Development of an automatic analysis system for radiotherapy planning / 中华放射肿瘤学杂志

Objective:An automatic analysis system for radiotherapy planning was developed to realize the automatic analysis of dose parameters of radiotherapy planning through the intelligent analysis of the underlying data of Pinnacle 3 treatment planning system (TPS). Methods:The radiotherapy plans of 12 patients with esophagus cancer were analyzed. The automatic analysis system automatically retrieved the Pinnacle 3 TPS database, obtained the raw data of 12 cases of treatment plan, and automatically analyzed the underlying raw data, reconstructed contours, radiation fields, and dose parameters, and recalculated dose distribution and dose-volume histograms. The accuracy of the recalculation of the volume and dose data of the new system was evaluated by comparing with volume and dose data from the original plans of online TPS. Results:The automatic analysis system successfully parsed the underlying data of the treatment plan and reconstructed the parameters of the treatment plan. The volume deviation between the contour calculated by the new system and the original plans was ≤0.1%; Compared with the reference dose of the original plans, the deviations of dose parameters (D max, D mean, D 95, and D 50 for GTV, PGTV, CTV, and PTV) recalculated by the new analysis system were ≤1.0%; The deviations of D max and D mean of recalculated ROIs from the original plans were <5%. Conclusions:The automatic analysis system can directly analyze the underlying data of the Pinnacle 3 TPS treatment plan, reconstruct the treatment plan, calculate the contour volume and dose parameters, and the dose deviations from the original plans meet clinical requirements

Quantification and construction of the effective point calculation model of ionization chamber in Monacao treatment planning system / 中华放射肿瘤学杂志

Objective Because of statistical noise in Monte Carlo dose calculations,the effective point doses may not be accurately calculated.A user-defined sphere volume was adopted to substitute the effective point to take sphere sampling around the effective point,which minimize the random errors and improve the accuracy of statistical dose.Methods Direct dose measurements were performed at 0°and 90° using a 0.125 cm3 Semiflex ionization chamber (IC) 31010 isocentrically placed in the center of a homogeneous Cylindric sliced RW3 phantom (PTW,Germany).In the scanned CT phantom series,the sensitive volume length of the IC (6.5 mm) was delineated and the isocenter was defined as the simulated effective point.All beams were simulated in the treatment planning system (TPS) in accordance to the measured model.The grid spacing was calculated by 2 mm voxels and the relative standard deviation should be ≤ 0.5％.The statistical and measured doses were statistically compared among three IC models with different electron densities (ED;esophageal lumen ED =0.210 g/cm3 for model A,air ED =0.001 g/cm3 for model B and the default CT scanned ED for model C) at different sampling sphere radius (2.5,2.0,1.5 and 1.0 mm) to evaluate the effect of Monte Carlo.calculation uncertainty upon the dose accuracy.Results In the Monaco TPS,the statistical value was in the highest accordance with the measured value with an absolute average deviation of 0.49％ when the IC was set as esophageal lumen ED =0.210 g/cm3 and the sampling sphere radius was 1.5 mm.When the IC was set as air ED=0.001 g/cm3 and default CT scanned ED,and,the recommended statistical sampling sphere radius was 2.5 mm,the absolute average deviations were 0.61％ and 0.70％.Conclusion In the Monaco TPS,the calculation model with an ED of 0.210 g/cm3 and a sampling radius of 1.5 mm is recommended for the ionization chamber 31010 to substitute the effective point dose measurement to decrease the random stochastic errors of Monte Carlo.

Determination of multiple optical parameters of red blood cell suspension / 军事医学

Objective To develop a measurement method for determination of optical parameters of a red blood cell ( RBC) suspension based on the measurement of spatial scattered light signals without using an integrating sphere.Methods Multiple independent photoelectric sensors and light intensity modulation were used to obtain the measured values of diffuse reflectance,diffuse transmittance and collimated transmittance.The measured data results were imported into a Monte Carlo simulation based RTE to inversely determine the absorption coefficient, scattering coefficient and anisotropy factor of the measured sample using a new perturbation method.Results The described measurement method was applied to determine the optical parameters of a polystyrene microsphere suspension with a mean diameter of 2.6μm,and the results were essen-tially consistent with the calculated optical parameters by Mie code.Then, the RBC suspension was used for testing optical parameters,and the results were basically consistent with the parameters in the literature.Conclusion The system based on the measurement of spatial scattered light signals without using an integrating sphere will provide a quick and accurate approach for quantitative analysis of free hemoglobins and RBC suspensions.

An analysis of the advantage of biologically equivalent dose of unconventionally fractionated radiotherapy / 中华放射医学与防护杂志

Objective To analyze the advantage of altered fractionation radiotherapy by calculating the accumulative effects of daily biologically effective dose (BED) to find out the difference between conventional fractionated radiotherapy and altered fractionation radiotherapy.Methods The data in the report of hyperfractionated or accelerated radiotherapy for head and neck cancer published by Cochrane Collaboration in 2010 was analyzed.Based on the radiotherapy processes mentioned in this report,the accumulative effects of daily BED were calculated and compared in different radiotherapy processes by using linear-quadratic mode.The variation of BED in different radiotherapy processes was find out.Results In total dose of unity as the premise of 70 Gy,altered fractionation especially the hyperfractionated accelerated radiotherapy could give a higher BED to the tumor during a shorter period,hyperfractionated radiotherapy could give a lower BED to normal tissues,and hyperfractionated radiotherapy with split course could give higher BED to the tumor while lower BED to normal tissues.Conclusions The variation of BED in different radiotherapy processes can be shown clearly by linear-quadratic mode.It can be simple and shortcut through mathematical models for the evaluation of different radiotherapy plan,on clinical symptomatic selection play a guiding role in tumor therapy.

The application of stereology in radiology imaging and cell biology fields / 生物医学工程学杂志

Stereology is an interdisciplinary method for 3D morphological study developed from mathematics and morphology. It is widely used in medical image analysis and cell biology studies. Because of its unbiased, simple, fast, reliable and non-invasive characteristics, stereology has been widely used in biomedical areas for quantitative analysis and statistics, such as histology, pathology and medical imaging. Because the stereological parameters show distinct differences in different pathology, many scholars use stereological methods to do quantitative analysis in their studies in recent years, for example, in the areas of the condition of cancer cells, tumor grade, disease development and the patient's prognosis, etc. This paper describes the stereological concept and estimation methods, also illustrates the applications of stereology in the fields of CT images, MRI images and cell biology, and finally reflects the universality, the superiority and reliability of stereology.