Dosimetric consequences of the shift towards computed tomography guided target definition and planning for breast conserving radiotherapy

Table 3 PTV volumes and dimensions

	CT-based target definition	Conventional target definition	p-values
Absolute volumes (cm³)
Breast PTV	753 (209 – 1548)	-	-
Boost PTV	117 (40 – 243)	-	-
Breast PTV_CT beyond conventional field borders (cm)
Medial	0.03 (-1.5 – 1.1)		ns
Lateral	0.37 (-1.1 – 1.2)		0.01
Dimensions boost fields and PTVs (cm)
Field length	7.9 (5.4 – 10.4)	6.7 (4.5 – 8.5)	< 0.001
PTV_CT extending beyond PTV_CON
right	0.18 (-0.6 – 1.2)		0.03
left	0.36 (-0.4 – 1.7)		0.01
ventral	0.22 (-1.7 – 1.7)		ns
dorsal	0.23 (-0.7 – 2.5)		ns

PTV: planning target volume; PTV_CT: computed tomography (CT)-based PTV; PTV_CON: conventional PTV. Data presented as mean values, with ranges in parentheses.

ISSN: 1748-717X