Pediatric computed tomography doses in Germany from 2016 to 2018 based on large-scale data collection.

PURPOSE: Accumulating evidence from epidemiological studies that pediatric computed tomography (CT) examinations can be associated with a small but non-zero excess risk for developing leukemia or brain tumor highlights the need to optimize doses of pediatric CT procedures. Mandatory dose reference levels (DRL) can support reduction of collective dose from CT imaging. Regular surveys of applied dose-related parameters are instrumental to decide when technological advances and optimized protocol design allow lower doses without sacrificing image quality. Our aim was to collect dosimetric data to support adapting current DRL to changing clinical practice. METHOD: Dosimetric data and technical scan parameters from common pediatric CT examinations were retrospectively collected directly from Picture Archiving and Communication Systems (PACS), Dose Management Systems (DMS), and Radiological Information Systems (RIS). RESULTS: We collected data from 17 institutions on 7746 CT series from the years 2016 to 2018 from examinations of the head, thorax, abdomen, cervical spine, temporal bone, paranasal sinuses and knee in patients below 18 years of age. Most of the age-stratified parameter distributions were lower than distributions from previously-analyzed data from before 2010. Most of the third quartiles were lower than German DRL at the time of the survey. CONCLUSIONS: Directly interfacing PACS, DMS, and RIS installations allows large-scale data collection but relies on high data-quality at the documentation stage. Data should be validated by expert knowledge or guided questionnaires. Observed clinical practice in pediatric CT imaging suggests lowering some DRL in Germany is reasonable.

Difference between clinical and pathologic renal tumor size, correlation with survival, and implications for patient counseling regarding nephron-sparing surgery.

OBJECTIVE: The aim of the current study was to evaluate the difference between clinical tumor size and pathologic tumor size and the influence of both parameters on cancer-specific survival in patients with renal cell carcinoma. MATERIALS AND METHODS: Clinical tumor size was measured by CT in 834 patients undergoing nephrectomy and was compared with pathologic tumor size. Clinical tumor size and clinical tumor stages were assessed in a central radiologic review. Several variables were analyzed regarding their impact on cancer-specific survival by use of the Kaplan-Meier method, multivariable Cox regression, and receiver operating characteristic analysis. RESULTS: The mean duration of follow-up for patients who were alive at the end of the study (n = 564) was 85 months. The mean clinical and pathologic tumor size was 5.93 and 5.53 cm, respectively (p = 0.005). Of 265 patients with cT1a tumors, only 3.0% (n = 8) had pathologic tumor stage pT3a or higher. In contrast, 15.2% of 317 patients with cT1b tumors had pathologic tumor stage pT2 or higher. Five-year cancer-specific survival according to clinical tumor size was 94% (≤ 4 cm), 83% (4.01-7 cm), and 68% (> 7 cm), respectively (p < 0.001). Multivariable regression analysis revealed that metastasis, sex, age, and clinical tumor size significantly influenced cancer-specific survival. Integration of pathologic tumor size instead of clinical tumor size into multivariable analysis resulted in a reduction of predictive accuracy of 2.3%. CONCLUSION: CT significantly overestimated tumor size in the overall study group, but this overestimation is unlikely to be of clinical importance regarding the decision about radical versus nephron-sparing surgery. However, clinical understaging in 15% of cT1b tumors should be considered in treatment decision making. Clinical tumor size had an independent impact on cancer-specific survival and revealed a higher prognostic value compared with pathologic tumor size.