A study of the effect of setup errors and organ motion on prostate cancer treatment with IMRT.
OBJECTIVE
To assess the influence of setup errors and organ motion in terms of the probability of tumor control and normal-tissue complications by tumor control probability and normal-tissue complication probability.


METHODS
Twelve patients were treated for prostate cancer with intensity-modulated radiation therapy. Two orthogonal portal images were taken daily. All patients underwent three computed tomography scans during the 8-week treatment time (i.e., baseline, intermediate, and final). The original treatment plans were re-evaluated, taking into account setup errors and organ motion.


RESULTS
The mean shifts +/- standard deviation of the whole patient population in the lateral, anterior-posterior, and craniocaudal direction were 1.0 +/- 1.5 mm, 0.9 +/- 2.1 mm, and 1.9 +/- 2.1 mm, respectively. In most of the recalculated dose-volume histograms, the coverage of clinical target volume was granted despite organ motion, whereas the rectal wall histograms were often very different from the planned ones.


CONCLUSIONS
We have studied the impact of prostate and rectum motion, as well as setup errors, on dose-volume histograms. The estimate of these effects may have implications for predictive indications when planning intensity-modulated radiation therapy treatments on prostate.
Landoni
Valeria
V
Laboratorio di Fisica Medica e Sistemi Esperti, Istit4uto Regina Elena, Rome, Italy. landoni@ifo.it
Saracino
Bianca
B
Marzi
Simona
S
Gallucci
Michaele
M
Petrongari
Maria G
MG
Chianese
Enrico
E
Benassi
Michaela
M
Iaccarino
Giuseppe
G
Soriani
Antonella
A
Arcangeli
Giorgio
G
D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009068:Movement; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011859:Radiography; D050397:Radiotherapy, Intensity-Modulated; D012007:Rectum / Q000000981:diagnostic imaging; D012062:Relative Biological Effectiveness; D013679:Technology, Radiologic / Q000379:methods