Comparison of attenuation correction factor, C att, estimated by calculation to the true correction factor derived by plan replication.
nTRPcorr versus lesion volume for all lesions in the study. The range of nTRPcorr at any given volume is wide, other than at the very smallest volumes, for which nTRPcorr tends toward 60 Gy.
Mean nTRPcorr versus mean volume for binned data. The coefficients of the fitted polynomial (expectation curve) are displayed on the chart (R2 = 0.998).
nTRPcorr of individual lesions (crosses) plotted against the expectation curve (solid), plus curves representing one (long dashes) and two (short dashes) SD from this mean curve. Lesions with the lowest PEI selected for replanning are seen as outliers (circled). nTRPcorr values achieved by replanning these cases are also indicated (diamonds).
Factors affecting treatment time. Some factors are inter-related, e.g., lesion volume may partially determine the prescription dose, or proximity to OAR may necessitate blocking.
Comparison between mean values of various parameters for replans and original clinical plans. Stated p values relate to two-tailed t-tests for a hypothesized mean difference of zero. Of these 14 replanned cases, numbers in parentheses indicate the total that met locally set planning aims for each of the dosimetric quality indicators. For PEI scores, the numbers in parentheses indicate those exceeding mean−1 SD (i.e., exceeding 0.8).
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