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Title: SU-F-T-323: A Post-Mastectomy Radiation Therapy Dose Distribution Study Using Nanodots and Films

Abstract

Purpose: In post-mastectomy radiation therapy (RT), skin dose must be accurately estimated to assess skin reactions such as erythema, desquamation and necrosis. Planning systems cannot always provide accurate dosimetry for target volumes distal to skin. Therefore, in-vivo dosimetry is necessary. A female anthropomorphic phantom was used with optically stimulated luminescence dosimeters (nanoDots) to measure dose to chest wall skin. In addition, EBT2 films was employed to measure dose to left lung and heart in post-mastectomy RT. Methods: Films and nanoDots were calibrated under full buildup conditions at 100cm SAD for 6MV photons. Five pieces of films were placed between slabs of Rando phantom to assess dose to left lung and heart. Two layers of 0.5cm thick bolus were used to cover the whole left chest. Six pairs of nanoDots were placed at medical and lateral aspects on the bolus surface, between the 0.5cm bolus layers, and under the bolus. Three control nanoDots were placed on chest wall to quantify imaging dose. The phantom was CT scanned with all dosimeters in place, and treatment planning was performed with tangential fields (200cGy). All dosimeters were contoured on CT and dose was extracted. NanoDots were read using nanoDot reader and films were scannedmore » using film scanner. The measured and calculated doses were tabulated. Results: Dose to 12 nanoDots were evaluated. Dose variance for surface nanoDots were +3.8%, +2.7%, −5% and −9.8%. Those at lateral positions, with greater beam obliquity had larger variance than the medial positions. A similar trend was observed for other nanoDots (Table1). Point doses from films for heart and the left lung were 112.7cGy and 108.7cGy, with +10.2% and +9.04% deviation from calculated values, respectively. Conclusion: Dosimetry provided by the advanced planning system was verified using NanoDots and films. Both nanoDots and films provided good estimation of dose distribution in post-mastectomy RT.« less

Authors:
; ; ; ; ; ; ; ; ;  [1]
  1. Long Island Jewish Medical Center, Lake Success, NY (United States)
Publication Date:
OSTI Identifier:
22648929
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; CHEST; DOSEMETERS; DOSIMETRY; HEART; IN VIVO; LUNGS; PHANTOMS; PLANNING; QUANTUM DOTS; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIOTHERAPY; SKIN

Citation Formats

Qian, X, Vaidya, K, Puckett, L, Souri, S, Chen, Y, Cao, Y, Jamshidi, A, Lee, L, Klein, E, and Diaz, F. SU-F-T-323: A Post-Mastectomy Radiation Therapy Dose Distribution Study Using Nanodots and Films. United States: N. p., 2016. Web. doi:10.1118/1.4956508.
Qian, X, Vaidya, K, Puckett, L, Souri, S, Chen, Y, Cao, Y, Jamshidi, A, Lee, L, Klein, E, & Diaz, F. SU-F-T-323: A Post-Mastectomy Radiation Therapy Dose Distribution Study Using Nanodots and Films. United States. doi:10.1118/1.4956508.
Qian, X, Vaidya, K, Puckett, L, Souri, S, Chen, Y, Cao, Y, Jamshidi, A, Lee, L, Klein, E, and Diaz, F. 2016. "SU-F-T-323: A Post-Mastectomy Radiation Therapy Dose Distribution Study Using Nanodots and Films". United States. doi:10.1118/1.4956508.
@article{osti_22648929,
title = {SU-F-T-323: A Post-Mastectomy Radiation Therapy Dose Distribution Study Using Nanodots and Films},
author = {Qian, X and Vaidya, K and Puckett, L and Souri, S and Chen, Y and Cao, Y and Jamshidi, A and Lee, L and Klein, E and Diaz, F},
abstractNote = {Purpose: In post-mastectomy radiation therapy (RT), skin dose must be accurately estimated to assess skin reactions such as erythema, desquamation and necrosis. Planning systems cannot always provide accurate dosimetry for target volumes distal to skin. Therefore, in-vivo dosimetry is necessary. A female anthropomorphic phantom was used with optically stimulated luminescence dosimeters (nanoDots) to measure dose to chest wall skin. In addition, EBT2 films was employed to measure dose to left lung and heart in post-mastectomy RT. Methods: Films and nanoDots were calibrated under full buildup conditions at 100cm SAD for 6MV photons. Five pieces of films were placed between slabs of Rando phantom to assess dose to left lung and heart. Two layers of 0.5cm thick bolus were used to cover the whole left chest. Six pairs of nanoDots were placed at medical and lateral aspects on the bolus surface, between the 0.5cm bolus layers, and under the bolus. Three control nanoDots were placed on chest wall to quantify imaging dose. The phantom was CT scanned with all dosimeters in place, and treatment planning was performed with tangential fields (200cGy). All dosimeters were contoured on CT and dose was extracted. NanoDots were read using nanoDot reader and films were scanned using film scanner. The measured and calculated doses were tabulated. Results: Dose to 12 nanoDots were evaluated. Dose variance for surface nanoDots were +3.8%, +2.7%, −5% and −9.8%. Those at lateral positions, with greater beam obliquity had larger variance than the medial positions. A similar trend was observed for other nanoDots (Table1). Point doses from films for heart and the left lung were 112.7cGy and 108.7cGy, with +10.2% and +9.04% deviation from calculated values, respectively. Conclusion: Dosimetry provided by the advanced planning system was verified using NanoDots and films. Both nanoDots and films provided good estimation of dose distribution in post-mastectomy RT.},
doi = {10.1118/1.4956508},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = 2016,
month = 6
}
  • Purpose: To explore the effect of clinical tumor volume (CTV) displacement on the dosage of intensity-modulated radiation therapy (IMRT) plans for left-sided breast cancer after modified radical mastectomy. Methods: We created 2 sets of IMRT plans based on PTV0.5 and PTV0.7 (with CTV displacement of 0.5cm and 0.7cm respectively) for each of the ten consecutive left-sided breast cancer patients after modified radical mastectomy, and compared the difference in PTV coverage and organ at risk (OAR) sparing between the two groups. And then, we compared the difference in PTV coverage in IMRT plans based on PTV0.5 between the group with properlymore » estimated CTV displacement (presuming the actual CTV displacement was 0.5cm) and the one with underestimated CTV displacement (presuming the actual CTV displacement was 0.7cm). The difference in results between the corresponding two groups was compared using paired-sample t-test. P values less than 0.05 were considered statistically significant. Results: IMRT plans derived from PTV0.5 had more homogenous PTV coverage, and less heart, left lung, right breast, right lung, left humeral head and B-P radiation exposure, as well as less total Mu as compared with the ones stemmed from PTV0.7 (all p<0.05). IMRT plans with appropriate estimation of CTV displacement had better PTV coverage compared with the ones with underestimated CTV displacement (all p<0.01). Conclusion: The IMRT plans with smaller CTV displacement in post modified radical mastectomy radiotherapy for left-sided breast cancer has dosimetrical advantages over the ones with larger CTV displacement. Underestimation of CTV displacement can lead to significant reduction of PTV coverage. Individually quantifying and minimizing CTV displacement can significantly improve PTV coverage and OAR (including heart and left lung) sparing. This work was supported by the Medical Scientific Research Foundation of Guangdong Procvince (A2014455 to Changchun Ma)« less
  • The purpose of this work was to determine the risk of local-regional failure following post-mastectomy radiotherapy and the incidence of complications associated with such treatment. The authors retrospectively analyzed the results in 309 patients with Stage I--III invasive breast cancer treated with post-mastectomy radiation therapy between 1975 and 1985. The median radiotherapy dose was 45 Gy in 1.8 to 2.25 Gy fractions. One hundred forty-seven (48%) of the patients received adjuvant systemic chemotherapy with 115 (78%) of these receiving a CMF-based or doxorubicin-containing regime. The median follow-up time of surviving patients was 130 months (range, 28 to 191 months) aftermore » mastectomy. Seventeen patients (6%) developed a local-regional failure at an interval of 4 to 87 months after radiotherapy. Moderate or severe complications related to radiotherapy and requiring treatment were uncommon. Symptomatic radiation pneumonitis occurred in four patients (1.3%), arm edema in 18 (5.8%), and brachial plexopathy in 2 (0.6%). The authors conclude that post-operative radiotherapy is a safe and effective means of reducing local-regional failure following mastectomy. The efficacy of post-mastectomy radiotherapy in improving survival should be addressed in new large randomized controlled studies. 33 refs., 1 fig., 3 tabs.« less
  • Objective: To assess the impact of radiation management on male breast cancer (MBC) at London Regional Cancer Program (LRCP). Methods and Materials: Men with a diagnosis of breast cancer referred to LRCP were reviewed. The seventh American Joint Committee on Cancer staging system was used. Patients treated with and without post-mastectomy radiation therapy (PMRT) were analyzed. Disease-free survival (DFS) was defined as time duration from diagnosis to first recurrence. Overall survival (OS) was defined as time duration from pathologic diagnosis to death or last follow-up with any death defined as an event. Survival estimates were obtained using Kaplan-Meier methodology. Results:more » From January 1977 to December 2006, 81 men had invasive ductal carcinoma. The median age was 65 (range, 35-87 years). There were 15 Stage I, 40 Stage II, 20 Stage III, and 6 Stage IV patients. Median follow-up time was 46 months (range, 1-225 months). Of the 75 patients treated with curative intent, 29 did not receive PMRT and 46 completed PMRT. Patients who received PMRT demonstrated no benefit in overall survival (p = 0.872) but significantly better local recurrence free survival (p < 0.001) compared with those who did not receive RT. There was trend toward improving locoregional recurrence with PMRT in patients with high-risk features (node-positive, advanced stage, and {<=}2 mm or unknown surgical margin). The median, 5-year, and 10-year disease-free survival and overall survival for the 75 patients were 77.7 months, 66.3%, 32.7%, and 91.2 months, 73.9%, and 36.6%, respectively. Conclusion: The experience at LRCP suggests that high-risk MBC patients should consider PMRT to improve their chance of local recurrence-free survival.« less
  • No abstract prepared.
  • Purpose: Breast cancer radiotherapy delivered using voluntary deep inspiration breath-hold (DIBH) requires reproducible breath holds, particularly when matching supraclavicular fields to tangential fields. We studied the impact of variation in DIBHs on CTV and OAR dose metrics by comparing the dose distribution computed on two DIBH CT scans taken at the time of simulation. Methods: Ten patients receiving 50Gy in 25 fractions to the left chestwall and regional lymph nodes were studied. Two simulation CT scans were taken during separate DIBHs along with a free-breathing (FB) scan. The treatment was planned using one DIBH CT. The dose was recomputed onmore » the other two scans using adaptive planning (Pinnacle 9.10) in which the scans are registered using a cross-correlation algorithm. The chestwall, lymph nodes and OARs were contoured on the scans following the RTOG consensus guidelines. The overall translational and rotational variation between the DIBH scans was used to estimate positional variation between breath-holds. Dose metrics between plans were compared using paired t-tests (p < 0.05) and means and standard deviations were reported. Results: The registration parameters were sub-millimeter and sub-degree. Although DIBH significantly reduced mean heart dose by 2.4Gy compared to FB (p < 0.01), no significant changes in dose were observed for targets or OARs between the two DIBH scans. Nodal coverage as assessed by V90% was 90%±8% and 89%±8% for supraclavicular and 99%±2% and 97%±22% for IM nodes. Though a significant decrease (10.5%±12.4%) in lung volume in the second DIBH CT was observed, the lung V20Gy was unchanged (14±2% and 14±3%) between the two DIBH scans. Conclusion: While the lung volume often varied between DIBHs, the CTV and OAR dose metrics were largely unchanged. This indicates that manual DIBH has the potential to provide consistent dose delivery to the chestwall and regional nodes targets when using matched fields.« less