Technical Note: Evaluation of the systematic accuracy of a frameless, multiple image modality guided, linear accelerator based stereotactic radiosurgery system

PURPOSE

To evaluate the total systematic accuracy of a frameless, image guided stereotactic radiosurgery system.

METHODS

The localization accuracy and intermodality difference was determined by delivering radiation to an end-to-end prototype phantom, in which the targets were localized using optical surface monitoring system (OSMS), electromagnetic beacon-based tracking (Calypso®), cone-beam CT, "snap-shot" planar x-ray imaging, and a robotic couch. Six IMRT plans with jaw tracking and a flattening filter free beam were used to study the dosimetric accuracy for intracranial and spinal stereotactic radiosurgery treatment.

RESULTS

End-to-end localization accuracy of the system evaluated with the end-to-end phantom was 0.5 ± 0.2 mm with a maximum deviation of 0.9 mm over 90 measurements (including jaw, MLC, and cone measurements for both auto and manual fusion) for single isocenter, single target treatment, 0.6 ± 0.4 mm for multitarget treatment with shared isocenter. Residual setup errors were within 0.1 mm for OSMS, and 0.3 mm for Calypso. Dosimetric evaluation based on absolute film dosimetry showed greater than 90% pass rate for all cases using a gamma criteria of 3%/1 mm.

CONCLUSIONS

The authors' experience demonstrates that the localization accuracy of the frameless image-guided system is comparable to robotic or invasive frame based radiosurgery systems.

[Epidemic profile of mumps in China during 2004-2013]

OBJECTIVE

To analyze the epidemiological characteristics of mumps in China from 2004 to 2013.

METHODS

Data of mump cases occurring between 2004 and 2013 were gathered from the national notifiable disease reporting system in China (excluding Hong Kong, Macao, and Taiwan); only cases classified as "final card" , laboratory confirmed, or clinical diagnosis were included. Descriptive epidemiology techniques were used to analyze features of sex, age, trends over time, and geography.

RESULTS

Average incidence of mumps between 2004 to 2013 was 24.20/100 000. Peaks were in 2011 and 2012, with incidence 33.9/100 000 (454 385/1.340 million) and 35.6/100 000 (479 518/1.347 million). Two seasonal peaks occurred regularly in years, one from April to July in the first year, and the other from November to January in the next year. During the study period, provinces with the highest incidence were Ningxia, Tibet, Xinjiang, and Guangxi; incidences were 72.1/100 000 (4 425/6.13 million), 48.5/100 000 (1 396/3 million), 51.7/100 000 (10 887/21.04 million), and 40.8/100 000 (19 179/46.99 million), respectively. Guangdong (28 078), Sichuan (21 924), Guangxi (21 616), and Zhejiang (20 000) provinces reported the highest number of mumps cases. Beijing, Tianjin, and Shanghai showed a consistently low incidence. Mumps cases occurred primarily among children aged 5-9 years, with incidence ranging from 118.2/100 000 to 281.4/100 000. In 2004-2008, the peak age was 6-8 years (174.1/100 000) and in 2009-2013, peak age was 5-7 years (234.5/100 000).

CONCLUSION

The highest incidences of mumps in China were reported in 2011 and 2012, with children of school age constituting the majority of cases.