Recumbent Total Skin Electron Beam Therapy

Abstract

Purpose: Our purpose was to describe preliminary dosimetric and clinical results of a recumbent total skin electron beam therapy (TSEBT) technique and compare this to a conventional standing TSEBT technique.

Methods and materials: A customized treatment platform with recessed side wheels was constructed and commissioned for patients to be treated in a recumbent position. Dosimetric and clinical information was collected for patients treated with this new recumbent technique in addition to that of a cohort of patients treated contemporaneously using the conventional standing method. Dose delivery and clinical outcomes were compared for patients treated with the recumbent and standing techniques.

Results: Between 2017 and 2019, 27 patients were treated with TSEBT with the recumbent (n = 13) or conventional standing technique (n = 14) at our institution. Measured dose at 15 body sites could be directly compared. Of these, 10 showed no significant difference between the two techniques while five sites showed significant differences in median measured dose, including the top of left shoulder, right biceps, bend of left elbow, upper back, and medial right thigh (P < .003). Measured dose was significantly higher with the standing technique at these sites with the exception of the upper back. Rates of complete response (25% vs 23%), partial response (50% vs 69%), and stable disease (17% vs 8%) were similar between the standing and recumbent cohorts, respectively (P = .78).

Conclusions: We have developed, commissioned, and implemented a floor-based, recumbent technique that allows for treatment of patients who would otherwise not be eligible for TSEBT. Dosimetric and clinical measurements suggest that this technique is a viable alternative to the standing method.

Figure 1

Recumbent total skin electron beam therapy setup (oblique field). Cu filter at interface mount; imagers retracted; couch raised and pulled out; phantom patient on platform; gantry at 300°; source-skin distance (SSD) = 305 cm.

Figure 2

Beams for recumbent total skin electron beam therapy. Patient positioned supine and placed under gantry for three anteroposterior fields. Platform is rolled out and rotated 90° for 4 left anterior oblique and then rotated 180° for 5 right anterior oblique. Patient is then positioned prone and two oblique fields treated. Final three posteroanterior fields then treated.

Figure 3

Progression-free survival by total skin electron beam technique (recumbent vs standing).