Dosimetric comparison of conventional and field-infield techniques in early-stage breast cancerradiotherapy

Background: breast conserving surgery followed by adjuvant whole breastradiotherapy is the accepted treatment in early-stage breast cancer. due tobreast irregularities, it is difficult to achieve homogenous dose distributionwith conventional techniques. currently, it is possible to use varied breastirradiation techniques such as field-in-field (fif) that is claimed to producemore homogenous distribution of doses within the target volumes whilesparing the organs at risk, leading to a better treatment outcome. the presentstudy aimed to compare the conventional and the fif techniquesdosimetrically. materials and methods: twenty patients with early-stagebreast cancer underwent computed tomography. two different treatmentplans were created for each patient: the wedge-based (conventional) planand the fif plan. dosimetric parameters and monitor units were comparedwith paired sample t-test. results: fif technique obtained significantly lowerdose homogeneity index, lower maximum doses and higher median doses inptv (p<0.05). similarly, the conformity index, and mean doses were higher inthe fif technique but the differences were not significant (p>0.05). inipsilateral lungs, fif significantly reduced the maximum and mean doses(p<0.05), and showed a tendency to reduce v20 (p>0.05). in patients with left-sided breast cancer, minimum and maximum doses and v40 of heart weresignificantly decreased in fif plans (p<0.05). doses to the contralateral lungsdid not differ significantly. conclusion: these results along with significantlyless monitor units required for therapy in fif suggest that this technique maybe more advantageous during breast irradiation.