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Title: Inverse-planned, dynamic, multi-beam, intensity-modulated radiation therapy (IMRT): A promising technique when target volume is the left breast and internal mammary lymph nodes

Abstract

The purpose of this study was to determine the optimum beam number and orientation for inverse-planned, dynamic intensity-modulated radiation therapy (IMRT) for treatment of left-sided breast cancer and internal mammary nodes (IMNs) to improve target coverage while reducing cardiac and ipsilateral lung irradiation. Computed tomography (CT) data was used from 5 patients with left-sided breast cancer in whom the heart was close to the chest wall. The planning target volume (PTV) was the full breast plus ipsilateral IMNs. Two geometric beam arrangements were investigated, 240{sup o} and 190{sup o} sector angles, and the number of beams was increased from 7 to 9 to 11. Dose comparison metrics included: PTV homogeneity and conformity indices (HI, CI), heart V30, left lung V20, and mean doses to surrounding structures. To assess clinical application, the IMRT plans with 11 beams equally spaced in a 190{sup o} sector angle were compared to conventional plans. Treatment times were modeled. The 190{sup o} IMRT plans improved PTV HI and CI and reduced mean dose to the heart, lungs, contralateral breast, and total healthy tissue (all p < 0.05) compared to a 240{sup o} sector angle. The 11-beam plan significantly improved PTV HI and CI, heart V30, leftmore » lung V20, and healthy tissue V5 compared to a 7-beam plan (all p < 0.05). The 11-beam plan reduced heart V30 and left lung V20 (p < 0.05) without compromising PTV coverage, compared to a 9-beam plan. Compared to a conventional plan, the IMRT class solution significantly improved PTV HI and CI (both p < 0.01), heart V30 (p = 0.01), and marginally reduced left lung V20 (p = 0.07) but increased contralateral breast and lung mean dose (p < 0.001) and healthy tissue V5 (p < 0.001). An 11-beam 190{sup o} sector angle IMRT technique as a class solution is clinically feasible.« less

Authors:
 [1];  [2];  [3];  [2];  [2];  [3];  [2];  [3]
  1. Radiation Therapy Program, British Columbia Cancer Agency-Vancouver Island Centre, Victoria, British Columbia (Canada). E-mail: cpopescu@bccancer.bc.ca
  2. Radiation Therapy Program, British Columbia Cancer Agency-Vancouver Island Centre, Victoria, British Columbia (Canada)
  3. (Canada)
Publication Date:
OSTI Identifier:
20858084
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Dosimetry; Journal Volume: 31; Journal Issue: 4; Other Information: DOI: 10.1016/j.meddos.2006.05.003; PII: S0958-3947(06)00127-0; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; BEAMS; CHEST; COMPARATIVE EVALUATIONS; COMPUTERIZED TOMOGRAPHY; HEART; IRRADIATION; LUNGS; LYMPH NODES; MAMMARY GLANDS; NEOPLASMS; PATIENTS; PLANNING; RADIATION DOSES; RADIOTHERAPY

Citation Formats

Popescu, Carmen C., Olivotto, Ivo, Division of Radiation Oncology and Developmental Radiotherapeutics, University of British Columbia, Vancouver, British Columbia, Patenaude, Veronica, Wai, Elaine, Division of Radiation Oncology and Developmental Radiotherapeutics, University of British Columbia, Vancouver, British Columbia, Beckham, Wayne A., and Physics and Astronomy Department, University of Victoria, Victoria, British Columbia. Inverse-planned, dynamic, multi-beam, intensity-modulated radiation therapy (IMRT): A promising technique when target volume is the left breast and internal mammary lymph nodes. United States: N. p., 2006. Web. doi:10.1016/j.meddos.2006.05.003.
Popescu, Carmen C., Olivotto, Ivo, Division of Radiation Oncology and Developmental Radiotherapeutics, University of British Columbia, Vancouver, British Columbia, Patenaude, Veronica, Wai, Elaine, Division of Radiation Oncology and Developmental Radiotherapeutics, University of British Columbia, Vancouver, British Columbia, Beckham, Wayne A., & Physics and Astronomy Department, University of Victoria, Victoria, British Columbia. Inverse-planned, dynamic, multi-beam, intensity-modulated radiation therapy (IMRT): A promising technique when target volume is the left breast and internal mammary lymph nodes. United States. doi:10.1016/j.meddos.2006.05.003.
Popescu, Carmen C., Olivotto, Ivo, Division of Radiation Oncology and Developmental Radiotherapeutics, University of British Columbia, Vancouver, British Columbia, Patenaude, Veronica, Wai, Elaine, Division of Radiation Oncology and Developmental Radiotherapeutics, University of British Columbia, Vancouver, British Columbia, Beckham, Wayne A., and Physics and Astronomy Department, University of Victoria, Victoria, British Columbia. Sun . "Inverse-planned, dynamic, multi-beam, intensity-modulated radiation therapy (IMRT): A promising technique when target volume is the left breast and internal mammary lymph nodes". United States. doi:10.1016/j.meddos.2006.05.003.
@article{osti_20858084,
title = {Inverse-planned, dynamic, multi-beam, intensity-modulated radiation therapy (IMRT): A promising technique when target volume is the left breast and internal mammary lymph nodes},
author = {Popescu, Carmen C. and Olivotto, Ivo and Division of Radiation Oncology and Developmental Radiotherapeutics, University of British Columbia, Vancouver, British Columbia and Patenaude, Veronica and Wai, Elaine and Division of Radiation Oncology and Developmental Radiotherapeutics, University of British Columbia, Vancouver, British Columbia and Beckham, Wayne A. and Physics and Astronomy Department, University of Victoria, Victoria, British Columbia},
abstractNote = {The purpose of this study was to determine the optimum beam number and orientation for inverse-planned, dynamic intensity-modulated radiation therapy (IMRT) for treatment of left-sided breast cancer and internal mammary nodes (IMNs) to improve target coverage while reducing cardiac and ipsilateral lung irradiation. Computed tomography (CT) data was used from 5 patients with left-sided breast cancer in whom the heart was close to the chest wall. The planning target volume (PTV) was the full breast plus ipsilateral IMNs. Two geometric beam arrangements were investigated, 240{sup o} and 190{sup o} sector angles, and the number of beams was increased from 7 to 9 to 11. Dose comparison metrics included: PTV homogeneity and conformity indices (HI, CI), heart V30, left lung V20, and mean doses to surrounding structures. To assess clinical application, the IMRT plans with 11 beams equally spaced in a 190{sup o} sector angle were compared to conventional plans. Treatment times were modeled. The 190{sup o} IMRT plans improved PTV HI and CI and reduced mean dose to the heart, lungs, contralateral breast, and total healthy tissue (all p < 0.05) compared to a 240{sup o} sector angle. The 11-beam plan significantly improved PTV HI and CI, heart V30, left lung V20, and healthy tissue V5 compared to a 7-beam plan (all p < 0.05). The 11-beam plan reduced heart V30 and left lung V20 (p < 0.05) without compromising PTV coverage, compared to a 9-beam plan. Compared to a conventional plan, the IMRT class solution significantly improved PTV HI and CI (both p < 0.01), heart V30 (p = 0.01), and marginally reduced left lung V20 (p = 0.07) but increased contralateral breast and lung mean dose (p < 0.001) and healthy tissue V5 (p < 0.001). An 11-beam 190{sup o} sector angle IMRT technique as a class solution is clinically feasible.},
doi = {10.1016/j.meddos.2006.05.003},
journal = {Medical Dosimetry},
number = 4,
volume = 31,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Purpose: This study was to investigate the dosimetric benefit of a novel intensity modulated radiation therapy (IMRT) technique for irradiating the left breast and regional lymph node (RLN). Methods: The breast and RLN (internal mammary node and periclavicular node) and normal tissue were contoured for 16 consecutive left-sided breast cancer patients previously treated with RT after lumpectomy. Nine equi-spaced fields IMRT (9 -field IMRT), tangential multi-beam IMRT (tangential-IMRT) and IMRT with fixed-jaw technique (FJT-IMRT) were developed and compared with three-dimensional conformal RT (3DCRT). Prescribed dose was 50 Gy in 25 fractions. Dose distributions and dose volume histograms were used tomore » evaluate plans. Results: All IMRTs achieved similar target coverage and substantially reduced heart V30 and V20 compared to the 3DCRT. The average heart mean dose had different changes, which were 9.0Gy for 9-field IMRT, 5.7Gy for tangential-IMRT and 4.2Gy for FJT-IMRT. For the contralateral lung and breast, the 9-field IMRT has the highest mean dose; and the FJT-IMRT and tangential-IMRT had similar lower value. For the thyroid, both 9-field IMRT and FJT-IMRT had similar V30 (20% and 22%) and were significantly lower than that of 3DCRT (34%) and tangential-IMRT (46%). Moreover, the thyroid mean dose of FJT-IMRT is the lowest. For cervical esophagus and humeral head, the FJT-IMRT also had the best sparing. Conclusion: All 9-field IMRT, tangential-IMRT and FJT-IMRT had superiority for targets coverage and substantially reduced the heart volume of high dose irradiation. The FJT-IMRT showed advantages of avoiding the contralateral breast and lung irradiation and decreasing the thyroid, humeral head and cervical esophagus radiation dose at the expense of a slight monitor units (MUs) increasing.« less
  • Purpose: Volumetric modulated arc therapy (VMAT) is a novel extension of conventional intensity-modulated radiotherapy (cIMRT), in which an optimized three-dimensional dose distribution may be delivered in a single gantry rotation. VMAT is the predecessor to RapidArc (Varian Medical System). This study compared VMAT with cIMRT and with conventional modified wide-tangent (MWT) techniques for locoregional radiotherapy for left-sided breast cancer, including internal mammary nodes. Methods and Materials: Therapy for 5 patients previously treated with 50 Gy/25 fractions using nine-field cIMRT was replanned with VMAT and MWT. Comparative endpoints were planning target volume (PTV) dose homogeneity, doses to surrounding structures, number ofmore » monitor units, and treatment delivery time. Results: For VMAT, two 190 deg. arcs with 2-cm overlapping jaws were required to optimize over the large treatment volumes. Treatment plans generated using VMAT optimization resulted in PTV homogeneity similar to that of cIMRT and MWT. The average heart volumes receiving >30 Gy for VMAT, cIMRT, and MWT were 2.6% +- 0.7%, 3.5% +- 0.8%, and 16.4% +- 4.3%, respectively, and the average ipsilateral lung volumes receiving >20 Gy were 16.9% +- 1.1%, 17.3% +- 0.9%, and 37.3% +- 7.2%, respectively. The average mean dose to the contralateral medial breast was 3.2 +- 0.6 Gy for VMAT, 4.3 +- 0.4 Gy for cIMRT, and 4.4 +- 4.7 Gy for MWT. The healthy tissue volume percentages receiving 5 Gy were significantly larger with VMAT (33.1% +- 2.1%) and IMRT (45.3% +- 3.1%) than with MWT (19.4% +- 3.7%). VMAT reduced the number of monitor units by 30% and the treatment time by 55% compared with cIMRT. Conclusions: VMAT achieved similar PTV coverage and sparing of organs at risk, with fewer monitor units and shorter delivery time than cIMRT.« less
  • We assessed the feasibility and impact of simultaneous-integrated boost intensity-modulated radiation therapy (SIB-IMRT) in the treatment of left breast carcinoma and compared target coverage and normal tissue doses with SIB-IMRT and 3-dimensional (3D) conformal RT using opposed tangential fields. For each of 10 patients with early-stage left-sided invasive breast carcinoma, 5 plans were generated; the first 4 were 3D conformal opposed tangential fields-2 with wedges, 2 with compensators and either photon or electron boost. A dose of 50.4 Gy in 28 fractions was prescribed to the left breast and an additional 16 Gy in 8 fractions to the lumpectomy bed.more » When compared to the tangential plans, SIB-IMRT maintained coverage (V{sub 95%}) to the left breast and lumpectomy bed without significantly increasing the left breast maximum dose. SIB-IMRT was able to reduce the lung mean dose, maximum dose, and the V{sub 20} by 55-104 cGy, 983-1298 cGy (p < 0.001), and 3.7-4.4%, respectively. In addition, SIB-IMRT reduced the maximum heart dose by 1032-1173 cGy and contralateral breast dose was increased (although p = NS). The mean and maximum dose to the unspecified tissues was also significantly reduced by 81-88 cGy and 516-942 cGy, respectively. SIB-IMRT resulted in a significant improvement in target dose conformality by up to 67%. Our findings that SIB-IMRT could improve dose conformality, reduce total treatment times, and reduce some of the normal structure doses presents it as an alternative technique for adjuvant breast radiotherapy; however this needs to be studied further in the clinic setting.« less
  • Purpose: To calculate planning target volume (PTV) margins for chest wall and regional nodal targets using daily orthogonal kilovolt (kV) imaging and to study residual setup error after kV alignment using volumetric cone-beam computed tomography (CBCT). Methods and Materials: Twenty-one postmastectomy patients were treated with intensity modulated radiation therapy with 7-mm PTV margins. Population-based PTV margins were calculated from translational shifts after daily kV positioning and/or weekly CBCT data for each of 8 patients, whose surgical clips were used as surrogates for target volumes. Errors from kV and CBCT data were mathematically combined to generate PTV margins for 3 simulatedmore » alignment workflows: (1) skin marks alone; (2) weekly kV imaging; and (3) daily kV imaging. Results: The kV data from 613 treatment fractions indicated that a 7-mm uniform margin would account for 95% of daily shifts if patients were positioned using only skin marks. Total setup errors incorporating both kV and CBCT data were larger than those from kV alone, yielding PTV expansions of 7 mm anterior–posterior, 9 mm left–right, and 9 mm superior–inferior. Required PTV margins after weekly kV imaging were similar in magnitude as alignment to skin marks, but rotational adjustments of patients were required in 32% ± 17% of treatments. These rotations would have remained uncorrected without the use of daily kV imaging. Despite the use of daily kV imaging, CBCT data taken at the treatment position indicate that an anisotropic PTV margin of 6 mm anterior–posterior, 4 mm left–right, and 8 mm superior–inferior must be retained to account for residual errors. Conclusions: Cone-beam CT provides additional information on 3-dimensional reproducibility of treatment setup for chest wall targets. Three-dimensional data indicate that a uniform 7-mm PTV margin is insufficient in the absence of daily IGRT. Interfraction movement is greater than suggested by 2-dimensional imaging, thus a margin of at least 4 to 8 mm must be retained despite the use of daily IGRT.« less
  • The purpose of this study was to evaluate the clinical implementation of tangential field IMRT using sliding window technique and to compare dosimetric parameters with 3-dimensional conformal radiation therapy (3DCRT). Twenty breast cancer patients were randomly selected for comparison of intensity modulated radiation therapy (IMRT)-based treatment plan with 3DCRT. Inverse treatment was performed using the sliding window technique, employing the Eclipse Planning System (version 7.1.59, Varian, Palo Alto, CA). The dosimetric parameters compared were V{sub 95} (the percentage of target volume getting {>=}95% of prescribed dose), V{sub 105}, V{sub 110}, and dose homogeneity index, DHI (percentage of target volume gettingmore » between 95% and 110% of prescribed dose). The mean V{sub 95}, DHI, V{sub 105}, and V{sub 110} for target volume for IMRT vs. 3D were 90.6% (standard deviation [SD]: 3.2) vs. 91% (SD: 3.0), 87.7 (SD: 6.0) vs. 82.6 (SD: 7.8), 27.3% (SD: 20.3) vs. 49.4% (SD: 14.3), and 2.8 (SD: 5.6) vs. 8.4% (SD: 7.4), respectively. DHI was increased by 6.3% with IMRT compared to 3DCRT (p < 0.05). The reductions of V{sub 105} and V{sub 110} for the IMRT compared to 3DCRT were 44.7% and 66.3%, respectively (p < 0.01). The mean dose and V{sub 30} for heart with IMRT were 2.3 (SD: 1.1) and 1.05 (SD: 1.5) respectively, which was a reduction by 6.8% and 7.9%, respectively, in comparison with 3D. Similarly, the mean dose and V{sub 20} for the ipsilateral lung and the percentage of volume of contralateral volume lung receiving > 5% of prescribed dose with IMRT were reduced by 9.9%, 2.2%, and 35%, respectively. The mean of total monitor units used for IMRT and 3DCRT was about the same (397 vs. 387). The tangential field IMRT for intact breast using sliding window technique was successfully implemented in the clinic. We have now treated more than 1000 breast cancer patients with this technique. The dosimetric data suggest improved dose homogeneity in the breast and reduction in the dose to lung and heart for IMRT treatments, which may be of clinical value in potentially contributing to improved cosmetic results and reduced late treatment-related toxicity.« less