The variation of oer with dose rate

Ling, C. Clifton; Spiro, Ira J.; Mitchell, James B.; Stickler, Rebecca

doi:10.1016/0360-3016(85)90253-6

Cited by 69 publications

(6 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The effect of oxygen (or lack thereof) on the response to ionizing radiations has been extensively studied in vitro, in preclinical models, and in patients (Vordermark and Horsman 2016). This effect is typically quantified according to the OER, the ratio of the dose in anoxia to the dose in air required to achieve a defined rate of cell survival, and has been measured under a wide range of radiation dose rates (Ling et al 1985(Ling et al , 2010. Oxygen enhancement of radiation damage is achieved when oxygen is present at the time of the irradiation or up to a few milliseconds after irradiation (Michael et al 1973).…”

Section: Theorymentioning

confidence: 99%

A computational model of radiolytic oxygen depletion during FLASH irradiation and its effect on the oxygen enhancement ratio

2019

View full text Add to dashboard Cite

Recent results from animal irradiation studies have rekindled interest in the potential of ultra-high dose rate irradiation (also known as FLASH) for reducing normal tissue toxicity. However, despite mounting evidence of a "FLASH effect", a mechanism has yet to be elucidated. This article hypothesizes that the radioprotecting effect of FLASH irradiation could be due to the specific sparing of hypoxic stem cell niches, which have been identified in several organs including the bone marrow and the brain. To explore this hypothesis, a new computational model is presented that frames transient radiolytic oxygen depletion (ROD) during FLASH irradiation in terms of its effect on the oxygen enhancement ratio (OER). The model takes into consideration oxygen diffusion through the tissue, its consumption by metabolic cells, and its radiolytic depletion to estimate the relative decrease in radiosensitivity of cells receiving FLASH irradiation. Based on this model, several predictions are made that could be tested in future experiments: (1) the FLASH effect should gradually disappear as the radiation pulse duration is increased from <1s to 10 s; (2) dose should be deposited using the smallest number of radiation pulses to achieve the greatest FLASH effect; (3) a FLASH effect should only be observed in cells that are already hypoxic at the time of irradiation; and (4) changes in capillary oxygen tension (increase or decrease) should diminish the FLASH effect.

show abstract

Section: Theorymentioning

confidence: 99%

A computational model of radiolytic oxygen depletion during FLASH irradiation and its effect on the oxygen enhancement ratio

2019

View full text Add to dashboard Cite

show abstract

“…The estimated OER value can be as low as 1.6−1.7 in LDR irradiation. 64,65 Tumor hypoxia has been observed in many human cancers and has been shown to correlate with local treatment failure in brachytherapy. [66][67][68][69][70][71][72] Also, there is in vitro experimental evidence of resensitization due to progression of synchronized cells through the cell cycle, which could be important in LDR brachytherapy, although it has not been possible to exploit this phenomenon clinically to achieve a therapeutic gain.…”

Section: Assumptions and Known Limitationsmentioning

confidence: 99%

AAPM Task Group Report 267: A joint AAPM GEC‐ESTRO report on biophysical models and tools for the planning and evaluation of brachytherapy

Chen,

Li,

Brenner

et al. 2024

Medical Physics

View full text Add to dashboard Cite

Brachytherapy utilizes a multitude of radioactive sources and treatment techniques that often exhibit widely different spatial and temporal dose delivery patterns. Biophysical models, capable of modeling the key interacting effects of dose delivery patterns with the underlying cellular processes of the irradiated tissues, can be a potentially useful tool for elucidating the radiobiological effects of complex brachytherapy dose delivery patterns and for comparing their relative clinical effectiveness. While the biophysical models have been used largely in research settings by experts, it has also been used increasingly by clinical medical physicists over the last two decades. A good understanding of the potentials and limitations of the biophysical models and their intended use is critically important in the widespread use of these models. To facilitate meaningful and consistent use of biophysical models in brachytherapy, Task Group 267 (TG‐267) was formed jointly with the American Association of Physics in Medicine (AAPM) and The Groupe Européen de Curiethérapie and the European Society for Radiotherapy & Oncology (GEC‐ESTRO) to review the existing biophysical models, model parameters, and their use in selected brachytherapy modalities and to develop practice guidelines for clinical medical physicists regarding the selection, use, and interpretation of biophysical models. The report provides an overview of the clinical background and the rationale for the development of biophysical models in radiation oncology and, particularly, in brachytherapy; a summary of the results of literature review of the existing biophysical models that have been used in brachytherapy; a focused discussion of the applications of relevant biophysical models for five selected brachytherapy modalities; and the task group recommendations on the use, reporting, and implementation of biophysical models for brachytherapy treatment planning and evaluation. The report concludes with discussions on the challenges and opportunities in using biophysical models for brachytherapy and with an outlook for future developments

show abstract

“…Fig. 4a presents the oxygen enhancement ratio (OER), which is defined as the ratio of the dose in anoxia to the dose in air required to achieve a given biological endpoint (e.g., a defined cell SF), as a function of oxygen tension (the scattered data points, extracted from previous experiments [37][38][39][40][41] , were used as references). Higher OER values at lower oxygen tensions meant that the cells were more radioresistant.…”

Section: Theoretical Cellular Response Analysis Of the Flash Effect Bmentioning

confidence: 99%

“…Theoretical analysis of cellular response based on the radiolytic oxygen depletion hypothesis. a Oxygen enhancement ratio (OER) as a function of oxygen tension (data were extracted from references[37][38][39][40][41] ). FLASH irradiation led to rapid oxygen depletion in cells, resulting in an increase in OER values (i.e., an increase of radioresistance).…”

mentioning

confidence: 99%

First demonstration of the FLASH effect with ultrahigh dose-rate high-energy X-rays

Gao

Yang

Zhu

et al. 2020

Preprint

View full text Add to dashboard Cite

The ultrahigh dose-rate (FLASH) radiotherapy, which is efficient in tumor control while sparing healthy tissue, has attracted intensive attention due to its revolutionary application prospect. This so-called FLASH effect has been reported in preclinical experiments with electrons, kilo-voltage X-rays, and protons, thus making FLASH a promising revolutionary radiotherapy modality. High energy X-ray (HEX) should be the ideal radiation type for clinical applications of FLASH due to its advantages in deep penetration, small divergence, and cost-friendly. In this work, we report the first implementation of HEXs with ultrahigh dose-rate (HEX-FLASH) and corresponding application of in vivo study of the FLASH effect produced by a high-current (10 mA), high-energy (6-8 MeV) superconducting linac. Joint measurements using radiochromic film, scintillator and Fast Current Transformer device validated that a maximum dose rate of over 1000 Gy/s was achieved in the mice and the mean value within several square centimeters keeps higher than 50 Gy/s within a depth of over 15 cm. The performance of the present HEX can satisfy the requirement of the FLASH study on animals. Breast cancer (EMT6) inoculated into BAL b/c mice was found efficiently controlled by HEX-FLASH. The radio-protective effect of normal tissue was observed on the C57BL/6 mice after thorax/abdomen irradiation by HEX-FLASH. Theoretical analyses of cellular response following HEX-FLASH irradiation based on the radiolytic oxygen depletion hypothesis were performed to interpret experimental results and future experiment design. This work provided the first demonstration of the FLASH effect triggered by HEX, which paved the way for future preclinical research and clinical application of HEX-FLASH.

show abstract

The variation of oer with dose rate

Cited by 69 publications

References 12 publications

A computational model of radiolytic oxygen depletion during FLASH irradiation and its effect on the oxygen enhancement ratio

A computational model of radiolytic oxygen depletion during FLASH irradiation and its effect on the oxygen enhancement ratio

AAPM Task Group Report 267: A joint AAPM GEC‐ESTRO report on biophysical models and tools for the planning and evaluation of brachytherapy

First demonstration of the FLASH effect with ultrahigh dose-rate high-energy X-rays

Contact Info

Product

Resources

About