ABSTRACT
Objective@#To study the effects of different CT values assignment methods on the dose calculation of radiotherapy plan for brain metastases, which will provide a reference for radiotherapy treatment planning based on MR images.@*Methods@#A total of 35 patients treated with radiotherapy for brain metastases were selected, with pre-treatment CT and MR simulated positioning performed at the same day. Based on the simulation CT images, three dimensional conformal radiation therapy (3D-CRT) or intensity modulated radiation therapy (IMRT) plans were calculated as the original plan (Plan1). The CT and MR images were rigidly registered and then the main tissues and organs were delineated on CT and MR images. The average CT values of each tissue and organ were calculated. Three groups of pseudo CT were generated by three CT values assignment methods based on the CT images: whole tissue was assigned 140 HU; cavity, bone and other tissues were assigned -700 HU, 700 HU and 20 HU, respectively; different tissues and organs were assigned corresponding CT values. The dose distribution of Plan1 was recalculated on three groups of pseudo-CT to obtain Plan2, Plan3 and Plan4, respectively. Finally, the dosimetric difference between Plan1 and other plans (including Plan2, Plan3 and Plan4) were compared.@*Results@#The average CT values of bone and cavity were (735.3±68.0) HU and (-723.9±27.0) HU, respectively. The average CT values of soft tissues was mostly distributed from -70 to 70 HU. The dosimetric differences between Plan2, Plan3, Plan4, and Plan1 decreased in turn. The differences of maximum dose of lens were the biggest, which can reach more than 5.0%, 1.5%-2.0% and 1.0%-1.5%, respectively, and the differences of other dose parameters were basically less than 2.0%, 1.2% and 0.8%, respectively. In the pixelwise dosimetric comparison, the areas with more than 1% difference in the local target cases were mainly distributed in the skin near the field. On the other hand, those in the whole brain target cases were mainly distributed at the bone, cavity, bone and soft tissues junction, and the skin near the field. In addition, the dose calculation error of CT value assignment methods in 3D-CRT plan was slightly larger than that in IMRT plan, and that in whole brain target cases were significantly larger than that in local target cases.@*Conclusions@#Different CT value assignment methods have a significant effect on the dose calculation of radiotherapy for brain metastases. When appropriate CT values are given to bone, air cavity and soft tissue, respectively, the deviation of dose calculation can be basically controlled within 1.2%. And by assigning mass CT values to various tissues and organs, the deviation can be further controlled within 0.8%, which can meet the clinical requirements.
ABSTRACT
Objective To study the effects of different CT values assignment methods on the dose calculation of radiotherapy plan for brain metastases,which will provide a reference for radiotherapy treatment planning based on MR images.Methods A total of 35 patients treated with radiotherapy for brain metastases were selected,with pre-treatment CT and MR simulated positioning performed at the same day.Based on the simulation CT images,three dimensional conformal radiation therapy (3D-CRT) or intensity modulated radiation therapy (IMRT) plans were calculated as the original plan (Plan1).The CT and MR images were rigidly registered and then the main tissues and organs were delineated on CT and MR images.The average CT values of each tissue and organ were calculated.Three groups of pseudo CT were generated by three CT values assignment methods based on the CT images:whole tissue was assigned 140 HU;cavity,bone and other tissues were assigned-700 HU,700 HU and 20 HU,respectively;different tissues and organs were assigned corresponding CT values.The dose distribution of Plan1 was recalculated on three groups of pseudo-CT to obtain Plan2,Plan3 and Plan4,respectively.Finally,the dosimetric difference between Plan1 and other plans (including Plan2,Plan3 and Plan4) were compared.Results The average CT values of bone and cavity were (735.3 ± 68.0) HU and (-723.9 ± 27.0) HU,respectively.The average CT values of soft tissues was mostly distributed from-70 to 70 HU.The dosimetric differences between Plan2,Plan3,Plan4,and Plan1 decreased in turn.The differences of maximum dose of lens were the biggest,which can reach more than 5.0％,1.5％-2.0％ and 1.0％-1.5％,respectively,and the differences of other dose parameters were basically less than 2.0％,1.2％and 0.8％,respectively.In the pixelwise dosimetric comparison,the areas with more than 1％ difference in the local target cases were mainly distributed in the skin near the field.On the other hand,those in the whole brain target cases were mainly distributed at the bone,cavity,bone and soft tissues junction,and the skin near the field.In addition,the dose calculation error of CT value assignment methods in 3D-CRT plan was slightly larger than that in IMRT plan,and that in whole brain target cases were significantly larger than that in local target cases.Conclusions Different CT value assignment methods have a significant effect on the dose calculation of radiotherapy for brain metastases.When appropriate CT values are given to bone,air cavity and soft tissue,respectively,the deviation of dose calculation can be basically controlled within 1.2％.And by assigning mass CT values to various tissues and organs,the deviation can be further controlled within 0.8％,which can meet the clinical requirements.
ABSTRACT
This study was aimed to observe the therapeutic effect of qi-supplementing,blood-activating and phlegmresolving on chronic obstructive pulmonary disease (COPD) patients with blood stasis syndrome in the acute stage,and to evaluate the lung function improvement condition.Observation was also made on plasma fibrinogen and D-dimer,in order to provide references for traditional Chinese medicine (TCM) clinical treatment of COPD.A total of 174 acute COPD patients with blood stasis syndrome were selected from October 2015 to July 2017 in the Linqu County People's Hospital of Shandong Province.Patients were randomly divided into the control group and the study group.Conventional western medicine treatment was given to the control group.On the basis of routine western medicine treatment,the study group was treated with TCM qi-supplementing,blood-activating and phlegm-resolving method.The clinical efficacy,changes of lung function,plasma fibrinogen and D-dimer before and after treatment were observed in both groups.The results showed that the total efficacy of the study group was 95.4％,and the total efficacy of the control group was 79.3％.The difference was statistically significant (P ＜ 0.05).Pearson correlation study showed that plasma fibrinogen (r =-0.79,P ＜ 0.05) and D-dimer (r =-0.84,P ＜ 0.05) were negatively correlated with PaO2.Before treatment,there was no significant difference in lung function,plasma fibrinogen and D-dimer between two groups (P ＞ 0.05).After treatment,indicators of both groups were significantly improved,in which the improvement of the study group was more obvious.The difference between two groups was statistically significant (P ＜ 0.05).It was concluded that the expression levels of plasma fibrinogen and D-dimer were closely related to COPD.Qi-supplementing,blood-activating and phlegmresolving method can improve clinical symptoms,blood stasis status and lung function of COPD patients in the acute stage with remarkable curative effect.