Setup accuracy for prone and supine whole breast irradiation

Abstract

In this series, setup accuracy is significantly worse in prone compared to supine position for the LA and LO directions. However, without proper image-guidance, uncertainty margins of about 1 cm are also necessary for supine WBI. For patients with a higher BMI, larger margins are required.

Feasibility evaluation of prone breast irradiation with the Sagittilt© system including residual-intrafractional error assessment

“…The population systematic and random errors achieved by Sagittilt © were comparable to studies with daily CBCT verification [13,14,16,[21][22][23][24] (Table 2). Notably, the direction of the largest margin varied across these published data.…”

“…Prone treatments would require more than 10 mm CTV-PTV margin at least in one direction, while for supine it is consistently less than 10 mm in each direction [5,14,23]. Factors which may influence set-up errors included system type, platform design (flat/tilted), set-up technique (breast-torso-oriented), set-up verification (EPID/CBCT), CBCT registration method (clip and/or chest wall), learning curve, study design and patient related factors (body mass index) [14,16,21,23,24]. Despite the heterogeneity of the above mentioned factors in the previous studies, the achieved reproducibility remained more or less the same.…”

“…Moreover, prone deep inspiration breath-hold opened a new horizon to further reduce the heart dose, even with small cup sizes, while maintaining the drastic dose reduction to the lungs [12,20]. One major drawback of prone position is the higher set-up error [13,14,16,[21][22][23][24].…”

A simple clinical method for predicting the benefit of prone vs. supine positioning in reducing heart exposure during left breast radiotherapy

“…PTV contouring depends on repositioning accuracy and the method of treatment verification. Interfractional differences may be especially large in the prone position [18,30]. Lakosi et al found population systematic error values of 4.5/3.9/3.3 mm in the lateral/longitudinal/vertical directions, while the random error was 5.4/3.8/2.8 mm [27].…”

Individualised radiotherapy serving reduced toxicity in breast and prostate cancer

“…PTV contouring depends on repositioning accuracy and the method of treatment verification. Interfractional differences may be especially large in the prone position[13,66]. Lakosi et al found population systematic error values of 4.5/3.9/3.3 mm in the lateral/longitudinal/vertical directions, while the random error was 5.4/3.8/2.8 mm[15].…”