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. 2020 Jul;21(7):209-215.
doi: 10.1002/acm2.12893. Epub 2020 May 8.

Technical Note: A step-by-step guide to Temporally Feathered Radiation Therapy planning for head and neck cancer

Shireen Parsai  1 , Richard L J Qiu  2 , Peng Qi  1 , Juan C L Alfonso  3 , Jeremy Donaghue  1 , Eric Murray  1 , David Majkszak  1 , Nicole Dorio  1 , Clifton D Fuller  4 , Kristy Brock  4 , Shlomo Koyfman  1 , Neil Woody  1 , Nikhil Joshi  1 , Jacob G Scott  1
Affiliations

Technical Note: A step-by-step guide to Temporally Feathered Radiation Therapy planning for head and neck cancer

Shireen Parsai et al. J Appl Clin Med Phys. 2020 Jul.

Abstract

Purpose: Prior in silico simulations propose that Temporally Feathered Radiation Therapy (TFRT) may reduce toxicity related to head and neck radiation therapy. In this study we demonstrate a step-by-step guide to TFRT planning with modern treatment planning systems.

Methods: One patient with oropharyngeal cancer planned for definitive radiation therapy using intensity-modulated radiation therapy (IMRT) techniques was replanned using the TFRT technique. Five organs at risk (OAR) were identified to be feathered. A "base plan" was first created based on desired planning target volumes (PTV) coverage, plan conformality, and OAR constraints. The base plan was then re-optimized by modifying planning objectives, to generate five subplans. All beams from each subplan were imported onto one trial to create the composite TFRT plan. The composite TFRT plan was directly compared with the non-TFRT IMRT plan. During plan assessment, the composite TFRT was first evaluated followed by each subplan to meet preset compliance criteria.

Results: The following organs were feathered: oral cavity, right submandibular gland, left submandibular gland, supraglottis, and OAR Pharynx. Prescription dose PTV coverage (>95%) was met in each subplan and the composite TFRT plan. Expected small variations in dose were observed among the plans. The percent variation between the high fractional dose and average low fractional dose was 29%, 28%, 24%, 19%, and 10% for the oral cavity, right submandibular, left submandibular, supraglottis, and OAR pharynx nonoverlapping with the PTV.

Conclusions: Temporally Feathered Radiation Therapy planning is possible with modern treatment planning systems. Modest dosimetric changes are observed with TFRT planning compared with non-TFRT IMRT planning. We await the results of the current prospective trial to seeking to demonstrate the feasibility of TFRT in the modern clinical workflow (NCT03768856). Further studies will be required to demonstrate the potential benefit of TFRT over non-TFRT IMRT Planning.

Keywords: IMRT; TFRT; head and neck planning; reduce toxicity; temporally feathered radiation therapy.

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Conflict of interest statement

The author has no conflict of interests to disclose.

Figures

Fig. 1
Fig. 1
Schematic representation of Temporally Feathered Radiation Therapy. The target volume (purple pentagon) is surrounded by five organs at risk (circles). Five individual radiation plans are created for each day of the week whereby a higher fractional dose, dH (red), is delivered to the deprioritized OAR of interest and the four prioritzed OARs receive a lower fractional dose, dL (blue)
Fig. 2
Fig. 2
Planning flowchart to develop five TFRT subplans and the final composite plan. First, planning structures such as normal tissue rings, OAR‐PTV, mid‐line structures, etc., were created. A good “base” plan, which does not push on the five TFRT feathering target OARs, was generated before making the five TFRT subplans. Then, planning goals for OARs B‐E were added to the planning objectives. Further optimizations were run to create subplan A from the base plan. Subplan B, C, D, and E were created by copying the previous subplan and optimizing after modifying prioritized and deprioritized OARs. Further improvements were made to each subplan to meet the planning criteria. At the end, a composite plan was made by importing all the beams from the subplans into one trial. The fraction number of each prescription was changed to 7, for a total of 35 fractions for the composite plan
Fig. 3
Fig. 3
Representation of variation between dH and dL. Axial slices with dose distributions are illustrated with associated dose volume histogram (DVH) for each feathered organ. The differences in dose distributions between the higher fractional dose (i.e., OAR deprioritized) and lower fractional dose can be observed (i.e., OAR constrained). The DVH demonstrates the dose to the OAR for each of five subplans
See this image and copyright information in PMC

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