Using Radiation-free Ultrasound for Screening Scoliosis Among School Children in Hong Kong to Reduce Unnecessary X-ray Exposure

Using Radiation-free Ultrasound for Screening Scoliosis Among School Children in Hong Kong to Reduce Unnecessary X-ray Exposure

Using Radiation-free Ultrasound for Screening Scoliosis Among School Children in Hong Kong to Reduce Unnecessary X-ray Exposure

In the scoliosis screening program of the Student Health Service (SHS), Department of Health (DH), in Hong Kong, more than 50% of screened school children prescribed with x-ray examination basing on the screening protocol did not have Cobb angle greater than the referral threshold of 20°; ie they did not need specialist referral and thus were subjected to unnecessary x-ray exposure. Our primary objective is to determine whether a new radiation-free ultrasound system could identify subjects with Cobb angle greater than the referral threshold of 20° thus avoiding unnecessary x-rays in the referral workflow. The secondary objective is to evaluate if Angle of Trunk Rotation (ATR) can further increase the accuracy of ultrasound assessment.

This is a cross-sectional study on screened school children recommended for radiographic assessment in the scoliosis screening program of SHS in Hong Kong. Both x-ray, ultrasound and ATR measurement of the spine will be performed on the same day at Prince of Wales Hospital.

Scolioscan, the ultrasound system reported to be reliable and valid for spinal deformity assessment, will be used. The system composes of an ultrasound scanner with a linear probe of 100 mm in width and frequency range of 4-10MHz, a frame structure and a spatial sensor which is attached to the ultrasound probe for spatial data capture. Daily calibration will be performed using a phantom to assure accuracy of spine image formation and subsequent angle measurement. Subjects will stand on the Scolioscan platform with a standardized posture kept stable with pegs throughout the scanning process.. After adjusting the ultrasound scanner setting, the probe will be steered from L5 to T1 spinous process for scanning. SPA will be used to determine the ultrasound-based Referral Status through predicting whether the Cobb angle is beyond the referral threshold of ≥20° or not. There are two values for the Referral Status: either "for specialist referral" or "not for specialist referral".

"for specialist referral" or "not for specialist referral", through predicting whether the Cobb angle is beyond the referral threshold of ≥20° or not in scoliosis screening

Inclusion Criteria: i. Schoolchildren in Hong Kong attending School Screening Program provided by Student Health Service ii. Recommended for radiographic assessment in the scoliosis screening program Exclusion Criteria: i. Patients with standing height <1 m, or >2 m ii. Patients with body mass index (BMI) ≥25 kg/m2 iii. Subjects with skin diseases iv. Subjects with fracture or wound that affect ultrasound scanning v. Subjects with ferromagnetic implants vi. Subjects with surgery done for the spine vii. Subjects with winged scapula or other irregularity of back contour that affect ultrasound scanning viii. Subjects who cannot stand steadily during scanning ix. Subjects with allergy to ultrasound gel

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