scholarly journals The advantages of abdominal compression with shallow breathing during left-sided postmastectomy radiotherapy by Helical TomoTherapy

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254934
Author(s):  
Chalardchay Pratoomchart ◽  
Pitchayaponne Klunklin ◽  
Somsak Wanwilairat ◽  
Wannapha Nobnop ◽  
Kittikun Kittidachanan ◽  
...  
Keyword(s):  
Helical Tomotherapy ◽  
Organs At Risk ◽  
Limited Resource ◽  
Free Breathing ◽  
Target Volume ◽  
Breast Cancer Patients ◽  
Abdominal Compression ◽  
Heart Dose ◽  
Organ Volume ◽  
Shallow Breathing

Background Left-sided post-mastectomy radiotherapy (PMRT) certainly precedes some radiation dose to the cardiopulmonary organs causing many side effects. To reduce the cardiopulmonary dose, we created a new option of the breathing adapted technique by using abdominal compression applied with a patient in deep inspiration phase utilizing shallow breathing. This study aimed to compare the use of abdominal compression with shallow breathing (ACSB) with the free breathing (FB) technique in the left-sided PMRT. Materials and methods Twenty left-sided breast cancer patients scheduled for PMRT were enrolled. CT simulation was performed with ACSB and FB technique in each patient. All treatment plans were created on a TomoTherapy planning station. The target volume and dose, cardiopulmonary organ volume and dose were analyzed. A linear correlation between cardiopulmonary organ volumes and doses were also tested. Results Regarding the target volumes and dose coverage, there were no significant differences between ACSB and FB technique. For organs at risk, using ACSB resulted in a significant decrease in mean (9.17 vs 9.81 Gy, p<0.0001) and maximum heart dose (43.79 vs 45.45 Gy, p = 0.0144) along with significant reductions in most of the evaluated volumetric parameters. LAD doses were also significantly reduced by ACSB with mean dose 19.24 vs 21.85 Gy (p = 0.0036) and the dose to 2% of the volume (D2%) 34.46 vs 37.33 Gy (p = 0.0174) for ACSB and FB technique, respectively. On the contrary, the lung dose metrics did not show any differences except the mean V5 of ipsilateral lung. The positive correlations were found between increasing the whole lung volume and mean heart dose (p = 0.05) as well as mean LAD dose (p = 0.041) reduction. Conclusions The ACSB technique significantly reduced the cardiac dose compared with the FB technique in left-sided PMRT treated by Helical TomoTherapy. Our technique is uncomplicated, well-tolerated, and can be applied in limited resource center.

scholarly journals The Advantages of Abdominal Compression with Shallow Breathing During Left-sided Postmastectomy Radiotherapy by Helical Tomotherapy

2021 ◽  
Author(s):  
Chalardchay Pratoomchart ◽  
Pitchayaponne Klunklin ◽  
Imjai Chitapanarux ◽  
Somsak Wanwilairat ◽  
Wannapha Nobnop ◽  
...  
Keyword(s):  
Helical Tomotherapy ◽  
Organs At Risk ◽  
Free Breathing ◽  
Target Volume ◽  
Breast Cancer Patients ◽  
Abdominal Compression ◽  
Heart Dose ◽  
Organ Volume ◽  
Ct Simulation ◽  
Shallow Breathing

Abstract BackgroundLeft-sided post-mastectomy radiotherapy (PMRT) certainly precedes some radiation dose to the cardiopulmonary organs causing many side effects. To reduce the cardiopulmonary dose, we created a new option of the breathing adapted technique by using abdominal compression applied with a patient in deep inspiration phase utilizing shallow breathing. This study aimed to compare the use of abdominal compression with shallow breathing (ACSB) with the free breathing (FB) technique in the left-sided PMRT.MethodsTwenty left-sided breast cancer patients scheduled for PMRT were enrolled. CT simulation was performed with ACSB and FB technique in each patient. All treatment plans were created on a TomoTherapy planning station. The target volume and dose, cardiopulmonary organ volume and dose were analyzed. A linear correlation between cardiopulmonary organ volumes and doses were also tested.ResultsRegarding the target volumes and dose coverage, there were no significant differences between ACSB and FB technique. For organs at risk, using ACSB resulted in a significant decrease in mean (9.17 vs 9.81 Gy, p < 0.0001) and maximum heart dose (43.79 vs 45.45 Gy, p = 0.0144) along with significant reductions in most of the evaluated volumetric parameters. LAD doses were also significantly reduced by ACSB with mean dose 19.24 vs 21.85 Gy (p = 0.0036) and the dose to 2% of the volume (D2%) 34.46 vs 37.33 Gy (p = 0.0174) for ACSB and FB technique, respectively. On the contrary, the lung dose metrics did not show any differences except the mean V5 of ipsilateral lung. The positive correlations were found between increasing the whole lung volume and mean heart dose (p = 0.05) as well as mean LAD dose (p = 0.041) reduction.ConclusionsThe ACSB technique significantly reduced the cardiac dose compared with the FB technique in left-sided PMRT treated by Helical Tomotherapy. Our technique is uncomplicated, well-tolerated, and can be applied in daily clinical practice.Trial registrationThai Clinical Trials Registry (TCTR), TCTR20201215008. Registered 14 December 2020 - Retrospectively registered, http:// http://www.clinicaltrials.in.th/ TCTR20201215008

scholarly journals Helical tomotherapy with a complete-directional-complete block technique effectively reduces cardiac and lung dose for left-sided breast cancer

2020 ◽  
Vol 93 (1108) ◽  
pp. 20190792 ◽  
Author(s):  
Hsin-Pei Yeh ◽  
Yu-Chuen Huang ◽  
Li-Ying Wang ◽  
Pei-Wei Shueng ◽  
Hui-Ju Tien ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Patients ◽  
Helical Tomotherapy ◽  
Organs At Risk ◽  
Intensity Modulated Radiation Therapy ◽  
Target Volume ◽  
Conformity Index ◽  
Breast Cancer Patients ◽  
Lung Dose ◽  
The Mean

Objectives: To evaluate the feasibility and optimal restricted angle of the complete-directional-complete block (CDCB) technique in helical tomotherapy (HT) by including regional nodal irradiation (RNI) with the internal mammary node (IMN) in left-sided breast cancer. Methods: Ten left-sided breast cancer patients treated with 50 Gy in 25 fractions were compared with five-field intensity-modulated radiation therapy (5F-IMRT) and six types of HT plans. In the HT plans, complete block (CB), organ-based directional block (OBDB) and CDCB with different restricted angles were used. Results: The conformity index (CI) between the CDCB0,10,15,20 and 5F-IMRT groups was similar. Compared to CB, OBDB and 5F-IMRT, CDCB20 resulted in a decreased ipsilateral mean lung dose. The low-dose region (V5) of the ipsilateral lung in OBDB (84.0%) was the highest among all techniques (p < 0.001). The mean dose of the heart in CB was significantly reduced (by 11.5–22.4%) compared with other techniques. The V30 of the heart in CDCB20 (1.9%) was significantly lower than that of CB, OBDB and 5F-IMRT. Compared to the mean dose of the left anterior descending (LAD) artery of 5F-IMRT (27.0 Gy), CDCB0, CDCB10, CDCB15, CDCB20 and OBDB reduced the mean dose effectively by 31.7%, 38.3%, 39.6%, 42.0 and 56.2%, respectively. Considering the parameters of the organs-at-risk (OARs), CDCB10,15,20 had higher expectative values than the other techniques (p = 0.01). Conclusions: HT with the CDCB technique is feasible for treating left-sided breast cancer patients. The CDCB10-20 techniques not only achieved similar planning target volume coverage, homogeneity and dose conformity but also allowed better sparing of the heart and bilateral lungs. Advances in knowledge: For left-sided breast cancer patients whose RNI field includes the IMN, heart avoidance is an important issue. The CDCB technique achieved good PTV coverage, homogeneity and dose conformity and allowed better sparing of the mean dose of the lung, the LAD artery, and the heart and reduced the V30 of the heart.

Stereotactic body radiation therapy for pancreatic cancer: Assessing motion with and without abdominal compression.

2016 ◽  
Vol 34 (4_suppl) ◽  
pp. 234-234 ◽  
Author(s):  
Priscilla K. Stumpf ◽  
Bernard Jones ◽  
Supriya K. Jain ◽  
Arya Amini ◽  
Dale A. Thornton ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Radiation Therapy ◽  
Stereotactic Body Radiation Therapy ◽  
Organs At Risk ◽  
Locally Advanced ◽  
Advanced Pancreatic Cancer ◽  
Free Breathing ◽  
Tumor Motion ◽  
Abdominal Compression ◽  
Stereotactic Body Radiation

234 Background: Stereotactic body radiation therapy (SBRT) is an emerging treatment option for locally advanced pancreatic cancer. This ablative therapy requires highly accurate delivery due to nearby organs at risk. To minimize tumor motion, our institution applies abdominal compression during computed tomography (CT) simulation. The purpose of this study is to evaluate the effect of compression in the context of pancreatic SBRT. Methods: In the last 6 months, 32 patients who completed SBRT to the pancreas at our institution were selected for analysis. In each patient, two 4DCT images were acquired, one with and one without abdominal compression. Abdominal compression was achieved with an indexed compression belt with a customized degree of inflation. Each patient had fiducial markers implanted in or near the pancreatic tumor prior to simulation. These fiducials were contoured on both planning CT scans for each gated phase. Motion was assessed by fiducial position changes throughout each gated phase. Results: In the anterior to posterior, transverse, and superior to inferior dimension, compression decreased motion in 19 of 32 cases (59%), 21 of 32 cases (66%), and 28 of 32 cases (88%) respectively. In the anterior to posterior (AP) dimension compression decreased motion by a mean of 0.43mm ± 1.7mm with a range of -2.1-6.5mm (p = 0.16). The mean decrease in motion with compression in the transverse dimension was 0.93mm ± 1.9mm with a range of -1.6-8.6mm (p = 0.01). In the superior to inferior dimension, compression decreased motion by a mean of 2.72mm ± 2.8mm with a range of -1.2-11.5mm (p < 0.001). Displacement of tissue due to compression led to increased patient AP separation at the level of T12 by a mean of 9.1±5.8mm (p < 0.001). Conclusions: Abdominal compression significantly reduced tumor motion in the superior to inferior and transverse directions for patients undergoing SBRT to the pancreas. This decrease in motion allows for significant reductions in the size of the volume necessary to treat the tumor. Given our findings, we would recommend using abdominal compression over free-breathing for pancreatic SBRT.

The radiation doses to the heart and the left anterior descending coronary artery for various modes of radiation treatment of the breast cancer patients.

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e12092-e12092
Author(s):  
Elizaveta Maslyukova ◽  
Luiza Korytova ◽  
Anna Bondarenko ◽  
Razifa Zhabina ◽  
Oleg Korytov ◽  
...  
Keyword(s):  
Breast Cancer ◽  
At Risk ◽  
Cancer Patients ◽  
Supine Position ◽  
Radiation Treatment ◽  
Organs At Risk ◽  
Free Breathing ◽  
Breast Cancer Patients ◽  
Heart Volume ◽  
Treatment Plans

e12092 Background: The comparison of the radiation load to the organs at risk for three modes of radiation treatment of the breast cancer patients. Methods: The research includes the dosimetric radiation treatment plans for the 20 breast cancer patients with the left-side localization. They all underwent a computed tomography (CT) scan in standard supine position in free-breathing (FB), supine position with Active Breathing Control (ABC) device in deep inspiratory breath hold, and prone position in free-breathing (PP). Three-dimensional treatment plans were made for all 3 CTs. The dose valuations for 3D-planning were carried out for three CT- series. For each mode of radiation, the doze-volume parameters of organs at risk were estimated. Results: For all cases the contoured heart volume varied from 477 см3 - 1056 см3, with medium volume 769 см3. The best marks such as V25heart, medium doses to the heart and LAD, were achieved with on ABC methods (V25heart 4,26%, Dmean heart 3,13Gy, DmeanLAD 13,8Gy) in comparison FB (V25heart 9,49%, Dmean heart 4,97Gy, DmeanLAD 19,55Gy) and PP (V25heart 12,8%, Dmean heart 9,06Gy, DmeanLAD 24,18 Gy) (V25heart P = 0.00153, Dmean heart: P =0,000; Dmean LAD: P = 0.00088), when both the breast and the axillary nodes were included in the volume. The advantage of the dosimetric indexes for FB and ABC did not change while axillary and supraclavicular nodes were added to the radiation volume ABC (V25heart 3,49%, Dmean heart 3,08Gy, DmeanLAD 13,88Gy) in comparison with FB methods (V25heart 7,91%, Dmean heart 4,99Gy, DmeanLAD 19,89Gy) (V25heart P = 0.00205, Dmean heart: P =0,004; Dmean LAD: P = 0.03). Conclusions: Radiation treatment in the position on the back with controlled delay of breath on inspiration height contributed to the statistically significant reduction of the heart volume exposed to more than 25 Gy (V25heart), mean dose to the heart and mean dose to LAD.

scholarly journals Dosimetric Comparison of Helical Tomotherapy, Volumetric-Modulated Arc Therapy, and Intensity-Modulated Proton Therapy for Angiosarcoma of the Scalp

2021 ◽  
Vol 20 ◽  
pp. 153303382098586
Author(s):  
Tomoki Mizuno ◽  
Natsuo Tomita ◽  
Taiki Takaoka ◽  
Masashi Tomida ◽  
Hiroshi Fukuma ◽  
...  
Keyword(s):  
Proton Therapy ◽  
Helical Tomotherapy ◽  
Organs At Risk ◽  
Volumetric Modulated Arc Therapy ◽  
Target Volume ◽  
The Other ◽  
Intensity Modulated Proton Therapy ◽  
Intensity Modulated ◽  
Arc Therapy ◽  
Dose Constraint

Objective: We compared radiotherapy plans among helical tomotherapy (HT), volumetric-modulated arc therapy (VMAT), and intensity-modulated proton therapy (IMPT) for angiosarcoma of the scalp (AS). Methods: We conducted a planning study for 19 patients with AS. The clinical target volume (CTV) 1 and CTV2 were defined as the gross tumor volume with a specific margin and total scalp, respectively. For HT and VMAT, the planning target volume (PTV) 1 and PTV2 were defined as CTV1 and CTV2 with 0.5-cm margins, respectively. For IMPT, robust optimization was used instead of a CTV-PTV margin (i.e. CTV robust). The targets of the HT and VMAT plans were the PTV, whereas the IMPT plans targeted the CTV robust. In total, 70 Gy and 56 Gy were prescribed as the D95% (i.e. dose to 95% volume) of PTV1 (or CTV1 robust) and PTV2 (or CTV2 robust), respectively, using the simultaneous integrated boost (SIB) technique. Other constraint goals were also defined for the target and organs at risk (OAR). Results: All dose constraint parameters for the target and OAR met the goals within the acceptable ranges for the 3 techniques. The coverage of the targets replaced by D95% and D98% were almost equivalent among the 3 techniques. The homogeneity index of PTV1 or CTV1 robust was equivalent among the 3 techniques, whereas that of PTV2 or CTV2 robust was significantly higher in the IMPT plans than in the other plans. IMPT reduced the Dmean of the brain and hippocampus by 49% to 95%, and the Dmax of the spinal cord, brainstem, and optic pathway by 70% to 92% compared with the other techniques. Conclusion: The 3 techniques with SIB methods provided sufficient coverage and satisfactory homogeneity for the targets, but IMPT achieved the best OAR sparing.

scholarly journals Analysis of Geometric and Dosimetric Effects of Bra Application to Support Large or Pendulous Breasts During Radiotherapy Planning: A Retrospective Single-Center Study

2021 ◽  
Vol 20 ◽  
pp. 153303382110279
Author(s):  
So Hyun Park ◽  
Jinhyun Choi
Keyword(s):  
Clinical Target Volume ◽  
Organs At Risk ◽  
Target Volume ◽  
Radiotherapy Planning ◽  
Homogeneity Index ◽  
Breast Volume ◽  
Breast Cancer Patients ◽  
Single Center Study ◽  
Radiotherapy Field ◽  
Dose Reductions

Purpose: To evaluate geometric and dosimetric effects of bra application during radiotherapy planning for breast cancer patients with large and pendulous breasts. Materials and Methods: Twenty patients with chest sizes >38 inches between April 2019 and July 2019 underwent radiotherapy planning with and without a radiation bra (Chabner XRT®). Geometric and dosimetric parameters included the breast volume, superior-inferior (SI) distance, separation (S) as the distance of the longest diameter of the clinical target volume (CTV), conformity number (CN), and homogeneity index (HI) of CTV. The organs at risk (OARs) were defined as the lungs, heart, and liver. Results: The use of the radiation bra provided mean changes of −0.51 cm for S, −1.45 cm for SI, and −61.18 cc for breast volume (all P < 0.05). Breast volume was correlated with bra-related changes in cross diameter (r = 0.641, P = 0.002) and volume (r = 0.680, P = 0.001). Significant dose reductions were observed for the lungs (mean V10: 19.58 cc, V20: 17.13 cc, Dmean: 86.24 cGy) and heart (Dmean: 170.23 cGy). No significant differences were observed for CN (0.62-0.67) and HI (0.19-0.20) of the CTV. Conclusion: The application of a radiation bra was associated with better geometric and dosimetric planning parameters, with a smaller CTV and lower doses to the OARs (lungs and heart) in the radiotherapy field. In addition, we expect that bra use during radiotherapy would provide emotional benefits.

scholarly journals Deep inspiration breath-hold intensity modulated radiation therapy in a large clinical series of 239 left-sided breast cancer patients: a dosimetric analysis of organs at risk doses and clinical feasibility from a single center experience

2019 ◽  
Vol 92 (1101) ◽  
pp. 20190150 ◽  
Author(s):  
Alessandro Testolin ◽  
Stefano Ciccarelli ◽  
Giulia Vidano ◽  
Rossella Avitabile ◽  
Francesca Dusi ◽  
...  
Keyword(s):  
At Risk ◽  
Maximum Dose ◽  
Organs At Risk ◽  
Intensity Modulated Radiation Therapy ◽  
Target Volume ◽  
Contralateral Breast ◽  
Breath Hold ◽  
Deep Inspiration ◽  
Breast Cancer Patients ◽  
Deep Inspiration Breath Hold

Objective: To evaluate dose to organs at risk, target coverage and treatment compliance in left-sided breast cancer patients (LSBCP) treated with deep inspiration breath-hold (DIBH) and intensity modulated radiation therapy (IMRT) technique in a contest of daily clinical practice. Methods: A total of 280 consecutive LSBCP referred for adjuvant radiotherapy were systematically screened for suitability of DIBH technique. 239 were able to comply with the requirement for DIBH. Whole breast or chest wall were irradiated in DIBH, monitored by Varian RPM™ Respiratory Gating System, and two tangential inverse-planned beams with dynamic dose delivery. Dose prescription was 42.4 Gy/16 fractions in 205 patients and 50 Gy/25 fractions in 34. 23 patients received local and nodal treatment. Boost to tumor bed, of 10 Gy/5 fractions was used in 135 patients. Relevant dose metrics for heart, left anterior descending (LAD) coronary artery, lungs, contralateral breast and planning target volume were retrospectively analyzed. Results: The average mean heart dose (MHD) for all patients was 0.94 Gy and mean maximum LAD dose was 13.82 Gy. MHD and LAD maximum dose were significantly higher in patients treated with conventional fractionation whether expressed in absolute dose (1.44 vs 0.85 Gy, p < 0.0005 and 20.78 vs 12.45 Gy, p < 0.0005 respectively) or in equivalent doses of 2 Gy fractionation (0.88 vs 0.52 Gy, p =< 0.0005 and 17.68 vs 10.63 Gy, p = 0.0002 respectively). In 57 patients (23.8%) the maximum LAD dose was >20 Gy. Mean V20 ipsilateral lung dose was 8.5%. Mean doses of contralateral breast and lung were 0.13 Gy and 0.09 Gy respectively. Mean planning target volume V95% coverage was 96.1%. Compliance rate of DIBH technique was 84.5% (239/280). Conclusion: DIBH and IMRT in daily clinical practice are feasible in high percentage of unselected patients and allows low levels of irradiation of organs at risk without compromising target coverage. However, despite low MHD a significant proportion of patients receives a maximum LAD dose superior to 20 Gy. Advances in knowledge: The value of MHD used exclusively is not able to describe entirely the risk of late heart toxicity, which can be better evaluated with the joint analysis of the maximum dose to LAD region. The vast majority of LSBCP referred to adjuvant radiotherapy in the setting of routine practice are able to comply with the requirement of DIBH.

scholarly journals Potential Morbidity Reduction for Lung Stereotactic Body Radiation Therapy Using Respiratory Gating

Cancers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 5092
Author(s):  
Kim Melanie Kraus ◽  
Cristoforo Simonetto ◽  
Pavel Kundrát ◽  
Vanessa Waitz ◽  
Kai Joachim Borm ◽  
...  
Keyword(s):  
Organs At Risk ◽  
Respiratory Gating ◽  
Target Volume ◽  
Normal Tissue Complication Probability ◽  
Heart Dose ◽  
Toxicity Risk ◽  
Treatment Plans ◽  
Selection For ◽  
Pre Treatment ◽  
Mean Lung Dose

We investigated the potential of respiratory gating to mitigate the motion-caused misdosage in lung stereotactic body radiotherapy (SBRT). For fourteen patients with lung tumors, we investigated treatment plans for a gating window (GW) including three breathing phases around the maximum exhalation phase, GW40-60. For a subset of six patients, we also assessed a preceding three-phase GW20-40 and six-phase GW20-70. We analyzed the target volume, lung, esophagus, and heart doses. Using normal tissue complication probability (NTCP) models, we estimated radiation pneumonitis and esophagitis risks . Compared to plans without gating, GW40-60 significantly reduced doses to organs at risk without impairing the tumor doses. On average, the mean lung dose decreased by 0.6 Gy (p < 0.001), treated lung V20Gy by 2.4% (p = 0.003), esophageal dose to 5cc by 2.0 Gy (p = 0.003), and maximum heart dose by 3.2 Gy (p = 0.009). The model-estimated mean risks of 11% for pneumonitis and 12% for esophagitis without gating decreased upon GW40-60 to 7% and 9%, respectively. For the highest-risk patient, gating reduced the pneumonitis risk from 43% to 32%. Gating is most beneficial for patients with high-toxicity risks. Pre-treatment toxicity risk assessment may help optimize patient selection for gating, as well as GW selection for individual patients.

scholarly journals Dosimetric Comparison of Radiation Techniques for Comprehensive Regional Nodal Radiation Therapy for Left-Sided Breast Cancer: A Treatment Planning Study

2020 ◽  
Author(s):  
Heejoo Ko ◽  
Jee Suk Chang ◽  
Jin Young Moon ◽  
Won Hee Lee ◽  
Chirag Shah ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Organs At Risk ◽  
Volumetric Modulated Arc Therapy ◽  
Three Dimensional ◽  
Conformal Radiotherapy ◽  
Free Breathing ◽  
Proton Beam Therapy ◽  
Target Volume ◽  
Internal Mammary ◽  
Bonferroni Test

Abstract Background: Radiotherapy (RT) target volumes in breast cancer treatment increasingly include the internal mammary nodes, potentially increasing doses delivered to the heart and lung. The aim of this study was to compare cardiac and pulmonary doses in three-dimensional conformal radiotherapy (3DCRT), volumetric modulated arc therapy (VMAT), and proton beam therapy (PBT) with and without continuous positive airway pressure (CPAP), delivered in conventional fractionation (CF) or in hypofractionated (HF) schedules.Methods: In a dataset of 15 patients with left-sided breast cancer, partial wide tangential 3DCRT delivered in CF (50/25) and in HF (40/15) schedules as well as PBT delivered in CF and two-partial arc VMAT delivered in a HF schedule, each under CPAP and free breathing (FB) conditions were extensively examined. Target volume coverage and doses to organs-at-risk (OARs) were calculated for each technique. Outcomes were compared with one-way analysis of variance and the Bonferroni test, with P-values <0.05 considered significant. Results: Target volume coverage was within acceptable levels in all interventions, except for internal mammary lymph nodes D90 (99% in PBT, 90% in VMAT-CPAP, 84% in VMAT-FB, and 74% in 3DCRT). Mean heart dose (MHD) was the lowest and highest in PBT (<1 Gy) and 3DCRT with CF/FB (7.8 Gy), respectively. In photon-based techniques, the use of VMAT in HF schedules with CPAP resulted in an MHD of 2.2 Gy. Lung V20 and mean lung dose (MLD) were the highest in 3DCRT-CF-FB (44% and 20 Gy, respectively) and lowest in both VMAT-HF-CPAP and PBT (7–9% and approximately 5–6 Gy, respectively). VMAT-HF-CPAP and PBT delivered a comparable maximum dose to the left ascending artery (7.2 Gy and 6.70 Gy, respectively, with the highest dose delivered by 3DCRT [47.6 Gy]). The average doses to the contralateral breast were 0.004, 1, and 2.1 Gy in PBT, 3DCRT, and VMAT, respectively.Conclusions: PBT delivered the lowest doses to most OARs in RT for left-sided breast cancer with regional nodal irradiation. However, the dosimetric gap between proton and photon RT has narrowed substantially with modern techniques such as VMAT and CPAP; the clinical relevance of these differences is yet to be elucidated.

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