ABSTRACT
X-ray examination is an important part of modern precision medicine,and plays an irreplaceable role in the diagnosis and evaluation of disease outcomes as well as the surgical planning.With the widespread use of digital radiology and CT examinations,repeated and excessive X-ray examinations occur that cause the subject to receive excessive or additional radiation doses which cause radiation damage.How to optimize the radiation dose to meet the diagnosis of the disease and reduce the radiation damage of the subject is an important topic for researchers and equipment developers.As a result,X-ray radiation damage has attracted the attention of governments,society,subjects and X-ray inspection workers.This article explores ways to reduce radiation dose and reviews its progress.
ABSTRACT
Objective To invesigate the influence of breathing motion on intensity-modulated radiotherapy (IMRT) of chest wall after radical mastectomy,and explore clinical value of accurately determined target volume.Methods A total of 17 radical mastectomy patients underwent 3DCT simulation scans sequentially followed by 4DCT simulation scans during free breathing.The targets and normal organs was determined based on CT images respectively.Three sets of radiotherapy plan were designed for each patient:plan 3D,plan 4D and plan 3D-A.The Plan 3D and plan 4D was designed based on 3D and 4D targets respectively.Plan 3D was copied to 4D target with the same isocenter coordinates.The dose distribution was calculated separately to evaluate the dose-volume histograms parameters for PTV,ipsilateral lung and heart,respectively.Two planning parameters was compared with paired t-test or Wilcoxon sign-rank test.Results The average volume of PTV4D was (10.35 ± 4.80) ％ larger than PTV3D (P =0.000).Compared with plan 3D,the V100,V95,V90,D95,D90,Dmin of plan 3D-A were reduced,that were (0.78 -18.0)％ (P=0.000),(0.01-3.90)％ (P=0.000),(0-2.12)％ (P=0.000),(13-222) cGy (P=0.000),(1-118) cGy (P=0.000),(6-1 910) cGy (P=0.000).However,the V20,V10,V5,Dmean of the ipsilateral lung and V30 of heart were same between 3D plan and 4D plan (P =0.288,0.407,0.435,0.758,0.575).Conclusions The respiratory motion may reduce the target dose and its coverage in chest wall treatments,so 4DCT plan could accurately define target volume without increasing the exposure dose of normal tissues.
ABSTRACT
Objective To study the PTV by ng 4DCT and compare target,target displacement and dose distribution of 3D and 4D planning for thoracic middle or lower esophageal cancer,evaluate the clinical value of 4DCT in esophageal cancer radiotherapy.Methods From Jan to Dec 2012patients with primary esophageal cancer underwent 3DCT simulation scans first,then followed by 4DCT simulation scan.PTV and OARs were sketched in the ordinary 3DCT and 4DCT respectively.And designing two sets of radiotherapy plan for each patient:3D and 4D plan.We compare PTV,PTV displacement and OARs dosimetry's differences in the 3D plan and 4D plan.Using the paired t-test or Wilcoxon sign-rank test to compare the difference between the two sets of plans.Results The volume of PTV4D was larger than the PTV3D (195.19 cm3 vs.175.67 cm3,P =0.001) in all patients.The center displacement had only significantly difference (displacement was 0.25 cm,P =0.014) in left-right direction for 10 patients of thoracic middle esophageal cancer.The center displacement had no significantly different in the three direction for 9 patients of thoracic under esophageal cancer (P=0.722,0.307,0.208).The dose target area of V100,V95 and V90 in Plan3DC were significantly than those in Plan-3D for 19 patients of thoracic middle-lower esophageal cancer (88.62％ vs.95.69％,P=0.000;95.17％ vs.99.79％,P=0.001;97.19％ vs.99.99％,P=0.001).In 4D plan the lung V5,V20 and Dmean of heart were higher than that in 3D plan for all patients (39.49％vs.37.44％,P=0.016;19.93％ vs.18.87％,P=0.018 and 2607.74 cGy vs.2389.16 cGy,P=0.004).Conclusions 4DCT positioning technology can accuracy determine individualized expanding boundary by target area of radiotherapy for thoracic middle or lower esophageal cancer.The enlarging target volume increase the dose of radiotherapy for lung,and in the dose range in the 4D plan,but the increased dose of heart should be noted.