Three-dimensional radiation dosimetry using polymer gel and solid radiochromic polymer: From basics to clinical applications

Accurate dose measurement tools are needed to evaluate the radiation dose delivered to patients by using modern and sophisticated radiation therapy techniques. However, the adequate tools which enable us to directly measure the dose distributions in threedimensional(3D) space are not commonly available. One such 3D dose measurement device is the polymerbased dosimeter, which changes the material property in response to radiation. These are available in the gel form as polymer gel dosimeter(PGD) and ferrous gel dosimeter(FGD) and in the solid form as solid plastic dosimeter(SPD). Those are made of a continuous uniform medium which polymerizes upon irradiation. Hence, the intrinsic spatial resolution of those dosimeters is very high, and it is only limited by the method by which one converts the dose information recorded by the medium to the absorbed dose. The current standard methods of the dose quantification are magnetic resonance imaging, optical computed tomography, and X-ray computed tomography. In particular, magnetic resonance imaging is well established as a method for obtaining clinically relevant dosimetric data by PGD and FGD. Despite the likely possibility of doing 3D dosimetry by PGD, FGD or SPD, the tools are still lacking wider usages for clinical applications. In this review article, we summarize the current status of PGD, FGD, and SPD and discuss the issue faced by these for wider acceptance in radiation oncology clinic and propose some directions for future development.

Experimental measurement of radiation dose in a dedicated breast CT system

Radiation dose is an important performance indicator of a dedicated breast CT（DBCT）.In this paper,the method of putting thermoluminescent dosimeters（TLD） into a breast shaped PMMA phantom to study the dose distribution in breasts was improved by using smaller TLDs and a new half-ellipsoid PMMA phantom.Then the weighted CT dose index（CTDI_w） was introduced to average glandular assessment in DBCT for the first time and two measurement modes were proposed for different sizes of breasts.The dose deviations caused by using cylindrical phantoms were simulated using the Monte Carlo method and a set of correction factors were calculated.The results of the confirmatory measurement with a cylindrical phantom（11 cm/8 cm） show that CTDI_w gives a relatively conservative overestimate of the average glandular dose comparing to the results of Monte Carlo simulation and TLDs measurement.But with better practicability and stability,the CTDI_w is suitable for dose evaluations in daily clinical practice.Both of the TLDs and CTDI_w measurements demonstrate that the radiation dose of our DBCT system is lower than conventional two-view mammography.

Clinical observation on the time-effect relationship of moxibustion for primary dysmenorrhea due to stagnation and congelation of cold-damp

Objective:To observe the time-effect relationship of moxibustion for primary dysmenorrhea(PD)due to stagnation and congelation of cold-damp,thus explore the optimal choice of moxibustion duration,and provide evidence for achieving satisfactory efficacy in moxibustion treatment.Methods:A total of 90 patients with PD due to stagnatin and congelation of cold-damp were divided into three groups by the random number table method,with 30 cases in each group.All the patients in the three groups were given moxibustion treatment at Guanyuan(CV 4),20 min in group A,40 min in group B and 60 min in group C.The changes in the pain measurement score in the three groups were observed after treatment.Results:After treatment,there were significant differences in the clinical efficacy among the three groups(P<0.05);the clinical efficacy was better in group B and group C than that in group A(P<0.05),and that in group B was better than that in group C(P<0.05).Besides,the pain measurement score changed significantly after treatment in the three groups(all P<0.05),and the between-group differences were also statistically significant(P<0.05);the pain measurement scores in group B and group C were lower than that in group A(P<0.05),and that in group B was lower than that in group C(P<0.05).Conclusion:Given the same stimulating frequency and intervention time of moxibustion,40-minute duration demonstrates relatively better efficacy for PD due to stagnation and congelation of cold-damp.