International journal of radiation oncology, biology, physics
-
Int. J. Radiat. Oncol. Biol. Phys. · Jan 2000
Clinical TrialPostimplant analysis of transperineal interstitial permanent prostate brachytherapy: evidence for a learning curve in the first year at a single institution.
The utilization of transperineal interstitial permanent prostate brachytherapy (TIPPB) is increasing in the United States. Quality assessment of TIPPB is in its infancy, and to date, dosimetric analyses have only been reported from centers with a large experience in prostate brachytherapy. The purpose of this report is to critically analyze the dosimetric coverage achieved following TIPPB in the first 63 cases performed by a multidisciplinary group of investigators with no prior experience with TIPPB. ⋯ In this single institution experience with the first 63 men receiving TIPPB by a multidisciplinary group of investigators, there is evidence for a learning curve. All quantifiers of implant adequacy improved as clinicians gained experience. In the most recent group of patients, quantifiers of implant adequacy are similar to those reported from other groups with significantly more experience with TIPPB.
-
Int. J. Radiat. Oncol. Biol. Phys. · Jan 2000
The early supra-additive apoptotic response of R3327-G prostate tumors to androgen ablation and radiation is not sustained with multiple fractions.
The treatment of R3327-G tumor-bearing rats with androgen ablation (AA) via castration results in a supra-additive increase in apoptosis when 2-8 Gy gamma-irradiation (RT) is given as a single dose 3-14 days afterwards. We report here the dose response and effect of multiple fractions on this supra-additive apoptotic response. ⋯ The early supra-additive apoptotic response from AA and single fraction radiation is not seen at high single fraction doses and is not sustained with repeated fractions. Therefore, the classical apoptotic response that occurs within 24 h of irradiation is not likely to be the main mechanism responsible for any clinical benefit seen with this combination.
-
Int. J. Radiat. Oncol. Biol. Phys. · Jan 2000
Optimal radiotherapy for prostate cancer: predictions for conventional external beam, IMRT, and brachytherapy from radiobiologic models.
To determine, on the basis of radiobiological models, optimal modalities of radiotherapy for localized prostate cancer, and to provide a rational basis for therapeutic decisions. ⋯ The radiobiological models presented suggest a rational basis for choosing among several radiotherapeutic modalities based on biologic risk factors. In addition, they suggest that IMRT may potentially be superior to 3D-CRT in allowing dose escalation without increased morbidity, and that brachytherapy, as monotherapy or as boost, may achieve superior tumor control compared with dose escalation 3D-CRT. The latter conclusion is supported by clinical data.
-
Int. J. Radiat. Oncol. Biol. Phys. · Jan 2000
Case Reports Comparative StudyThe potential for sparing of parotids and escalation of biologically effective dose with intensity-modulated radiation treatments of head and neck cancers: a treatment design study.
Conventional radiotherapy for cancers of the head and neck (HN) can yield acceptable locoregional tumor control rates, but toxicity of many normal tissues limits our ability to escalate dose. Xerostomia represents one of the most common complications. The purpose of this study is to investigate the potential of intensity-modulated radiotherapy (IMRT) to achieve adequate sparing of parotids and to escalate nominal and/or biologically-effective dose to achieve higher tumor control without exceeding normal tissue tolerances. ⋯ IMRT has the potential to significantly improve radiotherapy of HN cancers by reducing normal tissue dose and simultaneously allowing escalation of dose. SIB strategy is not only more efficient and yields better dose distributions, but may also be biologically more effective. Dose-volume-based criteria is better than purely dose-based criteria. The quality of plans improves with number of beams, reaching a saturation level for a certain number of beams, which for the plans studied was found to be 9.