A Study of CT-derived Radiation Dose Calculation in Lung Q-SPECT/CT Imaging

Area of Science:

• Radiology and Imaging
• Medical Physics
• Nuclear Medicine

Background:

• Lung perfusion-single-photon emission computed tomography (Q-SPECT)/CT combines functional and anatomical imaging.
• The computed tomography (CT) component contributes to the overall effective dose (ED).
• Optimizing CT dose reduction strategies is crucial for patient safety in Q-SPECT/CT procedures.

Purpose of the Study:

• To quantify the effective dose (ED) from the CT component of Q-SPECT/CT.
• To compare ED between patients with and without pulmonary embolism (PE).
• To evaluate the impact of CT dose reduction (CTDR) protocols on ED.

Main Methods:

• Retrospective analysis of 327 Q-SPECT/CT patient cases (2016-2022).
• Recorded CT parameters including tube voltage, dose-length product (DLP), and calculated ED.
• Statistical comparison of ED using Mann-Whitney U test, stratified by PE status and CTDR protocol.

Main Results:

• ED was significantly higher in PE (+) cases (1.54 ± 1.04 mSv) compared to PE (-) cases (1.20 ± 0.70 mSv), a 28% increase.
• The non-CTDR protocol resulted in significantly lower ED for PE (-) cases (0.87 ± 0.72 mSv) compared to CTDR (1.55 ± 0.47 mSv).
• Specific tube voltage protocols showed substantial ED reductions: 42% for PE (+) and 41% for PE (-) cases when using lower tube voltage (100 kVp implied).

Conclusions:

• The non-CTDR protocol is effective for reducing ED in PE (-) cases.
• Applying 100 kVp tube voltage is recommended for PE (+) cases to minimize radiation dose.
• Tailored CT parameters can optimize radiation safety in Q-SPECT/CT imaging.