Skin dose effects of postmastectomy chest wall radiation therapy using brass mesh as an alternative to tissue equivalent bolus

157 Background: The use of brass mesh as an alternative to a bolus is relatively uncommon in post-mastectomy chest wall radiation therapy (PMRT). This study aimed to characterize the skin dose effects of using 2mm fine brass mesh as an alternative to the traditional tissue-equivalent bolus during chest wall PMRT. Methods: Data was collected from patients who received PMRT using brass mesh at UC Davis Medical Center’s Department of Radiation Oncology between January 2008 and June 2011. Several patient characteristics including age, body habitus, and ethnicity were analyzed along with several disease and treatment characteristics to determine whether or not they had an impact on the skin reaction observed during radiation treatment. In addition to assessing skin toxicity visually using standardized National Cancer Institute scores (NCIS), surface doses were measured for 16 of the 48 patients (33%) to quantify radiation exposure to the chest wall. Results: 48 female patients aged 28-83 received PMRT using brass mesh. As expected, the severity of skin toxicity increased with subsequent doses of radiation with all patients beginning treatment with no skin reaction (NCIS = 0) and the majority of patients completing treatment with either faint to moderate erythema (N = 19, 40%, NCIS = 1) or moderate to brisk erythema (N = 23, 48%, NCIS = 2). In vivo dosimetry analysis revealed surface doses between 81% and 110% of the prescribed dose, with an average of 99% of the prescribed radiation dose being delivered and a standard deviation of 10%. Conclusions: For post-mastectomy chest wall radiation therapy, brass mesh is an effective alternative to the tissue-equivalent bolus. The brass mesh achieved moderate erythema in the majority of patients at the end of treatment and the surface dose was validated using in vivo dosimetry.

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Dosimetric Evaluation of Photons Versus Protons in Postmastectomy Planning for Ultrahypofractionated Breast Radiotherapy

10.21203/rs.3.rs-1113856/v1 ◽

2021 ◽

Author(s):

Puntiwa Oonsiri ◽

Chonnipa Nantavithya ◽

Chawalit Lertbutsayanukul ◽

Thanaporn Sarsitthithum ◽

Mananchaya Vimolnoch ◽

...

Keyword(s):

Radiation Therapy ◽

Chest Wall ◽

Organs At Risk ◽

Skin Dose ◽

Proton Radiation ◽

Breast Radiotherapy ◽

Left Chest ◽

Ipsilateral Lung ◽

Heart Dose ◽

The Right

Abstract Background: Ultrahypofractionation can shorten the irradiation period. This study is the first dosimetric investigation comparing ultrahypofractionation using volumetric arc radiation therapy (VMAT) and intensity-modulated proton radiation therapy (IMPT) techniques in postmastectomy treatment planning. Materials and methods: Twenty postmastectomy patients (10-left and 10-right sided) were replanned with both VMAT and IMPT techniques. There were 4 scenarios: left chest wall, left chest wall including regional nodes, right chest wall, and right chest wall including regional nodes. The prescribed dose was 26 Gy (RBE) in 5 fractions. For VMAT, a 1-cm bolus was added for 2 in 5 fractions. For IMPT, robust optimization was performed on the CTV structure with a 3-mm setup uncertainty and a 3.5% range uncertainty. This study aimed to compare the dosimetric parameters of the PTV, ipsilateral lung, contralateral lung, heart, skin, esophageal, and thyroid doses. Results: The PTV-D95 was kept above 24.7 Gy in both VMAT and IMPT plans. The ipsilateral lung mean dose of the IMPT plans was comparable to that of the VMAT plans. In three of four scenarios, the V5 of the ipsilateral lung in IMPT plans was lower than in VMAT plans. The Dmean and V5 of heart dose were reduced by a factor of 4 in the IMPT plans of the left side. For the right side, the Dmean of the heart was less than 1 Gy for IMPT, while the VMAT delivered approximately 3 Gy. The IMPT plans showed a significantly higher skin dose owing to the lack of a skin-sparing effect in the proton beam. The IMPT plans provided lower esophageal and thyroid mean dose. Conclusion: Despite the higher skin dose with the proton plan, IMPT significantly reduced the dose to adjacent organs at risk, which might translate into the reduction of late toxicities when compared with the photon plan. Key words: proton therapy, ultrahypofractionation, postmastectomy, breast irradiation

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The choice of IMRT for early-stage right breast cancer.

Journal of Clinical Oncology ◽

10.1200/jco.2013.31.26_suppl.81 ◽

2013 ◽

Vol 31 (26_suppl) ◽

pp. 81-81

Author(s):

Sophia Edwards-Bennett ◽

Stephen Andrews ◽

Patrick Francke ◽

Frank Vicini

Keyword(s):

Breast Cancer ◽

Radiation Therapy ◽

Chest Wall ◽

Early Stage ◽

Treatment Plan ◽

Univariate Analysis ◽

Surrogate Marker ◽

Intensity Modulated Radiation Therapy ◽

Skin Dose ◽

Intensity Modulated

81 Background: The benefit of Intensity Modulated Radiation Therapy (IMRT) has been established for left breast cancer. However, IMRT is not routinely employed for right breast cancer. The purpose of this study is to (1) compare dosimetric parameters in women with early stage right breast cancer undergoing whole breast radiation therapy using 3-dimensional conformal radiation (3DCRT) versus intensity modulated radiation therapy (IMRT) (2) determine treatment planning and/or anatomical correlates for patients who may benefit from IMRT. Methods: IMRT versus 3DCRT treatment plans were compared for 20 consecutive female patients with early stage (T1-T2 N0M0 ) right breast cancer treated at our center from 1/2012 to 12/2012. The planned target volume (PTV), contoured according to the RTOG atlas guidelines, was prescribed to 46-8-50.4 Gy in 26-28 fractions with PTV coverage goal of ≥ 95 % receiving the prescription dose. Dosimetric and anatomic parameters: % right lung receiving 20 Gy (lung V20), maximum breast dose (Dmax), maximum skin dose (Dmax skin), chest wall separation (CWS) and medial gantry angle (MGA) were determined for each paired treatment plan. Wilcoxon-signed rank test was utilized to compare IMRT and 3DCRT dosimetric parameters. Univariate analysis was used to identify planning or anatomic correlates associated with favorable dosimetric outcomes. Results: The lung V20Gy for IMRT ( 10.86±2.81%) was significantly lower than for 3DCRT (12.92±3.45 %, p < 0.043). IMRT significantly reduced Dmax to 53.79 ± 2.17 Gy from 56.7 ± 2.24 Gy with 3DCRT (p 0.001). 3DCRT yielded significantly higher Dmax skin (33.47±3.21 Gy) than IMRT (24.16 ±2.65 Gy, p< 0.0001). Mean CWS and MGA were 22.4 ± 2.6 cm and 126 ± 5.1° respectively. There was a significant association between CWS and Dmax for 3DCRT (p < 0.026). Conclusions: The most significant impact of IMRT for right breast cancer was the reduction of Dmax and Dmax skin, with a more tempered advantage in the reduction of lung V20. Reduction of maximum breast and skin dose harbors clinical relevance as it relates to acute skin toxicity, long- term fibrosis and adverse cosmetic outcomes. Chest wall separation may be a potential planning surrogate marker to determine which right-sided breast cancer patients may benefit from IMRT.

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