Static beam tomotherapy (TD) can provide an effective method for whole breast radiation therapy (WBRT) that is comparable or superior to intensity-modulated radiation therapy (IMRT) in several ways: 1) TD plans achieved comparable target coverage and homogeneity as IMRT plans while reducing the median dose, maximum dose, and homogeneity index slightly but significantly. 2) TD significantly reduced the volume of ipsilateral lung receiving low doses of radiation compared to IMRT. 3) TD planning was significantly faster than IMRT, requiring approximately half the time with a mean savings of 17.8 minutes per patient. 4) Other organs at risk were comparable between the two techniques.

1. Static beam tomotherapy (TD) as an
optimisation method in whole breast
radiation therapy (WBRT)
Squires, M (BMRS (RT) MA MIR JP MBA(cand.)), Cheers, S (BAppSc (MRS)), Fong, A
(BSc(Med) MB BS MeH FRANZCR), Archibald-Heeren, B (BMRS (RT)), Hu, Y (BMP MSc), Teh,
A (BSc(Med) MB BS (Hons) FRANZCR)

2. • The linear accelerator traditionally used in whole breast radiation
therapy
• Is tomotherapy a viable alternative?
Background

3. • What is tomotherapy?
Background

4. Background

5. • Traditional tangents
• Helical (tomo / VMAT)
• TomoDirect
Background

6. To evaluate static beam tomotherapy (TD) as a method of dose
optimisation for the delivery of whole breast radiation therapy (WBRT)
Aim

7. • Treatment plans of 27 women previously optimised on RayStation
v4.5 (RaySearch, Stockholm, Sweden) were replanned using TomoDirect (Accuray,
Sunnyvale, California)
Methods and Materials

8. • A simple medial and lateral beam arrangement was utilised, with no
OARs included in optimisation
• A ring volume (+0.2cm-+2.0cm) was used to control integral dose.
Prescriptions were normalised to 50Gy and planning time recorded
Methods and Materials

9. • TD parameters included a field width of 2.5cm, a (default) pitch of
0.251 and a modulation factor of 2.000
Methods and Materials

10. • Both modalities fell within ICRU62 target homogeneity objectives
• Median
TD = 51.1Gy vs IMRT = 50.9Gy, p=0.03
• D1
TD = 53.5Gy vs IMRT = 53.0Gy, p=0.02
• Homogeneity index (HI)
TD = 0.11 vs IMRT = 0.10, p=0.03
Results

11. • Both modalities fell within ICRU62 target homogeneity objectives
• VTD
TD = 85.5% vs IMRT = 82.0%, p=0.09
(No significant difference)
• D99
TD = 48.0Gy vs IMRT = 48.1Gy, p=0.26
(No significant difference)
Results

12. • TD plans produced a statistically significant reduction in V5 ipsilateral
lung doses
TD V5 = 23.2% vs IMRT = 27.2%, p=0.04
• TD reduced planning time considerably
TD = 9.8m vs IMRT = 27.6m, p<0.01
saving an average planning time of 17.8 minutes per patient
Results

13. • Other queried OAR metrics remained statistically comparable
• Ipsilateral lung
TD V20 = 13.2% vs IMRT = 14.6%, p=0.30
• Heart
TD V5 = 2.7% vs IMRT = 2.8%, p=0.47
TD V10 = 1.7% vs IMRT = 1.8%, p=0.44
Results

14. Conclusion
Static beam tomotherapy (TD) can provide a superior method of
whole breast radiation therapy (WBRT):
• Comparable target metrics
• A reduced ipsilateral lung dose
• A reduced user optimisation time

15. ROC Gosford
[1] Fields E, Rabinovitch R, Ryan N, Miften M, Westerly D 2013, ‘Á detailed evaluation of TomoDirect 3DCRT planning for
whole-breast radiation therapy.’ Medical Dosimetry 38: 401-406
[2] Franco P, Catuzzo P, Cante D, La Porta MR, Sciacero P, Girelli G, Casanova Borca, V, Pasquino M, Numico G, Tofani S,
Meloni T, Ricardi U, Ozzello F 2011, ‘TomoDirect: an efficient means to deliver radiation at static angles with tomotherapy.’
Tumori 97: 498-502
[3] Franco P, Ricardi U 2012, ‘Tomo Direct to deliver static angle tomotherapy treatments.’ Nuclear Medicine and Radiation
Therapy 3:5
References & Acknowledgements