Studies show Accuray TomoTherapy increases precision, outcomes for total body irradiation

By News Release

Accuray Incorporated has announced that recently published data from two new studies demonstrate the benefits of the TomoTherapy System in the delivery of total body irradiation (TBI), a procedure commonly used to prepare patients being treated for leukemia and multiple myeloma for a bone marrow transplant. TBI involves irradiation of the entire body, elevating the need for precision, accuracy and homogeneity in radiation dose delivery. The TomoTherapy platform's unique architecture enables efficient and extremely effective delivery of radiation over large areas of the patient, making it a valuable part of the bone marrow transplantation conditioning regimen.

In TBI treatments, radiation is administered to the patient as part of a multimodality treatment regimen, typically in combination with high-dose chemotherapy. The irradiation contributes to the eradication of malignant cells, especially those that are chemotherapy-resistant or in sites not easily reached by chemotherapy drugs. TBI also helps prevent the body's immune system from rejecting the healthy donor cells after the transplant.

The TomoTherapy platform, including the next-generation Radixact System, has continuous gantry rotation and couch motion that enables helical delivery of therapy (TomoHelical). This treatment modality produces intensity-modulated radiation from 360 degrees around the patient over very long treatment fields, which significantly enhances the ability to achieve homogenous dose distributions for TBI, while also simplifying and streamlining the treatment delivery process. TBI treatments on conventional systems have been shown to pose a greater risk of over-dosing some areas and under-dosing others. Over-dosing may lead to toxicity and under-dosing means that the goal of eradicating the tumor cells is less likely to be achieved.

Study Highlights

Precise and homogeneous tumor coverage across the entire treatment area 
In one study, the clinical team from IUCT Oncopole in Toulouse, France shared results of their clinical experience with TomoHelical in a study titled, "Total body irradiation using Helical TomoTherapy: Treatment technique, dosimetric results and initial clinical experience," published in the February 2018 issue of the journal Cancer/Radiothérapie. They found:

  • The TomoTherapy platform enabled treatment of the entire body in only two segments, the upper body and the lower body. A highly conformal and homogeneous dose distribution was achieved throughout the body including at the junction between the upper and lower body fields
  • This approach to conditioning prior to stem cell transplantation facilitated the successful engraftment of all 11 patients included in the study while avoiding radiation pneumonitis, a common side effect following radiation therapy to the chest wall that results in inflammation of the lung. Engraftment is an important milestone in the transplant recovery process

"An important challenge in successfully providing TBI is attaining consistency of dose in the area of the junction between the treatment segments. In our study, we were able to achieve a 10% heterogeneity in the junction area; with a conventional linear accelerator, this would be higher than 20%. We want this number to be as low as possible because this means that we're delivering the dose we want to the area receiving radiation," said Dr. Françoise Izar, radiation oncologist, department of radiotherapy, IUCT Oncopole. "Using TomoHelical mode we were able to provide precise and homogeneous tumor coverage and excellent sparing of organs at risk. We significantly reduced the median dose to selected critical organs and it was possible to escalate dose to the sites at high risk of residual disease, improving long-term outcomes."

Simultaneous TBI and targeted radiation boost improves outcomes for high-risk or refractory/relapsed patients with leukemia 
In a second study, clinicians at Guangzhou General Hospital of Guangzhou Military Command and Sir Run Shaw Hospital in China, published results of their TBI study titled, "Haploidentical hematopoietic SCT using helical tomotherapy for total-body irradiation and targeted dose boost in patients with high-risk/refractory acute lymphoblastic leukemia," in the January 2018 issue of Bone Marrow Transplantation. Highlights of the study include:

  • In a novel approach, the clinical team used TomoHelical™ to simultaneously deliver TBI and a targeted radiation dose boost to total marrow, central nervous system, and disease sites outside of the bone, to improve outcomes for high-risk or refractory/relapsed patients with leukemia
  • TomoHelical mode provides a rotating beam source with a multileaf collimator moving in a spiral pattern relative to the patient, which allowed large areas to be delineated and treated, while neighboring areas were spared
  • All evaluable patients achieved sustained, full donor stem cell engraftment. One-year overall survival and disease free-survival rates following implantation were both reported as 70.7%
  • No patients experienced recurrent disease after a median follow-up of 14.6 months

"We took advantage of the TomoTherapy System's ability to deliver different radiation doses to very specific areas of the body at the same time to create an optimal treatment plan, providing one dose to accomplish TBI and simultaneously augmenting this with another dose to the sites that needed additional radiation," said Prof. Li, Jing, radiation oncologist and chief at the Helical TomoTherapy Center, Guangzhou General Hospital of Guangzhou Military Command. "We were extremely pleased with the results. Using TomoHelical mode we achieved satisfactory immunosuppression, excellent eradication of malignant tumor cells, and individual sparing of organs at high risk of radiation-induced toxicity, enabling us to achieve our clinical objectives."

"The approach to TBI described in these studies is a wonderful example of our customers leveraging the advanced and unique capabilities of the TomoTherapy System to update traditional approaches and offer patients effective treatments with low rates of toxicity, results we would also expect to see with the Radixact System," said Fabienne Hirigoyenberry-Lanson, PhD, Vice President Global Medical and Scientific Affairs, at Accuray. "I'm thrilled that our customers take our technologies to another level and look forward to partnering with them to further improve the quality of care they give to their patients."

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Studies show Accuray TomoTherapy increases precision, outcomes for total body irradiation.  Appl Rad Oncol. 

By News Release| May 30, 2018

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