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Title: SU-F-T-19: The Consistency Dosimetric Analysis of the Accelerated Breast Brachytherapy

Abstract

Purpose: To assess the best approach in accept a treatment plan for APBI Savi patients. Should we run a treatment verification test prior to delivering it to the patient? Should we check each CT scan in regards to the initial one in dosimetrical terms? Do we need deformable registration and adaptive planning for each fraction? These are the questions we want to answer running a dosimetric analysis of the dose variances for APBI treatments who receive 10 fractions and no re-planning has been done being considered unnecessary with today’s means of assessment. Methods: A retrospective analysis of 30 patients treated with SAVI applicators were considered for this study. The CT scans taken before each treatment were imported in the treatment planning system and registered with the initial CT scan. The images were fused together with respective to the applicator, using landmark registration. Dosimetric evaluations were performed. Dose received by skin, ribs and PTV on CT images with respect to the initial treatment plan were recorded including maximum, average and minimum dose Results: All the structures displayed changes in volume over the 10 fractions of treatment. The cavities reduction in volume was considerable with a maximum reduction of over 10%. Themore » PTV-eval is covered better due to this fact while the critical organs manifest an increase in the total and maximum dose delivered. Ribs and skin surface that are required by B39 protocol to be monitored can acquire maximum doses of 20% to 30% respectively. Conclusion: A dosimetric evaluation prior to the initial treatment and prior to each of the 10 fractions is proven to be necessary. Deformable registration and adaptive planning have to be studied more and eventually implemented for every patient who received more than one fraction of any type of brachytherapy treatment. Immobilization ad localization methods must be improved and studied further.« less

Authors:
; ;  [1]
  1. 21st Century Oncology, Boca Raton, FL (United States)
Publication Date:
OSTI Identifier:
22642269
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; BIOMEDICAL RADIOGRAPHY; BRACHYTHERAPY; COMPUTERIZED TOMOGRAPHY; CRITICAL ORGANS; IMAGE PROCESSING; MAMMARY GLANDS; PATIENTS; PLANNING; RADIATION DOSES; SKIN; VERIFICATION

Citation Formats

Pinder, J, Chandrasekara, S, and Pella, S. SU-F-T-19: The Consistency Dosimetric Analysis of the Accelerated Breast Brachytherapy. United States: N. p., 2016. Web. doi:10.1118/1.4956154.
Pinder, J, Chandrasekara, S, & Pella, S. SU-F-T-19: The Consistency Dosimetric Analysis of the Accelerated Breast Brachytherapy. United States. doi:10.1118/1.4956154.
Pinder, J, Chandrasekara, S, and Pella, S. 2016. "SU-F-T-19: The Consistency Dosimetric Analysis of the Accelerated Breast Brachytherapy". United States. doi:10.1118/1.4956154.
@article{osti_22642269,
title = {SU-F-T-19: The Consistency Dosimetric Analysis of the Accelerated Breast Brachytherapy},
author = {Pinder, J and Chandrasekara, S and Pella, S},
abstractNote = {Purpose: To assess the best approach in accept a treatment plan for APBI Savi patients. Should we run a treatment verification test prior to delivering it to the patient? Should we check each CT scan in regards to the initial one in dosimetrical terms? Do we need deformable registration and adaptive planning for each fraction? These are the questions we want to answer running a dosimetric analysis of the dose variances for APBI treatments who receive 10 fractions and no re-planning has been done being considered unnecessary with today’s means of assessment. Methods: A retrospective analysis of 30 patients treated with SAVI applicators were considered for this study. The CT scans taken before each treatment were imported in the treatment planning system and registered with the initial CT scan. The images were fused together with respective to the applicator, using landmark registration. Dosimetric evaluations were performed. Dose received by skin, ribs and PTV on CT images with respect to the initial treatment plan were recorded including maximum, average and minimum dose Results: All the structures displayed changes in volume over the 10 fractions of treatment. The cavities reduction in volume was considerable with a maximum reduction of over 10%. The PTV-eval is covered better due to this fact while the critical organs manifest an increase in the total and maximum dose delivered. Ribs and skin surface that are required by B39 protocol to be monitored can acquire maximum doses of 20% to 30% respectively. Conclusion: A dosimetric evaluation prior to the initial treatment and prior to each of the 10 fractions is proven to be necessary. Deformable registration and adaptive planning have to be studied more and eventually implemented for every patient who received more than one fraction of any type of brachytherapy treatment. Immobilization ad localization methods must be improved and studied further.},
doi = {10.1118/1.4956154},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = 2016,
month = 6
}
  • Purpose: Dosimetric findings in patients treated with the Contura multilumen balloon (MLB) breast brachytherapy catheter to deliver accelerated partial breast irradiation (APBI) on a multi-institutional Phase IV registry trial are presented. Methods and Materials: Computed tomography-based three-dimensional planning with dose optimization was performed. For the trial, new ideal dosimetric goals included (1) {>=}95% of the prescribed dose (PD) covering {>=}90% of the target volume, (2) a maximum skin dose {<=}125% of the PD, (3) maximum rib dose {<=}145% of the PD, and (4) the V150 {<=}50 cc and V200 {<=}10 cc. The ability to concurrently achieve these dosimetric goals usingmore » the Contura MLB was analyzed. Results: 144 cases were available for review. Using the MLB, all dosimetric criteria were met in 76% of cases. Evaluating dosimetric criteria individually, 92% and 89% of cases met skin and rib dose criteria, respectively. In 93% of cases, ideal target volume coverage goals were met, and in 99%, dose homogeneity criteria (V150 and V200) were satisfied. When skin thickness was {>=}5 mm to <7 mm, the median skin dose was limited to 120.1% of the PD, and when skin thickness was <5 mm, the median skin dose was 124.2%. When rib distance was <5 mm, median rib dose was reduced to 136.5% of the PD. When skin thickness was <7 mm and distance to rib was <5 mm, median skin and rib doses were jointly limited to 120.6% and 142.1% of the PD, respectively. Conclusion: The Contura MLB catheter provided the means of achieving the imposed higher standard of dosimetric goals in the majority of clinical scenarios encountered.« less
  • Purpose: To quantitatively evaluate the dosimetric impact of differing breast tissue compositions for electronic brachytherapy source for high dose rate accelerated partial breast irradiation. Methods: A series of Monte Carlo Simulation were created using the GEANT4 toolkit (version 10.0). The breast phantom was modeled as a semi-circle with a radius of 5.0 cm. A water balloon with a radius of 1.5 cm was located in the phantom with the Xoft AxxentTM EBT source placed at center as a point source. A mixed of two tissue types (adipose and glandular tissue) was assigned as the materials for the breast phantom withmore » different weight ratios. The proportionality of glandular and adipose tissue was simulated in four different fashions, 80/20, 70/30, 50/50 and 30/70 respectively. The custom energy spectrum for the 50 kVp XOFT source was provided via the manufacturer and used to generate incident photons. The dose distributions were recorded using a parallel three dimensional mesh with a size of 30 × 30 × 30 cm3 with 1 × 1 × 1 mm3 voxels. The simulated doses absorbed along the transverse axis were normalized at the distance of 1 cm and then compared with the calculations using standard TG-43 formalism. Results: All simulations showed underestimation of dose beyond balloon surface compared to standard TG-43 calculations. The maximum percentage differences within 2 cm distance from balloon surface were found to be 18%, 11%, 10% and 8% for the fat breast (30/70), standard breast (50/50), dense breast (70/30 and 80/20), respectively. Conclusion: The accuracy of dose calculations for low energy EBT source was limited when considering tissue heterogeneous composition. The impact of atomic number on photo-electric effect for lower energy Brachytherapy source is not accounted for and resulting in significant errors in dose calculation.« less
  • Purpose: To compare dosimetrically four different techniques of accelerated partial breast irradiation (APBI) in the same patient. Methods and Materials: Thirteen post-lumpectomy interstitial brachytherapy (IB) patients underwent imaging with preimplant computed tomography (CT) in the prone and supine position. These CT scans were then used to generate three-dimensional conformal radiotherapy (3D-CRT) and prone and supine helical tomotherapy (PT and ST, respectively) APBI plans and compared with the treated IB plans. Dose-volume histogram analysis and the mean dose (NTD{sub mean}) values were compared. Results: Planning target volume coverage was excellent for all methods. Statistical significance was considered to be a pmore » value <0.05. The mean V100 was significantly lower for IB (12% vs. 15% for PT, 18% for ST, and 26% for 3D-CRT). A greater significant differential was seen when comparing V50 with mean values of 24%, 43%, 47%, and 52% for IB, PT, ST, and 3D-CRT, respectively. The IB and PT were similar and delivered an average lung NTD{sub mean} dose of 1.3 Gy{sub 3} and 1.2 Gy{sub 3}, respectively. Both of these methods were statistically significantly lower than the supine external beam techniques. Overall, all four methods yielded similar low doses to the heart. Conclusions: The use of IB and PT resulted in greater normal tissue sparing (especially ipsilateral breast and lung) than the use of supine external beam techniques of 3D-CRT or ST. However, the choice of APBI technique must be tailored to the patient's anatomy, lumpectomy cavity location, and overall treatment goals.« less
  • Purpose: Accelerated partial breast irradiation (APBI) with balloon and catheter-based brachytherapy has gained increasing popularity in recent years and is the subject of ongoing phase III trials. Initial data suggest promising local control and cosmetic results in appropriately selected patients. Long-term data continue to evolve but are limited outside of the context of the American Society of Breast Surgeons Registry Trial. Methods and Materials: A retrospective review of 157 patients completing APBI after breast-conserving surgery and axillary staging via high-dose-rate {sup 192}Ir brachytherapy from June 2002 to December 2007 was made. APBI was delivered with a single-lumen MammoSite balloon-based applicatormore » to a median dose of 34 Gy in 10 fractions over a 5-day period. Tumor coverage and critical organ dosimetry were retrospectively collected on the basis of computed tomography completed for conformance and symmetry. Results: At a median follow-up time of 5.5 years (range, 0-10.0 years), the 5-year and 7-year actuarial incidences of ipsilateral breast control were 98%/98%, of nodal control 99%/98%, and of distant control 99%/99%, respectively. The crude rate of ipsilateral breast recurrence was 2.5% (n=4); of nodal failure, 1.9% (n=3); and of distant failure, 0.6% (n=1). The 5-year and 7-year actuarial overall survival rates were 89%/86%, with breast cancer–specific survival of 100%/99%, respectively. Good to excellent cosmetic outcomes were achieved in 93.4% of patients. Telangiectasia developed in 27% of patients, with 1-year, 3-year, and 5-year actuarial incidence of 7%/24%/33%; skin dose >100% significantly predicted for the development of telangiectasia (50% vs 14%, P<.0001). Conclusions: Long-term single-institution outcomes suggest excellent tumor control, breast cosmesis, and minimal late toxicity. Skin toxicity is a function of skin dose, which may be ameliorated with dosimetric optimization afforded by newer multicatheter brachytherapy applicators and a more rigorous skin dose constraint of ≤100%.« less
  • The purpose of this work was to report dosimetric experience with 2 kinds of multilumen balloon (MLB), 5-lumen Contura MLB (C-MLB) and 4-lumen MammoSite MLB (MS-MLB), to deliver accelerated partial-breast irradiation, and compare the ability to achieve target coverage and control skin and rib doses between 2 groups of patients treated with C-MLB and MS-MLB brachytherapy. C-MLB has 5 lumens, the 4 equal-spaced peripheral lumens are 5 mm away from the central lumen. MS-MLB has 4 lumens, the 3 equal-spaced peripheral lumens are 3 mm away from the central lumen. In total, 43 patients were treated, 23 with C-MLB, andmore » 20 with MS-MLB. For C-MLB group, 8 patients were treated with a skin spacing < 7 mm and 12 patients with rib spacing < 7 mm. For MS-MLB group, 2 patients were treated with a skin spacing < 7 mm and 5 patients with rib spacing < 7 mm. The dosimetric goals were (1) ≥ 95% of the prescription dose (PD) covering ≥ 95% of the target volume (V{sub 95%} ≥ 95%), (2) maximum skin dose ≤ 125% of the PD, (3) maximum rib dose ≤ 145% of the PD (if possible), and (4) the V{sub 150%} ≤ 50 cm{sup 3} and V{sub 200%} ≤ 10 cm{sup 3}. All dosimetric criteria were met concurrently in 82.6% of C-MLB patients, in 80.0% of MS-MLB patients, and in 81.4% of all 43 patients. For each dosimetric parameter, t-test of these 2 groups showed p > 0.05. Although the geometric design of C-MLB is different from that of MS-MLB, both applicators have the ability to shape the dose distribution and to provide good target coverage, while limiting the dose to skin and rib. No significant difference was observed between the 2 patient groups in terms of target dose coverage and dose to organs at risk.« less