Dosimetric assessment of static and helical TomoTherapy in the clinical implementation of breast cancer treatments.
OBJECTIVE
Investigation of the use of TomoTherapy and TomoDirect versus conventional radiotherapy for the treatment of post-operative breast carcinoma. This study concentrates on the evaluation of the planning protocol for the TomoTherapy and TomoDirect TPS, dose verification and the implementation of in vivo dosimetry.


METHODS
Eight patients with different breast cancer indications (left/right tumor, axillary nodes involvement (N+)/no nodes (N0), tumorectomy/mastectomy) were enrolled. TomoTherapy, TomoDirect and conventional plans were generated for prone and supine positions leading to six or seven plans per patient. Dose prescription was 42Gy in 15 fractions over 3weeks. Dose verification of a TomoTherapy plan is performed using TLDs and EDR2 film inside a home-made wax breast phantom fixed on a rando-alderson phantom. In vivo dosimetry was performed with TLDs.


RESULTS
It is possible to create clinically acceptable plans with TomoTherapy and TomoDirect. TLD calibration protocol with a water equivalent phantom is accurate. TLD verification with the phantom shows measured over calculated ratios within 2.2% (PTV). An overresponse of the TLDs was observed in the low dose regions (<0.1Gy). The film measurements show good agreement for high and low dose regions inside the phantom. A sharp gradient can be created to the thoracic wall. In vivo dosimetry with TLDs was clinically feasible.


CONCLUSIONS
The TomoTherapy and TomoDirect modalities can deliver dose distributions which the radiotherapist judges to be equal to or better than conventional treatment of breast carcinoma according to the organ to be protected.
Reynders
Truus
T
Radiotherapy Department, Oncology Center, UZ Brussel, 1090 Brussels, Belgium. truus.reynders@uzbrussel.be
Tournel
Koen
K
De Coninck
Peter
P
Heymann
Steve
S
Vinh-Hung
Vincent
V
Van Parijs
Hilde
H
Duchateau
Michaël
M
Linthout
Nadine
N
Gevaert
Thierry
T
Verellen
Dirk
D
Storme
Guy
G
D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000601:surgery; D015331:Cohort Studies; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008408:Mastectomy / Q000379:methods; D019047:Phantoms, Imaging; D016684:Prone Position; D011832:Radiation Injuries / Q000517:prevention & control; D011834:Radiation Monitoring / Q000379:methods; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D018714:Radiotherapy, Adjuvant; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D016683:Supine Position; D036542:Tomography, Spiral Computed; D016896:Treatment Outcome