Appraisal of radiation dose with 64-slice computed tomography perfusion in lung cancer patients with special reference to SSDE: An initial experience in a tertiary care hospital.

Context: Computed tomography perfusion (CTP) is an important functional tool for lung cancer. It is expected to deliver high radiation dose, making its accurate estimation important. Size-specific dose estimate (SSDE) is a new dose metric, which includes the scanner output as well as the patient size.

Aims: To determine radiation dose [CT dose index (CTDIvol ), dose length product (DLP), effective dose (ED), and SSDE] for CTP in lung cancer and the correlation of CTDIvol , DLP, and SSDE with effective diameter and SSDE with weight, body mass index (BMI), and the scan length.

Settings and Design: Cross-sectional study in the Department of Radio-diagnosis from October 2015 to March 2016.

Patients and Methods: Due ethical approval and informed consent was taken. Thirty consecutive adult patients of lung cancer undergoing CTP study were included; various radiation dose parameters were determined and presented as mean ± SD.

Statistical Analysis Used: Paired Student's t -test and Pearson correlation using Statistical Package for the Social Sciences, Version 16.

Results: Mean radiation dose was CTDIvol = 270.138 ± 1.627 mGy, DLP = 681 ± 53.496 mGy.cm, ED = 12.501 ± 0.923 mSv, SSDE = 388.90 ± 81.27 mGy. The CTDIvol and DLP had significant positive correlation ( r = 0.556, P = 0.000 and r = 0.522, P = 0.003, respectively) with effective diameter. SSDE had strong negative correlation ( r = -0.997, P = 0.000) with effective diameter, significant negative correlation with the BMI ( r = -0.889; P = 0.000) and weight ( r = -0.910, P = 0.000) of patients. Scan length was not significantly correlated in SSDE ( r = -0.012, P = 0.951).

Conclusions: Smaller sized patients had greater SSDE.