An evaluation of computerised tomography (CT) based treatment planning versus digitised image planning (standard planning technique) for carcinoma of the breast, using the four field breast technique

Abstract

Aim/research questions The aim of the study was to evaluate CT-based treatment planning versus digitised image planning (standard planning technique) for carcinoma of the breast, using the four-field breast technique, in terms of the depth of supraclavicular and axillary nodes, the variability of the breast tissue and the dose inhomogeneity at the matchline. The variability of the depth of supraclavicular and axillary nodes has not been documented in any local or national studies. When simulating patients for treatment, it is evident that the anatomical variability of patient chest wall thickness, shape and size is a contributing factor towards the final treatment plan and dose distribution achieved. Therefore knowing the correct depth of the nodes and being able to clearly demarcate the breast tissue should result in a favourable dose administration. The following questions were addressed:  What is the dose to the supraclavicular nodes from both plans?  What is the dose to the axillary nodes from both plans?  How do the plans differ in terms of dose coverage to the supraclavicular and axillary nodes?  What is the relationship between the depth of the supraclavicular nodes and the patient separation? ii  What is the relationship between the depth of the axillary nodes and the patient separation?  Does the target volume receive adequate dose coverage from the plans?  How is dose to the heart volume affected by target coverage on both plans?  How is dose to the lung volume affected by target coverage on both plans?  What is the dose variability along the matchline?  Are the plans over dosing?  Are the plans under dosing?