Analysis of interfraction and intrafraction variation during tangential breast irradiation with an electronic portal imaging device.
OBJECTIVE
To evaluate the daily setup variation and the anatomic movement of the heart and lungs during breast irradiation with tangential photon beams, as measured with an electronic portal imaging device.


METHODS
Analysis of 1,709 portal images determined changes in the radiation field during a treatment course in 8 patients. Values obtained for every image included central lung distance (CLD) and area of lung and heart within the irradiated field. The data from these measurements were used to evaluate variation from setup between treatment days and motion due to respiration and/or patient movement during treatment delivery.


RESULTS
The effect of respiratory motion and movement during treatment was minimal: the maximum range in CLD for any patient on any day was 0.25 cm. The variation caused by day-to-day setup variation was greater, with CLD values for patients ranging from 0.59 cm to 2.94 cm. Similar findings were found for heart and lung areas.


CONCLUSIONS
There is very little change in CLD and corresponding lung and heart area during individual radiation treatment fractions in breast tangential fields, compared with a relatively greater amount of variation that occurs between days.
Smith
Ryan P
RP
Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104, USA.
Bloch
Peter
P
Harris
Eleanor E
EE
McDonough
James
J
Sarkar
Abhirup
A
Kassaee
Alireza
A
Avery
Steven
S
Solin
Lawrence J
LJ
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006321:Heart; D006801:Humans; D008168:Lung; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009068:Movement; D019095:Point-of-Care Systems; D011859:Radiography; D011879:Radiotherapy Dosage; D012119:Respiration; D014894:Weights and Measures