Estimation of overall pulmonary function after irradiation using dose-effect relations for local functional injury.
OBJECTIVE
To predict the pulmonary function 3-4 months after irradiation for malignant lymphoma from the three-dimensional (3-D) dose distribution.


METHODS
Dose-effect relations for the relative reduction of local perfusion (Q) and local ventilation (V), were calculated in 25 patients, using correlated SPECT (Single Photon Emission Computed Tomography) and CT data. By combining the 3-D dose distribution of an individual patient with the dose-effect relations averaged over all patients, the average reduction of local Q and V (i.e., the overall response parameters) in the whole lung was estimated for each patient. Correlation coefficients were calculated between these overall response parameters and the change in standard lung function tests. In addition, the relation between the overall response parameters and the incidence of radiation pneumonitis was determined.


RESULTS
The overall response parameter for perfusion was correlated with the change in standard lung function tests, with correlation coefficients varying between 0.53 (p = 0.007) and 0.71 (p < 0.001) for the change of Vital Capacity and Forced Expiratory Volume at 1 s, respectively. For the overall response parameter for ventilation similar correlations were observed. Four out of the 25 patients developed radiation pneumonitis; in these four patients the overall response parameter for perfusion was on average somewhat higher (13.2 +/- 1.4% (1 standard error of the mean)) than in patients without radiation pneumonitis (10.5 +/- 1.0%), but this difference was not significant. A higher incidence of radiation pneumonitis was observed for larger values of the overall response parameter for perfusion; in patient groups with an overall response parameter for perfusion of 0-5%, 5-10%, 10-15%, and 15-20%, the incidence of radiation pneumonitis was 0 (0/1), 10 (1/10), 13 (1/8) and 33% (2/6), respectively.


CONCLUSIONS
By combining the 3-D dose distribution with the average dose-effect relations for local perfusion or ventilation, an overall response parameter can be calculated prior to irradiation, which is predictive for the radiation-induced change in the overall pulmonary function, and possibly for the incidence of radiation pneumonitis, in this group of patients.
Department of Radiotherapy, The Netherlands Cancer Institute (Antoni van Leeuwenhoek Huis), Amsterdam.
L J
LJ
Boersma
E M
EM
Damen
R W
RW
de Boer
S H
SH
Muller
R A
RA
Valdés Olmos
N
N
van Zandwijk
J V
JV
Lebesque
D000293:Adolescent; D000328:Adult; D000368:Aged; D003131:Combined Modality Therapy; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005541:Forced Expiratory Volume / Q000528:radiation effects; D006801:Humans; D015994:Incidence; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000528:radiation effects*; D008223:Lymphoma / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D011650:Pulmonary Alveoli / Q000528:radiation effects; D011653:Pulmonary Diffusing Capacity / Q000528:radiation effects; D011832:Radiation Injuries / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D017564:Radiation Pneumonitis / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000009:adverse effects; D012129:Respiratory Function Tests; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D014692:Ventilation-Perfusion Ratio / Q000528:radiation effects; D014797:Vital Capacity / Q000528:radiation effects