PMC6106951_01
(a) and (b) Left foot at presentation. (c) and (d) Left foot at follow-up 11 months later with a new 3-4 cm circular lesion that developed just proximal to the irradiated area. (e) Right foot at presentation. (f) Right foot at follow-up 11 months later.
CRIDM2018-5610925.001.jpg
PMC6106951_01_CRIDM2018-5610925.001.jpg
fig1
Physical exam revealed tender, confluent, erythematous, and desquamated patches on the skin extending from the dorsal and ventral surfaces of his left foot to the ankle (Figures 1(a) and 1(b)). His right foot had smaller, erythematous patches proximal to the 4th and 5th digits extending between the digits (Figure 1(e)). At each short-term follow-up (<= 6 weeks) after completing his HDR brachytherapy, he reported a rewarding response with improvement of disease-related erythema, pain, and swelling in all treated areas, with near resolution of treatment related hyperpigmentation (Figures 1(c), 1(d), and 1(f)). He did develop a new 3-4 cm mildly erythematous, circular lesion on the dorsal surface of his left foot just proximal to the irradiated area, which was treated and controlled with topical steroids (Figures 1(c) and 1(d)).
(a) Two-part thermoplastic mesh encompassing the left foot with proximal border of treatment area outlined in black. (b) Complete Freiburg device consisting of a total of 39 catheters. (c) Plantar aspect of the Freiburg device. (d) Positioning of the left foot for CT scan and treatment.
CRIDM2018-5610925.002.jpg
PMC6106951_01_CRIDM2018-5610925.002.jpg
fig2
This two-part, clam shell construction allowed the entire foot to be tightly enveloped by TM yet provided ease of ingress and egress (Figure 2(a)). The FF was attached to the TM with dental floss interwoven between the FF beads and through the TM struts. This TM design and position of the FF catheters enabled the Ir-192 HDR source to travel in close proximity to the cutaneous tissue to be treated. A total of 39 catheters were required to encompass the entire treatment area of his left foot (Figures 2(b) and 2(c)). TM to delineate the intended treatment borders (Figure 2(d)).
(a) Left foot treatment plan: 3D view of source dwell positions. (b) Left foot treatment plan: cutaneous planning treatment volume is shown in cyan, and the delivery of a highly conformal 4 Gy of radiation is shown in yellow isodose line.
CRIDM2018-5610925.003.jpg
PMC6106951_01_CRIDM2018-5610925.003.jpg
fig3
The path of each FF catheter was identified in three dimensions, and dwell positions for the HDR source were selected in step increments of 5 mm (Figure 3(a)). The dwell times of these source positions were adjusted to provide uniform coverage of 4 Gy to the peripheral margins of the PTV (Figure 3(b)).