional protons and X-ray exposures. Good levels of reduced oxygen concentration could be maintained in the absence of external gassing to quantify hypoxic effects and the data obtained provided an indication of an enhanced residual DNA DSB damage under hypoxic conditions at ultra-high dose rate compared to the conventional protons or X-rays.

Survival of mammalian cells exposed to X rays at ultra-high dose-rates

1969 ◽  
Vol 42 (494) ◽  
pp. 102-107 ◽  
Author(s):  
Roger J. Berry ◽  
Eric J. Hall ◽  
David W. Forster ◽  
Thomas H. Storr ◽  
Michael J. Goodman
Keyword(s):  
Mammalian Cells ◽  
High Dose ◽  
X Rays ◽  
Dose Rates

scholarly journals Back to the Future: Very High-Energy Electrons (VHEEs) and Their Potential Application in Radiation Therapy

Cancers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 4942
Author(s):  
Maria Grazia Ronga ◽  
Marco Cavallone ◽  
Annalisa Patriarca ◽  
Amelia Maia Leite ◽  
Pierre Loap ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Current Knowledge ◽  
High Energy ◽  
High Dose Rate ◽  
Point Of View ◽  
High Dose ◽  
Dose Rates ◽  
High Energy Electrons ◽  
Very High Energy ◽  
Very High

The development of innovative approaches that would reduce the sensitivity of healthy tissues to irradiation while maintaining the efficacy of the treatment on the tumor is of crucial importance for the progress of the efficacy of radiotherapy. Recent methodological developments and innovations, such as scanned beams, ultra-high dose rates, and very high-energy electrons, which may be simultaneously available on new accelerators, would allow for possible radiobiological advantages of very short pulses of ultra-high dose rate (FLASH) therapy for radiation therapy to be considered. In particular, very high-energy electron (VHEE) radiotherapy, in the energy range of 100 to 250 MeV, first proposed in the 2000s, would be particularly interesting both from a ballistic and biological point of view for the establishment of this new type of irradiation technique. In this review, we examine and summarize the current knowledge on VHEE radiotherapy and provide a synthesis of the studies that have been published on various experimental and simulation works. We will also consider the potential for VHEE therapy to be translated into clinical contexts.

Sign in / Sign up

Export Citation Format

Share Document