International journal of radiation oncology, biology, physics
-
Int. J. Radiat. Oncol. Biol. Phys. · Jun 2000
Comparative StudyThree-dimensional conformal therapy or standard irradiation in localized carcinoma of prostate: preliminary results of a nonrandomized comparison.
We present preliminary results of a nonrandomized comparison of three-dimensional conformal radiation therapy (3D CRT) and standard radiation therapy (SRT) in localized carcinoma of the prostate in two groups of patients with comparable prognostic factors treated during the same period. ⋯ Three-dimensional CRT spares more normal tissues, yields higher chemical disease-free survival, and results in less treatment morbidity than SRT in treatment of Stage T1-T2 prostate cancer. Longer follow-up is needed to confirm these preliminary observations.
-
Int. J. Radiat. Oncol. Biol. Phys. · Jun 2000
Dosimetric and volumetric criteria for selecting a source activity and a source type ((125)I or (103)Pd) in the presence of irregular seed placement in permanent prostate implants.
The dosimetric merit of a permanent prostate implant relies on two factors: the quality of the plan itself, and the fidelity of its implementation. The former factor depends on source type and on source strength, while the latter is a combination of skill and experience. The purpose of this study is to offer criteria by which to select a source type ((125)I or (103)Pd) and activity. ⋯ For both isotopes, the lower activities studied systematically result in lower EIs. If seeds can be placed within approximately 0.5 cm of their intended position (103)Pd should be preferred because its EI is lower than that of (125)I. For all activities the coverage indices and D90 are within the required range. If seed placement uncertainties are larger than 0.5 cm, (125)I provides slightly better target coverage; however, in terms of external volume (healthy tissue) covered, (103)Pd is superior to (125)I.
-
Int. J. Radiat. Oncol. Biol. Phys. · Jun 2000
Radiotherapy of prostate cancer with or without intensity modulated beams: a planning comparison.
To evaluate whether intensity modulated radiotherapy (IMRT) by static segmented beams allows the dose to the main portion of the prostate target to escalate while keeping the maximal dose at the anterior rectal wall at 72 Gy. The value of such IMRT plans was analyzed by comparison with non-IMRT plans using the same beam incidences. ⋯ IMRT significantly increases the ratio of TCP over NTCP of the rectum in the treatment of prostate cancer. However, constraints for TDI are needed, because a high degree of TDI reduced minimal target dose. IMRT improved uncomplicated local control probability. In our department, IMRT by static segmented beams is planned and delivered in a cost-effective way. IMRT-lim has replaced non-modulated conformal radiotherapy as the standard treatment for prostate cancer.
-
Int. J. Radiat. Oncol. Biol. Phys. · Jun 2000
Defining the appropriate radiation dose for pretreatment PSA < or = 10 ng/mL prostate cancer.
To investigate whether a dose response exists for biochemical no evidence of disease (bNED) control in prostate cancer patients with pretreatment prostate-specific antigen (PSA) < or = 10 ng/mL and to identify the patient subgroups affected. ⋯ The poor prognosis subset of PSA < or =10 ng/mL prostate cancer patients benefit from dose escalation. A dose response is not demonstrated for prostate cancer patients with pretreatment PSA < or =10 ng/mL and other favorable features.
-
Int. J. Radiat. Oncol. Biol. Phys. · Jun 2000
The impact of postimplant edema on the urethral dose in prostate brachytherapy.
The objective of this work is to determine the effect of timing of the postimplant CT scan on the assessment of the urethral dose. ⋯ The assessment of the urethral dose depends upon the timing of the postimplant CT scan. The mean D(10) dose derived from the CT scans obtained at 46 +/- 23 days postimplant was 90 +/- 56 Gy higher than that derived from the CT scans obtained on the day of the implant. Because of this large difference, the timing of the postimplant CT scan needs to be specified when specifying dose thresholds for urethral morbidity.