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Scientific session Scientific session 5: Interventional oncology: Biopsies/imaging guidance: Featured abstract| Volume 23, ISSUE 3, SUPPLEMENT , S28-S29, March 01, 2012

Abstract No. 62: Implementation of a low dose protocol for CT guided lung biopsy procedures

      Purpose

      Professional groups and society at large are concerned with the growing population dose associated with CT examinations. The aim of this study was to evaluate the impact of a low-dose CT guidance protocol on dose metrics for lung biopsy procedures. We hypothesize that such a protocol will decrease radiation exposure to the patient while providing satisfactory imaging guidance.

      Materials and Methods

      A low dose CT guidance protocol was implemented in August 2010, involving a 120 kVp spiral acquisition with a pitch of 0.8 and 80 mAs for planning, followed by sequential 100 kVp and 80 mAs acquisitions for guidance. Operators determined the imaging volume to be scanned and could modify the CT guidance protocol. All procedures were performed on a single 16-slice CT scanner (Somatom, Siemens Medical Solutions). IRB approval was obtained. Consecutive CT-guided lung biopsy procedures were identified through case log review of 50 patients before and 50 patients after the protocol change. Dosimetry data was obtained through PACS, including the number and type of acquisitions, the associated kVp and mAs, as well as the total mAs and dose length product (DLP). Image quality was assessed by a single investigator. Differences in means of continuous variables were assessed with a two-tailed student's t-test.

      Results

      The study population consisted of 50 lung biopsy procedures in 50 patients before and after the protocol change.
      The low dose protocol significantly reduced the average DLP for lung biopsy procedures from 747.9 mGy*cm (range 121 - 5559) to 251.8 mGy*cm (range 73 - 715) (p<0.0001). There was no significant difference in the number of CT acquisitions for needle guidance between groups (16.3 vs 14.5) (p=0.21).
      Sequential scanning for needle guidance was utilized in 0% (0 of 50) and 100% (50 of 50) of procedures before and after implementation. Image quality was adequate for guidance in all procedures.

      Conclusion

      The low dose protocol for CT guided lung biopsy procedures achieved a dose reduction of 66%, with 100% voluntary adherence to use of sequential scanning for needle guidance. Interventional radiologists should review CT guidance protocols aiming to reduce patent dose and improve patient safety.