Dose-escalation using intensity-modulated radiotherapy for prostate cancer--evaluation of the dose distribution with and without 18F-choline PET-CT detected simultaneous integrated boost.
OBJECTIVE
The aim of the study was to evaluate the impact of a dose escalation to an (18)F-choline PET-CT defined simultaneous integrated boost (IB) on the dose distribution and changes of the equivalent uniform dose (EUD).


METHODS
PET-CT was performed in 12 consecutive patients for treatment planning. An intraprostatic lesion was defined by a tumour-to-background uptake value ratio >2 (GTV(PET)). Dose escalation was focused only on the intraprostatic lesion. Two comparisons were evaluated: whole prostate irradiation to 76 Gy+/-boost to 80 Gy (C1) and whole prostate irradiation to 66.6 Gy+/-boost to 83.25 Gy (C2).


RESULTS
PTV/GTV(PET)+margins were covered by a mean EUD of 75.9/76.1 Gy vs. 77.1/80.1 Gy (C1) and 66.5/66.2 Gy vs. 71.1/82.9 Gy (C2) (p<0.01, respectively). Concerning the organs at risk, EUD increased slightly with an additional boost (mean EUD for bladder: C1 53.2 Gy vs. 53.8 Gy; C2 43.0 Gy vs. 45.1 Gy; for rectum: C1 52.0 Gy vs. 52.6 Gy; C2 43.0 Gy vs. 45.4 Gy; p<0.01, respectively). The distance to the organs at risk had a significant impact on the respective maximum doses in the treatment plans with IB.


CONCLUSIONS
Treatment planning with IB allows an individually adapted dose escalation. The therapeutic ratio can be improved by a considerable dose escalation to the macroscopic tumour, but only minor EUD changes to the bladder and rectum.
Pinkawa
Michael
M
Department of Radiation Oncology, RWTH Aachen University, Aachen, Germany. MPinkawa@ukaachen.de
Attieh
Charbel
C
Piroth
Marc D
MD
Holy
Richard
R
Nussen
Sandra
S
Klotz
Jens
J
Hawickhorst
Robert
R
Schäfer
Wolfgang
W
Eble
Michael J
MJ
D000368:Aged; D002794:Choline / Q000031:analogs & derivatives*; D005462:Fluorine Radioisotopes; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects; D014057:Tomography, X-Ray Computed
D005462:Fluorine Radioisotopes; C514960:fluorocholine; D002794:Choline