The influence of the use of CT-planning on the irradiated boost volume in breast conserving treatment.
OBJECTIVE
The purpose of this study was to investigate the effect of CT-based delineation and planning on the irradiated boost volume. For this specific purpose we used the data as derived from 2 prospective phase III randomised trials.


METHODS
Data from 1331 patients (<or=50 years) were analyzed with a reported boost volume from a simulation-based treatment plan (EORTC boost vs no boost trial, n=922), and a CT-scan-based treatment plan (Young Boost Trial, n=409) group. Tumour diameter, irradiation technique (photons vs electrons), lumpectomy size, and age were used as covariates.


RESULTS
Median V(95%) in the conventional simulation-based treatment plans was 99 cc (range 9-628) for photons and was 98 cc (13-651) for electrons, whereas in the CT-planned patients, these figures were 178 cc (37-2699) and 150 cc (43-1272), respectively. Multivariable analysis showed an association of the irradiated boost volume with tumour size (p<0.0067), lumpectomy size (p<0.0002), and boost technique (p<0.0004). The use of a CT-scan for volume delineation and treatment planning remained significant (p<0.0001).


CONCLUSIONS
The use of a CT-scan for delineation and treatment planning led to a significant increase of the irradiated boost volume by a factor of 1.5-1.8, compared to conventional simulator-based plans.
Al Uwini
Shafak
S
Department of Radiotherapy, Erasmus Medical Centre, Rotterdam, The Netherlands. s.aluwini@erasmusmc.nl
Antonini
Ninja
N
Poortmans
Philip M
PM
Boersma
Liesbeth
L
Hurkmans
Coen
C
Leer
Jan Willem
JW
Horiot
Jean-Claude
JC
Struikmans
Henk
H
Bartelink
Harry
H
D000328:Adult; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000601:surgery; D017326:Clinical Trials, Phase III as Topic; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015412:Mastectomy, Segmental / Q000379:methods*; D008875:Middle Aged; D015999:Multivariate Analysis; D011182:Postoperative Care / Q000379:methods; D011300:Preoperative Care / Q000379:methods; D011336:Probability; D011446:Prospective Studies; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D018714:Radiotherapy, Adjuvant; D020266:Radiotherapy, Conformal / Q000379:methods; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome