Impacts and Improvement in Delineation of the Lumpectomy Cavity Boost Volume by using 3-D Implantable Tissue Markers Open Access

Xu, Tianyi (Spring 2018)

Permanent URL: https://etd.library.emory.edu/concern/etds/5h73pw073?locale=en
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Abstract

Background: For patients undergoing breast conserving surgery (BCS), adjuvant radiation therapy (RT) is the standard of care. For patients with high risk features lumpectomy cavity boost (LCB) is typically added in. There can be much discrepancy in defining these cavities when guided by the traditional methods. The ambiguity may lead to either overestimate or underestimate of the cavity’s actual size and affect the outcome, especially in the case of delay between surgery and adjuvant RT and oncoplastic reduction (OR). The dose RT boost Volume will be determined by the delineation of the cavity volume.

Methods and Materials: The records of 20 consecutive patients (41 to 76 years) who underwent BCS followed by adjuvant RT with a LCB at our institution were reviewed. Eight patients underwent BCS alone (40%) and 12 underwent BCS and OR (60%). At the time of surgery all patients had been placed a 3-D TM. The LCB volumes are determined by ten independent radiation oncologists. Paired T-tests and GEE model were used for statistical analysis.

Results: The mean LCB volume by using traditional methods was 33.2 cc (SD=29.2, SEM=6.9), while by using 3-D TM, the mean LCB volume was 13.2 cc (SD=13.8, SEM=2.5, P-value=0.072). By using the traditional methods, there was an average volume difference of being 17.4 cc larger than the actual treated boost volume. The corresponding percent overlap is 52% and an average DICE coefficient is 0.58.By using the 3-D TM method, the average volume difference was 2.6 cc smaller than the actual treated boost volume per patient. The corresponding percent overlap is 83.9% and an average DICE coefficient is 0.66.

Conclusion: Using 3-D TM method for planning will improve LCB volumes’ reproducibility and accuracy. On average, it gains a smaller and more precise LCB volumes than traditional methods. Moreover, using the 3-D TM can improve inter-rater reliability, which is consistent in different levels of raters. Higher level raters perform better than lower level raters, and it is more obvious by using 3-D TM method. Thus using novel 3-D implantable tissue markers is better in improving consistency among radiation oncologist boost volume contours.

Table of Contents

1. INTRODUCTION.. 1

2. METHODS AND MATERIALS. 2

2.1 Patients and Observation parameter. 2

2.2 Adjusting for Raters’ accuracy. 3

2.3 Statistical Analysis. 4

2.3.1 Descriptive analysis. 4

2.3.2 Statistical analysis. 4

2.3.3 Univariate and Multivariate Regression Analysis. 5

3. RESULTS. 7

3.1 Results of Descriptive analysis. 7

3.2 Results of Statistical analysis. 8

3.3 Results of Univariate and Multivariate Regression Analysis. 10

3.3.1 Results of univariate regression. 10

3.3.2 Results of multivariate regression. 12

4. CONCLUSION.. 12

5. DISCUSSION.. 13

6. REFERENCE.. 15

7. FIGURES AND TABLES. 16

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