International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2003
Impact of a micromultileaf collimator on stereotactic radiotherapy of uveal melanoma.
To evaluate the impact of a micro multileaf collimator (mMLC) on Linac-based stereotactic radiotherapy (SRT) of uveal melanoma by comparing circular arc with static conformal, dynamic arc, and intensity-modulated SRT. ⋯ Conformal mMLC and dynamic arc SRT are the treatment options of choice for Linac-based SRT of uveal melanoma. They present dosimetric advantages, while being highly efficient in treatment planning and delivery.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2003
Role of IMRT in reducing penile doses in dose escalation for prostate cancer.
In three-dimensional conformal radiotherapy (3D-CRT), penile tissues adjacent to the prostate are exposed to significant doses of radiation. This is likely to be a factor in development of posttreatment erectile dysfunction. In this study, we investigate whether intensity-modulated radiation therapy (IMRT) leads to lower radiation exposure to proximal penile tissues (PPT) when compared with 3D-CRT. ⋯ IMRT allows for dose escalation in prostate cancer while keeping penile tissue doses significantly lower compared to conformal radiotherapy. This may result in improved potency rates over current results observed with 3D-CRT.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2003
Improved conformality and decreased toxicity with intraoperative computer-optimized transperineal ultrasound-guided prostate brachytherapy.
We have developed an intraoperative three-dimensional (3D) conformal treatment planning system for permanent prostate implantation in an effort to reduce toxicity further and improve the accuracy of this procedure. We report the preliminary outcome of patients with localized prostate cancer treated with this approach. ⋯ The integration of an intraoperative optimization program with 3D dose evaluation throughout the target volume for prostate brachytherapy has consistently achieved excellent target coverage with the PD, and the dose levels to normal tissues were effectively restricted to tolerance ranges. These changes have led to a more favorable acute toxicity profile for patients treated with this technique without compromising biochemical control.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2003
Clinical implications of incorporating heterogeneity corrections in mantle field irradiation.
Patient dose calculations for mantle-field irradiation have traditionally been performed using homogeneous, water phantom data. The advent of computed tomography (CT)-based treatment planning now permits dose calculations to be corrected for actual patient density. Incorporation of full heterogeneity corrections is desirable, because calculations performed in this fashion more closely represent the actual dose delivered to the patient. In preparation for full clinical implementation of heterogeneity corrections in mantle irradiation, an evaluation of possible changes in dosimetry when transitioning from treatment plans generated without heterogeneity corrections to treatment plans that incorporated full heterogeneity corrections is presented. ⋯ In all patient treatment plans evaluated, no significant dosimetric differences were observed between heterogeneity-corrected and heterogeneity-uncorrected treatment plans. However, unpredictable differences in the prescription isodose (30.6 Gy) were observed. The differences in coverage at the 90% isodose volume were negligible. The dose administered to lung in heterogeneity-corrected plans demonstrates a higher dose overall, with the greatest increase occurring at volumes receiving at least 20 Gy. In light of these small dosimetric differences, we believe that heterogeneity corrections can be incorporated into full mantle-field treatment planning.
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Although numerous prostate cancer quality-of-life studies have been reported, a paucity of data exists regarding brachytherapy-related dysuria. In this study, we evaluated the incidence and temporal resolution of dysuria, along with the influence of multiple treatment, clinical, and dosimetric parameters. ⋯ After permanent prostate brachytherapy, dysuria is a relatively common event, but only rarely severe in frequency or intensity. At approximately 45 months after brachytherapy, dysuria appears to resolve in almost all patients.