Radiation injury after hypofractionated stereotactic radiotherapy for peripheral small lung tumors: serial changes on CT.
OBJECTIVE
We studied the serial changes and CT manifestations of pulmonary radiation injury after hypofractionated stereotactic radiation therapy for peripheral small lung tumors. SUBJECTS AND METHODS. Hypofractionated stereotactic radiation therapy was applied to 20 patients with proven primary (n = 11) or metastatic (n = 9) lung cancer, for a total of 22 lesions of 3 cm or less in diameter located within 3 cm from the parietal pleural surface. Follow-up CT was scheduled at 1 and 3 months, and every 3 months thereafter.


RESULTS
Ground-glass opacities were observed around four (18%) of 22 lesions at 3-6 months. The opacities nearly corresponded to the planned target volume, but half of them were unevenly distributed. Ground-glass opacities gradually disappeared or evolved into dense consolidation while shrinking. Dense consolidations developed in 16 (73%) of 22 lesions, including seven in the center of the planned target volume and nine in the periphery of the planned target volume. Dense consolidations moved in six of these 16 lesions and gradually shrank, becoming fixed as solid or linear opacities approximately 12 months later.


CONCLUSIONS
The pulmonary opacities observed after hypofractionated stereotactic radiation therapy for peripheral small lung tumors may not precisely correspond to the planned target volume (unlike those with conventional radiation therapy) and may change in shape and location dynamically during the first year. Knowledge of these findings is necessary to avoid misunderstandings concerning tumor regrowth or new tumors.
Takeda
Toshiaki
T
Department of Radiology, Tokyo Metropolitan Hiro-o General Hospital, 2-34-10 Ebisu, Shibuya-ku, Tokyo 150-0013, Japan. t-takeda@hiroo-hospital.metro.tokyo.jp
Takeda
Atsuya
A
Kunieda
Etsuo
E
Ishizaka
Akitoshi
A
Takemasa
Kazuhiko
K
Shimada
Kyoko
K
Yamamoto
Seika
S
Shigematsu
Naoyuki
N
Kawaguchi
Osamu
O
Fukada
Jun-Ichi
J
Ohashi
Toshio
T
Kuribayashi
Sachio
S
Kubo
Atsushi
A
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D011832:Radiation Injuries / Q000000981:diagnostic imaging* / Q000209:etiology*; D011878:Radiotherapy / Q000009:adverse effects / Q000379:methods; D014057:Tomography, X-Ray Computed