[Optimal scanning collimation for segmental bronchi: experimental study with low-dose helical CT].
OBJECTIVE
To evaluate the effects of low-dose helical CT with different scanning collimation on the visualization of segmental bronchi and to determine the optimal scanning collimation in CT screening for early central lung cancer.


METHODS
Forty healthy volunteers were randomly assigned to undergo the low-dose helical CT at 120 kVp, 50 mA, 0.75 s and pitch 1. One group (n = 20) underwent the sequential subsection scan of chest with the collimation of 10 mm for the apical and basilar zone, and of 8 mm and 5 mm for the hilar zone. The other (n = 20) went through CT scan with 10 mm collimation of the whole lung. The visualizations of lobar, segmental bronchi were compared at different collimations. ANOVA and multiple comparison were performed.


RESULTS
The visualization of segmental bronchi on low-dose scan at 10 mm collimation was 60%, being lower than that at 8 mm (88%) or 5 mm (91%) collimation (P < 0.01). The segmental bronchi of right upper lobe were easily identified at collimation of 10 mm (82%), 8 mm (96%) and 5 mm (98%), as well as those of left upper lobe at 10 mm (83%), 8 mm (95%) and 5 mm (97%), whereas those of lingular lobe were difficultly identified at 10 mm (30%), 8 mm (60%) and 5 mm (70%).


CONCLUSIONS
The lobar and segmental bronchi were visualized reliably by CT with 50 mA and 8 mm collimation, and therefore the sequential subsection scan of chest divided into three zones can be adapted to CT screening for early lung cancer.
Department of Radiology, West China Hospital, Sichuan University, Chengdu 610041, China.
Jian-qun
JQ
Yu
Zhi-gang
ZG
Yang
Zhen-lin
ZL
Li
Xian
X
Chen
D000328:Adult; D000368:Aged; D001980:Bronchi; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008175:Lung Neoplasms / Q000517:prevention & control*; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D011829:Radiation Dosage; D036542:Tomography, Spiral Computed / Q000379:methods*