Services by Radiation Therapy Treatment Modality
Image Guided Radiation Therapy (IGRT)
Image-guided radiation therapy (IGRT) is an image-based technology that allows clinicians to locate a tumor target prior to a radiation therapy treatment. Multi-imaging modalities, including CT, MRI, PET, and US, are used for IGRT in our department. CT based IGRT technologies include MV CT with TomoTherapy, KV CT with CT-on-Rail (CTVisionTM), KV Cone beam CT with Elekta Infinity and MV cone beam CT with Primus (MVision, Siemens). Each of these technologies offers distinct features to fit clinical needs. In addition, ultrasound (Clarity, Elekta) and Optical (VisionRT) systems are also used for motion management. The imaging systems used in the treatment room can localize tumor targets rapidly and accurately at the time of a radiation therapy treatment. This dramatically reduces the need for large target margins which have traditionally been used to compensate for errors in localization. As a result, the amount of healthy tissue exposed to radiation can be reduced, minimizing the incidence of side effects. Image-guided brachytherapy is also used in the treatment of gynecological cancers.
Treatment and Planning Machines
MV Cone Beam CT (MVision)
Stereotactic Body Radiotherapy (SBRT)
Stereotactic body radiotherapy (SBRT) is an emerging image-guided radiation technique that is used to treat small and well-defined targets within the body. SBRT normally delivers very high doses of radiation precisely to tumor sites within the body with the purpose of improving local control and limiting side effects. SBRT may be used for small lung cancers or metastases, small isolated liver tumors or bony tumors, and tumors in other sites that may not be appropriate for surgical resection or in patients who would not be candidates for surgery. SBRT is associated with few side effects because the treatment field is generally very small and treatment is precisely delivered. At the Froedtert Hospital and Medical College of Wisconsin, the delivery of SBRT involves in 4DCT based treatment planning, on-line CT guidance using cone beam CT or CT-on-Rails, real-time motion monitoring with Optical (VisionRT) or ultrasound systems (Clarity) and respiratory gating.
MV conebeam CT guided SBRT
Stereotactic Radiosurgery (SRS) with Gamma Knife
Gamma Knife is a dedicate technology offering stereotactic radiosurgery which concentrates high doses of radiation on targeted masses of brain tissue to “eradicate” lesions. Sometimes referred to "as brain surgery without a knife" it offers treatment to patients with certain brain masses and arteriovenous malformations that have been considered inaccessible or unsuitable for traditional neurosurgery. Conventional radiation therapy is delivered in many treatments over a period of time in low daily doses that accumulate to relatively high total doses. In contrast, with Gamma Knife SRS, multiple beams of radiation merge on the intended mass from several directions simultaneously. Healthy tissue is therefore subject to minimal exposure, while the targeted mass receives a concentrated dose. The growth can be treated in one session.
In certain locations in the body, such as the lungs and abdomen, tumors can move as the patient breathes. In the past, this movement has confounded doctors' ability to accurately deliver radiation therapy to these tumors. Respiratory gating is an emerging technology specifically introduced to solve this problem. During respiratory gating, radiation treatment is timed to an individual's breathing pattern, targeting the tumor only when it is in the best breathing phase. This approach decreases amount of normal tissue being irradiated, thus, reduces complications and side effects, while using higher doses and getting better outcomes. At the Froedtert and the Medical College of Wisconsin, we have been able to deliver respiratory gating since 2005 for treating many tumor sites including thorax, abdomen, and left-sided breast.
Intensity Modulated Radiation Therapy (IMRT)
Intensity modulated radiation therapy is changing the way radiation is delivered to treat head and neck cancers, prostate cancer, and many other cancers. Using a multi-leaf (MLC) collimator, IMRT focuses radiation directly on the tumor, delivering a higher, more effective radiation dose while decreasing toxicity to adjacent organs. This precise targeting is especially important in delivering IMRT. At Froedtert & Medical College of Wisconsin, we deliver image guided IMRT in multiple forms including fix-gantry IMRT, rotational IMRT with Tomotherapy and VMAT. Multiple image modalities (CT, MRI, PET) are used to guide IMRT planning in our department.
Adaptive Radiation Therapy (ART)
Adaptive Radiation Therapy (ART) is a state-of-the-art approach that uses a feedback process to account for patient-specific anatomic and/or biological changes, thus, delivering highly individualized radiation therapy for cancer patients. Basic components of ART include: (1) detection of anatomic and biological changes, often facilitated by multi-modality images, (2) treatment plan optimization to account for the patient-specific spatial morphological and biological changes with consideration of radiation responses, and (3) technologies to precisely deliver the optimized plan to the patient. Interventions of ART may consist of both on-line and off-line approaches. Accumulated clinical data have demonstrated the need for ART in clinical settings, assisted by the wide application of IMRT and IGRT. At Froedtert & the Medical College of Wisconsin, we deliver both online and offline ART for selected tumor sites.
High Dose Rate (HDR) Brachytherapy
Brachytherapy is defined as the placement of radioactive sources directly into or close to a tumor. High radiation doses are delivered to the cancer cells with rapid fall-off in dose to normal tissues. Brachytherapy is often combined with external beam radiation therapy (EBRT), serving as a 'boost dose' to the area of suspected or gross tumor residual. Brachytherapy alone or in conjunction with other treatment modalities has become an important part of radiation treatment. HDR brachytherapy is used in our department to treat gynecological, breast, and prostate cancers. At Froedtert & the Medical College of Wisconsin, CT and/or MRI are used to plan HDR brachytherapy.
Seed Implants (Brachytherapy for Prostate Cancer)
Radioactive "seeds" are implanted in the prostate gland, where they fight cancerous tumors for several months. One of the advantages of using this technique for prostate cancer is that it limits the dose received by normal structures and patients are not required to return for daily radiation treatments.
Eye Plaque Brachytherapy
Eye plaques containing radioactive seeds are used in the treatment of choroidal melanomas.
Intravascular Brachytherapy is used as a treatment modality for reducing coronary restenosis after angioplasty procedures, especially for in stent restenosis.