RESUMO
Objective To investigate the correlations of the whole breast displacement in different respiratory cycle during free breathing (FB) following breast-conserving surgery to the displacement of selected skin marker,nipple,and selected surgical clip based on four-dimensional computed tomography (4D-CT).Methods Thirteen breast cancer patients who had undergone breast-conserving surgery received whole breast intensity-modulated radiotherapy (IMRT).Respiration-synchronized 4D-CT image data were gathered during FB and were exported to the Varian Eclipse treatment planning system,and the whole breast target,nipple,superior clip,and metal marker on the skin at the anterior body midline were delineated on the CT images of ten phases of the respiratory cycle by the same radiotherapist based on the same delineating criteria.The displacement distances of the delineated target in the mediolateral (x),anteroposterior (y),and superoinferior (z) axles were achieved,and the correlations of the whole breast target displacement to the displacement of the clip,nipple,and skin marker were analyzed.The ipsilateral lung was delineated on the CT images of every phase of the respiratory cycle,and the changes in ipsilateral lung volume were analyzed during the respiratory cycle relative to the displacement of the breast.Results The maximal displacement distances of the whole breast target in the x,y,and z axles during FB were 0.71,0.76 and 1.29 mm,respectively ( F =5.755,P ＜ 0.05 ).There was no relationship between the three-dimensional (3D) displacement of the whole breast and the volume of the whole breast (r =-0.264,P ＜ 0.05 ),and there was no relationship between the displacemeat of the whole breast and the volume change of the ipsilateral lung ( r =0.346,P ＜ 0.05).There was no significant difference among the mean target displacement distances in 3 axles,and among 2 selected successive end-inspiration (EI) phases and 3 selected successive end-expiration (EE) phases.There was no significant difference between the volumes of the whole breast targets at the selected El and EE phases.There was no relationship between the displacement of the whole breast target and the displacement of the nipple,skin marker or superior clip in the cavity along the x- and z-axles.Along the y-axle,8/13,7/11 and 9/13 of the patients showed displacement of the whole breast target relative to the displacement of the nipple,skin marker and superior clip respectively.However,according to a population-based analysis,the displacement of the whole breast target was only significantly associated with the displacement of the superior clip ( r =0.657,P ＜ 0.05 ).Conclusions The clip registration is more credible and sensitive than a skin marker or the nipple for measuring and correcting the displacement of the whole breast target during radiotherapy.
RESUMO
Objective To explore the influence of different delineators and different delineating time on target determination of the whole breast and to explore intrafraction and interaction target displacements of the breast on moderate deep inspiration breathing hold (mDIBH) assisted by active breathing control (ABC) after breast conservative surgery. Methods Twenty patients received primary CT-simulation assisted by ABC to get five sets of CT image on the three breathing condition which included one set from free breath ( FB), two sets from mDIBH and two sets from deep expiration breathing control (DEBH). After radiotherapy with ten to fifteen fractions, the repeat CT-simulation was carried out to get the same five sets of CT image as the primary CT-simulation. The whole breast target were delineated at different time by the same delineator and delineated respectively by five delineators on the first set of CT images got with mDIBH from the primary CT-simulation,and to compare the influence of delineator and delineating time on the whole breast target. The total silver clips in the cavity were marked respectively on the two sets of CT images got with mDIBH from the primary CT-simulation, and to compare the intrafraction displacement of geometric body structured by the total of silver clips. The two ribs near the isocentric plane of the breast target were delineated respectively on two sets of the mDIBH CT image from the primary CT-simulation and on one set of the mDIBH CT image from the repeat CT-simulation, and comparing the movement of the point of interest (POI) of the ribs delineated to get the value of intrafraction and interfraction thoracic expansion. Results There was not statistically significant between the four volumes of whole breast targets delineated by the same delineator at different time, but with statistics significant between the volumes of whole breast target delineated by the different delineators(F = 19.681, P = 0.000). There was not statistically significant between the intrafraction displacements of the POI of the geometric body at each direction, and with no statistically significant between intrafraction displacements of the POI of the ribs delineated on the same mDIBH condition. There was not statistically significant between the interfraction displacements of the POI of the ribs delineated. Conclusions The influence of different delineators on the whole breast target is statistically significant. The difference of displacement of the breast target with the same mDIBH eondition assisted by ABC at the different direction is not statistically significant.