Crawl positioning improves set-up precision and patient comfort in prone whole breast irradiation

Abstract

Prone positioning for whole-breast irradiation (WBI) reduces dose to organs at risk, but reduces set-up speed, precision, and comfort. We aimed to improve these problems by placing patients in prone crawl position on a newly developed crawl couch (CrC). A group of 10 right-sided breast cancer patients requiring WBI were randomized in this cross-over trial, comparing the CrC to a standard prone breastboard (BB). Laterolateral (LL), craniocaudal (CC) and anterioposterior (AP) set-up errors were evaluated with cone beam CT. Comfort, preference and set-up time (SUT) were assessed. Forty left and right-sided breast cancer patients served as a validation group. For BB versus CrC, AP, LL and CC mean patient shifts were - 0.8 ± 2.8, 0.2 ± 11.7 and - 0.6 ± 4.4 versus - 0.2 ± 3.3, - 0.8 ± 2.5 and - 1.9 ± 5.7 mm. LL shift spread was reduced significantly. Nine out of 10 patients preferred the CrC. SUT did not differ significantly. The validation group had mean patient shifts of 1.7 ± 2.9 (AP), 0.2 ± 3.6 (LL) and - 0.2 ± 3.3 (CC) mm. Mean SUT in the validation group was 1 min longer (P < 0.05) than the comparative group. Median SUT was 3 min in all groups. The CrC improved precision and comfort compared to BB. Set-up errors compare favourably to other prone-WBI trials and rival supine positioning.

Conflict of interest statement

Ghent University is the applicant of the patent entitled Radiotherapy Board and Couch [WO2015144654A1] filed on 25.03.2014. Inventors are Wilfried De Neve, Bruno Speleers, Bert Boute and Liv Veldeman. Status of the patent: pending. The patent applies to the Prone Crawl Breast Couch used in this study.

Figures

Figure 1

Patient set-up on a crawl couch prototype. (A) The prototype allows unobstructed anterior access to the ipsilateral lymphatic drainage areas. The projection of a red floor laser is seen along the sagital plane. (B) The contralateral side resembles current prone breastboards, overhanging design allows projection of a floor laser to decrease lateral positioning errors, while the patient is wearing a custom made unilateral bra, which retracts the contralateral breast away from the target volume.

Figure 2

Distribution of individual patient shifts registered on 3 axes for the standard and crawl prone positioning devices. Shifts were extracted by positioning patients on reference lines and noting the shift needed to match the CBCT to the simulation CT as closely as possible. Each patient is represented by a separate colour.

Figure 3

Pressure/tension scores for the 11 different localizations as indicated by individual patients in the comparative group, to be viewed side by side with Fig. 4. Different circle sizes indicated different pressure/tension scores per patient. Overlapping circles intensify the circle colour. (A) Standard prone breastboard at simulation, (B) crawl couch at simulation, (C) standard prone breastboard after treatment (D) crawl couch after treatment.

Figure 4

Pain scores for the 11 different localizations as indicated by individual patients in the comparative group, to be viewed side by side with Fig. 3. Different circle sizes indicated different pain scores per patient. Overlapping circles intensify the circle colour. (A) Standard prone breastboard at simulation, (B) crawl couch at simulation, (C) standard prone breastboard after treatment, (D) crawl couch after treatment.

Figure 5

Scores on the pain/pressure scale and answers to yes/no questions for the validation group at simulation (end), on day 5 of treatment and end of treatment. ? = missing, SP = slight pressure, PP = pronounced pressure, Numb = numbness, Ips = ipsilateral, Contr = contralateral.