Active breathing control for patients receiving mediastinal radiation therapy for lymphoma: Impact on normal tissue dose.
OBJECTIVE
Active breathing control (ABC) is emerging as a tool to reduce heart and lung dose for lymphoma patients receiving mediastinal radiation therapy (RT). The objective of this study was to report our early institutional experience with this technique, with emphasis on quantifying the changes in normal tissue dose and exploring factors that could be used to select patients with the greatest benefit.


METHODS
Patients receiving mediastinal involved-field RT (IFRT) for lymphoma were eligible. The ABC was performed using a moderate deep-inspiration breath-hold (mDIBH) technique. All patients were replanned with free-breathing (FB) computed tomographic data sets and comparisons of lung, cardiac, and female breast tissue doses were made between mDIBH and FB plans. Logistic regression models were used to identify factors associated with improvement in mean lung and heart dose with mDIBH.


RESULTS
Forty-seven patients were analyzed; the majority (87.2%) had Hodgkin lymphoma. Median prescribed dose was 30 Gy (range, 20-36 Gy), with 78.7% of cases being treated with parallel-opposed beams. The use of mDIBH significantly improved average mean lung dose (FB: 11.0 Gy; mDIBH: 9.5 Gy; P < .0001), lung V20 (28% vs 22%; P < .0001), and mean heart dose (14.3 Gy vs 11.8 Gy; P = .003), but increased the mean breast dose (FB: 3.0 Gy; mDIBH 3.6 Gy; P = .0005). The magnitude of diaphragmatic excursion on the inhale scan was significantly associated with dosimetric improvement in both heart and lung dose with mDIBH.


CONCLUSIONS
Mediastinal IFRT for lymphoma delivered with mDIBH can significantly reduce lung and heart dose compared with FB, although not for all patients, and may increase breast dose in females. Its implementation is achievable in both adult and pediatric populations. Further work is necessary to better predict which patients benefit from this technique.
Radiation Medicine Program, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada.
Anne-Marie
AM
Charpentier
Radiation Medicine Program, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada.
Tatiana
T
Conrad
Department of Biostatistics, Princess Margaret Hospital, University Health Network, Toronto, Ontario, Canada.
Jenna
J
Sykes
Radiation Medicine Program, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada.
Angela
A
Ng
Radiation Medicine Program, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada.
Rachel
R
Zhou
Radiation Medicine Program, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada.
Amy
A
Parent
Radiation Medicine Program, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada.
Catherine
C
Coolens
Radiation Medicine Program, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada.
Richard W
RW
Tsang
Radiation Medicine Program, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada.
Mary K
MK
Gospodarowicz
Radiation Medicine Program, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada.
Alexander
A
Sun
Radiation Medicine Program, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada. Electronic address: David.hodgson@rmp.uhn.on.ca.
David C
DC
Hodgson
D000293:Adolescent; D000328:Adult; D000368:Aged; D001945:Breathing Exercises / Q000379:methods*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D001239:Inhalation; D008223:Lymphoma / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012189:Retrospective Studies; D055815:Young Adult