Retrospective cohort study of bronchial doses and radiation-induced atelectasis after stereotactic body radiation therapy of lung tumors located close to the bronchial tree.
OBJECTIVE
To evaluate the dose-response relationship between radiation-induced atelectasis after stereotactic body radiation therapy (SBRT) and bronchial dose.


METHODS
Seventy-four patients treated with SBRT for tumors close to main, lobar, or segmental bronchi were selected. The association between incidence of atelectasis and bronchial dose parameters (maximum point-dose and minimum dose to the high-dose bronchial volume [ranging from 0.1 cm(3) up to 2.0 cm(3)]) was statistically evaluated with survival analysis models.


RESULTS
Prescribed doses varied between 4 and 20 Gy per fraction in 2-5 fractions. Eighteen patients (24.3%) developed atelectasis considered to be radiation-induced. Statistical analysis showed a significant correlation between the incidence of radiation-induced atelectasis and minimum dose to the high-dose bronchial volumes, of which 0.1 cm(3) (D(0.1cm3)) was used for further analysis. The median value of D(0.1cm3) (α/β = 3 Gy) was EQD(2,LQ) = 147 Gy3 (range, 20-293 Gy3). For patients who developed atelectasis the median value was EQD(2,LQ) = 210 Gy3, and for patients who did not develop atelectasis, EQD(2,LQ) = 105 Gy3. Median time from treatment to development of atelectasis was 8.0 months (range, 1.1-30.1 months).


CONCLUSIONS
In this retrospective study a significant dose-response relationship between the incidence of atelectasis and the dose to the high-dose volume of the bronchi is shown.
Department of Medical Physics, Karolinska University Hospital, Stockholm, Sweden; Department of Oncology-Pathology, Karolinska Institute, Stockholm, Sweden. Electronic address: kristin.karlsson@karolinska.se.
Kristin
K
Karlsson
Jan
J
Nyman
Pia
P
Baumann
Peter
P
Wersäll
Ninni
N
Drugge
Giovanna
G
Gagliardi
Karl-Axel
KA
Johansson
Jan-Olov
JO
Persson
Eva
E
Rutkowska
Owe
O
Tullgren
Ingmar
I
Lax
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001980:Bronchi / Q000528:radiation effects*; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000601:surgery*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D001261:Pulmonary Atelectasis / Q000209:etiology*; D011832:Radiation Injuries / Q000150:complications*; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D013548:Sweden