Body radiation exposure in breast cancer radiotherapy: impact of breast IMRT and virtual wedge compensation techniques.
OBJECTIVE
Recent reports demonstrate a dramatically increased rate of secondary leukemia for breast cancer patients receiving adjuvant high-dose anthracycline and radiotherapy, and that radiation is an independent factor for the development of leukemia. This study aimed to evaluate the radiation body exposure during breast radiotherapy and to characterize the factors associated with an increased exposure.


METHODS
In a prospective cohort of 120 women, radiation measurements were taken from four sites on the body at the time of adjuvant breast radiotherapy. Multiple regression analysis was performed to analyze patient and treatment factors associated with the amount of scattered radiation.


RESULTS
For standard 50 Gy breast radiotherapy, the minimal dose received by abdominal organs is on average 0.45 Gy, ranging from 0.06 to 1.55 Gy. The use of physical wedges as a compensation technique was the most significant factor associated with increased scattered dose (p < 0.001), resulting in approximately three times more exposure compared with breast intensity-modulated radiation therapy (IMRT) and dynamic wedge.


CONCLUSIONS
The amount of radiation that is scattered to a patient's body is consistent with exposure reported to be associated with excess of leukemia. In accordance with the As Low As Reasonably Achievable (ALARA) principle, we recommend using breast IMRT or virtual wedging for the radiotherapy of breast cancer receiving high-dose anthracycline chemotherapy.
Woo
Tony C S
TC
Department of Radiation Oncology, Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada.
Pignol
Jean-Philippe
JP
Rakovitch
Eileen
E
Vu
Toni
T
Hicks
Deanna
D
O'Brien
Peter
P
Pritchard
Kathleen
K
D001827:Body Height; D001835:Body Weight; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D007953:Leukemia, Radiation-Induced / Q000209:etiology*; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D012044:Regression Analysis; D012542:Scattering, Radiation