 The PUS group received pulse mode of ultrasound sonoplus 490s, with frequency of 1MHZ and intensity of 1.5wcm according to Ebadi et al 10. Greys formula was used to estimate the duration of ultrasound US for each patient 21. The average local exposure time was one minute and the effective radiating area of the transducer head was 5 cm2. For a patient with an area of low back pain of 40 cm2, the required total treatment time was: 1 min × 40 cm25 cm2 8 minutes. US was applied using slow circular movements, with the transducer head placed over the painful paravertebral low back region and Lofnac gel used as coupling medium. 