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Biomedical Physics in Radiation Oncology

Division of Biomedical Physics in Radiation Oncology

Prof. Dr. Joao Seco

FLASH radiotherapy

Radiation therapy is the most common treatment for cancer, being used in approximately 70% of all cancers either alone or combined with surgery or chemotherapy. It uses high-energy particles or waves, such as x-rays, gamma rays, electron beams, protons, carbon ions, to "kill" or "damage" cancer cells. Ultra-high-dose-rate (UHDR) radiotherapy, or FLASH-RT, is a novel technology involving the use of ultra-fast delivery of radiotherapy treatment at dose-rates that are several orders of magnitude higher than the conventional radiotherapy (CONV) in clinical practice (FLASH>=40Gy/s and CONV~0.01Gy/s). FLASH radiotherapy demonstrates a striking biological sparing effect of normal tissues while keeping similar anti-tumor efficacy, termed the “FLASH effect”. The molecular mechanism behind the FLASH effect is still unknown. Several possible mechanisms have been proposed to explain the FLASH effect such as oxygen depletion, radical recombination, immune response, etc. In addition, The FLASH effect has been shown in several studies to depend heavily not only on the dose-rate but also on the time structure of the pulses. My Current Research interests are: 1) to investigate the mechanism behind the FLASH effect, 2) to investigate the mechanism of radiation triggered DNA damage via reactive oxygen species (ROS), 3) to develop novel imaging technologies to reduce the Bragg peak positioning "uncertainties" for ion-beam radiotherapy, using Helium beam imaging and prompt gamma spectroscopy.

In principle, in order to take full advantage ion-beam radiotherapy a better control is needed of the Bragg peak within the patient (cancer) and a better understanding of the radiation triggered DNA damage is required. Once we can control very accurately the positioning of the Bragg peak within the cancer to within 1mm, then it will be possible to reduce radiation side-effects, while simultaneously boosting the cancer with more radiation. In addition, a better understanding is needed of the radiation effects within living cells for both cancer and healthy tissue.


Prof. Dr. Joao Seco
Biomedical Physics in Radiation Oncology (E041)
Deutsches Krebsforschungszentrum
Im Neuenheimer Feld 280
69120 Heidelberg
Tel: +49 (0) 6221 42 2554

Selected Publications

  • Seco J, et al, “Modulating Nucleus Oxygen Concentration by Altering Intramembrane Cholesterol Levels: Creating Hypoxic Nucleus in Oxic Conditions” International Journal of Molecular Sciences 2022 23(9), 5077,
  • Jansen J… Seco J,”Changes in radical levels as a cause for the FLASH effect: Impact of beam structure parameters at ultra-high dose rates on oxygen depletion in water” Radiotherapy and Oncology, 175 193-196 (2022)
  • Jansen J… Seco J,”Does FLASH deplete oxygen? Experimental evaluation for photons, protons and carbon ions” Medical Physics, 48(7) 3982-90 (2021)
  • Vol z…Seco J, “Experimental exploration of a mixed helium/carbon beam for online treatment monitoring in carbon ion therapy” Physics in Medicine and Biology 65(5) 055002 (2020)
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