Feasibility of postmastectomy treatment with helical TomoTherapy.
OBJECTIVE
To investigate the potential of helical tomotherapy for postmastectomy radiation therapy.


METHODS
By use of the TomoTherapy Hi-Art II treatment-planning system (TomoTherapy Inc., Madison, WI), helical tomotherapy dose plans were developed for 5 patients and compared with the mixed-beam (electron-photon) plans with which they had been treated. The TomoTherapy plans were evaluated by use of dose-volume quantities, tumor control probability, normal tissue complication probability (NTCP), and secondary cancer complication probability (SCCP).


RESULTS
The TomoTherapy plans showed better dose homogeneity in the planning treatment volume containing the chest wall and internal mammary nodes (p = 0.001) and eliminated the need for abutting fields. For the normal tissues, the TomoTherapy plans showed a smaller fractional volume receiving 20 Gy or greater for the ipsilateral lung (p = 0.05), no change in NTCP for postradiation pneumonitis, increased SCCP for each lung and both lungs together (p < 0.02), no change in the volume of the heart receiving more than 15 Gy, no change in NTCP for excess cardiac mortality, and a larger mean dose and SCCP in the contralateral breast (p < 0.001). For nonspecific tissues, the volume receiving between 5 Gy and 25 Gy and SCCP were both larger for the TomoTherapy plans (p < 0.01). Total SCCP was larger for the TomoTherapy plans (p = 0.001).


CONCLUSIONS
Overall, the TomoTherapy plans had comparable tumor control probability and NTCP to the mixed-beam plans and increased SCCP. The TomoTherapy plans showed significantly greater dose homogeneity in the chest wall, which offers the potential for improved cosmesis after treatment. These factors have resulted in TomoTherapy often being the treatment of choice for postmastectomy radiation therapy in our clinic.
Ashenafi
Michael
M
Department of Physics and Astronomy, Louisiana State University and Agricultural & Mechanical College, Baton Rouge, Louisiana, USA.
Boyd
Robert A
RA
Lee
Tae K
TK
Lo
Kenneth K
KK
Gibbons
John P
JP
Rosen
Isaac I
II
Fontenot
Jonas D
JD
Hogstrom
Kenneth R
KR
D000328:Adult; D000368:Aged; D001940:Breast / Q000528:radiation effects; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000601:surgery*; D005240:Feasibility Studies; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000528:radiation effects; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000528:radiation effects; D008198:Lymph Nodes / Q000000981:diagnostic imaging; D008408:Mastectomy; D008875:Middle Aged; D011184:Postoperative Period; D011832:Radiation Injuries / Q000517:prevention & control; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D035441:Thoracic Wall / Q000000981:diagnostic imaging / Q000528:radiation effects