*4.2.2.3.2 The integrated shape imaging system 1 and 2 (ISIS1 and 2)*

The Integrated Shape Imaging System (ISIS) is a widely used optical scanning system for the measurement of human back shape and posture within a clinical environment [65, 66]. The ISIS system consists of an optical scanner (A), which projects a horizontal beam of structured white light onto the patient's back (B). The camera (C), mounted below the projector, captures the position of the light blade on the back from different perspectives (see **Figure 10**). Based on the geometry of the illumination/camera system together with the coordinates of the blade of light, the three-dimensional shape information is derived.

The validation of this system was carried out in the late 1980s and early 1990s [67, 68]. Although the reliability and validity of this tool was good to excellent for clinical use, the original ISIS system was getting old and data acquisition was slow which led to potential movement errors. The system was modified and redesigned

**Figure 9.** *Example of Moiré topographic images of a subject with scoliosis (reproduced from Kotwicki et al. [60]).*

*Posture and Back Shape Measurement Tools: A Narrative Literature Review DOI: http://dx.doi.org/10.5772/intechopen.91803*

by Berryman et al. with the new addition of a clinical parameters and renamed ISIS2 [59]. This automated non-invasive surface topography system measures threedimensional shape of the back with improved speed, accuracy, reliability and ease of use [69].

Berryman et al. [59] described the data collection procedure, involving palpation and marking bony landmarks on the subject's back with small coloured stickers. A digital camera is then used to take a photo. The projector then projects a grid of horizontal black lines onto the patient's back. The pixel size is approximately 0.5 mm with fringe frequency of approximately 0.16 fringes/mm. Fourier transform profilometry is used to convert the distortion of the reference grid lines into a threedimensional surface map of the back.

The data processing with ISIS2 takes only 40 s, compared to 10 min in ISIS. Knott et al. [70] suggest that by reducing the duration of data collection, the error due to natural postural sway of the body decreases, thereby increasing the accuracy (±1 mm). The results are stored in a database so that the data of the particular patient can be recalled at any given point of time. ISIS2 helps in the screening and monitoring of the development of spinal deformity over time [71, 72].

Zubović et al. [69] carried out a study to validate the ISIS2 system against X-rays. They reviewed 520 ISIS2 scans on 242 scoliosis patients not only for quantifying postural variables but also to assess their validity. The average number of scans per patient was 2.01 with a range of 1–10 scans. The median values and 95% CI were reported for the linear, angular and volumetric asymmetry of scoliosis patients. The results of this study showed no statistically significant differences in their investigations between ISIS measurements and X-ray images.

Similarly, Berryman et al. [59], in their study on measuring three-dimensional back shape in scoliosis patients, also found good correlations (r = 0.84) between the Cobb angle and the lateral asymmetry of the ISIS scans.

As seen in **Figure 11**, the ISIS2 system provides additional data to simple radiographic examination, describing the three-dimensional characteristics of the back surface [59, 74]. Previous studies [71, 72] have demonstrated that the ISIS2 produces reliable, valid and accurate data that can monitor the progression of spinal deformities. Berryman et al. [59], Frerich et al. [75], Sadani et al. [76], Brewer et al. [77]

### **Figure 11.**

*Illustration of data processing and a sample report of ISIS2 method [74]. (A) the reference frame with calibration markers; (B) example of patient image with fringes projected onto the back; (C) representation of symmetry line analysis in frontal and sagittal planes to obtain lateral deviation, kyphosis and lordosis angles; (D) back height map with rib hump, contour plot (representing the shape using contour lines and colour; blue lowest to red highest); and (E) example of ISIS2 report with representation of contour plot and quantification of curve in all planes.*

and Knott et al. [33] suggest that the additional advantage of ISIS2 is to reduce the exposure to radiation.

However, Fortin et al. [9] and Bettany-Saltikov et al. [46] identify the ISIS2 system as being very heavy, is not easily moved and requires skilled clinicians to operate it. In addition, Berryman et al. [59] suggests that identifying the bony landmarks for marking spinous process is more difficult for patients who are extremely obese or have heavy musculature. Similarly, the above authors also found it difficult to mark bony landmarks in patients with congenital curves that had little rotation.

The main limitation of the ISIS2 system is that it can only measure back shape and not the whole body. Non-contact optical imaging techniques for the assessment of back shape and posture has also been achieved by using the laser triangulators method.
