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Title: SU-F-T-520: Dosimetric Comparison of Radiation Treatment Plans for Whole Breast Irradiation Between 3D Conformal in Prone and Supine Positions Vs. VMAT and IMRT in Supine Positions

Abstract

Purpose: The target volume for Whole Breast Irradiation (WBI) is dictated by location of tumor mass, breast tissue distribution, and involvement of lymph nodes. Dose coverage and Organs at Risk (OARs) sparing can be difficult to achieve in patients with unfavorable thoracic geometries. For these cases, inverse-planned and 3D-conformal prone treatments can be alternatives to traditional supine 3D-conformal plans. A dosimetric comparison can determine which of these techniques achieve optimal target coverage while sparing OARs. Methods: This study included simulation datasets for 8 patients, 5 of whom were simulated in both supine and prone positions. Positioning devices included breast boards and Vaclok bags for the supine position, and prone breast boards for the prone position. WBI 3-D conformal plans were created for patients simulated in both positions. Additional VMAT and IMRT WBI plans were made for all patients in the supine position. Results: Prone and supine 3D conformal plans had comparable PTV coverage. Prone 3D conformal plans received a significant 50% decrease to V20, V10, V5 and V30% for the ipsilateral lung in contrast to the supine plans. The heart also experienced a 10% decrease in maximum dose in the prone position, and V20, V10, V5 and V2 had significantlymore » lower values than the supine plan. Supine IMRT and VMAT breast plans obtained comparable PTV coverage. The heart experienced a 10% decrease in maximum dose with inverse modulated plans when compared to the supine 3D conformal plan, while V20, V10, V5 and V2 showed higher values with inverse modulated plans than with supine 3D conformal plans. Conclusion: Prone 3D-conformal, and supine inverse planned treatments were generally superior in sparing OARs to supine plans with comparable PTV coverage. IMRT and VMAT plans offer sparing of OARs from high dose regions with an increase of irradiated volume in the low dose regions.« less

Authors:
;  [1]
  1. University of Toledo Medical Center, Toledo, OH (United States)
Publication Date:
OSTI Identifier:
22649106
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; ANIMAL TISSUES; IRRADIATION; LYMPH NODES; MAMMARY GLANDS; PATIENTS; POSITIONING; RADIATION DOSES; RADIOTHERAPY; SIMULATION; TISSUE DISTRIBUTION

Citation Formats

Bejarano Buele, A, and Parsai, E. SU-F-T-520: Dosimetric Comparison of Radiation Treatment Plans for Whole Breast Irradiation Between 3D Conformal in Prone and Supine Positions Vs. VMAT and IMRT in Supine Positions. United States: N. p., 2016. Web. doi:10.1118/1.4956705.
Bejarano Buele, A, & Parsai, E. SU-F-T-520: Dosimetric Comparison of Radiation Treatment Plans for Whole Breast Irradiation Between 3D Conformal in Prone and Supine Positions Vs. VMAT and IMRT in Supine Positions. United States. doi:10.1118/1.4956705.
Bejarano Buele, A, and Parsai, E. Wed . "SU-F-T-520: Dosimetric Comparison of Radiation Treatment Plans for Whole Breast Irradiation Between 3D Conformal in Prone and Supine Positions Vs. VMAT and IMRT in Supine Positions". United States. doi:10.1118/1.4956705.
@article{osti_22649106,
title = {SU-F-T-520: Dosimetric Comparison of Radiation Treatment Plans for Whole Breast Irradiation Between 3D Conformal in Prone and Supine Positions Vs. VMAT and IMRT in Supine Positions},
author = {Bejarano Buele, A and Parsai, E},
abstractNote = {Purpose: The target volume for Whole Breast Irradiation (WBI) is dictated by location of tumor mass, breast tissue distribution, and involvement of lymph nodes. Dose coverage and Organs at Risk (OARs) sparing can be difficult to achieve in patients with unfavorable thoracic geometries. For these cases, inverse-planned and 3D-conformal prone treatments can be alternatives to traditional supine 3D-conformal plans. A dosimetric comparison can determine which of these techniques achieve optimal target coverage while sparing OARs. Methods: This study included simulation datasets for 8 patients, 5 of whom were simulated in both supine and prone positions. Positioning devices included breast boards and Vaclok bags for the supine position, and prone breast boards for the prone position. WBI 3-D conformal plans were created for patients simulated in both positions. Additional VMAT and IMRT WBI plans were made for all patients in the supine position. Results: Prone and supine 3D conformal plans had comparable PTV coverage. Prone 3D conformal plans received a significant 50% decrease to V20, V10, V5 and V30% for the ipsilateral lung in contrast to the supine plans. The heart also experienced a 10% decrease in maximum dose in the prone position, and V20, V10, V5 and V2 had significantly lower values than the supine plan. Supine IMRT and VMAT breast plans obtained comparable PTV coverage. The heart experienced a 10% decrease in maximum dose with inverse modulated plans when compared to the supine 3D conformal plan, while V20, V10, V5 and V2 showed higher values with inverse modulated plans than with supine 3D conformal plans. Conclusion: Prone 3D-conformal, and supine inverse planned treatments were generally superior in sparing OARs to supine plans with comparable PTV coverage. IMRT and VMAT plans offer sparing of OARs from high dose regions with an increase of irradiated volume in the low dose regions.},
doi = {10.1118/1.4956705},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}
  • Purpose: To compare biophysical indices of Volumetric Modulated Arc Therapy (VMAT) and Intensity Modulated Radiation Therapy (IMRT) treatment plans for whole brain radiation therapy following the NRG-CC001 protocol. Methods: In this retrospective study, a total of fifteen patients were planned with Varian Eclipse Treatment Planning System using VMAT (RapidArc) and IMRT techniques. The planning target volume (PTV) was defined as the whole brain volume excluding a uniform three-dimensional 5mm expansion of the hippocampus volume. Prescribed doses in all plans were 30 Gy delivered over 10 fractions normalized to a minimum of 95% of the target volume receiving 100% of themore » prescribed dose. The NRG Oncology protocol guidelines were followed for contouring and dose-volume constraints. A single radiation oncologist evaluated all treatment plans. Calculations of statistical significance were performed using Student’s paired t-test. Results: All VMAT and IMRT plans met the NRG-CC001 protocol dose-volume criteria. The average equivalent uniform dose (EUD) for the PTV for VMAT vs. IMRT was respectively (19.05±0.33 Gy vs. 19.38±0.47 Gy) for α/β of 2 Gy and (19.47±0.30 Gy vs. 19.84±0.42 Gy) for α/β of 10 Gy. For the PTV, the average mean and maximum doses were 2% and 5% lower in VMAT plans than in IMRT plans, respectively. The average EUD and the normal tissue complication probability (NTCP) for the hippocampus in VMAT vs. IMRT plans were (15.28±1.35 Gy vs. 15.65±0.99 Gy, p=0.18) and (0.305±0.012 Gy vs. 0.308±0.008 Gy, p=0.192), respectively. The average EUD and NTCP for the optic chiasm were both 2% higher in VMAT than in IMRT plans. Conclusion: Though statistically insignificant, VMAT plans indicate a lower hippocampus EUD than IMRT plans. Also, a small variation in NTCP was found between plans.« less
  • Purpose: Accelerated partial breast irradiation (APBI) is an effective treatment for early stage breast-cancer. Irradiation in a prone position can mitigate breast motion and spare heart and lung. In this study, a comprehensive study is performed to evaluate various treatment techniques for prone APBI treatment including: 3D-CRT, IMRT, co-planar and non-coplanar partial arcs treatment. Methods: In this treatment planning study, a left breast patient treated in prone position in our clinic was imported into Varian Eclipse TPS. Six beams tangential to chest wall were used in both 3D-CRT and IMRT plans. These six beams were coplanar in a transactional planemore » achieved by both gantry and couch rotation. A 60-beam IMRT plan was also created to explore the maximum benefit of co-planar IMRT. Within deliverable couch rotation range (±30°), partial arc treatment plans with one and up to ten couch positions were generated for comparison. For each plan, 30Gy in 6 fractions was prescribed to 95% PTV volume. Critical dosimetric parameters, such as conformity index, mean, maximum, and volume dose of organ at risk, are evaluated. Results: The conformity indexes (CI) are 3.53, 3.17, 2.21 and 1.08 respectively to 3D-CRT, 6-beam IMRT, 60-beam IMRT, and two-partial-arcs coplanar plans. However, arc plans increase heart dose. CI for non-coplanar arc plans decreases from 1.19 to 1.10 when increases couch positions. Maximum dose in ipsilateral lung (1.98 to 1.13 Gy), and heart (0.62 to 0.43 Gy) are steadily decreased with the increased number of non-coplanar arcs. Conclusions: The dosimetric evaluation results show that partial arc plans have improved CIs compared to conventional 3D-CRT and IMRT plans. Increasing number of partial arcs decreases lung and heart dose. The dosimetric benefit obtained from non-coplanar arcs should be considered with treatment delivery time.« less
  • Purpose: The prone treatment position has been used to reduce ipsilateral lung and heart dose in left breast radiation. We conducted a retrospective study to evaluate the difference in the dosimetry between prone and supine treatment positions. Methods: Eight left breast cancer patients were simulated in both the supine and prone positions as a pretreatment evaluation for the optimal treatment position. Treatment plans were created for all patients in both the supine and prone positions using a field in field three dimensional planning technique. Prescribed dose was 45 Gy delivered by two tangential photon fields. Irradiated volume (IV) was evaluatedmore » by V50, V100, and dose to lung and heart by V5, V10, V20, and the mean dose were evaluated. Results: All dosimetry metrics for both the supine and prone plans met our internal normal structure guidelines which are based on Quantec data. The average IVs (50% and 100%) were 2223cc and 1361cc prone, 2315cc and 1315cc supine. The average ipsilateral lung Mean dose (0.83Gy prone vs 5.8Gy supine), V5 (1.6% prone vs 20.9% supine), V10 (0.78% prone vs 15% supine) and V20 (0.36% prone vs 11% supine) were significantly lower in prone position. Heart Mean dose (1.4Gy prone vs 2.9Gy supine), V10 (1.4% prone vs 5.0% supine) and V20 (0.4% prone vs 3.5% supine) were found improved for all patients except one where the mean dose was the same and all other values were improved. Conclusion: The prone position offer preferable dosimetry for all patients planned in our study. These patients were chosen based on the physician’s belief that they would benefit from prone treatment either because they had large pendulous breasts or due to the amount of heart seen in the field on CT simulation.« less
  • Purpose: To evaluate the comparative dosimetric efficacy between field and field 3DCRT(FnF), multiple field Intensity modulated radiotherapy (SnS IMRT) and, partial arc volumetric modulated arc therapy (VMAT) in case of post operative left side breast and chest wall irradiation. Methods: CT study set of fifteen post-operative left breast and chest wall patient was tested for a treatment plan of 50Gy in 25 fraction using partial arc VMAT, SnSIMRT and tangential beam 3DCRT . 3DCRT FnF gantry angle was ranging for left medial tangential 290±17{sup 0} and Lt lateral tangential l14°±12{sup 0}. For IMRT four fixed beam at gantry angle G130{supmore » 0} G110{sup 0} G300{sup 0} and G330{sup 0} was used, in case of insufficient dose another beam G150{sup 0} was added. In case of partial arc VMAT, lateral tangential arc G130{sup 0}-G100{sup 0} and medial tangential arc G280{sup 0}-G310{sup 0}. Inverse optimization was opted to cover at least 95%PTV by 95% prescription dose (RxD) and a strong weightage on reduction of heart and lung dose. PTV coverage was evaluated for it’s clinically acceptability depending on the tumor spatial location and its quadrant. Out of the three plans, any one was used for the actual patient treatment. Results: Dosimetric analysis done for breast PTV, left lung, heart and the opposite breast. PTV mean dose and maximum dose was 5129.8±214.8cGy, 4749.0±329.7cGy, 5024.6±73.4cGy and 5855.2±510.7cGy, 5340.7±146.1cGy, 5347.2±196.8cGy for FnF, VMAT and IMRT respectively. Ipsilateral lung volume receiving 20Gy and 5Gy was 23.6±9.5cGy and 32.7±10.3cGy for FnF, 18.6±8.7cGy and 38.8±15.2cGy for VMAT and 25.7±9.6cGy and 50.7±8.4cGy for IMRT respectively. Heart mean and 2cc dose was 867.9±456.7cGy and 5038.5±184.3cGy for FnF, 532.6±263cGy and 3632.1±990.6 for VMAT, 711±229.9cGy and 4421±463.7cGy for IMRT respectively. VMAT shows minimum contralateral breast dose 168±113.8cGy. Conclusion: VMAT shows a better tumor conformity, minimum heart, ipsilateral lung and opposite breast dose. Cardiac Toxicity and risk of contralateral breast cancer can be reduce using VMAT.« less
  • Purpose: The objective of this study was to compare setup precision, respiration-related breast movement and treatment time between prone and supine positions for whole-breast irradiation. Methods and Materials: Ten patients with early-stage breast carcinoma after breast-conserving surgery were treated with prone and supine whole breast-irradiation in a daily alternating schedule. Setup precision was monitored using cone-beam computed tomography (CBCT) imaging. Respiration-related breast movement in the vertical direction was assessed by magnetic sensors. The time needed for patient setup and for the CBCT procedure, the beam time, and the length of the whole treatment slot were also recorded. Results: Random andmore » systematic errors were not significantly different between positions in individual patients for each of the three axes (left-right, longitudinal, and vertical). Respiration-related movement was smaller in prone position, but about 80% of observations showed amplitudes <1 mm in both positions. Treatment slots were longer in prone position (21.2 {+-} 2.5 min) than in supine position (19.4 {+-} 0.8 min; p = 0.044). Conclusion: Comparison of setup precision between prone and supine position in the same patient showed no significant differences in random and systematic errors. Respiratory movement was smaller in prone position. The longer treatment slots in prone position can probably be attributed to the higher repositioning need.« less