Background: The treatment of brain metastases with radiotherapy has shifted to the use of Stereotactic Radio-surgery (SRS). The technical issue of expanding the treatment volume around the Gross Tumor Volume (GTV) is ...Background: The treatment of brain metastases with radiotherapy has shifted to the use of Stereotactic Radio-surgery (SRS). The technical issue of expanding the treatment volume around the Gross Tumor Volume (GTV) is a current debate. Radiotherapy centers use variable GTV-PTV margins, ranging from one to 2 mm. Material and Methods: We performed a dosimetric comparison in plans of twenty patients using three margins: PTV zero, PTV1, and PTV2. We also developed imaginary Peel volumes. These volumes are described as follows: Peel1 = PTV1 − GTV, Peel2 = PTV2 − GTV. Results: Our results showed that the mean PTV volume differed significantly across the different margins (p = 0.000). The V12 of the brain significantly varied as a function of PTV margin (p = 0.000). The target coverage and plan quality indices were not significantly different. The Peel volume dosimetric analysis showed that the mean dose was significantly higher in the nearby normal brain tissue: Peel1 (p = 0.022) and Peel 2 (p = 0.013). Conclusion: According to our dosimetric analysis, expanding the GTV into a PTV by 1 mm margin is more convenient than 2 mm.展开更多
Radiation therapy after conservative breast surgery is an integral part of the treatment of early breast cancer</span><span style="font-family:Verdana;">.</span></span></span>&l...Radiation therapy after conservative breast surgery is an integral part of the treatment of early breast cancer</span><span style="font-family:Verdana;">.</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The aim of radiotherapy is</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> to achieve the best coverage of </span><span style="font-family:Verdana;">the</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Planning</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> Target Volume (PTV</span><span style="font-family:Verdana;">),</span><span style="font-family:Verdana;"> while reducing the dose to the Organs at Risk (OAR). Such goals are not always achievable with the conformal three dimensions plans (3DCRT). Recently, </span><span style="font-family:Verdana;">radiation</span><span style="font-family:Verdana;"> oncologist uses Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT)</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">for irradiating the breast. In this study, we compared 3DCRT, IMRT </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> VMAT for left breast cancer patients in terms of PTV coverage, OAR</span><span style="font-family:Verdana;">.</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">We</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> also revised the different dose distribution in 1) different breast volume categories, 2) nodal irradiation versus breast only, and 3) boost versus no boost. Results</span><span style="font-family:Verdana;">:</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> routinely reported dose </span><span style="font-family:Verdana;">constrains</span><span style="font-family:Verdana;"> for the ipsilateral lung and </span><span style="font-family:Verdana;">for</span><span style="font-family:Verdana;"> the heart were not significantly different on comparing the three techniques. While for the contralateral lung, the difference in mean dose was in favor of 3DCRT.</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">In large breast </span><span style="font-family:Verdana;">volume,</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">3DCRT provided a lower Max dose to the contralateral </span><span style="font-family:Verdana;">lung</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">and</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> the</span></span></span><span><span><span style="font-family:""> <span style="font-family:Verdana;">lowest</span><span style="font-family:Verdana;"> mean dose to the contralateral breast when compared to IMRT p < 0. 046</span><span style="font-family:Verdana;">.</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">In</span></span></span><span><span><span style="font-family:""> <span style="font-family:Verdana;">case</span><span style="font-family:Verdana;"> of no nodal irradiation, the contralateral breast </span><span style="font-family:Verdana;">mean</span><span style="font-family:Verdana;"> dose was lower in 3DCRT in comparison to IMRT and VMAT p < 0.037. When boost dose was given, 3DCRT plans had produced a lower Max dose to the contralateral lung p < 0.017. Conclusion</span><span style="font-family:Verdana;">:</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> three techniques (3DCRT, IMRT, and VMAT) can meet the clinical dosimetry demands of radiotherapy for left breast cancer after conservative surgery, as long as the routinely OARs only (heart and ipsilateral lung) </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">are</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> reported. Our study showed that 3CDRT can provide a lower dose to the contralateral organs (breast and lung), </span><span style="font-family:Verdana;">specially</span><span style="font-family:Verdana;">, in case of large breast volumes, no nodal irradiation </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> when a boost </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">given</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">.展开更多
文摘Background: The treatment of brain metastases with radiotherapy has shifted to the use of Stereotactic Radio-surgery (SRS). The technical issue of expanding the treatment volume around the Gross Tumor Volume (GTV) is a current debate. Radiotherapy centers use variable GTV-PTV margins, ranging from one to 2 mm. Material and Methods: We performed a dosimetric comparison in plans of twenty patients using three margins: PTV zero, PTV1, and PTV2. We also developed imaginary Peel volumes. These volumes are described as follows: Peel1 = PTV1 − GTV, Peel2 = PTV2 − GTV. Results: Our results showed that the mean PTV volume differed significantly across the different margins (p = 0.000). The V12 of the brain significantly varied as a function of PTV margin (p = 0.000). The target coverage and plan quality indices were not significantly different. The Peel volume dosimetric analysis showed that the mean dose was significantly higher in the nearby normal brain tissue: Peel1 (p = 0.022) and Peel 2 (p = 0.013). Conclusion: According to our dosimetric analysis, expanding the GTV into a PTV by 1 mm margin is more convenient than 2 mm.
文摘Radiation therapy after conservative breast surgery is an integral part of the treatment of early breast cancer</span><span style="font-family:Verdana;">.</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The aim of radiotherapy is</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> to achieve the best coverage of </span><span style="font-family:Verdana;">the</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Planning</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> Target Volume (PTV</span><span style="font-family:Verdana;">),</span><span style="font-family:Verdana;"> while reducing the dose to the Organs at Risk (OAR). Such goals are not always achievable with the conformal three dimensions plans (3DCRT). Recently, </span><span style="font-family:Verdana;">radiation</span><span style="font-family:Verdana;"> oncologist uses Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT)</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">for irradiating the breast. In this study, we compared 3DCRT, IMRT </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> VMAT for left breast cancer patients in terms of PTV coverage, OAR</span><span style="font-family:Verdana;">.</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">We</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> also revised the different dose distribution in 1) different breast volume categories, 2) nodal irradiation versus breast only, and 3) boost versus no boost. Results</span><span style="font-family:Verdana;">:</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> routinely reported dose </span><span style="font-family:Verdana;">constrains</span><span style="font-family:Verdana;"> for the ipsilateral lung and </span><span style="font-family:Verdana;">for</span><span style="font-family:Verdana;"> the heart were not significantly different on comparing the three techniques. While for the contralateral lung, the difference in mean dose was in favor of 3DCRT.</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">In large breast </span><span style="font-family:Verdana;">volume,</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">3DCRT provided a lower Max dose to the contralateral </span><span style="font-family:Verdana;">lung</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">and</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> the</span></span></span><span><span><span style="font-family:""> <span style="font-family:Verdana;">lowest</span><span style="font-family:Verdana;"> mean dose to the contralateral breast when compared to IMRT p < 0. 046</span><span style="font-family:Verdana;">.</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">In</span></span></span><span><span><span style="font-family:""> <span style="font-family:Verdana;">case</span><span style="font-family:Verdana;"> of no nodal irradiation, the contralateral breast </span><span style="font-family:Verdana;">mean</span><span style="font-family:Verdana;"> dose was lower in 3DCRT in comparison to IMRT and VMAT p < 0.037. When boost dose was given, 3DCRT plans had produced a lower Max dose to the contralateral lung p < 0.017. Conclusion</span><span style="font-family:Verdana;">:</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> three techniques (3DCRT, IMRT, and VMAT) can meet the clinical dosimetry demands of radiotherapy for left breast cancer after conservative surgery, as long as the routinely OARs only (heart and ipsilateral lung) </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">are</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> reported. Our study showed that 3CDRT can provide a lower dose to the contralateral organs (breast and lung), </span><span style="font-family:Verdana;">specially</span><span style="font-family:Verdana;">, in case of large breast volumes, no nodal irradiation </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> when a boost </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">given</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">.