PV QA 4 - Poster Viewing Q&A 4
TU_5_3368 - A Prospective Trial to Compare Deep Inspiratory Breath Hold (DIBH) with Prone Breast Irradiation
Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3
A Prospective Trial to Compare Deep Inspiratory Breath Hold (DIBH) with Prone Breast Irradiation
N. K. Gerber1, B. Levinson2, S. X. Yan3, C. A. Perez3, I. J. Das3, O. G. Maisonet3, N. E. Huppert3, D. No3, C. Hitchen3, N. Mistry3, J. Kelley4, and J. Goldberg2; 1Department of Radiation Oncology, NYU School of Medicine, New York, NY, 2NYU School of Medicine, New York, NY, 3Department of Radiation Oncology, NYU Langone Health, New York, NY, 4Cornell University, New York, NY
Purpose/Objective(s): Early stage breast cancer is highly curable; thus minimizing late cardiac morbidity and secondary malignancy is a critical aim of treatment strategies. This study compares heart and lung doses between radiation plans generated supine with deep inspiratory breath hold (S-DIBH) and prone with free-breathing (P-FB) and examines the effect of breast volume (BV) on these dosimetric parameters.
Materials/Methods: Patients with left breast DCIS or invasive cancer who require whole breast irradiation after lumpectomy were enrolled on a single-institutional prospective protocol. Patients were simulated P-FB and S-DIBH; plans were generated using both scans. BV was measured on the P-FB scan. Wilcoxon Signed Rank Test and Wilcoxon Rank Sum Test were used to compare the within-patient differences (WPD) between plans (S-DIBH minus P-FB) for the entire cohort and within BV groups defined by tertiles. The primary endpoint was difference in mean heart dose (MHD). All tests were 2-sided with alpha of 0.05 and no adjustment for multiplicity.
Results: Forty patients were enrolled on the protocol. Thirty-four patients are included in the analysis due to patient withdrawal (n=3) or inability to hold their breath (n=3). Sixteen patients were treated to a whole breast dose of 4005cGy, 10 to 4050cGY, and 8 to 4256cGy. Statistical analyses revealed WPD were similar across the 3 doses. Average MHD was 80cGy in S-DIBH; lower by 3cGy in P-FB (p=0.08). Average mean ipsilateral lung dose (MLD) was 453cGy in S-DIBH; lower by 408cGy in P-FB (p<.0001). Average mean and max LAD dose was 251cGy and 551cGy in S-DIBH respectively; higher by 73cGy (p=0.1) and 442cGy in P-FB (p=0.3) respectively. Average hot spot and separation was 109% and 22cm in S-DIBH respectively; lower by 2% and 6cm in P-FB respectively (p<0.0001). For patients with the smallest BV, S-DIBH improved MHD and max and mean LAD doses whereas for those with the largest BV, P-FB had improved cardiac dosimetry. With increasing BV, there was an increasing advantage of P-FB for MHD (p=0.05), and max (p=0.03) and mean (p=0.02) LAD dose. Similarly, as BV increased, the reduction in MLD, hot spot, and separation with P-FB (vs. S-DIBH) increased (p<0.05) (table).
Conclusion: While mean heart dose did not differ between the P-FB and S-DIBH, mean lung dose was significantly lower with P-FB. Increasing breast size was significantly associated with improved cardiac dosimetry and hot spot reduction with P-FB. Small-breasted women are more likely to benefit from S-DIBH compared to P-FB for cardiac sparing with less disadvantage in lung dose and hot spot, than larger breasted women. WPD (S-DIBH – P-FB) based on BV
| || Small BV <592.1 cc (n=11) || Intermediate BV 592.1cc- 920.3 cc (n=11) || Large BV >920.3 cc (n=12) || P Value |
| MHD, cGy || -5.8* || 1.2 || 13.4 || 0.05 |
| Mean LAD dose, cGy || -174.4* || -83.3* || 30.0 || 0.02 |
| Max LAD dose, cGy || -1004.9* || -573.3* || 193.5 || 0.03 |
| MLD, cGy || 357.4 || 373.8 || 484.2 || 0.04 |
| Hot Spot % || .9 || 1 || 2 || 0.01 |
| Max separation, cm || 4.6 || 5.2 || 7.2 || 0.02 |
*A negative value indicates that the values for S-DIBH were lower than for P-FB
Author Disclosure: N.K. Gerber: None. S.X. Yan: None. C.A. Perez: None. I.J. Das: Honoraria; JASTRO, Japanese Society of Therapeutic Radiation. Speaker's Bureau; JASTRO, Japanese Society of Therapeutic Radiation. Travel Expenses; JASTRO, Japanese Society of Therapeutic Radiation. Committee Member and surveyor; ACR. Associate Editor; Br J Radiology, Medical Physics. examiner; ABR. Committe member and Chair; AAPM. O.G. Maisonet: None. N.E. Huppert: None. D. No: None. N. Mistry: None.