Vx

Recommendations for standardized naming of targets, organs at risk and dose-volume metrics. Section 9 sets out the DVH-metric nomenclature DoseLab follows: Vx (volume receiving at least dose x), Dx (minimum dose to the hottest sub-volume x), CVx and DCx (the "cold" complements), output units in square brackets (Gy or % of prescription; cc or % of the structure), and an EQD2Gy unit with the α/β written in parentheses — for example D90%(10)[EQD2Gy]. Section 10 asks that DVH metrics say whether a lower-dose PTV is segmented (excludes the higher-dose PTV) or not. Read in the AAPM report PDF.

The template NRG Oncology gives investigators for writing the radiation section of a lung SBRT trial. Its imaging section allows PET/CT or MRI for structure definition, asks that the images be registered accurately to the planning scan (following AAPM TG-132 for deformable registration), notes that PET may be needed to separate tumor from atelectasis or fibrosis, and suggests an extra margin when a fused image is the primary image for the GTV. Its target and planning sections (5.2.4 and 5.2.6–5.2.8) define the plan-quality measures for lung SBRT trials: the prescription as the dose covering 95% of the PTV, a D99% requirement, R100% (prescription isodose volume ÷ PTV), R50% (50% prescription isodose volume ÷ PTV) and D2cm (maximum dose at 2 cm from the PTV in any direction, as a percentage of the prescription), with a table of allowable dose spillage by PTV volume. It describes a 20 mm PTV expansion structure used to control intermediate dose spillage, asks that dose above 105% of prescription be avoided outside the PTV, describes a deliberately heterogeneous dose with the hotspot in the central GTV, defines the maximum dose on a 0.03 cc volume, and ranks planning priorities when target coverage and organ limits conflict.

An editorial history of the UT Southwestern SABR constraint tables — often called the “Timmerman tables” — covering how they were developed and revised, and their relationship to AAPM TG-101 and NRG/RTOG protocols. Tables 2–11 separate serial tissues (listed with a volume, a volume max and a max point dose) from parallel tissues (listed with a critical volume and a critical-volume dose max). In Tables 2–7 a footnote defines “point” as ≤0.035 cm³; Tables 8–11 add a contouring-instructions column for each structure.