**5. Radiographic analysis**

All radiographs should be taken in the 'neutral' standing position with the feet positioned with the heels at hips width apart. This is to avoid any induced postural deviations due to foot position. Also, to ensure a reproducible neutral (i.e. natural) body position, the subject should close their eyes and nod the head back and forth a couple times to where the subject should stop in their preferred position and then open their eyes while maintaining this adopted stance. Any postural misalignments seen in the subject should not be corrected. The lower body mass on the particular view being taken should be centered to the bucky. All X-rays should be taken without footwear.

It should be mentioned that the measurement of different sagittal spinal contours including regional curves or absolute rotation angles (ARAs) (i.e. cervical/lumbar lordosis; thoracic kyphosis) and intersegmental relative rotation angles (RRAs) between adjacent vertebrae can be easily quantified by use of the Harrison posterior tangent (HPT) lines (**Figure 9**) [25–28]. The HPT method is preferred for three main reasons, 1. The posterior margins of the vertebral bodies are less affected by osteoarthritic changes as compared to the anterior margins which makes anatomical measurements more reliable and valid; 2. The posterior tangents are contiguous with the slope of the spinal curves and represent the first derivative in an engineering analysis and therefore, their intersection accurately depicts the sagittal configuration; 3. The HPT method has a small standard error of measurement (SEM) of approximately 2° versus higher SEMs with the Cobb (4.5–10°) [25–27]. This is why the HPT method is superior to other methods of sagittal spine mensuration including the popular Cobb method.

Generally, the global curves are measured as C2-C7, T1-T12, and L1-L5, however since the inflection of the cervical lordosis to thoracic kyphosis occurs at T1, some clinicians prefer to measure the cervical curve from C1-T1, and the thoracic curve from T2-T11 or T3-T10. Anterior sagittal translation distances are simply measured by the horizontal displacement offset between comparison vertebrae such as C2-S1, C2-C7 or T1, T1-T12, etc.

The anterior-to-posterior (AP) or PA X-rays are taken using the same postural positioning. The modified Risser-Ferguson method is employed to measure coronal plane alignment (**Figure 10**) [28]. On the AP/PA cervicothoracic view an upper angle is created as the angle between the best fit line of the upper cervical segments and intersection with the bite line, and a lower angle is formed between the best fit lines of the upper to lower spine segments [28]. The Rz angle is the angle formed by a vertical axis line (VAL) drawn from T4 and the lower cervicothoracic best fit line. Normal upper angle, lower angle and Rz cervicothoracic angles are 90°, 0° and 0°, respectively. The AP/PA thoracic view may show an angle. The lumbopelvic view has an upper angle, the angle between the best fit line of the upper versus lower lumbar segments, and a lower angle, the angle between the best

*DOI: http://dx.doi.org/10.5772/intechopen.102686 An Introduction to Chiropractic BioPhysics® (CBP®) Technique: A Full Spine Rehabilitation…*

**Figure 10.** *AP radiographic line drawing by modified Risser-Ferguson method.*

fit line between the lower segments and the horizontal pelvic line [28]. The upper angle and lower angle should be 0° and 90°, respectively. Any regional or full-spine coronal balance offset (i.e. imbalance) can be easily quantified as the horizontal distance between the uppermost segment to the lowermost segment (e.g. C2-T2, T1-T12, T12-S1, C2-S1).
