Geometric and Dosimetric Approach to Determine Probability of Late Cardiac Mortality in Left Tangential Breast Irradiation: Comparison Between Wedged Beams and Field-in-Field Technique

Journal Article · Tue Nov 01 00:00:00 EDT 2011 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2010.12.021· OSTI ID:21590473

Pili, Giorgio; Grimaldi, Luca; Fidanza, Christian; Florio, Elena T ^[1]; Petruzzelli, Maria F ^[2]; D'Errico, Maria P ^[3]; De Tommaso, Cristina; Tramacere, Francesco ^[2]; Musaio, Francesca ^[1]; Castagna, Roberta; Francavilla, Maria C ^[2]; Gianicolo, Emilio A.L. ^[4]; Portaluri, Maurizio ^[2]

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1. Department of Medical Physics, 'A. Perrino' Hospital, Brindisi (Italy)
2. Department of Radiation Oncology, 'A. Perrino' Hospital, Brindisi (Italy)
3. Department of Laboratory Medicine, 'A. Perrino' Hospital, Brindisi (Italy)
4. National Research Council-Clinical Physiology Institute, Pisa-Lecce (Italy)

Purpose: To evaluate the probability of late cardiac mortality resulting from left breast irradiation planned with tangential fields and to compare this probability between the wedged beam and field-in-field (FIF) techniques and to investigate whether some geometric/dosimetric indicators can be determined to estimate the cardiac mortality probability before treatment begins. Methods and Materials: For 30 patients, differential dose-volume histograms were calculated for the wedged beam and FIF plans, and the corresponding cardiac mortality probabilities were determined using the relative seriality model. As a comparative index of the dose distribution uniformity, the planning target volume (PTV) percentages involved in 97-103% of prescribed dose were determined for the two techniques. Three geometric parameters were measured for each patient: the maximal length, indicates how much the heart contours were displaced toward the PTV, the angle subtended at the center of the computed tomography slice by the PTV contour, and the thorax width/thickness ratio. Results: Evaluating the differential dose-volume histograms showed that the gain in uniformity between the two techniques was about 1.5. With the FIF technique, the mean dose sparing for the heart, the left anterior descending coronary artery, and the lung was 15% (2.5 Gy vs. 2.2 Gy), 21% (11.3 Gy vs. 9.0 Gy), and 42% (8.0 Gy vs. 4.6 Gy) respectively, compared with the wedged beam technique. Also, the cardiac mortality probability decreased by 40% (from 0.9% to 0.5%). Three geometric parameters, the maximal length, angle subtended at the center of the computed tomography slice by the PTV contour, and thorax width/thickness ratio, were the determining factors (p = .06 for FIF, and p = .10 for wedged beam) for evaluating the cardiac mortality probability. Conclusion: The FIF technique seemed to yield a lower cardiac mortality probability than the conventional wedged beam technique. However, although our study demonstrated that FIF technique improved the dose coverage of the PTV, the restricted number of patients enrolled and the short follow-up did not allow us to evaluate and compare the breast cancer survival rates of the patients.

• OSTI ID: 21590473
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Vol. 81, Issue 3; Other Information: DOI: 10.1016/j.ijrobp.2010.12.021; PII: S0360-3016(10)03723-5; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
CHEST
COMPUTERIZED TOMOGRAPHY
CORONARIES
HEART
IRRADIATION
LUNGS
MAMMARY GLANDS
MORTALITY
NEOPLASMS
RADIATION DOSE DISTRIBUTIONS
RADIATION DOSES
ARTERIES
BLOOD VESSELS
BODY
CARDIOVASCULAR SYSTEM
DIAGNOSTIC TECHNIQUES
DISEASES
DOSES
GLANDS
ORGANS
RESPIRATORY SYSTEM
TOMOGRAPHY