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ABSTRACT: To introduce a four-dimensional (4D) tomotherapy treatment technique with improved motion control and patient tolerance.
Computed tomographic images at 10 breathing phases were acquired for treatment planning. The full exhalation phase was chosen as the planning phase, and the CT images at this phase were used as treatment-planning images. Region of interest delineation was the same as in traditional treatment planning, except that no breathing motion margin was used in clinical target volume-planning target volume expansion. The correlation between delivery and breathing phases was set assuming a constant gantry speed and a fixed breathing period. Deformable image registration yielded the deformation fields at each phase relative to the planning phase. With the delivery/breathing phase correlation and voxel displacements at each breathing phase, a 4D tomotherapy plan was obtained by incorporating the motion into inverse treatment plan optimization. A combined laser/spirometer breathing tracking system has been developed to monitor patient breathing. This system is able to produce stable and reproducible breathing signals representing tidal volume.
We compared the 4D tomotherapy treatment planning method with conventional tomotherapy on a static target. The results showed that 4D tomotherapy can achieve dose distributions on a moving target similar to those obtained with conventional delivery on a stationary target. Regular breathing motion is fully compensated by motion-incorporated breathing-synchronized delivery planning. Four-dimensional tomotherapy also has close to 100% duty cycle and does not prolong treatment time.
Breathing-synchronized delivery is a feasible 4D tomotherapy treatment technique with improved motion control and patient tolerance.
International Journal of Radiation OncologyBiologyPhysics 09/2007; 68(5):1572-8. · 4.11 Impact Factor
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ABSTRACT: Long-term brain metastases survivors are at risk for neurologic morbidity after whole-brain radiotherapy (WBRT). Retrospective radiosurgery (RS) reports found no survival difference when compared with WBRT. Before RS alone was evaluated with delayed WBRT in a phase III trial, the feasibility of RS alone was tested prospectively.
Patients with renal cell carcinoma, melanoma, or sarcoma; one to three brain metastases; and performance status of 0 to 2 were enrolled. Exclusion criteria were leptomeningeal disease; metastases in medulla, pons, or midbrain; or liver metastases. On the basis of tumor size, patients received 24, 18, or 15 Gy RS. At recurrence, management was discretionary. The primary end point was 3- and 6-month intracranial progression.
Between July 1998 and August 2003, 36 patients were accrued; 31 were eligible. Median follow-up was 32.7 months and the median survival was 8.3 months (95% CI, 7.4 to 12.2). Three- and 6-month intracranial failure with RS alone was 25.8% and 48.3%. Failure within and outside the RS volume, when in-field and distant intracranial failures were scored independently, was 19.3% and 16.2% (3 months) and 32.2% and 32.2% (6 months), respectively. Approximately 38% of patients experienced death attributable to neurologic cause. There were three grade 3 toxicities related to RS.
Intracranial failure rates without WBRT were 25.8% and 48.3% at 3 and 6 months, respectively. Delaying WBRT may be appropriate for some subgroups of patients with radioresistant tumors, but routine avoidance of WBRT should be approached judiciously.
Journal of Clinical Oncology 01/2006; 23(34):8870-6. · 18.37 Impact Factor
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ABSTRACT: Gorham's disease, also known as vanishing bone disease or massive osteolysis, is a rare disorder of uncertain etiology. It is characterized by uncontrolled proliferation of vascular or lymphatic capillaries within bone, leading to resorption and replacement with angiomatous tissue. It can be complicated by chylous pericardial and pleural effusions, which can be life threatening. Patients are also at risk of mortality or serious morbidity due to bone destruction, especially when the disease involves the spine. We report the case of a 31-year-old female with Gorham's disease involving several bones along with chylous pericardial and pleural effusions. She was effectively treated with definitive radiation therapy.
Clinical Medicine & Research 06/2005; 3(2):83-6.
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ABSTRACT: Non-small cell lung cancer continues to be a major oncologic problem, with approximately 3-month increase in median survival per decade since the 1970s. Thus, newer strategies are needed to improve outcomes in non-small cell lung cancer. New treatment strategies include optimizing and intensifying radiation therapy (RT) delivery, as well as improving systemic therapy with newly developed targeted agents. Three-dimensional treatment planning is a key technology for optimizing RT delivery. Additionally, improvements in radiation therapy will clearly require better target delineation and dose-intensification of RT. With newer, possibly less toxic agents such as the epidermal growth factor receptor inhibitors, RT and systemic therapy (with chemo- and/or targeted therapies) may be optimized in the concurrent setting, perhaps reserving more cytotoxic regimens either for the induction or maintenance settings.
Seminars in Oncology 05/2005; 32(2 Suppl 3):S25-34. · 3.50 Impact Factor
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ABSTRACT: Radiation therapy is a central modality in the treatment of glioblastoma multiforme (GBM). Integral to adequate radiation therapy delivery is the appropriate determination of tumor volume and extent at the time treatment is being delivered. As a matter of routine practice, radiation therapy treatment fields are designed based on tumor volumes evident on pre-operative or immediate post-operative MRIs; another MRI is generally not obtained for planning boost fields. In some instances the time interval from surgery to radiotherapy initiation is up to 5 weeks and the boost or "cone-down phase" commences 4-5 weeks later. The contrast enhanced T1 MRI may not be a totally reliable indicator of active tumor, especially in regions where such blood-brain barrier breakdown has not occurred. Moreover, these volumes may change during the course of treatment. This may lead to a geographic miss when mid-treatment boost volumes are designed based on a pre-radiotherapy MRI. The goal of this study is to examine how a mid-treatment MRI impacts the delineation and definition of the boost volume in GBM patients in comparison to the pre-treatment MRI scan, particularly when the tumor-specific agent Motexafin-Gadolinium is used.
Technology in cancer research & treatment 07/2004; 3(3):303-7. · 2.02 Impact Factor
