Optimization of radiological protection of patients undergoing digital radiography / 中华放射医学与防护杂志

Objective To identify the necessity to carry out optimization procedure in routine digital radiography (DR) by evaluating changes of patient radiation dose and image waste ratio before and after optimization.Methods Two hundred patients with near-standard body build were enrolled in the study.Half of them undertook routine examination,and the others undertook the examination with bestlyoptimized protocol.The dose-area product (DAP) and entrance surface dose (ESD) were recorded.The image waste ratios in 2 groups were calculated and the reasons for image waste were analyzed.The radiation dose and image waste ratio before and after optimization were compared.Results The ESD,DAP and image waste ratio in bestly-optimized radiography were significantly lower than those in non-optimized radiography (z =9.31,16.22,P＜0.05; x2 =36.5,P ＜ 0.05).Conclusion Using the bestlyoptimized digital radiography,the patient radiation dose and image waste ratio are effectively reduced.

Dose distribution of 125Ⅰ seed sources in brachytherapy prostate cancer model / 中华放射医学与防护杂志

Objective To study the dose distribution of the radioactive 125Ⅰ seeds sources in the treatment of prostate cancer and also to explore the more effective method for improving treatment planning system (TPS).Methods Choose the designated TPS and use TLDs dosimeter based on a prostate cancer model.Finally stimulated measurement was focused on dose distribution in prostate cancer.The number of 125Ⅰ seed sources implanted was 89, each with 1.37 × 107 ( ± 5% ) Bq.Results Maximum dose of every layer ranged from 151 to 241 Gy, by 4.1% to 66.0% higher than the prescribed dose (145 Gy).The Minimum dose of every layer ranged from 101 to 128 Gy, by 12% to 30% higher than the prescribed dose.The maximum dose of normal tissue at 10 mm from the edge of model ranged from 46 to 91 Gy.The deviation was 44% -63% compared with the prescribed dose.Conclusions The designated TPS shows that it could be used as a practical guide for treatment of prostate cancer with the radioactive 125Ⅰ seed sources.The research methods offered by the study can provide evaluation of the TPS.

Radiation dose to patients in cardiovascular disease interventional procedures / 中华放射医学与防护杂志

Objective To collect and analyze the radiation dose to patients in cardiovascular interventional procedures and the radiation dose-related indicators,in order to provide a basis for improving radiation protection of patients.MethodsThe clinical data of 26 cases of complete cardiovascular interventional procedures was collected in the municipal Grade A Class Three hospitals,including coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA),and the patient-received radiation doses and other related factors was studied.TLD personal dosimeter radiation field matrix method was used to measure fluorescence time,the entrance skin dose (ESD),the peak skin dose (PSD),dosearea product (DAP) and other indicators.TLD was used to measure the organ dose of the phantom under the cardiovascular interventional procedure condition.ResultsThe fluoroscopy time was (17.7 ±15.6) min during the range of 0.80-42.4 min.The average entrance skin dose (ESD) was (159 ± 138)mGy during the range of 4.40-459 mGy.The peak skin dose (PSD) was (769 ± 705) mGy during the range of 22.6 - 2.43 × 103mGy.The fluorescence time,entrance skin dose (ESD) ,peak skin dose (PSD) of the group CA + PTCA are greater than the group CA and the difference has statistical significan.The peak skin dose and the fluoroscopy time have good linear correlation (r = 0.84,P ＜ 0.01 ).Conclusion The peak skin dose the patient received in cardiovascular interventional radiological operation can be estimated through the fluoroscopy time.

Application value of computed radiography energy subtraction in detecting pulmonary soft-tissue:comparison with direct digital radiography / 中华放射医学与防护杂志

Objective To compare the efficiency of computed radiography energy subtraction (ES-CR) with direct digital radiography (DR) in detecting the pulmonary soft-tissue signals.Methods The adult chest phantom including TRG was imaged by ES-CR and DR separately and was estimated by 6 radiologists with 5-value-differentiation method. ROC was used to analyze the performance of two systems. Images of DR and ES-CR of 28 patients with small lung cancer were diagnosed by 3 radiologists. Results The area under the ROC curves was 0. 727 in ES-CR and 0.827 in DR (Z= 2.96,P ＜ 0. 05). 28 small lung cancer patients were significantly different between two systems (x2 = 5.14,P ＜0. 05). Conclusions The true positive proportion of DR might be higher than that of ES-CR. ES-CR is inferior to DR in detecting pulmonary soft-tissue signals.

Experimental measurements of dosimetric parameters of Ir-192 new source / 中华放射肿瘤学杂志

Objective To perform thermoluminescent measurements of radial dose function and anisotropy function of a newly designed 192Ir microSelectron-HDR source, and establish evaluation methods for HDR dosimetry.Methods A polystyrene phantom with sylindrical holes in different measure positions was designed to accommodate thermo luminescent dosimeter (TLD) rods and radiation source.TLD rods with similar sensitivity were placed on a semicircle around the source center which had been precisely localized by either radiographic means or dose measurement.Dose-rates were measured at θ = 90° and r = 1-14 cm to calculate radial dose function (gL (r)), while measured along polar angles θ = 0° -165°(interval 15°) at radial distances r = 1 cm, 3 cm and 5 cm to calculate anisotropy function (F(r,θ)).All data were compared with those calculated by Monte Carlo (MC) method.The t-test was used for the statistics.Results The values of gL (r) were 1.007 -0.681 by calculation and 1.007 -0.598 by measurement with r = 1 - 14 cm(t = 0.00 - 2.89, all P > 0.05).The values of F (r,θ) were 0.631 - 1,0.660 - 1 and 0.696 - 1 by calculation, while 0.701 - 1, 0.668 - 1 and 0.629 - 1 by measurement at 1 cm, 3 cm and 5 cm with θ=0° -165°(t=0.40 -1.63, 0.02 -2.10, 0.08 -2.03, all P>0.05).Conclusions The results of radial dose function and anisotropy function measured by TLD measurement are in consistent with those calculated by MC calculations, which can be applied in treatment planning system as original input.

Estimation of solar radiation and its effects on tooth enamel electron spin resonance dosimetry / 中华放射医学与防护杂志

Objective To investigate solar radiation and its effects on human tooth enamel electron spin resonance (ESR) dosimetry. Methods 11 tooth enamel samples were prepared by mechanical method. The intensity of solar iUuminanee was measured with a light meter, the measured illuminance was converted to insolation using a coefficient. Summation of solar radiation was evaluated. Enamel samples were exposed to 60 Co γ rays followed by sunlight on sunny days, and ESR spectra were scanned after different exposure. Results The solar radiation to the samples was (580 ± 16) MJ/m2. Solar exposure also caused dosimetrie signal. The perpendicular component of dosimetrie signal increased linearly with the amount of solar radiation, another signal close to background tended to saturation. Conclusions The average effect of the solar radiation on the signal was be used to recognize the effect of solar radiation on the enamel, and estimate external dose accurately.

Three-dimensional dose rate table for 103pd radioactive stent / 中华放射肿瘤学杂志

Objective To investigate three-dimensional dose distribution for 103Pd radioactive stent.Methods The surface dose,the axial dose and radial dose in surface for 103pd stent (3 mm × 13 mm) were estimated by experimental simulating method, analytic function and MCNP4b code. Three-dimensional dose distribution was calculated by MCNP4b code. Results The surface dose of 103pd stent was 0. 109 and 0. 106 Gy estimated by experimental simulating method and MCNP4b code,between which the difference was less than 3%. The axial dose calculated by analytic function and MCNP4b code was well consistent,and so was the radial dose estimated by the three methods. Dose rate table were estimated by MCNP4b code. Conclnsions Dose distribution for 103 Pd stent estimated by the three methods is relatively accurate. Three-dimensional dose table estimated by MCNP4b may be used to calculate dose for 103Pd stent in animal experiment and clinical application.