The impact of breast size on mean lung dose for patients receiving tangential radiotherapy to the whole breast. Issue 2 (4th April 2016) - Schembri, Ashley
Abstract: Purpose: To explore the impact of breast size on mean lung dose (MLD) for patients receiving breast radiotherapy. Methodology: Chest wall separation (CWS), volume of tissue receiving 95% isodose and MLD were measured on 80 radiotherapy treatment plans of patients receiving tangential radiotherapy treatment to the whole breast. Breast size was categorised as small (CWS<25 cm and planned target volume (PTV)<1, 500 cm 3 ) and large (CWS>25 cm and PTV>1500 cm 3 ). Pearson's correlation and independent sample t -test were used to analyse data. Results: MLD was not affected by CWS ( r =−0·13, p =0·24) nor volume of tissue receiving 95% isodose ( r =−0·08, p =0·49). Significant variation between small and large breasts was noted for CWS ( t =8·24, p =0·00) and volume of tissue receiving 95% isodose ( t =5·68, p =0·00). No significant variation was noted between small and large breast for MLD ( t =−0·26, p =0·80) and between left and right breasts for CWS ( t =1·42, p =0·16) and volume of tissue receiving 95% isodose ( t =−1·08, p =0·28). Significant difference between left (18–808 cGy) and right breast (325–365 cGy) was demonstrated for MLD ( t =3·03, p =0·00). Conclusion: This study demonstrated lack of correlation between breast size and MLD. Further research is recommended for justification of alternative techniques for this subgroup of patients to provide optimised radiotherapy delivery.