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. Author manuscript; available in PMC: 2008 Dec 1.
Published in final edited form as: Int J Radiat Oncol Biol Phys. 2007 Dec 1;69(5):1572–1578. doi: 10.1016/j.ijrobp.2007.08.011

Table I.

The parameters used for dose specification and reporting for RTOG 95-17. The parameters are based on those recommended by the ICRU.[11]

Target Volume, (TV): The TV is a volume enclosed by a surface 2 cm outside the surgical cavity peripherally and 1 cm superficially and 1 cm deep, as defined by the clips.
Prescribed Dose: The dose intended by the prescribing physician, and documented in the patient's chart. The Prescribed Dose was to be 45 Gy for LDR implants, and 34 Gy for HDR implants.
Peripheral Dose (PD): The minimum target dose, defined by the ICRU as the minimum dose at the periphery of the TV. This would ideally be equal to the Prescribed Dose.
Central Plane: The plane through the geometric center of the implant, passing perpendicularly through the catheters.
Coronal Plane: The plane parallel to and midway between the two implant planes.
Sagittal Plane: The plane orthogonal to the Central and Coronal planes through the center of the implant.
Mean Central Dose (MCD): Average of all local dose minima, calculated by averaging the geometric center doses (GCD). The GCD is the dose at the center of the triangle formed by adjacent seed trains at their intersection with the central plane (see Figure 1). The MCD is the arithmetic mean of the GCDs. In this protocol, the GCD was modified for an obtuse triangle; the geometric center was determined at the boundary of the triangle rather than outside the triangle as required by the IRCU definition.
High Dose Region: The area encompassed by the isodose line corresponding to 150% of the MCD, as measured in the central plane.
Low Dose Region: The area within the target volume (TV) encompassed by an isodose line corresponding to 90% of the prescribed dose.
Dose Homogeneity Index (DHI): The ratio Prescribed Dose/MCD.
Average Peripheral Dose (APD): The average of the four doses calculated at the intersections of the coordinate axes with the edges of the TV in a specific plane (see Figure 2). If the peripheral dose at any of the four points exceeded the prescribed dose, the prescribed dose was used in the sum. Therefore, only doses less than the prescribed dose impacted this parameter.
Percent Deviation (Dav): The difference between the APD and the Prescribed Dose, expressed as a percentage. D = 100(PD-APD)/PD. The Percent Deviation was calculated in the central plane (Dc) and sagittal plane (Ds) and the two were averaged to obtain Dav = (Dc + Ds)/2.