Xu Cao

Research Interests

Ultra-high dose rate radiotherapy; flash radiotherapy; Oxygen imaging; fluorescence imaging; molecular imaging

Education

• BS, Northwestern Polytechnical University 2007
• MS, China Agricultural University 2009
• PhD, Biomedical Engineering, Tsinghua University 2013

Research Projects

• Exploring the role of oxygen in ultra high dose rate radiotherapy

  Exploring the role of oxygen in ultra high dose rate radiotherapy

  Ultra-high dose rate (UHDR) radiotherapy (RT) is an emerging cancer treatment that delivers high-energy beams (>40 Gy/s) to target tumors. Unlike conventional radiotherapy, which can damage healthy tissue, UHDR RT has been shown to spare normal tissue while maintaining tumor-killing effectiveness—a phenomenon known as the FLASH effect. The underlying mechanisms of this effect remain unclear. Our research focuses on investigating the role of oxygen in the FLASH effect using optical methods to measure tissue oxygen levels in real time during treatment.

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• Cerenkov imaging in radiation therapy

  Cerenkov imaging in radiation therapy

  Radiation therapy is used to treat cancer tumors by killing the tissue with high ionizing radiation doses. Until recently it has not been possible to image the radiation dose delivered to tissue, but through Cherenkov light imaging, this delivered dose can be mapped with high resolution cameras. The research group focuses on quantification of the imaging, and developing tools which allow radiation therapy to be delivered in a safer and more validated manner.

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• Optical molecular imaging

  Optical molecular imaging

  Optical molecular imaging is being used to provide molecular guidance in cancer surgery. Fluorescent contrast agents are in pre-clinical and clinical studies to image cancer tumors in vivo, with a dual focus, first on getting more accurate information out of the tissue, and secondly to provide better information about the specificity of the molecules as markers. Systems and algorithms for diffuse fluorescence imaging of tissue are studied, both as a stand-alone system, and as coupled to magnetic resonance imaging and computed tomography imaging. Tracer kinetic modeling is also being developed to allow quantitative imaging of molecular binding in vivo.

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Selected Publications

• Xu Cao, Aubrey Parks, William Thomas, Matthew Reed, Wesley S Culberson & Brian W Pogue* "Hydrated electron yield dependence on instantaneous dose rates with electron ultra-high dose rate (UHDR) irradiation" Physics in Medicine and Biology 70:125013, 2025
• Xu Cao, Kristen E Muller, Mary D Chamberlin, Jiang Gui, Peter A Kaufman, Gary N Schwartz, Roberta M diFlorio-Alexander, Brian Pogue, Keith Paulsen & Shudong Jiang* "Near-infrared spectral tomography for predicting residual cancer burden during early-stage neoadjuvant chemotherapy for breast cancer" Clinical Cancer Research 29(23):4822–4829, 2023
• Tingting Bai, Fei Kang, Shouping Zhu, Xueli Chen, Yihan Wang* & Xu Cao* "Painted radioluminescence imaging with radioluminescent nanophosphors" Applied Physics Letters 121:233701, 2022
• Xu Cao, Rongxiao Zhang, Tatiana V Esipova, Srinivasa Rao Allu, Ramish Ashraf, Mahbubur Rahman, Jason R Gunn, Petr Bruza, David J Gladstone, Benjamin B Williams, Harold M Swartz, P Jack Hoopes, Sergei A Vinogradov & Brian W Pogue* "Quantification of oxygen depletion during FLASH irradiation in vitro and in vivo" International Journal of Radiation Oncology, Biology, Physics 111(1):240–248, 2021
• Xu Cao, Srinivasa Rao Allu, Shudong Jiang, Jason R Gunn, Cuiping Yao, Jing Xin, Petr Bruza, David J Gladstone, Lesley A Jarvis, Jie Tian, Harold M Swartz, Sergei A Vinogradov & Brian W Pogue* "High-resolution pO₂ imaging improves quantification of the hypoxic fraction in tumors during radiotherapy" International Journal of Radiation Oncology, Biology, Physics 109(13):603–613, 2021
• Xu Cao, Srinivasa Rao Allu, Shudong Jiang, Mengyu Jia, Jason R Gunn, Cuiping Yao, Ethan P LaRochelle, Jennifer R Shell, Petr Bruza, David J Gladstone, Lesley A Jarvis, Jie Tian, Sergei A Vinogradov & Brian W Pogue* "Tissue pO₂ distributions in xenograft tumors dynamically imaged by Cherenkov-excited phosphorescence during fractionated radiation therapy" Nature Communications 11:573, 2020