Lung Tumor Tracking by Radar for Gated Radiation Therapy

Technology #d-0827

Lung Tumor Tracking by Radar for Radiation Therapy

Lung cancer causes millions of deaths per year worldwide. Radiotherapy is the major lung cancer treatment, either alone or combined with surgery and chemotherapy.

Lung tumors present a particular problem because they often float freely, making targeted radiation therapy difficult. Compound that with the movement caused by the patient's breathing and targeted radiation becomes exponentially more difficult. 

This radar-guided respiration monitoring will help make lung cancer treatment safer, more effective and more comfortable for the patients with floating lung tumors. The project utilizes radar sensor technology for respiratory gating (measurement) and tumor tracking. It uses a non-contact, software-configurable, Doppler radar system to deliver absolute measurements of respiratory motion and provide accurate tumor location to precisely deliver the prescribed radiation dose.


Doppler Radar Helps Linear Accelerator (LINAC) Target Lung Tumors

The radar-based tumor tracking system uses an external Doppler radar software system to measure the patient's breathing, for a precise, gated (targeted) radiation delivery. The patient’s CT scan is used to calibrate the device and guide the linear accelerator (LINAC) that delivers X-rays to the tumor. The beam is fixed, delivers a high density radiation dose to the tumor as it moves, and minimizes exposure of healthy tissue and the associated severe radiation side effects of current treatments.

This radar respiration monitor overcomes the risks and challenges of current respiration-gated, radiation treatments that require invasive implanted reference markers or infrared cameras, and aren't accuracy because of the motion of a floating tumor and the patient's breathing. Lung tumors can move significantly, making it very difficult for these techniques to deliver a sufficient radiation dose without damaging the surrounding healthy lung tissue.

Test results showed that the radar-based system was able to supply reliable breathing motions and accurate gating signals for treatment of mobile tumors. The wireless radar signal that sends the tumor information back to a computer proved to be more sensitive and more accurate than current treatments that rely on reference markers inserted inside or near the tumor. 


  • Cancers that present with floating tumors
  • Radiation treatment that needs to account for a patient's respiration

Intellectual Property

A US patent was issued on 4/19/2016, US patent no. 9,314,648.


    This software-defined radar respiration monitor for respiratory-gated radiotherapy:

    • offers a unique software method for live accurate tracking of mobile tumors, specifically in lung cancer, using a non-contact Doppler radar
    • avoids the invasive implantation procedure that can cause various side effects such as pneumothorax, bleeding/lung collapse, infections, respiratory failure requiring ventilator support, vasovagal reaction causing cardiac arrhythmias, and even death
    • guides the LINAC to deliver high-energy X-rays to a patient’s tumor, no matter where it is in the body
    • does not employ any kind of marker, so there is no discomfort at all and it is totally non-invasive
    • is built with commercial integrated-circuit chips at a low cost of approximatley $100
    • is the most accurate method for tracking tumors
    • penetrates through clothing and tracks muscle movement and bones


    C. Gu, R. Li, C. Li, S.B Jiang. “Doppler Radar Respiration Measurement for Gated Lung Cancer Radiotherapy.” IEEE Topical Conference on Biomedical Wireless Technologies, Networks & Sensing Systems, Phoenix, AZ, January 18, 2011.
    C. Li, C. Gu, R. Li, S.B. Jiang. “Radar Motion Sensing for Accurate Tumor Tracking in Radiation Therapy.” 12th Annual IEEE Wireless and Microwave Technology Conference, Clearwater, FL, April 2011.