International journal of radiation oncology, biology, physics
-
Int. J. Radiat. Oncol. Biol. Phys. · Aug 2002
A predictive model for survival in metastatic cancer patients attending an outpatient palliative radiotherapy clinic.
To develop a predictive model for survival from the time of presentation in an outpatient palliative radiotherapy clinic. ⋯ Clinical prognostic factors can be used to predict prognosis among patients attending a palliative radiotherapy clinic. If validated in an independent series of patients, the model can be used to guide clinical decisions, plan supportive services, and allocate resource use.
-
Int. J. Radiat. Oncol. Biol. Phys. · Aug 2002
A pilot study of topical intrarectal application of amifostine for prevention of late radiation rectal injury.
Clinical symptomatic late injury to the rectal wall occurs in about one-third of patients with prostate cancer treated with external beam irradiation. Reducing the physical dose to the anterior rectal wall without a similar reduction in the posterior peripheral zone is difficult because of the proximity of the prostate to the anterior rectal wall. On the basis of our previous observations in an animal model that intrarectal application of amifostine resulted in very high concentrations of amifostine and its active metabolite WR-1065 in the rectal wall, a Phase I dose-escalation clinical trial was undertaken. ⋯ Intrarectal application of amifostine is feasible and well tolerated. Systemic absorption of amifostine and its metabolites is negligible, and close monitoring of patients is not required with rectal administration. Proctoscopy is superior to symptom score as a method of assessing radiation damage of the rectal wall. The preliminary efficacy data are encouraging, and further clinical studies are warranted.
-
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.
-
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.
-
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.