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ESTRO 2020

Session Item

Physics track: Dose measurement and dose calculation
9319
Poster
Physics
00:00 - 00:00
Dental radiation dosimetry maps from IMRT planning for head and neck cancers
Bhupesh Parashar, USA
PO-1401

Abstract

Dental radiation dosimetry maps from IMRT planning for head and neck cancers
Authors: Jeffrey Antone.(Northwell health, Radiation Medicine, Lake Success, USA), Gogineni Emile.(Zucker School of Medicine at Hofstra/Northwell Health, Radiation Medicine, Lake Success, USA), Douglas Frank.(Zucker School of Medicine at Hofstra/Northwell Health, Radiation Medicine, Lake Success, USA), Bhupesh Parashar.(Zucker School of Medicine at Hofstra/Northwell Health, Radiation Medicine, Lake Success, USA), Simran Polce.(Stony Brook School of Medicine, Medicine, Stony Brook, USA), Louis Potters.(Zucker School of Medicine at Hofstra/Northwell Health, Radiation Medicine, Lake Success, USA), Joshua Segal.(Zucker School of Medicine at Hofstra/Northwell Health, Radiation Medicine, Lake Success, USA)
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Purpose or Objective

Dental professionals often request radiation doses to teeth, maxillae and mandibles from radiation oncologists who treat cancers of the head and neck. This frequently occurs before patients undergo CT simulation, precluding precise dose calculations. The purpose of this study was to create dental radiation maps, using exact dental numbering to provide to dental professionals the mean RT dose to teeth, maxilla and mandible for commonly treated primary head and neck cancers using intensity modulated radiation therapy (IMRT). 

Material and Methods

Nineteen common clinical settings were chosen for this retrospective study. Patients had received prior curative radiation treatment using IMRT. Radiation plans were extracted from ‘Velocity’ planning software for primary cancers that included nasopharyngeal, oropharyngeal, and oral cavity cancer among others, both in the definitive and adjuvant setting. Each tooth was contoured and labeled at the junction of the tooth and the gingiva based on dental numbering. Dental numbering was based on the Universal numbering system (American System). In addition, left lateral 3rd, middle 3rd and right lateral 3rd of the mandible and lower maxilla were contoured. Dose distribution to each tooth and mandible, maxilla were obtained. Dose wash images in axial, sagittal and coronal were also captured for each plan.

Results

Dosimetric data was calculated for 19 patients. All were treated with prescribed doses of 50-70Gy in 1.8-2Gy/fxn using dose painting IMRT. Tables with mean doses to each 3rd of the mandible and maxilla, along with each tooth were created, labeled 1-32. Two examples are provided in image format. Map 1: A 48 year old female with cT2N1 left tonsillar SCC. She was treated definitively with 70Gy to the primary and involved lymph node, 63Gy to left level II and 58.1Gy to left levels III-IV. The contralateral neck did not receive radiation. The ipsilateral 3rd of the mandible and 2 teeth (#16 and #17) received mean doses >50Gy, while the rest of the teeth, mandible and maxilla received mean doses <50Gy. Map 2: A 61 year old male with pT2N2b left oropharyngeal squamous cell carcinoma (SCC). He was treated adjuvantly with 66Gy to high-risk regions, 60Gy to left levels II-V, and 56Gy to right levels II-V. No tooth or region of maxilla or mandible received a mean dose of >50Gy.

Conclusion

We believe this to be the first study generating dental radiation dosimetric maps of estimated doses to each tooth and each third of the mandible and the maxilla for common examples of head and neck cancer faced by radiation oncologists. Adoption of these dental maps may help improve clinical work flow efficiency for dental providers and radiation oncologists by providing estimates of dental doses for common primary head and neck cancers, both for patients pending future radiation treatment and for previously irradiated patients when radiation plans are not available.