Liebe Mitstreiter,
hier in Deutsch nur die Schlussfolgerung vom M. D. Anderson Hospital bezüglich der korrekten Größe des Bestrahlungsfeldes bei IMRT, um eine ausreichender Bestrahlung der Samenblasen zu gewährleisten. Der gesamte Text steht darunter in Englisch.
Günter
Schlussfolgerung: Der 3 mm intrafraktionale Abstand war ausreichend für die Bestrahlung der Prostata. Bei einer nicht geringen Anzahl von Patienten wurden hiermit die Samenblasen nicht ausreichend hoch dosiert bestrahlt. Die Dosierungsanpassung an das Rektum beeinträchtigte die Dosishöhe der Samenblasen deutlich. Bei fortgeschrittenem PCa raten wir größere Bestrahlungsfelder zu wählen, oder aber die Immobilisierung der Prostata zu verbessern (z. B. Rektalballon), um eine ausreichende Bestrahlung der Samenblasen durchführen zu können.
To determine whether a 3-mm isotropic target margin adequately covers the prostate and seminal vesicles (SVs) during administration of an intensity-modulated radiation therapy (IMRT) treatment fraction, assuming that daily image-guided setup is performed just before each fraction
In-room computed tomographic (CT) scans were acquired immediately before and after a daily treatment fraction in 46 patients with prostate cancer. An eight-field IMRT plan was designed using the pre-fraction CT with a 3-mm margin and subsequently recalculated on the post-fraction CT. For convenience of comparison, dose plans were scaled to full course of treatment (75.6Gy). Dose coverage was assessed on the post-treatment CT image set.
During one treatment fraction (21.4+/-5.5min), there were reductions in the volumes of the prostate and SVs receiving the prescribed dose (median reduction 0.1% and 1.0%, respectively, p<0.001) and in the minimum dose to 0.1 cm(3) of their volumes (median reduction 0.5 and 1.5Gy, p<0.001). Of the 46 patients, three patients' prostates and eight patients' SVs did not maintain dose coverage above 70Gy. Rectal filling correlated with decreased percentage-volume of SV receiving 75.6, 70, and 60Gy (p<0.02).
The 3-mm intrafractional margin was adequate for prostate dose coverage. However, a significant subset of patients lost SV dose coverage. The rectal volume change significantly affected SV dose coverage. For advanced-stage prostate cancers, we recommend to use larger margins or improve organ immobilization (such as with a rectal balloon) to ensure SV coverage.
Melancon AD, O'daniel JC, Zhang L, Kudchadker RJ, Kuban DA, Lee AK, Cheung RM, de Crevoisier R, Tucker SL, Newhauser WD, Mohan R, Dong L
Reference
Radiother Oncol. 2007 Sep 22; [Epub ahead of print]
doi:10.1016/j.radonc.2007.08.008
PubMed Abstract
PMID:17892900
UroToday.com Prostate Cancer Section
hier in Deutsch nur die Schlussfolgerung vom M. D. Anderson Hospital bezüglich der korrekten Größe des Bestrahlungsfeldes bei IMRT, um eine ausreichender Bestrahlung der Samenblasen zu gewährleisten. Der gesamte Text steht darunter in Englisch.
Günter
Schlussfolgerung: Der 3 mm intrafraktionale Abstand war ausreichend für die Bestrahlung der Prostata. Bei einer nicht geringen Anzahl von Patienten wurden hiermit die Samenblasen nicht ausreichend hoch dosiert bestrahlt. Die Dosierungsanpassung an das Rektum beeinträchtigte die Dosishöhe der Samenblasen deutlich. Bei fortgeschrittenem PCa raten wir größere Bestrahlungsfelder zu wählen, oder aber die Immobilisierung der Prostata zu verbessern (z. B. Rektalballon), um eine ausreichende Bestrahlung der Samenblasen durchführen zu können.
| Gesamter Text: Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, USA; Program in Medical Physics, The University of Texas Graduate School of Biomedical Sciences at Houston, TX, USA. |
To determine whether a 3-mm isotropic target margin adequately covers the prostate and seminal vesicles (SVs) during administration of an intensity-modulated radiation therapy (IMRT) treatment fraction, assuming that daily image-guided setup is performed just before each fraction
In-room computed tomographic (CT) scans were acquired immediately before and after a daily treatment fraction in 46 patients with prostate cancer. An eight-field IMRT plan was designed using the pre-fraction CT with a 3-mm margin and subsequently recalculated on the post-fraction CT. For convenience of comparison, dose plans were scaled to full course of treatment (75.6Gy). Dose coverage was assessed on the post-treatment CT image set.
During one treatment fraction (21.4+/-5.5min), there were reductions in the volumes of the prostate and SVs receiving the prescribed dose (median reduction 0.1% and 1.0%, respectively, p<0.001) and in the minimum dose to 0.1 cm(3) of their volumes (median reduction 0.5 and 1.5Gy, p<0.001). Of the 46 patients, three patients' prostates and eight patients' SVs did not maintain dose coverage above 70Gy. Rectal filling correlated with decreased percentage-volume of SV receiving 75.6, 70, and 60Gy (p<0.02).
The 3-mm intrafractional margin was adequate for prostate dose coverage. However, a significant subset of patients lost SV dose coverage. The rectal volume change significantly affected SV dose coverage. For advanced-stage prostate cancers, we recommend to use larger margins or improve organ immobilization (such as with a rectal balloon) to ensure SV coverage.
Melancon AD, O'daniel JC, Zhang L, Kudchadker RJ, Kuban DA, Lee AK, Cheung RM, de Crevoisier R, Tucker SL, Newhauser WD, Mohan R, Dong L
Reference
Radiother Oncol. 2007 Sep 22; [Epub ahead of print]
doi:10.1016/j.radonc.2007.08.008
PubMed Abstract
PMID:17892900
UroToday.com Prostate Cancer Section