SARS-CoV-2 is causing an unprecedented stress on healthcare systems around the world, due to its high rate of infection and the high morbidity and mortality.

The COVID-19 infection triggers an inflammatory cascade with cytokine synthesis, prompting the immune response. Low dose radiotherapy (LD-RT) (≤ 100 cGy) induces an anti-inflammatory response, lowering levels of pro-inflammatory cytokines such as IL-1β or inhibit leukocyte recruitment. LD-RT has been used historically for the pneumonia treatment reporting a rapid clinical improvement (within the first week), as well as a reduced mortality (from around 30% to 10%). Considering these results, LD-RT can potentially afford a therapeutic benefit against SARS-CoV-2. The study purpose is to evaluate prospectively the safety and efficacy of LD-RT for SARS-CoV-2.

Inclusion Criteria:

1. Age ≥ 60 years.
2. COVID19 + confirmed by PCR.
3. Thoracic imaging study (chest X-ray, chest CT or PET-CT), compatible with lung involvement.
4. Phase II or lung phase without any improvement with pharmacological treatment.
5. Phase III or hyper-inflammatory phase without any improvement with pharmacological treatment
6. Poor clinical and functional respiratory evolution: > 30 breaths / minute, SpO2 <93%, PaO2 / FiO2 <300.
7. D-dimer> 1000 ng / mL or rising, ferritin> 1000 ng / mL, PCR> 10 mg / dL or double than before.

Exclusion Criteria:

1. Severe comorbidities that could hamper the radiation treatment.