Intra-fraction respiratory motion and baseline drift during breast Helical Tomotherapy.
To investigate the intra-fraction breast motion during long-lasting treatments of breast cancer with Helical Tomotherapy by means of an optical tracking system.



A set of seven radio-transparent passive markers was placed on the thoraco-abdominal surface of twenty breast cancer patients and tracked by an infrared tracking system. A continuous non-invasive monitoring of intra-fraction motion from patient setup verification and correction to the end of radiation delivery was thus obtained. The measured displacements were analysed in terms of cyclic respiratory motion and slow baseline drift.



The average monitoring time per patient was 15.57min. The breathing amplitude of the chest was less than 2mm, on average, along all anatomical directions. The baseline drift of the body led to more significant setup uncertainties than the respiratory motion. The main intra-fraction baseline drifts were in posterior and inferior directions and occurred within the first eight minutes of monitoring. Considering the intra-fraction motion only, the resultant clinical-to-planning target volume safety margins are highly patient-specific and largely anisotropic.



The non-respiratory motion occurring during prolonged treatments induces notable uncertainties. Non-invasive continuous monitoring of patient setup variations including baseline drifts is recommended in order to minimize dosimetric deviations, which might jeopardize the therapeutic ratio between target coverage and the sparing of organs at risk.
Department of Radiation Oncology, European Institute of Oncology, Milan, Italy. Electronic address: rosalinda.ricotti@ieo.it.
Rosalinda
R
Ricotti
Department of Radiation Oncology, European Institute of Oncology, Milan, Italy.
Delia
D
Ciardo
Dipartimento di Elettronica Informazione e Bioingegneria, Politecnico di Milano, Milan,Italy.
Giovanni
G
Fattori
Department of Radiation Oncology, European Institute of Oncology, Milan, Italy.
Maria Cristina
MC
Leonardi
Department of Radiation Oncology, European Institute of Oncology, Milan, Italy.
Anna
A
Morra
Department of Radiation Oncology, European Institute of Oncology, Milan, Italy; Department of Oncology and Hemato-oncology, University of Milan, Milan, Italy.
Samantha
S
Dicuonzo
Department of Radiation Oncology, European Institute of Oncology, Milan, Italy; Department of Oncology and Hemato-oncology, University of Milan, Milan, Italy.
Damaris Patricia
DP
Rojas
Unit of Medical Physics, European Institute of Oncology, Milan, Italy.
Floriana
F
Pansini
Unit of Medical Physics, European Institute of Oncology, Milan, Italy.
Raffaella
R
Cambria
Unit of Medical Physics, European Institute of Oncology, Milan, Italy.
Federica
F
Cattani
Dipartimento di Elettronica Informazione e Bioingegneria, Politecnico di Milano, Milan,Italy.
Chiara
C
Gianoli
Tecniche di radiologia medica, per immagini e radioterapia, University of Milan, Milan, Italy.
Chiara
C
Spinelli
Dipartimento di Elettronica Informazione e Bioingegneria, Politecnico di Milano, Milan,Italy.
Marco
M
Riboldi
Dipartimento di Elettronica Informazione e Bioingegneria, Politecnico di Milano, Milan,Italy; Bioengineering Unit, Centro Nazionale di Adroterapia Oncologica, Pavia, Italy.
Guido
G
Baroni
Department of Oncology and Hemato-oncology, University of Milan, Milan, Italy; Scientific Directorate, European Institute of Oncology, Milan, Italy.
Roberto
R
Orecchia
Department of Radiation Oncology, European Institute of Oncology, Milan, Italy; Department of Oncology and Hemato-oncology, University of Milan, Milan, Italy.
Barbara Alicja
BA
Jereczek-Fossa
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009038:Motion; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012119:Respiration
Baseline; Breast; Intra-fraction motion; Optical tracking system; Respiratory motion; Tomotherapy