RT Journal Article SR Electronic T1 Optimizing the Ventilation–Perfusion Lung Scan for Image Quality and Radiation Exposure JF Journal of Nuclear Medicine Technology JO J. Nucl. Med. Technol. FD Society of Nuclear Medicine SP 51 OP 54 DO 10.2967/jnmt.113.128900 VO 42 IS 1 A1 Seung Hur A1 Adam Bauer A1 Natalie McMillan A1 Elizabeth A. Krupinski A1 Phillip H. Kuo YR 2014 UL http://tech.snmjournals.org/content/42/1/51.abstract AB Our purpose was to compare the performance of an initial ventilation–perfusion (V/Q) scan protocol with that of a data-driven modified protocol to improve diagnostic quality without increasing radiation dose to the patient. Methods: The initial V/Q scan protocol consisted of a ventilation scan after inhalation of 99mTc-diethylenetriaminepentaacetic acid (DTPA) aerosol for 5 min followed by a 99mTc-macroaggregated albumin perfusion scan. Interim analysis after 34 scans under an initial protocol included calculations of ventilation efficiency, perfusion efficiency, and perfusion-to-ventilation counting rate ratio (Q:V). Ventilation efficiency was defined as ventilation counting rate divided by ventilation dose, perfusion efficiency as perfusion counting rate divided by perfusion dose, and Q:V as perfusion counting rate divided by ventilation counting rate. From these data, the protocol was modified to improve the Q:V ratio and was applied to 60 patients. Results from the 94 scans were tabulated, and a comparison of ventilation efficiency, perfusion efficiency, and Q:V between the 2 protocols was statistically analyzed. Results: The initial protocol returned a mean ventilation efficiency of 7.8% (SD, 4.6%; range, 1.4%–19%), mean perfusion efficiency of 100% (SD, 31%; range, 39%–160%), and mean Q:V of 2.4 (SD, 1.9; range, 0.51–9.0). All 3 parameters displayed a wide range. Fifty-four percent of these cases demonstrated an unacceptable Q:V (≤2) indicating that the perfusion dose did not overwhelm the ventilation dose. To improve Q:V, options included decreasing ventilation dose, increasing perfusion dose, or performing the ventilation scan with a much higher dose after the perfusion scan. To minimize radiation, the protocol was modified to decrease the ventilation from 5 min to 2.5 min. The modified protocol yielded a mean ventilation efficiency of 5.1% (SD, 1.8; range, 2.0–11), mean perfusion efficiency of 120% (SD, 27%; range, 65%–170%), and mean Q:V of 3.6 (SD, 1.7; range, 1.2–12). Differences between protocols were statistically significant for ventilation efficiency, perfusion efficiency, and Q:V (P < 0.02). Less than 8% of cases under the modified protocol exhibited an unacceptable Q:V. Conclusion: The initial V/Q scan protocol was successfully modified to improve image quality with less radiation. By decreasing the ventilation time by half, the percentage of studies with an unacceptable Q:V decreased from 54% to 8%. This analysis may help others to optimize their V/Q protocols.