Table 1 Structures, DVH parameters, and equations used in parameter calculations

PTV

Volume of the PTV (VPTV, cc), mean dose (Dmean, Gy), minimal dose covering the PTV (Dmin), the coverage (%), Conformity Index (CI), Conformity Number (CN) [11, 12].

Bladder wall

Volume (Vol., cc), D1cc and D2 cc (Gy)

Rectal/sigmoidal wall

Vol. (cc), mean dose (Gy), D1cc, D2cc as recommended by the GEC ESTRO Group [1, 2], Conformal Index (COIN) and the volume covered by the prescribed dose (Vref, Gy) [13]

Small bowel

Mean dose from CyberKnife (Dmean, Gy)

Calculations[11]–[13]

Conformal index (COIN)

COIN = CN * ∏ (1 - VORref, i/VOR, i)

CN) = 1/nCI;

Conformity index (nCI)

nCI = (Vref * PTV)/PTVref^2