Practical Aspects of Implementation of Helical Tomotherapy for Intensity-modulated and Image-guided Radiotherapy
University of Cambridge Department of Oncology, Oncology Centre, Addenbrooke's Hospital, Cambridge, UK. Clinical Oncology
(Impact Factor: 3.4).
03/2010; 22(4):294-312. DOI: 10.1016/j.clon.2010.02.003
Image-guided radiotherapy (IGRT) and intensity-modulated radiotherapy (IMRT) represent two important technical developments that will probably improve patient outcome. Helical tomotherapy, provided by the TomoTherapy HiArt system, provides an elegant integrated solution providing both technologies, although others are available. Here we report our experience of clinical implementation of daily online IGRT and IMRT using helical tomotherapy.
Methods were needed to select patients who would probably benefit. Machine-specific commissioning, a quality assurance programme and patient-specific delivery quality assurance were also needed. The planning target volume dose was prescribed as the median dose, with the added criterion that the 95% isodose should cover 99% of the target volume. Although back-up plans, for delivery on conventional linear accelerators, were initially prepared, this practice was abandoned because they were used very rarely.
In the first 12 months, 114 patients were accepted for treatment, and 3343 fractions delivered. New starts averaged 2.6 per week, with an average of 17.5 fractions treated per day, and the total number capped at 22. This has subsequently been raised to 24. Of the first 100 patients, 96 were treated with radical intent. Five were considered to have been untreatable on our standard equipment. IGRT is radiographer led and all patients were imaged daily, with positional correction made before treatment, using an action level of 1mm. A formal training programme was developed and implemented before installation. The in-room time fell significantly during the year, reflecting increasing experience and a software upgrade. More recently, after a couch upgrade in April 2009, the mean in-room time fell to 18.6 min.
Successful implementation of tomotherapy was the result of careful planning and effective teamwork. Treatment, including daily image guidance, positional correction and intensity-modulated delivery, is fast and efficient, and can be integrated into routine service. This should encourage the adoption of these technologies.
Available from: Tomasz Piotrowski
- "Rekomendacja zmodyfikowanego modelu BTE. Bauman G, 2007  (London, Kanada) 60 1,5 roku Tomoterapia Analiza opisowa Burnet NG, 2010  (Cambridge, Anglia) 114 1 rok Tomoterapia Analiza opisowa Sterzing F, 2008  (Heidelberg, Niemcy) 150 2 lata Tomoterapia Analiza opisowa Bijdekerke P, 2008  (Bruksela, Belgia) 99 1 rok Tomoterapia Propozycja modelu OTT i analiza danych własnych w oparciu o zaproponowany model Piotrowski T, 2013  "
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ABSTRACT: The aim of this study was to review the models that allow the prediction of the length of time of irradiation during radiotherapy and to describe the evolution of the problem of effective time management of medical accelerators following the development of radiation therapy. The analysis was based on the literature data selected using the medical search engine PubMed. Of the 234 publications from the years 1982 to 2013, 16 studies were selected for detailed analysis, which included respectively: 1) the evolution of models used in radiotherapy realised by conventional medical accelerators, 2) the determinants of the failure of these models in radiotherapy realised by unconventional medical accelerators, and 3) proposals for alternative models for these accelerators. The analysis showed that the classical models such as ESTV (equivalent simple treatment visit) or BTE (basic treatment equivalent) effectively describe the performance of conventional linear accelerators used in conventional radiation therapy. Nevertheless, implemen-tation of new procedures such as in vivo dosimetry and image guidance or introducing new technology (multi leaf collimator, dynamic techniques) forces modifications of the developed models. The example of the modified model is the solution developed by the Addenbrooke hospital. The analysed models correctly describe the therapeutic efficiency of conventional linear accelerators. In the case of innovative solutions such as the Cyber Knife, Gamma Knife or Tomotherapy there is a need to develop new models. An example of one of the first models describing the performance of non-conventional linear accelerators is OTT (overall treatment time) developed for the Tomotherapy.
Available from: Sergey Usychkin
- "Reproducibility of patient positioning is especially important in highly conformal radiotherapy techniques such as HT. The use of daily pretreatment imaging with MVCT allows to reduce the PTV margins and thereby to reduce the amount of normal tissues receiving high doses . That in turn may lead to reduced rate of the long-term side effects. "
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ABSTRACT: Radiation therapy plays a central role in the management of many childhood malignancies and Helical Tomotherapy (HT) provides potential to decrease toxicity by limiting the radiation dose to normal structures. The aim of this article was to report preliminary results of our clinical experience with HT in pediatric malignancies.
In this study 66 consecutive patients younger than 14 years old, treated with HT at our center between January 2006 and April 2010, have been included. We performed statistical analyses to assess the relationship between acute toxicity, graded according to the RTOG criteria, and several clinical and treatment characteristics such as a dose and irradiation volume.
The median age of patients was 5 years. The most common tumor sites were: central nervous system (57%), abdomen (17%) and thorax (6%). The most prevalent histological types were: medulloblastoma (16 patients), neuroblastoma (9 patients) and rhabdomyosarcoma (7 patients). A total of 52 patients were treated for primary disease and 14 patients were treated for recurrent tumors. The majority of the patients (72%) were previously treated with chemotherapy. The median prescribed dose was 51 Gy (range 10-70 Gy). In 81% of cases grade 1 or 2 acute toxicity was observed. There were 11 cases (16,6%) of grade 3 hematological toxicity, two cases of grade 3 skin toxicity and one case of grade 3 emesis. Nine patients (13,6%) had grade 4 hematological toxicity. There were no cases of grade 4 non-hematological toxicities. On the univariate analysis, total dose and craniospinal irradiation (24 cases) were significantly associated with severe toxicity (grade 3 or more), whereas age and chemotherapy were not. On the multivariate analysis, craniospinal irradiation was the only significant independent risk factor for grade 3-4 toxicity.
HT in pediatric population is feasible and safe treatment modality. It is characterized by an acceptable level of acute toxicity that we have seen in this highly selected pediatric patient cohort with clinical features of poor prognosis and/or aggressive therapy needed. Despite of a dosimetrical advantage of HT technique, an exhaustive analysis of long-term follow-up data is needed to assess late toxicity, especially in this potentially sensitive to radiation population.
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ABSTRACT: The purpose of our study is to find the potential best options for the registration selection parameters when performing automatic registration between kilovoltage computed tomography (KVCT) and megavoltage computed tomography (MVCT) images in helical tomotherapy. We compared nine different combinations of automatic registration parameters, including technique and resolution in automatic registration control and tomoimage filtering in scan image control. In the phantom study, we compared the translational and the rotational adjustments between the original position (lateral 0 cm; longitudinal 0 cm; vertical 0 cm) and the manually moved position (lateral 1 cm; longitudinal 1 cm; vertical 1 cm). In the patient study, we compared translational (lateral, longitudinal, vertical) and rotational (pitch, roll, yaw) adjustments between the KVCT and the MVCT images for different anatomic treatment sites. The ranges of translational and rotational displacements in the phantom study were 14.87 ± 0.12 ∼ 15.70 ± 0.04 mm and 0° ∼ 1.03 ± 0.58°, respectively. In cranial cases, the ranges of translational and rotational root-mean-square values were 4.3 ± 0.4 mm ∼ 5.3 ± 0.6 mm, and 0.3 ± 0.3° ∼ 0.7 ± 0.4°, respectively. In the extra cranial cases, the ranges of translational and rotational root-mean-square values were 14.1 ± 3.6 mm − 16.1 ± 2.5 mm, and 0.5 ± 0.3° ∼ 1.0 ± 0.5°, respectively. We found that the combination of “full image - super fine” could minimize the mechanical deviations in the cranial case, and that both the combinations of “bone tissue - super fine” and “full image - super fine” were the best options in extra cranial cases.
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