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

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

Trajectory modulated arc therapy using quasi-continuous couch motion layered on top of volumetric modulated arc therapy in left breast and chest wall irradiation: a feasibility study

2017 ◽  
Vol 16 (2) ◽  
pp. 133-140 ◽  
Author(s):  
Biplab Sarkar ◽  
Anirudh Pradhan
Keyword(s):  
Chest Wall ◽  
Organs At Risk ◽  
Treatment Plan ◽  
Volumetric Modulated Arc Therapy ◽  
Left Breast ◽  
Left Chest ◽  
Heart Dose ◽  
Arc Therapy ◽  
Prescription Dose ◽  
The Difference

AbstractAimTo investigate the dosimetric advantage of quasi-continuous couch motion-enabled trajectory modulated arc radiotherapy therapy (TMAT) over the coplanar tangential partial arcs volumetric modulated arc radiotherapy (VMAT) for treating left breast and chest wall patients.MethodTreatment plans of 43 patients who received radiotherapy for left breast (17) or for left chest wall (26) using coplanar partial tangential arcs VMAT (reference plan) were considered for this study. For each patient, in addition to the treatment plan, a TMAT plan was also generated using quasi-continuous couch rotation. The TMAT plan consisted of original two 30° tangential arc beams and two supplementary beams having a couch rotation of ±10°, ±20° and ±30°, respectively. The difference in PTV volume coverage (PTV V95%) between TMAT plan and VMAT plan was calculated for all the cases and normalised to the plan’s prescription dose. Similarly, differences in PTV_V105% and several dose-volume parameters related to organs at risk (OAR) were also computed and tabulated.ResultTMAT shows an increment in the PTV dose coverage V95% with respect to reference plan by 4·7±2·5% when averaged overall prescription dose levels. Mean PTV dose (averaged overall prescription levels) for reference and TMAT plan was 4638·6±423·8 and 4793·5±447·2 cGy, respectively, and statistically insignificant (p=0·06). However mean PTV_V105% values for TMAT and for reference plans were 6·7±4·8 and 7·2±5·2%, respectively, and were not statistically different (p=0·85). Mean heart dose in TMAT was less than in VMAT plans, but not significantly. As regarding D1% to heart, TMAT plan was again found to be better with a mean difference of 137·1 cGy over VMAT plan. Other parameters evaluated were: mean dose and D1% to contralateral breast, and V20 Gy and V5 Gy for lung.ConclusionTMAT plans were found to be better than VMAT plans in terms of PTV coverage and D1% for heart. For evaluated dose parameters apart from PTV coverage and D1% to the heart, no significant differences were observed. Thus, TMAT plans yielded better dose distribution in terms of PTV dose coverage, hot spots and OAR doses.

Predictors of lymphopenia in esophageal cancer patients receiving photon or proton radiation therapy: A dosimetric analysis.

2019 ◽  
Vol 37 (4_suppl) ◽  
pp. 147-147 ◽  
Author(s):  
David M. Routman ◽  
Thomas J Whitaker ◽  
Courtney N. Day ◽  
William S. Harmsen ◽  
Michelle A. Neben-Wittich ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Esophageal Cancer ◽  
Radiation Therapy ◽  
Lymphocyte Count ◽  
Organs At Risk ◽  
Absolute Lymphocyte Count ◽  
Continuous Variable ◽  
Oncologic Outcomes ◽  
Proton Radiation ◽  
Curative Intent

147 Background: Lymphopenia during radiation therapy (RT) has been associated with worse oncologic outcomes in a number of malignancies, including esophageal cancer (EC). No studies to date have investigated specific dosimetric parameters associated with this lymphopenia in EC. We performed an analysis of RT dose to multiple organs at risk (OARs) to investigate associations with grade 4 lymphopenia (G4L). Methods: Consecutive EC patients receiving curative intent chemoradiotherapy +/- surgery between July of 2015 and December of 2017 were included. Lymphocyte nadir was defined as the lowest lymphocyte count during RT. G4L was defined as absolute lymphocyte count <200/mm3. Dose to OARs including aorta, body, bone marrow, heart, liver, lung, and spleen were calculated. Univariate logistic regression analyses were performed for each OAR at the 1, 5, 10, 15, 20, 30, 35, 40, and 50 Gy levels with volume receiving dose ‘x’(VxGy) analyzed as a continuous variable per 10% increase. Clinical tumor volume (CTV) and RT modality (photon vs. proton) as well clinical factors including sex, stage (I/II vs. III/IV), age (per 10 year increase), and BMI (per 5 unit increase) were also analyzed. Results: One hundred forty-four pts were identified for inclusion. Seventy-nine pts received photon RT and 65 proton RT. Chemotherapy was weekly carbotaxol (99%). G4L at nadir was 40% overall (56% photon, 22% proton). By organ, body V1-V30Gy (OR 1.45-8.18, p<0.01), heart V1-V30Gy (OR 1.24-1.49, p<0.01), liver V1-V35Gy (OR 1.23-2.75, p<0.01), lung V1-V30Gy (OR 1.26-5.73 p<0.01), and spleen V1-V40Gy (OR 1.26-1.49 p<0.01) were highly associated with G4L whereas dose to aorta and bone marrow were not. Advanced stage (OR, 3.92 p<0.01), photon vs. proton (OR 4.58 p<0.01), and CTV (per 100 cc’s (OR=1.21, p<0.01)) were also associated with G4L. Sex, age, and BMI were not associated with G4L. Conclusions: Low to intermediate dose volumes to OARs including body, spleen, liver, lungs, and heart were associated with G4L. These findings provide rational for the differences seen in rates of G4L for photon versus proton RT.

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

2013 ◽  
Vol 3 (2) ◽  
pp. e45-e53 ◽  
Author(s):  
Erin Healy ◽  
Shawnee Anderson ◽  
Jing Cui ◽  
Laurel Beckett ◽  
Allen M. Chen ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Chest Wall ◽  
Skin Dose ◽  
Tissue Equivalent ◽  
Dose Effects

scholarly journals Proton Versus Intensity-Modulated Radiation Therapy: First Dosimetric Comparison for Total Scalp Irradiation

2019 ◽  
Vol 6 (3) ◽  
pp. 19-26
Author(s):  
Ankur Markand Sharma ◽  
Emily Kowalski ◽  
Nathan McGovern ◽  
Mingyao Zhu ◽  
Mark Vikas Mishra
Keyword(s):  
Radiation Therapy ◽  
Organs At Risk ◽  
Treatment Plan ◽  
Intensity Modulated Radiation Therapy ◽  
High Dose ◽  
Proton Radiation ◽  
Dosimetric Comparison ◽  
Intensity Modulated ◽  
Volumetric Arc Therapy ◽  
Cutaneous Lymphomas

Abstract Purpose: Total scalp irradiation (TSI) is used to treat malignancies of the scalp and face, including angiosarcomas, nonmelanoma skin cancers, and cutaneous lymphomas. Owing to the irregularity of the scalp contour and the presence of underlying critical organs at risk (OARs), radiation planning is challenging and technically difficult. To address these complexities, several different radiation therapy techniques have been used. These include the combined lateral photon-electron technique (3DRT), intensity-modulated radiation therapy (IMRT)/volumetric arc therapy (VMAT), helical tomotherapy (HT), and mold-based high-dose-rate brachytherapy (HDR BT). However, the use of proton radiation therapy (PRT) has never been documented. Materials and Methods: A 71-year-old, immunosuppressed man presented with recurrent nonmelanoma skin cancer of the scalp. He was successfully treated at our center with PRT to deliver TSI. A comparative VMAT treatment plan was generated and dose to critical OARs was compared. Results: We present the first clinical case report of PRT for TSI and dosimetric comparison to a VMAT plan. The PRT and VMAT plans provided equivalent target volume coverage; however, the PRT plan significantly reduced dose to the brain, hippocampi, and optical apparatus. Conclusion: TSI planned with PRT is relatively straightforward from a planning perspective and does not require a bolus. It also has the potential to decrease radiation therapy–related toxicity. However, PRT is relatively expensive and not universally available. The uncertainty surrounding the end-range of the proton beam is a consideration. Although there are potential disadvantages to using PRT for TSI, its use should be considered by treating radiation oncologists and referring physicians.

scholarly journals A Dosimetric and Radiobiological Evaluation of VMAT Following Mastectomy for Patients With Left-sided Breast Cancer

2021 ◽  
Author(s):  
Yun Zhang ◽  
Yuling Huang ◽  
Shenggou Ding ◽  
Xingxing Yuan ◽  
Yuxian Shu ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Radiation Therapy ◽  
Chest Wall ◽  
Treatment Time ◽  
Absolute Risk ◽  
Statistical Significance ◽  
Conformity Index ◽  
Delivery Time ◽  
Ipsilateral Lung ◽  
Contralateral Lung

Abstract Background: To compare the dosimetric normal tissue complication probability (NTCP), secondary cancer complication probabilities (SCCP), and excess absolute risk (EAR) differences of volumetric modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) for left-sided breast cancer after mastectomy. Methods and materials: Thirty patients with left-sided breast cancer treated with post-mastectomy radiation therapy (PMRT) were randomly enrolled in this study. Both IMRT and VMAT treatment plans were created for each patient. Planning target volume (PTV) doses for the chest wall and internal mammary nodes, PTV1, and PTV of the supraclavicular nodes, PTV2, of 50 Gy were prescribed in 25 fractions. The plans were evaluated based on PTV1 and PTV2 coverage, homogeneity index (HI), conformity index, conformity number (CN), dose to organs at risk, NTCP, SCCP, EAR, number of monitors units, and beam delivery time. Results: VMAT resulted in more homogeneous chest wall coverage than did IMRT. The percent volume of PTV1 that received the prescribed dose of VMRT and IMRT was 95.9 ± 1.2% and 94.5 ± 1.6%, respectively (p < 0.001). The HI was 0.11 ± 0.01 for VMAT and 0.12 ± 0.02 for IMRT, respectively (p = 0.001). The VMAT plan had better conformity (CN: 0.84 ± 0.02 vs. 0.78 ± 0.04, p < 0.001) in PTV compared with IMRT. As opposed to IMRT plans, VMAT delivered a lower mean dose to the ipsilateral lung (11.5 Gy vs 12.6 Gy) and heart (5.2 Gy vs 6.0 Gy) and significantly reduced the V5, V10, V20, V30, and V40 of the ipsilateral lung and heart; only the differences in V5 of the ipsilateral lung did not reach statistical significance (p = 0.409). Although the volume of the ipsilateral lung and heart encompassed by the 2.5 Gy isodose line (V2.5) was increased by 6.7% and 7.7% (p < 0.001, p = 0.002), the NTCP was decreased by 0.8% and 0.6%, and SCCP and EAR were decreased by 1.9% and 0.1% for the ipsilateral lung. No significant differences were observed in the contralateral lung/breast V2.5, V5, V10, V20, mean dose, SCCP, and EAR. Finally, VMAT reduced the number of monitor units by 31.5% and the treatment time by 71.4%, as compared with IMRT. Conclusions: Compared with IMRT, VMAT is the optimal technique for PMRT patients with left-sided breast cancer due to better target coverage, a lower dose delivered, NTCP, SCCP, and EAR to the ipsilateral lung and heart, similar doses delivered to the contralateral lung and breast, fewer monitor units and a shorter delivery time.

scholarly journals A dosimetric and radiobiological evaluation of VMAT following mastectomy for patients with left-sided breast cancer

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yun Zhang ◽  
Yuling Huang ◽  
Shenggou Ding ◽  
Xingxing Yuan ◽  
Yuxian Shu ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Radiation Therapy ◽  
Chest Wall ◽  
Treatment Time ◽  
Absolute Risk ◽  
Statistical Significance ◽  
Conformity Index ◽  
Delivery Time ◽  
Ipsilateral Lung ◽  
Contralateral Lung

Abstract Background To compare the dosimetric, normal tissue complication probability (NTCP), secondary cancer complication probabilities (SCCP), and excess absolute risk (EAR) differences of volumetric modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) for left-sided breast cancer after mastectomy. Methods and materials Thirty patients with left-sided breast cancer treated with post-mastectomy radiation therapy (PMRT) were randomly enrolled in this study. Both IMRT and VMAT treatment plans were created for each patient. Planning target volume (PTV) doses for the chest wall and internal mammary nodes, PTV1, and PTV of the supraclavicular nodes, PTV2, of 50 Gy were prescribed in 25 fractions. The plans were evaluated based on PTV1 and PTV2 coverage, homogeneity index (HI), conformity index, conformity number (CN), dose to organs at risk, NTCP, SCCP, EAR, number of monitors units, and beam delivery time. Results VMAT resulted in more homogeneous chest wall coverage than did IMRT. The percent volume of PTV1 that received the prescribed dose of VMRT and IMRT was 95.9 ± 1.2% and 94.5 ± 1.6%, respectively (p < 0.001). The HI was 0.11 ± 0.01 for VMAT and 0.12 ± 0.02 for IMRT, respectively (p = 0.001). The VMAT plan had better conformity (CN: 0.84 ± 0.02 vs. 0.78 ± 0.04, p < 0.001) in PTV compared with IMRT. As opposed to IMRT plans, VMAT delivered a lower mean dose to the ipsilateral lung (11.5 Gy vs 12.6 Gy) and heart (5.2 Gy vs 6.0 Gy) and significantly reduced the V5, V10, V20, V30, and V40 of the ipsilateral lung and heart; only the differences in V5 of the ipsilateral lung did not reach statistical significance (p = 0.409). Although the volume of the ipsilateral lung and heart encompassed by the 2.5 Gy isodose line (V2.5) was increased by 6.7% and 7.7% (p < 0.001, p = 0.002), the NTCP was decreased by 0.8% and 0.6%, and SCCP and EAR were decreased by 1.9% and 0.1% for the ipsilateral lung. No significant differences were observed in the contralateral lung/breast V2.5, V5, V10, V20, mean dose, SCCP, and EAR. Finally, VMAT reduced the number of monitor units by 31.5% and the treatment time by 71.4%, as compared with IMRT. Conclusions Compared with IMRT, VMAT is the optimal technique for PMRT patients with left-sided breast cancer due to better target coverage, a lower dose delivered, NTCP, SCCP, and EAR to the ipsilateral lung and heart, similar doses delivered to the contralateral lung and breast, fewer monitor units and a shorter delivery time.

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

2012 ◽  
Vol 30 (27_suppl) ◽  
pp. 157-157
Author(s):  
Erin Healy ◽  
Shawnee Anderson ◽  
Jing Cui ◽  
Laurel Beckett ◽  
Allen M. Chen ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Skin Reaction ◽  
Chest Wall ◽  
Radiation Treatment ◽  
Skin Toxicity ◽  
In Vivo Dosimetry ◽  
Skin Dose ◽  
Tissue Equivalent ◽  
Dose Effects

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.

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

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.

scholarly journals Kimura’s disease affecting multiple body parts in a 57-year-old female patient: a case report

2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Bo Yu ◽  
Guoxing Xu ◽  
Xiaofan Liu ◽  
Wen Yin ◽  
Hao Chen ◽  
...  
Keyword(s):  
Lymph Nodes ◽  
Chest Wall ◽  
Immunoglobulin E ◽  
The Body ◽  
Unknown Etiology ◽  
Kimura’S Disease ◽  
Body Parts ◽  
Tissue Mass ◽  
Left Chest ◽  
The Right

Abstract Background Kimura’s disease (KD) is a rare chronic inflammatory disease with unknown etiology. It usually manifests as a painless soft tissue mass or subcutaneous nodule on one side of the patient’s head and/or neck and rarely affects multiple parts of the body. The disease is more common among young Asian males. Case presentation A 57-year-old Chinese woman complained of multiple masses on her body surface. Ultrasonography was used to examine the retroperitoneal, bilateral neck, bilateral supraclavicular, bilateral axillary, and bilateral inguinal superficial lymph nodes. Enlargement of multiple lymph nodes was found in all areas. Many solid nodules were also found in the right parotid gland and right posterior neck area, respectively. Numerous solid nodules were seen on the left chest wall. Laboratory tests showed that the percentage of eosinophils in the whole blood was 39.40%, total immunoglobulin E (IgE) level was > 5000 kU/L, and serum special IgE to Phadiatop (inhaled allergens) and fx5 (food allergens) were 1.01 and 1.04 kUA/L, respectively. After a complete examination, the masses located in the right neck, retroauricular and left axillary regions, and left chest wall were resected directly. Postoperative pathological findings revealed KD. Conclusions The case discussed in this study is extremely rare and did not meet the common affected areas and age characteristics of KD. This presentation can be used to improve disease awareness among physicians.

scholarly journals Dose reduction to organs at risk with deep-inspiration breath-hold during right breast radiotherapy: a treatment planning study

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Chloe Pandeli ◽  
Lloyd M. L. Smyth ◽  
Steven David ◽  
Andrew W. See
Keyword(s):  
Breast Cancer ◽  
Maximum Dose ◽  
Organs At Risk ◽  
Breath Hold ◽  
Deep Inspiration ◽  
Breast Radiotherapy ◽  
Deep Inspiration Breath Hold ◽  
Total Lung Volume ◽  
Ipsilateral Lung ◽  
Dose Volume

Abstract Background The addition of regional nodal radiation (RNI) to whole breast irradiation for high risk breast cancer improves metastases free survival and new data suggests it contributes additional benefit to overall survival. Deep inspiration breath hold (DIBH) has been shown to reduce cardiac and pulmonary dose in the context of left-sided disease treated with or without RNI, yet few studies have investigated its utility for right-breast cancer. This study investigates the potential advantages of DIBH in local and locoregional radiotherapy for right-sided breast cancer. Methods Free-breathing (FB) and DIBH computed tomography datasets were obtained from twenty patients who previously underwent radiotherapy for left-sided breast cancer. Ten patients were retrospectively planned for whole right breast only irradiation and ten patients were planned for irradiation to the whole breast plus ipsilateral supra-clavicular (SC) nodes, with and without irradiation of the ipsilateral internal mammary nodes (IMN). Dose-volume metrics for the clinical target volume, lungs, heart, left anterior descending artery, right coronary artery (RCA) and liver were recorded. Differences between FB and DIBH plans were analysed using Wilcoxon signed-rank tests, with P < 0.05 considered statistically significant. Results DIBH increased the average total lung volume compared to FB in both breast only and breast plus RNI cohorts (P = 0.001). For the breast only group, there was no significant improvement in any ipsilateral lung dose-volume metric between FB and DIBH. However, for the breast plus RNI group, there was an improvement in ipsilateral lung mean dose (18.9 ± 3.2 Gy to 15.9 ± 2.3 Gy, P = 0.002) and V20Gy (45.3 ± 13.3% to 32.9 ± 9.4%, P = 0.002). In addition, DIBH significantly reduced the maximum dose to the RCA for RNI (11.6 ± 7.2 Gy to 5.6 ± 2.9 Gy, P = 0.03). Significant reductions in the liver V20Gy and maximum dose were observed in all cohorts during DIBH compared to FB. Conclusions DIBH is a promising approach for right-breast radiotherapy with considerable sparing of normal tissue, particularly when the ipsilateral IMNs are also irradiated.

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