International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2012
Comparative StudyBiological optimization in volumetric modulated arc radiotherapy for prostate carcinoma.
To investigate the potential benefits achievable with biological optimization for modulated volumetric arc (VMAT) treatments of prostate carcinoma. ⋯ Biological optimization can significantly increase the organs-at-risk sparing in VMAT optimization for prostate carcinoma. In some particular cases, however, the DVH-based optimization resulted in superior treatment plans.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2012
Monitoring dosimetric impact of weight loss with kilovoltage (kV) cone beam CT (CBCT) during parotid-sparing IMRT and concurrent chemotherapy.
Parotid-sparing head-and-neck intensity-modulated radiotherapy (IMRT) can reduce long-term xerostomia. However, patients frequently experience weight loss and tumor shrinkage during treatment. We evaluate the use of kilovoltage (kV) cone beam computed tomography (CBCT) for dose monitoring and examine if the dosimetric impact of such changes on the parotid and critical neural structures warrants replanning during treatment. ⋯ Although patient weight loss and parotid volume shrinkage was observed, overall, there was no significant excess dose to the organs at risk. No replanning was felt necessary for this patient cohort, but a larger patient sample will be investigated to further confirm these results. Nevertheless, kilovoltage CBCT is a valuable tool for patient setup verification and monitoring of dosimetric variation during radiotherapy.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2012
Tumor shrinkage assessed by volumetric MRI in long-term follow-up after fractionated stereotactic radiotherapy of nonfunctioning pituitary adenoma.
To evaluate tumor control and side effects associated with fractionated stereotactic radiotherapy (FSRT) in the management of residual or recurrent nonfunctioning pituitary adenomas (NFPAs). ⋯ By using 3D MRI in all patients undergoing FSRT of an NFPA, tumor shrinkage is detected. Our data demonstrate that volumetric assessment based on 3D MRI adds additional information to routinely used radiological response measurements. After FSRT a mean relative size reduction of 51% can be expected within 5 years.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2012
Pathologic validation of a model based on diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging for tumor delineation in the prostate peripheral zone.
For focal boost strategies in the prostate, the robustness of magnetic resonance imaging-based tumor delineations needs to be improved. To this end we developed a statistical model that predicts tumor presence on a voxel level (2.5×2.5×2.5 mm3) inside the peripheral zone. Furthermore, we show how this model can be used to derive a valuable input for radiotherapy treatment planning. ⋯ We developed a logistic regression with a high diagnostic performance for voxelwise prediction of tumor presence. The model output can be used to define different risk levels for tumor presence, which in turn could serve as an input for dose planning. In this way the robustness of tumor delineations for focal boost therapy can be greatly improved.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2012
Multimodality local therapy for retroperitoneal sarcoma.
Soft-tissue sarcomas of the retroperitoneum are rare tumors comprising less than 1% of all malignancies. Although surgery continues as the mainstay of treatment, the large size of these tumors coupled with their proximity to critical structures make resection with wide margins difficult to achieve. The role and timing of radiotherapy are controversial. This study updates our institutional experience using multimodality local therapy for resectable retroperitoneal sarcoma and identifies prognostic factors impacting disease control and survival. ⋯ For retroperitoneal sarcoma, local control remains a challenge and combined-modality therapy may be associated with significant acute and late morbidity. Our patterns of failure data suggest that improvements in local control may translate into a survival benefit.