PMC9875822_01
Proton beam therapy treatment plan highlighting dose distribution, as depicted by the color key, to the maxilla and mandible for treatment of an embryonal rhabdomyosarcoma of the nasopharynx. Doses given in Gy(RBE = 1.1). For example, the area depicted in red received a mean of 50.5 Gy.
i2331-5180-9-3-50-f02.jpg
PMC9875822_01_i2331-5180-9-3-50-f02.jpg
i2331-5180-9-3-50-f02
PBT was started on week 13 and delivered a total dose of 50.4 Gy(RBE = 1.1) in 28 fractions at the University of Florida Health Proton Therapy Institute (Figure 2).
A series of dental panoramic radiographs taken following treatment completion at different age timepoints (A) 6 years 11 months, (B) 7 years 10 months, and (C) 8 years 11 months. Dental abnormalities are labelled 1 to 5 as follows: (1) Arrested root development of UR6, UL6, and LL6; (2) microdontia UR5, UL5, LL7, LR5 and LR7; (3) failure of development UR7, UL7, and LL5; (4) severe hypoplasia of roots (upper anterior teeth); and (5) mild hypoplasia of LR6 roots.
i2331-5180-9-3-50-f03.jpg
PMC9875822_01_i2331-5180-9-3-50-f03.jpg
i2331-5180-9-3-50-f03
The developmental stage of the teeth in Figure 3A suggests an abrupt halt to root development coincident with the timing of treatment.
Anterior periapical radiographs taken 8.5 years after treatment showing the short tapering root form of the UR3, UR2, UR1, UL1, UL2, and UL3. (A) Periapical radiograph maxillary right anterior segment. (B) Periapical radiograph maxillary left anterior segment.
i2331-5180-9-3-50-f04.jpg
PMC9875822_01_i2331-5180-9-3-50-f04.jpg
i2331-5180-9-3-50-f04
The poor prognosis of the anterior maxillary teeth is evidenced in Figure 4.
Dose-volume histogram (DVH) of the maxilla and the mandible. Doses given in Gy(RBE = 1.1). (A) DVH of the entire maxilla, Dmean 30 Gy. (B) DVH mandibular body, Dmean 14.1 Gy. (C) DVH mandibular rami, Dmean 43.9 Gy.
i2331-5180-9-3-50-f05.jpg
PMC9875822_01_i2331-5180-9-3-50-f05.jpg
i2331-5180-9-3-50-f05
In this case, it was estimated that 75.4% of the maxilla received 20 Gy(RBE = 1.1) and 50% received 30 Gy(RBE = 1.1), with a Dmax of 52.7 Gy(RBE = 1.1) (Figure 5A).