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CyberKnife, TomoTherapy and MR-Guided Linear Accelerators
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
Thomas Lacornerie, Albert Lisbona, Andrew W. Beavis
The TomoTherapy concept is well suited to adaptive radiotherapy, facilitating the development of techniques for adapting the planning and delivery of doses based on accurate positioning and responding to patient anatomical changes throughout the treatment schedule (see Section 48.4).
Helical Tomotherapy Treatment and Dosimetry
Published in Arash Darafsheh, Radiation Therapy Dosimetry: A Practical Handbook, 2021
Tomotherapy treatments are planned and delivered based on time, given a known, fixed dose rate. In this aspect, a tomotherapy treatment is like radioactive source treatment, such as high dose rate (HDR) brachytherapy or cobalt external beam therapy. (By contrast, in conventional linac-based systems, the treatment plan specifies a number of monitor units, and the beam turns off when the exact number of monitor units has been delivered). The time-based planning and delivery approach is well-suited to tomotherapy treatments, for which the couch translates at a constant velocity, and targets are treated from the superior end to the inferior end. Each voxel within the target passes through the beam plane during a limited amount of time, and is affected only by the dose delivered while that voxel is in the beam plane (or within scatter's reach of the beam plane).
Medical Linear Accelerators
Published in Eric Ford, Primer on Radiation Oncology Physics, 2020
The TomoTherapy® system (Accuracy Inc.) is a ring-based system that delivers modulated radiation therapy (Figure 9.2.2). From outside the unit appears much like a CT scanner (Figure 9.2.2A), but inside it contains a compact X-band linac operating at 6 MV (treatment mode) and a detector to acquire MV CT images with the linac operating in imaging mode at 3.5 MV (Figure 9.2.2B). This technology was originally pioneered by Dr. T. Rock Mackie and colleagues at the University of Wisconsin–Madison. The system treats in a helical mode. That is, the gantry rotates around continuously as the patient slides through the bore and, as such, long treatment lengths (up to 135 cm) are possible. The first human patients were treated with TomoTherapy in 2002. This device was one of the first to allow for volumetric imaging at the time of treatment via megavoltage CT. This helped to usher in the era of image-guided radiation therapy, IGRT (Chapter 21).
Sub-regional analysis of the parotid glands: model development for predicting late xerostomia with radiomics features in head and neck cancer patients
Published in Acta Oncologica, 2023
Thomas Berger, David J. Noble, Zhuolin Yang, Leila EA. Shelley, Thomas McMullan, Amy Bates, Simon Thomas, Linda J. Carruthers, George Beckett, Aileen Duffton, Claire Paterson, Raj Jena, Duncan B. McLaren, Neil G. Burnet, William H. Nailon
A total of 117 HNC patients treated with external beam RT at Addenbrooke’s hospital in Cambridge between 2014 and 2017 recruited to the VoxTox study (UK CRN ID 13716) [26,27], were selected for analysis. Toxicity, which was prospectively collected based on the Common Terminology Criteria for Adverse Events (CTCAEv4.03) scoring system, was reported for 112 patients at 6 months and 95 patients at 12 months. The endpoint of interest was moderate-to-severe xerostomia after radiotherapy and was defined by a toxicity score ≥ 2. The treatment characteristics and relevant clinical information are detailed in Table 1. All patients were treated with 30–35 fractions of 2–2.167 Gy per fraction on a TomoTherapy HiArt System (Accuray, Sunnyvale, CA, USA). For the purpose of image-guidance, Mega Voltage CT (MVCT) images (voxel dimensions: 0.7647 × 0.7647 × 6 mm3) were acquired daily. Following enhancements of the quality assurance programme, HU stability of the TomoTherapy machines improved between 2014 and 2017, corresponding to the time interval of patient selection [28]. Relevant target-related and organ-at-risk contours, including the parotid glands, were delineated using the approach described in the previously published article [23]. In particular, parotid glands were contoured by experienced clinicians on planning CTs and propagated to daily MVCTs using a deformable image registration algorithm. An illustration of contra-lateral parotid contours on MVCTs can be seen in Supplementary Material A for one patient who reported xerostomia at 6 and 12 months after radiotherapy and one that did not.
Outcomes of allogeneic haematopoietic stem cell transplantation with intensity-modulated total body irradiation by helical tomotherapy: a 2-year prospective follow-up study
Published in Annals of Medicine, 2022
Tatsuya Konishi, Hiroaki Ogawa, Yuho Najima, Shinpei Hashimoto, Satoshi Kito, Yuya Atsuta, Atsushi Wada, Hiroto Adachi, Ryosuke Konuma, Yuya Kishida, Akihito Nagata, Yuta Yamada, Satoshi Kaito, Junichi Mukae, Atsushi Marumo, Yuma Noguchi, Naoki Shingai, Takashi Toya, Aiko Igarashi, Hiroaki Shimizu, Takeshi Kobayashi, Kazuteru Ohashi, Noriko Doki, Keiko Nemoto Murofushi
We performed allo-HSCT with 12 Gy in 6 fractions twice daily for 3 consecutive days of IMRT-TBI using helical tomotherapy, and all patients were successfully irradiated without physical or technical problems. Although previous studies have assessed the clinical safety of IMRT-TBI [9,10], this relatively larger study evaluated the safety and feasibility of IMRT-TBI. Conventional irradiation planning of TBI using lead blocks for shielding is difficult to finely customize for each patient (Supplementary Figure 1(A)). This study demonstrated the safety and feasibility of IMRT-TBI using helical tomotherapy, which allows for accurate radiation dose calculation and dose conformity (Supplementary Figure 1(B)), and included the incidence of complications observed in the organs at risk (Tables 3 and 4). In addition, no patient developed primary graft failure or Grade III to IV aGVHD in this study.
Palliative short-course hypofractionated radiotherapy followed by chemotherapy in esophageal adenocarcinoma: the phase II PALAESTRA trial
Published in Acta Oncologica, 2020
David Borg, Jan Sundberg, Eva Brun, Elisabeth Kjellén, Kristoffer Petersson, Michael Hermansson, Jan Johansson, Jakob Eberhard, Anders Johnsson
A combined 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) was done for radiotherapy dose-planning. It was at the discretion of the radiation oncologist to use three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), volumetric-modulated arc therapy (VMAT) or helical tomotherapy. A total radiation dose of 20 Gy was delivered in five daily fractions, i.e., 4 Gy/fraction. An overall treatment time of up to eight days was allowed to account for a gap during the weekend for patients not starting on a Monday. Target volumes were defined as follows: Gross Tumor Volume (GTV): esophageal primary tumor; Clinical Target Volume (CTV): GTV + 5 mm radial margin (limited by pleuras, pericardium and vertebral bodies) and + 20 mm proximal and distal margin; Internal Target Volume (ITV): CTV + 5 mm radial margin and + 10 mm cranio-caudal margin (could be smaller if four-dimensional CT was used); Planning Target Volume (PTV): ITV + set-up margin according to local routines. In case of metastatic disease limited to adjacent local lymph nodes it was optional to include these in the GTV. The study protocol also permitted additional separate targets, e.g., painful bone metastases, to be treated according to local routines.