Frequently Asked Questions

  • What is the TomoTherapy® System?

    The TomoTherapy System is the only radiation system specifically designed for integrated, 3D image-guided, intensity modulated radiation therapy (IG-IMRT). The radiation treatment is guided by CT imaging taken in the treatment room just before radiation is given. The precisely delivered radiation beam conforms to the shape of the patient’s tumor while minimizing exposure of normal healthy tissue to radiation. Minimizing radiation dose to normal tissue reduces the likelihood of side effects. Key technologies integrated into the TomoTherapy System include:

    • CT scanner: The device enables daily imaging of the tumor to ensure accurate targeting, even when the tumor’s size or position has changed. In addition, the scanner facilitates the delivery of extremely precise radiation doses from 360 degrees around the body, from the first to the last treatment session.
    • Multileaf collimator (MLC): A patented device with many “leaves” or “slats” that open and close quickly to enable, or block, the passage of radiation as it is delivered from different angles around the patient. The TomoTherapy System’s MLC divides the radiation beams into thousands of smaller beamlets that deliver uniform doses of radiation to the tumor, enabling customized and precise delivery of radiation to the tumor site.
  • What is the Radixact™ System?

    The Radixact System is the next generation TomoTherapy® platform. The Radixact System, in combination with the Precision™ Treatment Planning System and iDMS™ Data Management System, is intended to provide clinicians with a foundation for expanded clinical capabilities to help ensure the platform will be highly utilized for years to come, while driving excellence in outcomes across a wide range of patient cases.

    The new Radixact System is a uniquely smart radiation therapy system that enables optimal treatment for more patients.

  • What is radiation therapy?

    Radiation therapy uses focused beams of intense energy to destroy cancer cells and shrink or control the growth of tumors. Radiation therapy works by preventing targeted cells from multiplying. The objective of radiation therapy is to destroy the harmful cells while minimizing damage to healthy cells.

    • Radiation may be recommended as an alternative or in addition to surgery or other therapies. It also can be used to manage pain caused by lesions. Radiation can be delivered internally or externally. This FAQ focuses on one type of externally delivered radiation therapy.
  • What types of cancers or areas of the body can the TomoTherapy® and Radixact™ Systems treat?

    The Systems can be used to treat any cancers and body sites where radiation has been shown to be effective, whether the size of the targeted disease is very small or very large, and its shape is routine or complex.

    The TomoTherapy System is commonly used to treat tumors in the breast, prostate, brain, head and neck and lung, as well as bone/blood-related disease. The system is used for both adult and pediatric patients, and may be well suited for treating tumors that have reoccurred, even when these patients are not candidates to receive additional radiation from conventional delivery systems.

  • What happens to the cancer following treatment? Is it still in a patient’s body?

    Radiation kills the tumor cells so they cannot regenerate, but it does not remove the affected organ/site from the body as surgery does. When treatment is effective the tumor may shrink or disappear entirely, or its growth may be stopped.

  • What are the patient benefits of treatment with the TomoTherapy® and Radixact™ Systems?

    The Systems efficiently deliver superior dose homogeneity – the entire tumor or treated region – and conformity with excellent sparing of organs at risk (OAR). Treatment accuracy is based on daily 3D image guidance with integrated megavoltage CT (MVCT) imaging. This daily imaging reduces error in patient setup, which, if left uncorrected, would require larger margins to assure the diseased tissue is adequately treated and increases dose to normal, healthy tissue.

    The clinical efficacy of the Systems has been demonstrated in studies by TomoTherapy clinicians. In addition, some TomoTherapy clinicians have pioneered innovative clinical applications that leverage the system’s unique features.

  • What are the side effects associated with treatment?

    Most patients experience mild and temporary side effects that may include nausea, fatigue and skin irritation. These side effects may increase in severity during and just after radiotherapy and resolve within weeks or months. The likelihood and severity of side effects varies greatly across patients with different diseases and characteristics. As with any radiation treatment, side effects also can be severe in some patients and lead to permanent injury or even death.

  • Will treatment with the TomoTherapy® or Radixact™ System result in scar tissue?

    Treatment with the TomoTherapy® or Radixact™ System does not involve cutting of the skin, so in most cases it does not result in a scar.

    When the irradiated region is near the skin, however, all radiation therapies may cause skin damage. These side effects range from mild reddening and swelling that disappears with time to open lesions that require medical attention and, after healing, leave a permanent scar. The goal of any radiation therapy is to treat the disease while limiting side effects, including skin irritation or damage.

  • How long does each treatment take?

    On average, a daily treatment takes 10 to 20 minutes, from entering the treatment room until leaving. This time includes initial patient setup and the application of any motion restraints, CT image-guided correction of patient positioning if necessary, the radiation treatment delivery itself, and getting on and off the treatment couch.

  • How many treatments are usually needed?

    A typical course of radiation therapy involves a daily visit, Monday through Friday, for 20 to 40 sessions over four to six weeks, though this will vary by individual.

    The Systems also can be used for hypofractionated therapy, which enables the number of treatments to be reduced by giving higher doses during each treatment session. This type of treatment is possible because of the precision of the Systems in providing radiation only to the tumor where it’s needed, without increasing risk of radiation delivered to surrounding healthy tissue.

  • How do the TomoTherapy® and Radixact™ Systems differ from other radiation therapy devices?

    The Systems’ unique combination of CT scanner-based design, helical delivery mode and high-speed multileaf collimator (MLC), differentiate them from other radiation therapy devices.


    • The TomoTherapy and Radixact Systems enable efficient daily 3D CT imaging immediately before each treatment, helping ensure patients are set up accurately based on internal anatomy for that day. This is called image guidance, a technique the TomoTherapy System was originally designed to do. Errors in patient setup, if left uncorrected, would require larger margins to assure the disease is adequately treated and increases dose to normal, healthy tissue. As a result of their imaging capabilities, the TomoTherapy and Radixact Systems can reduce margins and more precisely deliver radiation treatments.


    • The TomoTherapy and Radixact Systems are the only radiation therapy devices capable of delivering radiation in a helical, or spiral, continuous 360-degree, pattern around a patient’s body. This approach enables clinicians to reach the target from more angles, while simultaneously sparing healthy organs or tissue nearby.
    • The TomoTherapy and Radixact Systems' unique MLC divides the radiation beam into thousands of smaller beamlets that deliver different intensities of radiation to the tumor, directly to where it’s needed, enabling a customized and precise delivery of radiation to the tumor site and minimizing exposure of healthy surrounding tissue.


    • The Systems can treat large fields, the exact places on the patient’s body where the radiation beam will be aimed, including multiple metastases and sizeable tumors, with a single treatment plan and setup. The result is less overall treatment time for patients.
      • Other conventional radiation therapy systems are limited in the size of the tumor they can treat in a single session; multiple treatment plans and patient setups are required to treat multiple tumors.
    • The effectiveness of the TomoTherapy System has been well documented in hundreds of peer-reviewed research papers authored by a multitude of researchers around the world since its FDA clearance in 2002. Findings are typically favorable for the use of this technology in the treatment of a broad range of cancer cases.
      • In some cases improved clinical outcomes, including better cancer control and reduced side effects, have been demonstrated. In one study, patients with head and neck cancer reported less xerostomia, or dry mouth, after TomoTherapy treatment than after another form of IMRT.1
      • The unique pattern of radiation delivery has also enabled clinicians to target radiation precisely to the bone marrow in patients with leukemia prior to blood stem cell transplant. Higher, potentially more effective, doses can be delivered to the bone marrow with less of the severe toxicity associated with more conventional, total body irradiation.2

    The Radixact™ Treatment Delivery System is the next generation TomoTherapy platform, designed to enable doctors to more efficiently and effectively deliver precise radiation treatments to more patients.


    1. Chen AM, Yang CC, Marsano J, et al. Intensity-modulated radiotherapy for nasopharyngeal carcinoma: improvement of the therapeutic ratio with helical tomotherapy vs. segmental multileaf collimator-based techniques. The British journal of radiology 2012;85:e537-543.
    2. Kim JH, Stein A, Tsai N, et al. Extramedullary relapse following total marrow and lymphoid irradiation in patients undergoing allogeneic hematopoietic cell transplantation. Int J Radiat Oncol Biol Phys 2014;89:75-81.
  • Will insurance cover the procedure?

    TomoTherapy and Radixact treatments are covered as other radiation therapy treatments are covered, depending on the diagnosis and clinical application per public and private insurer guidelines by geography.