International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Aug 2002
Flat-panel cone-beam computed tomography for image-guided radiation therapy.
Geometric uncertainties in the process of radiation planning and delivery constrain dose escalation and induce normal tissue complications. An imaging system has been developed to generate high-resolution, soft-tissue images of the patient at the time of treatment for the purpose of guiding therapy and reducing such uncertainties. The performance of the imaging system is evaluated and the application to image-guided radiation therapy is discussed. ⋯ A kV cone-beam CT imaging system based on a large-area, flat-panel detector has been successfully adapted to a medical linear accelerator. The system is capable of producing images of soft tissue with excellent spatial resolution at acceptable imaging doses. Integration of this technology with the medical accelerator will result in an ideal platform for high-precision, image-guided radiation therapy.
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Int. J. Radiat. Oncol. Biol. Phys. · Aug 2002
Pronounced radiosensitization of cultured human cancer cells by COX inhibitor under acidic microenvironment.
To demonstrate the influence of pH on the cytotoxicity and radiosensitization by COX (cyclooxygenase) -1 and -2 inhibitors using established human cancer cells in culture. ⋯ An acidic pH was an important factor affecting the increased cytotoxicity and radiosensitization by ibuprofen. Radiation response was enhanced at shoulder portion of the cell survival curve by selective COX-2 inhibitor.
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Int. J. Radiat. Oncol. Biol. Phys. · Aug 2002
High-dose intensity modulated radiation therapy for prostate cancer: early toxicity and biochemical outcome in 772 patients.
To report the acute and late toxicity and preliminary biochemical outcomes in 772 patients with clinically localized prostate cancer treated with high-dose intensity-modulated radiotherapy (IMRT). ⋯ These data demonstrate the feasibility of high-dose IMRT in a large number of patients. Acute and late rectal toxicities seem to be significantly reduced compared with what has been observed with conventional three-dimensional conformal radiotherapy techniques. Short-term PSA control rates seem to be at least comparable to those achieved with three-dimensional conformal radiotherapy at similar dose levels. Based on this favorable risk:benefit ratio, IMRT has become the standard mode of conformal treatment delivery for localized prostate cancer at our institution.
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Int. J. Radiat. Oncol. Biol. Phys. · Aug 2002
Metabolic imaging of low-grade gliomas with three-dimensional magnetic resonance spectroscopy.
The role of radiotherapy (RT) seems established for patients with low-grade gliomas with poor prognostic factors. Three-dimensional (3D) magnetic resonance spectroscopy imaging (MRSI) has been reported to be of value in defining the extent of glioma infiltration. We performed a study examining the impact MRSI would have on the routine addition of 2-3-cm margins around MRI T2-weighted hyperintensity to generate the treatment planning clinical target volume (CTV) for low-grade gliomas. ⋯ Metabolically active tumor, as detected by MRSI, is restricted mainly to the T2 hyperintensity in low-grade gliomas, but can extend outside it in a limited and nonuniform fashion up to 2 cm. Therefore, a CTV including T2 and areas of CNI extension beyond the T2 hyperintensity would result in a reduction in the size and a change in the shape of the standard clinical target volumes generated by adding uniform margins of 2-3 cm to the T2 hyperintensity.
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Int. J. Radiat. Oncol. Biol. Phys. · Aug 2002
Initial experience with ultrasound localization for positioning prostate cancer patients for external beam radiotherapy.
Transabdominal ultrasound localization of the prostate gland and its immediate surrounding anatomy has been used to guide the positioning of patients for the treatment of prostate cancer. This process was evaluated in terms of (1) the reproducibility of the ultrasound measurement; (2) a comparison of patient position between ultrasound localization and skin marks determined from a CT treatment planning scan; (3) the predictive indicators of patient anatomy not well suited for ultrasound localization; (4) the measurement of prostate organ displacement resulting from ultrasound probe pressure; and (5) quality assurance measures. ⋯ The ultrasound positioning system is reproducible and may indicate the need for significant positioning moves. Factors that predict poor image quality are the depth to the isocenter, thickness of tissue overlying the bladder, and position of the prostate relative to the pubic symphysis. The prostate gland may be displaced a small amount by the pressure of the ultrasound probe. A quality assurance program is necessary to detect ultrasound equipment defects that could result in patient alignment errors.