Abstract: Objective: To investigate the effects of different detector widths and respiratory cooperation status on radiation dose and image quality in chest computed tomography (CT). Methods: A total of 160 patients who underwent chest CT examinations in the emergency department of our hospital between April 2025 and December 2025 were selected as study participants. The patients were divided into four groups of 40 patients each based on different detector widths and breathing states: Groups A (80 mm detector width, breath-hold), B (160 mm detector width, breath-hold), C (80 mm detector width, free breathing), and D (160 mm detector width, free breathing). The scanning direction for all groups was from lung apex to base. Subjective and objective evaluations were compared between the groups. In addition, the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), volume CT dose index (CTDI_vol), dose-length product (DLP), effective dose (ED), and scanning exposure time of each slice were measured and recorded. Results: Statistically significant differences were observed in subjective image quality scores among the four groups. The scores in Groups A, B, and D were all significantly higher than those in Group C, whereas no significant difference was noted between Groups B and D (P=0.462). Detector width and breathing mode had significant effects on the SNR and CNR, whereas no significant interaction was observed between them. The SNR and CNR at each slice in the breath-hold group were significantly higher than those in the free-breathing group, and the DLP and ED in Group A were significantly lower than those in Group B (P = 0.012). The DLP and ED in Group C were significantly lower than those in Groups B and D. Notably, the exposure time in the 160 mm detector width group was significantly shorter than that in the 80 mm detector width group. Conclusion: Breathing status is a key factor affecting chest CT image quality, with breath-hold scans yielding higher quality images than free-breathing scans. Using a 160-mm wide-body detector, the scanning time can be significantly reduced. Chest CT examinations performed with patients breathing freely can yield image quality comparable to that obtained with breath-holding. This technique is suitable for patients who are unable to hold their breath during chest CT scanning. Scanning with an 80-mm detector provides better radiation dose control and is applicable to routine chest CT examinations in patients who can hold their breath.