Application of CT values in calculation of proton incident energy in proton treatment planning system / 中华放射医学与防护杂志

Objective To explore the application of CT value in calculating the proton incident energy in proton treatment planning system. Methods Bethe-Block formula and the formula for calculating the proton range were analyzed to study the correlation of the range of proton beam ( 70-250 MeV ) between a variety of radiation equivalent material and water. Procedure of Monte Carlo SRIM2008 was used to verify the possibility of a constant proportional coefficient of range ( Ci ). The proportional coefficient ( Ci ) of range in radiation-equivalent material and the CT value were fitted by using Origin 8.0 software to study the functional relation of CT value and Ci. The actual range of proton was equivalent to a range of water and incident proton energy could be calculated. Results There was a constant range of Ci of proton beam (70-250 MeV) between a variety of radiation equivalent material and water. There was a functional relation between CT value and Ci ( r = 0.999). The actual range of proton in radiation equivalent material can be equivalent to a range of the water. Conclusions CT values and a range of proportional coefficient ( Ci ),and the actual required range of the tumor could be used to accurately calculate the water equivalent range,and the incident proton energy to the position of Bragg peak. A new exploration for using CT technology in proton treatment planning system could be obtained.

Study on P Wave Detection Method Based on Optimal Fitting Function / 航天医学与医学工程

Objective To accurately detect ECG P wave,a P wave detection algorithm based on fitting function in the optimal interval is proposed and evaluated in this paper,for resolving very difficult problems.Such as differences of positions and figures in ECG P wave as well as easily suffered diversified interferences.Methods In this algorithm the quadratic function to fit the P wave with least square method in every interval was used,which was shifted in local range.Then the optimal fitting interval of P wave was found by comparing the error of fitting.Finally,the characteristic points of P wave were obtained with the fitting function to fit P wave in the optimal interval.Results The performance of this algorithm tested with the records of the MIT-BIH database was effective and accurate.Conclusion This algorithm on the wide range of heart rate variation and small P wave of ECG P wave detection has good effect.Also it has some capabilities of anti-interference and quite low dismissal probability in particular.