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Comparisons of treatment optimization directly incorporating random patient setup uncertainty with a margin-based approach
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10.1118/1.3176940
/content/aapm/journal/medphys/36/9/10.1118/1.3176940
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/36/9/10.1118/1.3176940

Figures

Image of FIG. 1.
FIG. 1.

PTP optimization flow using fluence convolution used in this study.

Image of FIG. 2.
FIG. 2.

Typical isodose profiles on a transverse slice passing through the isocenter for (a) the optimized margin-based plan, without inclusion of the effect of the random patient setup errors, (b) the optimized margin-based plan, with inclusion of the random patient setup errors, and (c) the PTP-based plan, which inherently incorporates the effect of random patient setup errors.

Image of FIG. 3.
FIG. 3.

(a) The percentage difference in the CTV doses to 98% of the volume between the margin-based and PTP-based plans for each patient. The average difference of −0.5% is indicated by the small bar. Negative values indicate a lower dose for the PTP-based plans. 0.5% corresponds to a 39.6 cGy difference. (b) The percentage difference in the LNT volumes receiving 5000 cGy. The average difference of −48% is indicated by the small bar. Negative values indicate a lower volume for the PTP-based plans. 48% corresponds to a 409 cc reduction in volume. (c) The percentage difference in the local normal tissue maximum doses between the margin-based and PTP-based plans for each patient. The average difference of −1.9% is indicated by the small bar. 1.9% corresponds to a 120.7 cGy difference.

Image of FIG. 4.
FIG. 4.

(a) The percentage difference in CTV mean dose between the margin-based and PTP-based plans for each patient. The average difference of 0.7% is indicated by the small bar. Negative values indicate a lower dose for the PTP plans. 0.7% corresponds toh a 60.1 cGy difference. (b) The percentage difference in LNT mean dose between the margin-based and PTP-based plans for each patient. The average difference of 12.9% is indicated by the small bar. 12.9% corresponds to a 268 cGy difference.

Image of FIG. 5.
FIG. 5.

(a) The absolute difference in between the margin-based and PTP-based plans for each patient. The average difference of 2.45% is indicated by the small bar. Positive values indicate a better treatment outcome for the PTP-based plans. (b) The absolute difference in rectum NTCPs between the margin-based and PTP-based plans for each patient. The average difference of 1.9% is indicated by the small bar. Negative values indicate a lower complication rate for the PTP-based plans. (c) The absolute difference in bladder NTCPs between the margin-based and PTP-based plans for each patient. The average difference of 0.7% is indicated by the small bar. (d) The absolute difference in LNT NTCPs between the margin-based and PTP-based plans for each patient. The average difference of 0.06% is indicated by the small bar.

Image of FIG. 6.
FIG. 6.

Dosimetric margin distributions for sample (a) margin-based plan and (b) PTP-based plan. The average dosimetric margin for margin-based plans is 9.8 mm as indicated by the bar on (a). The average dosimetric margin for PTP plans is 7.2 mm as indicated by the bar on (b).

Tables

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TABLE I.

Optimization criteria used for generating patient plans, based on RTOG0126. Values of “Max.” for the volume indicate that the specified dose should not be exceeded anywhere within the volume.

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TABLE II.

Parameters used in TCP and NTCP evaluations. Values are equivalent to the default values given by the Pinnacle TPS (Refs. 40–42).

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TABLE III.

Minimum, maximum, range, mean, and standard deviation of DVH criteria observed over the 100 simulated treatment courses for the CTV and LNT structures compared with convolution. Average difference is the convolution value minus the mean of the simulated treatment courses. RMS value is the sum of the squared differences of each simulated course from the convolution value. Simulated treatment course values are the difference from convolution for volumes and the percentage difference relative to convolution for doses.

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TABLE IV.

Mean, maximum, minimum, and value for the difference in doses and difference in volumes between margin-based and PTP-based plans for the listed objectives. Plan objectives not listed were met by both methods for all plans. is used to indicate “difference in.”

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TABLE V.

Mean, maximum, and minimum differences in mean doses between margin-based and PTP-based plans, with associated values for objective structures. is used to indicate “difference in.”

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TABLE VI.

Mean, maximum, and minimum differences in , TCP, and NTCP between margin-based and PTP-based plans with associated values for objective structures. is used to indicate “difference in.”

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TABLE VII.

Mean, maximum, and minimum dosimetric margins for 7100 and 3960 cGy for both margin-based and PTP-based plans with values of the difference between margin-based and PTP-based plans.

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TABLE VIII.

Differences in the structure mean dose values when the patient plan is subject to half and double the estimated random uncertainty used during the optimization for margin-based and PTP-based plans.

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TABLE IX.

Mean dose and standard deviation over 28 patients for the listed criteria for plans optimized with but recomputed with , 3, and 6 mm. As uncertainty increases, the dose at target objectives decreases and vice-versa. As uncertainty increases, the dose at OAR objectives decreases and vice-versa. Objectives not listed were met by all plans.

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/content/aapm/journal/medphys/36/9/10.1118/1.3176940
2009-08-11
2014-04-23
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Comparisons of treatment optimization directly incorporating random patient setup uncertainty with a margin-based approach
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/36/9/10.1118/1.3176940
10.1118/1.3176940
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