Dosimetric consequences of a translational isocenter correction based on image guidance for intensity modulated radiotherapy (IMRT) of the prostate

Interfractional prostate motion during radiotherapy can have deleterious clinical consequences. It has become clinical practice to re-position the patient according to ultrasound or other imaging techniques. We investigated the dosimetric consequences of the linear translational position correction...

Full description

Saved in:
Bibliographic Details
Published in:Physics in medicine & biology 2007-09, Vol.52 (18), p.5655-5665
Main Authors: Wertz, H, Lohr, F, Dobler, B, Mai, S, Welzel, G, Boda-Heggemann, J, Wenz, F
Format: Article
Language:English
Subjects:
Humans
Male
Motion
Prostatic Neoplasms - diagnostic imaging
Prostatic Neoplasms - radiotherapy
Radiometry - methods
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted - methods
Radiotherapy, Computer-Assisted - methods
Radiotherapy, Conformal - methods
Relative Biological Effectiveness
Reproducibility of Results
Sensitivity and Specificity
Tomography, X-Ray Computed - methods
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Interfractional prostate motion during radiotherapy can have deleterious clinical consequences. It has become clinical practice to re-position the patient according to ultrasound or other imaging techniques. We investigated the dosimetric consequences of the linear translational position correction (isocenter correction) when a conformal IMRT technique with nine fields was used. Treatment plans of seven patients with empty and distended rectums were analyzed. The reference plans were calculated on the CT with an empty rectum. The treatment plans were transferred to a second CT with a distended rectum for an uncorrected setup of the patient referenced to bony anatomy and a corrected setup after translational position correction of the isocenter. The dosimetric consequences (with and without correction) were analyzed. For single treatment fractions, organ motion decreased the volume of the prostate encompassed by the 95% isodose (V95%) by up to -24%-p (percentage points). The mean rectum dose increased by up to 41%-p. Linear translational correction increased V95% of the prostate by up to 17%-p while the mean rectum dose was reduced by up to -23%-p compared to the uncorrected setup. Linear translational correction can improve radiation treatment accuracy for prostate cancer if geometrical changes are within certain limits.
ISSN:0031-9155
1361-6560
DOI:10.1088/0031-9155/52/18/012