Radiographic pulmonary and pleural changes after carbon ion irradiation.
OBJECTIVE
For the treatment of Stage I non-small-cell lung cancers, a Phase I/II study of carbon ion irradiation was undertaken. In the present study, we focus on posttreatment radiographic lung damage: specifically, its timing, features, and relation to dose-volume factors.


METHODS
Forty-three patients with 44 Stage I non-small-cell lung cancers were treated with carbon ion irradiation ranging from 59.4 to 95.4 photon Gy equivalent dose (GyE) in 18 fractions over 6 weeks, according to our dose escalation protocols. Primary lesions were irradiated by 2-4 portals. Follow-up evaluation with computed tomography (CT) was sequentially performed to assess changes in the lung. CT findings were classified into two categories: pulmonary reaction and pleural reaction. A dose-volume histogram for each patient was calculated, using a three-dimensional CT planning system. Statistical analysis was conducted using Spearman's rank test.


RESULTS
The median appearance period of pulmonary reactions was 3 months after the start of carbon ion irradiation, whereas the maximum period was 6 months. The severity of pulmonary reactions statistically correlated with lung volumes irradiated no less than 20 GyE (vol. 20) and 40 GyE (vol. 40) (p = 0.017 and p = 0.0089). Geometrically unique findings in the irradiated fields were observed in 7 patients (16%). The median appearance period of pleural reactions was 4 months after the start of carbon ion irradiation. The occurrence of pleural reactions significantly correlated with planning target volume (p = 0.000098), vol. 20 (p = 0.00011), and vol. 40 (p = 0.00097).


CONCLUSIONS
Lung damage after carbon ion irradiation was observed in the parenchyma and in the pleura. The severity of pulmonary reactions was correlated with dose-volume factors. These findings might provide useful information in the planning and management of carbon ion irradiation.
Nishimura
Hideki
H
Research Center of Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan. westvill@med.kobe-u.ac.jp
Miyamoto
Tadaaki
T
Yamamoto
Naoyoshi
N
Koto
Masashi
M
Sugimura
Kazuro
K
Tsujii
Hirohiko
H
D000368:Aged; D000369:Aged, 80 and over; D002244:Carbon / Q000627:therapeutic use*; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D004307:Dose-Response Relationship, Radiation; D005260:Female; D063193:Heavy Ion Radiotherapy; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000528:radiation effects*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010994:Pleura / Q000000981:diagnostic imaging / Q000528:radiation effects*; D011832:Radiation Injuries / Q000000981:diagnostic imaging*; D012720:Severity of Illness Index; D013997:Time Factors; D014057:Tomography, X-Ray Computed
D002244:Carbon