gh.r. fallahmohammadi

Diagnosing an anterior cruciate ligament (ACL) rupture based on a physical examination is a challenge for both surgeons and surgeon’s assistant. The Lever sign test has been developed as a new physical examination to overcome the practical limitations of routine clinical trials and optimize diagnosis. The aim of the present study was to evaluate the reliability and diagnostic value and outcome of the Lever test.

In this prospective diagnostic study, 154 patients who were candidates for arthroscopic surgery were evaluated. Prior to the tests, patients' clinical manifestations were recorded. Lever, Drawer, Lachman and pivot diagnostic tests were performed by an orthopedic surgeon and an experienced surgeon assistant before and after anesthesia. The accuracy, sensitivity and specificity of these tests compared to arthroscopy findings were calculated as a gold standard. The ease of performing the tests was assessed from the point of view of the performers as well as the patients' pain during the test with the standard pain score (Visual Analog Scale, VAS).

The accuracy, sensitivity and specificity of Lever test before anesthesia were calculated as 70.5, 63, and 91.3 and after anesthesia 74.5, 66.51, 90.23 respectively. Among the tests, Lever was the easiest before anesthesia with 68%, and after anesthesia with 74.5% it was the easiest after drawer test from the point of view of the operators. Lever test with a vas score of 4.01 had the least pain during the test.

The lever test can be performed clinically easily and has little pain for the patient and is comparable to other orthopedic tests in terms of accuracy, sensitivity and specificity. This test is recommended as an effective orthopedic maneuver, along with other ACL tear diagnostic tools, especially when other tests are associated with severe pain.

Conventional radiation dosimetry methods in computed tomography (CT) are not able to measure the dose distribution along the patient’s longitudinal axis. To calculate the dose index on a CT scan, the dose distribution from the center of the radiation field must be calculated. In this study, the most appropriate integral interval for calculating the CT dose index in the axial mode was determined using the Monte Carlo (MC) method based on X-ray photon energy and slice thickness.

The computed tomography dose index (CTDI) phantom was simulated in the EGSnrc/BEAMnrcMC system and was irradiated with several X-ray energies and several slice thicknesses and dose profiles in phantom were investigated. The area under the dose profile and the scatter to primary radiation dose ratio (SPR) were calculated.

The range of scattered beams from the center of the radiation field reaches 450 mm in 140 kV and a 40 mm slice thickness. The SPR value for all levels of X-ray photon energy (between 80 and 140 kV) significantly decreases as slice thickness increases. CT scan imaging technical factors greater than 310 mm from the center of the slice thickness have no effect on the behavior of the scattered radiation.

The primary beams are more affected by the energy of the photons, and the scatter beams are more strongly affected by the slice thickness. For 64-slice scanners, the polymethyl methacrylate (PMMA) phantom length should be between 700 mm and 900 mm to yield accurate CTDI estimations.