Is there any supportive evidence for low dose radiotherapy for COVID-19 pneumonia?

Sisko Salomaa, Simon Bouffler, Michael J. Atkinson, Elisabeth Cardis, Nobuyuki Hamada*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

14 Citations (Scopus)


Since early April 2020, there has been intense debate over proposed clinical use of ionizing radiation to treat life-threatening pneumonia in Coronavirus Disease 2019 (COVID-19) patients. At least twelve relevant papers appeared by 20 May 2020. The radiation dose proposed for clinical trials are a single dose (0.1–1 Gy) or two doses (a few mGy followed by 0.1–0.25 Gy involving a putative adaptive response, or 1–1.5 Gy in two fractions 2–3 days apart). The scientific rationale for such proposed so-called low dose radiotherapy (LDRT) is twofold (note that only doses below 0.1 Gy are considered as low doses in the field of radiation protection, but here we follow the term as conventionally used in the field of radiation oncology). Firstly, the potentially positive observations in human case series and biological studies in rodent models on viral or bacterial pneumonia that were conducted in the pre-antibiotic era. Secondly, the potential anti-inflammatory properties of LDRT, which have been seen when LDRT is applied locally to subacute degenerative joint diseases, mainly in Germany. However, the human and animal studies cited as supportive evidence have significant limitations, and whether LDRT produces anti-inflammatory effects in the inflamed lung or exacerbates ongoing COVID-19 damage remains unclear. Therefore, we conclude that the available scientific evidence does not justify clinical trials of LDRT for COVID-19 pneumonia, with unknown benefit and known mortality risks from radiogenic cancer and circulatory disease. Despite the significant uncertainties in these proposals, some clinical trials are ongoing and planned. This paper gives an overview of current situations surrounding LDRT for COVID-19 pneumonia.

Original languageEnglish
Pages (from-to)1228-1235
Number of pages8
JournalInternational Journal of Radiation Biology
Issue number10
Early online date13 Jul 2020
Publication statusE-pub ahead of print - 13 Jul 2020

Bibliographical note

Funding Information: The authors would like to thank Drs Mark P. Little (NCI, USA) and Lydia Zablotska (UCSF, USA) for helpful discussion. ISGlobal acknowledges support from the Spanish Ministry of Science, Innovation and Universities through the ‘Centro de Excelencia Severo Ochoa 2019–2023’ Program (CEX2018-000806-S), and support from the Generalitat de Catalunya through the CERCA Program.

Open Access: No Open Access

Publisher Copyright: © 2020 Taylor & Francis Group LLC.

Citation: Sisko Salomaa, Simon D. Bouffler, Michael J. Atkinson, Elisabeth Cardis
& Nobuyuki Hamada (2020) Is there any supportive evidence for low dose radiotherapy for COVID-19 pneumonia?, International Journal of Radiation Biology, 96:10, 1228-1235,



  • COVID-19
  • adaptive response
  • clinical trials
  • low dose radiotherapy
  • pneumonia


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