The impact of Semi Lateral Decubitus Position on the Dose Volume Parameters of the Heart and Lung for Left Sided Breast Cancer Patients: A Comparative Dosimetric Study

Publication date: Available online 2 December 2017
Source:Practical Radiation Oncology
Author(s): Azza Helal, Mohamed Farouk, Sherief H Gamie, Mahran Abdo, Lila Mosa, Amr Abdul Aziz
IntroductionWhen treating breast cancer with radiation therapy, the impact of treatment position on heart and lung dose volume parameters (DVPs) is largely dependent on the maximal heart distance (MHD) and central lung distance (CLD).Purposeto evaluate how much heart and lung sparing can be achieved using the semi lateral decubitus (SLD) position without and with breath hold compared to the standard supine position for left sided breast cancer patients. A secondary aim was to investigate the impact of MHD & CLD on heart and lung DVPs.MethodsThirty five left-sided breast cancer patients were simulated in supine, free breathing SLD and SLD with breath hold positions. A dosimetry plan was developed for each of these and three plans were compared for target coverage and organs at risk sparing. A correlation between CLD, MHD and PTV, heart and ipsilateral lung DVPs was tested.ResultsSLD breath hold position showed a significant reduction in heart V5Gy, V10Gy, V25Gy, V30Gy, mean dose & max dose (p<0.001) and ipsilateral lung V20Gy and mean dose compared to supine (p<0.001) & free breathing SLD (p=0.003 & 0.006). There was also a significant reduction in the heart DVPs (p<0.001) & ipsilateral lung DVPs (p<0.001 & 0.007) with free breathing SLD compared to the supine position. SLD with or without breath hold were associated with significant reduction in MLD (p<0.001) and CLD (p=0.030 & 0.003) as compared to the supine position.ConclusionTreatment plans for patients in the semi lateral decubitus position with or without breath hold for left-sided breast cancer patients demonstrated a superior heart and lung sparing compared to the supine position due to significant reduction in MHD & CLD. MHD and CLD are important simulation factors which impact the heart and lung dose volume parameters.



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