![]() After all, which of these techniques has greatest promise for reducing cardiac morbidity depends critically upon the nature of cardiac organ motion during the respiratory cycle, as well as upon the reproducibility of cardiac position during breath-hold states. Furthermore, because of the growing interest in breathing-controlled radiation, an understanding of positional reproducibility in breath-hold states is necessary to determine the appropriate role of breathing control in breast cancer treatment. As Figure 1 depicts, motion of the heart with respiration may be quite substantial in some patients. Accurate information about respiratory motion is necessary not only regarding target structures, in order to define appropriate margins, but also regarding critical normal tissues, in order to allow optimization of treatment planning studies and minimization of treatment-related toxicities. The ability to compare and evaluate treatment plans generated by different planning techniques depends critically upon access to a sophisticated model of the patient, including an understanding of the effects of respiratory motion upon organ position. 13, 14, 15, 16, 17, 18, 19, 20, 21 The aim of these techniques is to reduce still further the dose received by the heart, in the hopes of minimizing the long-term morbidity and mortality associated with the treatment of breast cancer. ![]() 9įurther innovations in treatment planning are therefore under investigation, including intensity modulation 10, 11, 12 and various techniques for the control of respiratory motion. 1, 2, 3, 4, 5, 6, 7 While there are some indications that the increased risk of ischemic heart disease associated with radiation therapy has decreased as target definition and treatment techniques have improved over time, 8 cardiac perfusion defects have been documented even in patients treated from 1998-2002 with three-dimensional planning. 1, 2 However, several studies have suggested increased risks of mortality from ischemic heart disease in breast cancer patients treated with radiation, particularly to the left side of the chest. Adjuvant radiation therapy (RT) is an integral component of breast cancer treatment. ![]()
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