It has been previously reported that an MR on the first fraction of brachytherapy for cervical cancer may sufficiently define the target geometry for future fractions, and CT based normal tissue definition may allow for adequate customization of the plan to spare organs at risk (OAR), obviating the need for an MR on each fraction. The current report expands upon this with a larger cohort to determine if there are any subpopulations, such as large tumors, or those with residual parametrial extension that may benefit more from MR imaging on every brachytherapy fraction. As previously reported, women treated with tandem and ovoid or ring brachytherapy from 2011-2014 for cervical cancer were identified, in whom a planning MR was obtained on every fraction. The dose from this “MR optimized course” was captured for the HRCTV (D90 and D98), the IRCTV (D90), and OARs (bladder, rectum, sigmoid, and bowel, calculated to D2cc). Two simulated courses were then developed. The dwell positions from the first MR guided fraction were applied to the later fractions without any edits to define a “single plan course.” A “CT optimized course” was then created by developing new plans using only CT OAR anatomy from the latter fractions, with the HRCTV fused from the first fraction. If the applicator was changed, both simulations assumed that a new MR based plan would be developed with the new applicator. Doses were then calculated for the MR based HRCTVs and OARs, and both simulations were compared to the MR optimized course. Doses were converted to the equivalent dose at 2Gy per fraction (EQD2) via the BED equation (α/β = 10 for target, and 3 for normal tissue). Three patient factors at the time of the first fraction were then examined for impact on these findings: MR complete response (CR) vs partial response (PR), residual parametrial extension (PME), and the HRCTV volume. The Wilcoxon signed rank test was used for paired data, and the Mann-Whitney U test for unpaired, with a two tailed p-value of <0.05 considered significant. 19 women were identified; each undergoing 4-5 fractions of MR guided brachytherapy after 45Gy external beam with weekly cisplatin, 7 of whom had residual PME, and 7 with an MR CR. There was no systematic deviation in the D90 or D98 dose to HRCTV, or IRCTV D90 in either simulated course compared to the MR optimized fraction (p>0.05 for all comparisons). Fractional doses as a percent of the MR-optimized plan to the rectum were significantly lower with the CT-optimized plan (Rectal D2cc 94%,IQR 71-107%, p=0.024), higher to the bladder with the single plan course (Bladder D2cc 110%, IQR 89-124%, p=0.047), and higher to the small bowel with the single plan course (Bowel D2cc 105%, IQR 90-123%, p=0.011). There were no other significant systematic deviations in normal tissue dose. For those with greater than the median HRCTV volume (23.7cc), the doses to targets were no lower than those with smaller tumors. There was a modest significant decrease in D98 dose as a fraction of the MR optimized dose in those with residual PME, compared to those without (97% with PME, 102% without, p=0.018), and there were no other. The presence of MR CR or PR had no systematic effect on doses with either strategy. Women with residual parametrial extension at first brachytherapy had a slightly lower coverage of D98 with a CT-optimized plan compared to those without, however the absolute difference is likely clinically insignificant. Otherwise, neither tumor size, nor the lack of an MR complete response predicted for worse performance of either the single plan or CT-optimized plan. The CT-optimized plan had improved sparing of rectum, bladder, and small bowel compared to the single plan.