Deep Inspiration Breath Hold Reduces Dose to the Left Ventricle and Proximal Left Anterior Descending Artery during Radiotherapy for Left-Sided Breast Cancers

The purpose of this study was to analyze motion of the left anterior descending coronary artery (LAD) and left ventricle during normal breathing and deep inspiration breath hold (DIBH). This is a dosimetric study utilizing free-breathing and static DIBH scans from eleven patients treated with radiotherapy for breast cancer. The anterior-posterior displacement along the length of the LAD was measured in each respiratory phase. Standard treatment plans targeting the whole breast without treatment of the internal mammary lymph nodes were generated and dose to the LAD and LV calculated. Non-uniform movement of the LAD during respiratory maneuvers with the proximal third exhibiting the greatest displacement was observed. In DIBH compared to end-expiration (EP), the mean posterior displacement of the proximal 1/3 of the LAD was 8.99 mm, the middle 1/3 of the artery was 6.37 mm, and the distal 1/3 was 3.27 mm. In end-inspiration (IP) compared to end-expiration the mean posterior displacements of the proximal 1/3 of the LAD was 2.08 mm, the middle 1/3 of the artery was 0.91 mm, and the distal 1/3 was 0.97 mm. Mean doses to the LAD using tangential treatment fields and a prescribed dose of 50.4 Gy were 11.32 Gy in EP, 8.98 Gy in IP, and 3.50 Gy in DIBH. Mean doses to the LV were 2.38 Gy in EP, 2.31 Gy in IP, and 1.24 Gy in DIBH. In conclusion, inspiration and especially DIBH, cause a displacement of the origin and proximal 2/3 of the LAD away from the chest wall, resulting in sparing of the most critical segment of the artery during tangential radiotherapy.

Mammographic Findings Associated with Accelerated Partial Breast Irradiation Using Single Fraction Intraoperative Radiotherapy

Purpose: To evaluate the mammographic findings of women treated with accelerated partial breast irradiation (APBI) using single-fraction intraoperative radiotherapy (IORT). Materials/Methods: Women ≥ 40 years of age with unifocal invasive or intraductal carcinoma ≤ 2.5 cm on physical examination, mammography, and ultrasound were enrolled on an APBI trial using single fraction IORT. Post-treatment mammographic imaging was obtained at 6 months, 1 year, and then annually. Results: Between 12/02 and 6/04, 17 women underwent IORT at the time of lumpectomy (median age = 60 years;range = 40 - 83). The initial post-IORT mammogram showed increased density at the lumpectomy site in 11 patients (65%), while six patients (35%) had architectural distortion in the area of the irradiated tissue. Fifteen patients (88%) had numerous punctate, benign-appearing calcifications corresponding to the irradiated region. There was focal skin thickening near the incision in 13 patients (76%). At a median of 67 months, architectural distortion had stabilized and the benign-appearing calcifications remained stable in number and character. Eight patients (47%) had mammographic findings consistent with fat necrosis, ranging in size from 0.5 - 4 cm. Conclusions: After lumpectomy and IORT, mammographic changes include increased density and benign appearing calcifications in the irradiated region with focal skin thickening. These changes appear to stabilize over time and are consistent with post-treatment changes. These changes are important to identify in order to characterize benign changes from recurrent tumor.