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Cardiac substructure (CS) and coronary artery (CA) doses associated with post-mastectomy radiotherapy (pmrt) techniques to the chest wall (cw) and regional nodes
Proceedings of the 44th Annual ASTRO Meeting
165
Conclusions: An IMRT approach is feasible for prone-position breast radiotherapy and improves dose homogeneity, particularly in women with larger breast sizes. Further follow-up is necessary to determine if improvements in dose homogeneity impact on acute toxicity and cosmetic outcome in this cohort of women who have historically suffered from poor cosmesis after breast conserving therapy.
Mean Dmax Mean D05
1012
IMRT
Conventional
Ratio (IMRT/Conv)
107.2%⫾1.8% 105.3%⫾1.4%
113.0%⫾4.4% 109.1%⫾3.1%
95.0%⫾2.2% 96.6%⫾1.6%
Cardiac Substructure (CS) and Coronary Artery (CA) Doses Associated with Post-Mastectomy Radiotherapy (PMRT) Techniques to the Chest Wall (CW) and Regional Nodes
E.A. Krueger1, T. Koelling2, R.B. Marsh1, M.J. Schipper2, J.B. Butler1, L.J. Pierce1 1 Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 2Department of Cardiology, University of Michigan, Ann Arbor, MI Purpose/Objective: Minimal data exist regarding radiation (RT) doses received to the CS and CA following breast irradiation. To our knowledge, there are no published results of CS and CA dose following PMRT with or without inclusion of the internal mammary nodes (IMN), which are in close proximity to the heart. Therefore, the purpose of this study was to compare the estimated RT dose delivered to the entire heart, left/right atria (LA,RA) and ventricles (LV,RV), and proximal (prox) and distal (dist) segments of each CA for 5 PMRT techniques using 3D-based calculations. Materials/Methods: Twenty left-sided PMRT cases were studied. Clinical CW field borders were delineated with catheters. CW and IMN(first 3 interspaces) were outlined on contrast-enhanced CT’s. The RA, RV, LA, LV, left main(LMA), left anterior descending(LAD), left circumflex(LCX), right coronary(RCA), and posterior descending(PDA) arteries were contoured and verified by a cardiologist(T.K). Five PMRT techniques were applied to each case using 50/2Gy fx to the CW ⫹/- IMN targets: 1)Standard tangents (TAN) to CW only; 2)Cobalt (CO)using an AP IMN field and lateral tangents to CW; 3)Reverse hockey stick (RHS) using an AP IMN, medial CW electron field and lateral CW AP/PA photon fields; 4)mixed photon/electron beam (20/80) to the IMN with lateral tangents to the CW; and 5)partially wide tangent fields (PWTF) to IMN and CW. 3D dose calculations for 100 plans were performed for all structures defined. Dose volume metrics of V30 and V45 (volume receiving greater than 30 and 45 Gy, respectively) and Dmean (mean dose) to CS and CA were estimated by technique. Similarity groups were constructed using Tukey’s adjustment for pairwise tests to rank the techniques. Results: CO resulted in significantly greater Dmean to the heart (21.03Gy,SD3.5); RA (30.36Gy,SD5.06); LA (23.69Gy,SD3.30); RV (27.10Gy,SD6.51); prox-RCA (36.99Gy,SD3.52); dist-RCA (31.22Gy,SD4.41); left main (29.42Gy,SD4.00); dist-LCX (16.73Gy,SD8.52); and prox-PDA (21.22Gy,SD 9.02) than all other techniques. 20/80 resulted in significantly less dose than CO to these structures but significantly greater than the remaining 3 techniques (data to be presented). Both CO and 20/80 resulted in significantly greater Dmean to LV, dist-PDA, dist-& prox-LCX vs. the remaining 3 techniques (data to be presented). Only the prox- & dist-LAD did not receive maximal dose using CO. V30 for heart, RA, LA, RV, prox- & dist-RCA, and LMA demonstrated significantly worse results using CO. V45 was not found to be a significant discriminator between techniques, as only LA, dist-LCX resulted in values significantly greater with CO vs. the remaining 4 techniques. Unlike the CS and remaining CA results, Dmean to the prox-LAD was significantly greater for RHS and 20/80 and least for PWTF, with 9.5Gy,SD4.16 for PWTF vs. 20.52Gy,SD8.36 (p⫽0.000) for 20/80 and 17.64Gy,SD7.43 for RHS (p⫽0.008). Dist-LAD received significantly less Dmean with PWTF (11.02Gy,SD7.34) than all other techniques, with Dmean 31.70Gy,SD11.71 (p⫽0.000) for 20/80; 31.52Gy,SD16.84 (p⫽0.000) for TAN; 24.02Gy,SD17.56 (p⫽0.005) for CO; and 23.60Gy,SD12.75 (p⫽0.007) for RHS. Similar rankings were observed using V30. V45 was significantly less using PWTF than TAN for both prox-& dist-LAD. Conclusions: Among the techniques studied, CO and/or 20/80 resulted in the greatest Dmean to CS and CA with exception of the LAD. The other 3 techniques resulted in significantly less Dmean than CO and 20/80. PWTF resulted in a significantly smaller Dmean to the LAD and comparably low doses to the remaining CS and CA. Although TAN resulted in significant sparing of the majority of the cardiac structures, a significantly higher dose was delivered to the LAD. As cardiac toxicity secondary to RT and specific systemic therapies is well documented, there are increasing concerns of the potential additive risks. Our data suggest the least CS and CA radiation exposure following PMRT using PWTF. These results should serve as a baseline for future treatment planning studies of loco-regional treatment intended to further reduce cardiac exposure.
1013
Preservation of Oral Health-Related Quality of Life and Salivary Flow Rates After Inverse-Planned Intensity Modulated Radiotherapy (IMRT) for Head and Neck Cancer (HNC)
M.B. Parliament1, R. Scrimger1, E. Kurien1, S. Anderson1, C. Field2, H. Thompson2, J. Hanson3 1 Department of Radiation Oncology, University of Alberta, Edmonton, AB, Canada, 2Department of Medical Physics, University of Alberta, Edmonton, AB, Canada, 3Department of Epidemiology, Cross Cancer Institute, Edmonton, AB, Canada Purpose/Objective: To assess whether sequential static multi-leaf collimator (“step and shoot”) delivery of inverse-planned IMRT for comprehensive bilateral neck irradiation in HNC results in preservation of oral health-related quality of life and sparing of salivary flow. Materials/Methods: Between April 2000 and January 2002, 23 patients with head and neck carcinoma [primary sites: nasopharynx (5), oral cavity (12), oropharynx (3), all others (3)] were accrued to a phase I/II trial of inverse-planned IMRT for
165
Conclusions: An IMRT approach is feasible for prone-position breast radiotherapy and improves dose homogeneity, particularly in women with larger breast sizes. Further follow-up is necessary to determine if improvements in dose homogeneity impact on acute toxicity and cosmetic outcome in this cohort of women who have historically suffered from poor cosmesis after breast conserving therapy.
Mean Dmax Mean D05
1012
IMRT
Conventional
Ratio (IMRT/Conv)
107.2%⫾1.8% 105.3%⫾1.4%
113.0%⫾4.4% 109.1%⫾3.1%
95.0%⫾2.2% 96.6%⫾1.6%
Cardiac Substructure (CS) and Coronary Artery (CA) Doses Associated with Post-Mastectomy Radiotherapy (PMRT) Techniques to the Chest Wall (CW) and Regional Nodes
E.A. Krueger1, T. Koelling2, R.B. Marsh1, M.J. Schipper2, J.B. Butler1, L.J. Pierce1 1 Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 2Department of Cardiology, University of Michigan, Ann Arbor, MI Purpose/Objective: Minimal data exist regarding radiation (RT) doses received to the CS and CA following breast irradiation. To our knowledge, there are no published results of CS and CA dose following PMRT with or without inclusion of the internal mammary nodes (IMN), which are in close proximity to the heart. Therefore, the purpose of this study was to compare the estimated RT dose delivered to the entire heart, left/right atria (LA,RA) and ventricles (LV,RV), and proximal (prox) and distal (dist) segments of each CA for 5 PMRT techniques using 3D-based calculations. Materials/Methods: Twenty left-sided PMRT cases were studied. Clinical CW field borders were delineated with catheters. CW and IMN(first 3 interspaces) were outlined on contrast-enhanced CT’s. The RA, RV, LA, LV, left main(LMA), left anterior descending(LAD), left circumflex(LCX), right coronary(RCA), and posterior descending(PDA) arteries were contoured and verified by a cardiologist(T.K). Five PMRT techniques were applied to each case using 50/2Gy fx to the CW ⫹/- IMN targets: 1)Standard tangents (TAN) to CW only; 2)Cobalt (CO)using an AP IMN field and lateral tangents to CW; 3)Reverse hockey stick (RHS) using an AP IMN, medial CW electron field and lateral CW AP/PA photon fields; 4)mixed photon/electron beam (20/80) to the IMN with lateral tangents to the CW; and 5)partially wide tangent fields (PWTF) to IMN and CW. 3D dose calculations for 100 plans were performed for all structures defined. Dose volume metrics of V30 and V45 (volume receiving greater than 30 and 45 Gy, respectively) and Dmean (mean dose) to CS and CA were estimated by technique. Similarity groups were constructed using Tukey’s adjustment for pairwise tests to rank the techniques. Results: CO resulted in significantly greater Dmean to the heart (21.03Gy,SD3.5); RA (30.36Gy,SD5.06); LA (23.69Gy,SD3.30); RV (27.10Gy,SD6.51); prox-RCA (36.99Gy,SD3.52); dist-RCA (31.22Gy,SD4.41); left main (29.42Gy,SD4.00); dist-LCX (16.73Gy,SD8.52); and prox-PDA (21.22Gy,SD 9.02) than all other techniques. 20/80 resulted in significantly less dose than CO to these structures but significantly greater than the remaining 3 techniques (data to be presented). Both CO and 20/80 resulted in significantly greater Dmean to LV, dist-PDA, dist-& prox-LCX vs. the remaining 3 techniques (data to be presented). Only the prox- & dist-LAD did not receive maximal dose using CO. V30 for heart, RA, LA, RV, prox- & dist-RCA, and LMA demonstrated significantly worse results using CO. V45 was not found to be a significant discriminator between techniques, as only LA, dist-LCX resulted in values significantly greater with CO vs. the remaining 4 techniques. Unlike the CS and remaining CA results, Dmean to the prox-LAD was significantly greater for RHS and 20/80 and least for PWTF, with 9.5Gy,SD4.16 for PWTF vs. 20.52Gy,SD8.36 (p⫽0.000) for 20/80 and 17.64Gy,SD7.43 for RHS (p⫽0.008). Dist-LAD received significantly less Dmean with PWTF (11.02Gy,SD7.34) than all other techniques, with Dmean 31.70Gy,SD11.71 (p⫽0.000) for 20/80; 31.52Gy,SD16.84 (p⫽0.000) for TAN; 24.02Gy,SD17.56 (p⫽0.005) for CO; and 23.60Gy,SD12.75 (p⫽0.007) for RHS. Similar rankings were observed using V30. V45 was significantly less using PWTF than TAN for both prox-& dist-LAD. Conclusions: Among the techniques studied, CO and/or 20/80 resulted in the greatest Dmean to CS and CA with exception of the LAD. The other 3 techniques resulted in significantly less Dmean than CO and 20/80. PWTF resulted in a significantly smaller Dmean to the LAD and comparably low doses to the remaining CS and CA. Although TAN resulted in significant sparing of the majority of the cardiac structures, a significantly higher dose was delivered to the LAD. As cardiac toxicity secondary to RT and specific systemic therapies is well documented, there are increasing concerns of the potential additive risks. Our data suggest the least CS and CA radiation exposure following PMRT using PWTF. These results should serve as a baseline for future treatment planning studies of loco-regional treatment intended to further reduce cardiac exposure.
1013
Preservation of Oral Health-Related Quality of Life and Salivary Flow Rates After Inverse-Planned Intensity Modulated Radiotherapy (IMRT) for Head and Neck Cancer (HNC)
M.B. Parliament1, R. Scrimger1, E. Kurien1, S. Anderson1, C. Field2, H. Thompson2, J. Hanson3 1 Department of Radiation Oncology, University of Alberta, Edmonton, AB, Canada, 2Department of Medical Physics, University of Alberta, Edmonton, AB, Canada, 3Department of Epidemiology, Cross Cancer Institute, Edmonton, AB, Canada Purpose/Objective: To assess whether sequential static multi-leaf collimator (“step and shoot”) delivery of inverse-planned IMRT for comprehensive bilateral neck irradiation in HNC results in preservation of oral health-related quality of life and sparing of salivary flow. Materials/Methods: Between April 2000 and January 2002, 23 patients with head and neck carcinoma [primary sites: nasopharynx (5), oral cavity (12), oropharynx (3), all others (3)] were accrued to a phase I/II trial of inverse-planned IMRT for