Detection of urinary stones at reduced radiation exposure: a phantom study comparing computed radiography and a low-dose digital radiography linear slit scanning system

Identification of ureteral stones at reduced radiation exposure: a pilot study comparing conventional versus digital low-dosage linear slot scanning (Lodox®) radiography

PURPOSE

Digital low-dosage, linear slot scanning radiography (Lodox^®) is an imaging modality that can emit down to one-tenth the radiation of conventional X-ray systems. We prospectively evaluated Lodox^® as a diagnostic imaging modality in patients with ureterolithiasis.

METHODS

Conventional kidney-ureter-bladder (KUB) X-ray and Lodox^® were performed in 41 patients presenting with acute flank pain due to unilateral ureteral stone confirmed by computed tomography. KUB X-ray and Lodox^® images were then reviewed by four blinded readers (urology expert/resident, radiology expert/resident). Identification rates were compared using Pearson's Chi square test. The impact of different parameters on stone identification by Lodox^® was evaluated using logistic regression and generalized linear mixed models. Inter-reader agreement was tested using Cohen's kappa coefficient.

RESULTS

Median stone size was 5 mm (range 2-12), median stone density was 800 HU (range 200-1500). The identification rates of the urology expert were 68% for KUB X-ray and 90% for Lodox^® (p = 0.014), and for all four readers 61% for KUB X-ray and 62% for Lodox^® (p = 0.8). Radiation exposure for KUB X-ray and Lodox^® was 0.45 mSv (SD ± 0.64) and 0.027 mSv (SD ± 0.038), respectively. Multivariable analyses showed an association between stone identification by Lodox^® and stone size (p < 0.001), stone density (p = 0.005), lower body mass index (p = 0.005), and reader (p < 0.001).

CONCLUSIONS

The high identification rates and low radiation doses of Lodox^® make it a promising imaging modality for the diagnosis of ureteral stones. Further validation in larger cohorts, including performance evaluation for renal stones, is warranted.

TRIAL REGISTRATION

http://www.controlled-trails.com/ISRCTN12915426.

A review of full-body radiography in nontraumatic emergency medicine

This paper reports on the application of full-body radiography to nontraumatic emergency situations. The Lodox Statscan is an X-ray machine capable of imaging the entire body in 13 seconds using linear slit scanning radiography (LSSR). Nontraumatic emergency applications in ventriculoperitoneal (VP) shunt visualisation, emergency room arteriography (ERA), detection of foreign bodies, and paediatric emergency imaging are presented. Reports show that the fast, full-body, and low-dose scanning capabilities of the Lodox system make it well suited to these applications, with the same or better image quality, faster processing times, and lower dose to patients. In particular, the large format scans allowing visualisation of a greater area of anatomy make it well suited to VP shunt monitoring, ERA, and the detection of foreign bodies. Whilst more studies are required, it can be concluded that the Lodox Statscan has the potential for widespread use in these and other nontraumatic emergency radiology applications.

Digital tomosynthesis in the detection of urolithiasis: Diagnostic performance and dosimetry compared with digital radiography with MDCT as the reference standard

OBJECTIVE

The purpose of this study was to evaluate the diagnostic performance of digital tomosynthesis in comparison with digital radiography in the detection of urinary stones with MDCT as the reference standard.

SUBJECTS AND METHODS

Fifty consecutively enrolled patients (32 men, 18 women; mean age, 51.5 years; range, 19-83 years) referred for unenhanced MDCT of the abdomen with suspicion of urinary stones also underwent digital tomosynthesis and digital radiography (anteroposterior and bladder inlet views). Images from all examinations were randomly read by three blinded radiologists. The mean effective doses for digital tomosynthesis, digital radiography, and low- and high-dose MDCT were measured on a male phantom. Free-response receiver operating characteristics and receiver operating characteristics analyses were used to compare the diagnostic performance of digital radiography with that of digital tomosynthesis.

RESULTS

Both types of analysis showed significantly better performance of tomosynthesis over digital radiography for all urinary stones (p < 0.05). No such improvement was found for ureteral stones. The gain in sensitivity with tomosynthesis was largest for stones between 2 and 5 mm in diameter. The mean effective dose was 0.5 mSv for digital radiography, 0.85 mSv for tomosynthesis, 2.5 mSv for low-dose MDCT, and 12.6 mSv for high-dose MDCT.

CONCLUSION

Use of digital tomosynthesis of the abdomen results in improved detection of urinary stones in general over digital radiography with only a slight increase in effective dose. Use of tomosynthesis, however, was not associated with major improvement in the diagnosis of ureteral stones. The technique has potential as an alternative imaging technique in the detection and follow-up of urinary stones.