scholarly journals Cardiac-Sparing and Breast-Sparing Whole Lung Irradiation Using Intensity-Modulated Proton Therapy

2021 ◽  
Author(s):  
Ru Xin Wong ◽  
Jacqueline Faught ◽  
Melissa Gargone ◽  
William Myers ◽  
Matthew Krasin ◽  
...  
Keyword(s):  
Proton Therapy ◽  
Planning Target Volume ◽  
Pediatric Patients ◽  
Lung Metastases ◽  
Target Volume ◽  
Internal Target Volume ◽  
Intensity Modulated Proton Therapy ◽  
Intensity Modulated ◽  
Lung Irradiation ◽  
Whole Lung Irradiation

Abstract Purpose Whole lung irradiation (WLI) is indicated for certain pediatric patients with lung metastases. This study investigated whether WLI delivered as intensity-modulated proton therapy (IMPT) could significantly spare the heart and breasts when compared with conventional WLI delivered with anteroposterior/posteroanterior photon fields and with intensity-modulated photon therapy (IMRT) WLI. Materials and Methods Conventional, IMRT, and IMPT plans were generated for 5 patients (aged 5-22 years). The prescription dose was 16.5 GyRBE in 1.5-GyRBE fractions. Conventional plans used 6-MV photons prescribed to the midline and a field-in-field technique to cover the planning target volume (the internal target volume [ITV] + 1 cm). IMRT plans used 6-MV photons with a 7-beam arrangement with dose prescribed to the planning target volume. IMPT plans used scenario-based optimization with 5% range uncertainty and 5-mm positional uncertainty to cover the ITV robustly. Monte Carlo dose calculation was used for all IMPT plans. Doses were compared with paired Student t test. Results The ITV Dmean was similar for the IMPT, conventional, and IMRT plans, but the IMPT plans had a lower Dmin and a higher Dmax at tissue interfaces than conventional plans (Dmean ratio: 0.96, P > .05; Dmin ratio: 0.9, P < .001; Dmax ratio: 1.1, P = .014). Dmeans for breast and heart substructures were lower with IMPT plans than with conventional/IMRT plans (heart ratios, 0.63:0.73; left ventricle ratios, 0.61:0.72; right ventricle ratios, 0.45:0.57; left atrium ratios, 0.79:0.85; right atrium ratios, 0.81:0.86; left breast ratios, 0.40:0.51; right breast ratio, 0.46:0.52; all P < .05). Conclusions IMPT resulted in comparable ITV coverage and lower mean doses to the heart and breasts when compared with other techniques. Whole lung irradiation delivered as IMPT warrants prospective evaluation in pediatric patients.

scholarly journals A New Proton Therapy Solution Provides Superior Cardiac Sparing Compared With Photon Therapy in Whole Lung Irradiation for Pediatric Tumor Patients

2021 ◽  
Vol 10 ◽  
Author(s):  
Xue Sha ◽  
Jinghao Duan ◽  
Xiutong Lin ◽  
Jian Zhu ◽  
Ruohui Zhang ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Proton Therapy ◽  
Target Volume ◽  
Photon Radiation ◽  
Intensity Modulated ◽  
Lung Irradiation ◽  
Dose Sparing ◽  
The Right ◽  
Whole Lung Irradiation ◽  
Cardiac Sparing

ObjectiveWhole lung irradiation (WLI) plays a crucial role in local control in pediatric patients with lung metastases and improves patient survival. The intention of this research was to explore the advantage of cardiac sparing between photons and protons during WLI. We also propose a new solution for cardiac sparing with proton techniques.MethodsEleven patients with pediatric tumors and pulmonary metastasis treated with 12 Gy WLI (all received volumetric-modulated arc therapy (VMAT)) in our institute between 2010 and 2019 were retrospectively selected. Each patient was replanned with intensity-modulated radiation therapy (IMRT), helical tomotherapy (HT), and two intensity-modulated proton radiotherapy (IMPT) plans (IMPT-1 and IMPT-2). IMPT-1 considered the whole lung as the planning target volume (PTV), utilizing the anteroposterior technique (0/180°). IMPT-2 was a new proton solution that we proposed in this research. This approach considered the unilateral lung as the PTV, and 3 ipsilateral fields were designed for each lung. Then, IMPT-2 was generated by summing two unilateral lung plans. The primary objective was to obtain adequate coverage (95% of the prescription dose to the PTV) while maximally sparing the dose to the heart. The PTV coverage, conformity index (CI), homogeneity index (HI), and dose–volume statistics of the heart and substructures were assessed by means of the averages of each comparison parameter.ResultsAll treatment techniques achieved the target volume coverage required by clinical practice. HT yielded the best coverage and homogeneity for the target structure compared with other techniques. The CI from IMRT was excellent. For photon radiation therapy, the HT plan afforded superior dose sparing for the V5, V6, V7, V8, and Dmean of the heart and Dmean of the right ventricle (RV). IMRT displayed the most notable dose reductions in the V9, V10, V11, and V12 of the heart and Dmean of the right atrium (RA). The VMAT plan was the least effective on the heart and substructures. However, compared with photon radiation therapy, IMPT-1 did not show an advantage for heart protection. Interestingly, IMPT-2 provided significant superiority in cardiac sparing, including maximum dose sparing for the V5, V6, V7, V8, V9 and Dmean of the heart and Dmean of the RA, RV, left atrium (LA) and left ventricle (LV) compared to all other techniques.ConclusionsConsidering the complex anatomical relation between target volumes and organs at risk (OARs), IMPT can provide a dose advantage for organs located outside of the target area rather than within or surrounding the area. It is hoped that advances in proton therapy (PT) plan design will lead to further improvements in radiotherapy approaches and provide the best treatment choice for individual patients.

scholarly journals Is an analytical dose engine sufficient for intensity modulated proton therapy in lung cancer?

2020 ◽  
Vol 93 (1107) ◽  
pp. 20190583 ◽  
Author(s):  
Suliana Teoh ◽  
Francesca Fiorini ◽  
Ben George ◽  
Katherine A Vallis ◽  
Frank Van den Heuvel
Keyword(s):  
Lung Cancer ◽  
Proton Therapy ◽  
Dose Calculation ◽  
Target Volume ◽  
Pass Rates ◽  
Final Dose ◽  
Intensity Modulated Proton Therapy ◽  
Intensity Modulated ◽  
Mediastinal Disease ◽  
Mediastinal Involvement

Objective: To identify a subgroup of lung cancer plans where the analytical dose calculation (ADC) algorithm may be clinically acceptable compared to Monte Carlo (MC) dose calculation in intensity modulated proton therapy (IMPT). Methods: Robust-optimised IMPT plans were generated for 20 patients to a dose of 70 Gy (relative biological effectiveness) in 35 fractions in Raystation. For each case, four plans were generated: three with ADC optimisation using the pencil beam (PB) algorithm followed by a final dose calculation with the following algorithms: PB (PB-PB), MC (PB-MC) and MC normalised to prescription dose (PB-MC scaled). A fourth plan was generated where MC optimisation and final dose calculation was performed (MC-MC). Dose comparison and γ analysis (PB-PB vs PB-MC) at two dose thresholds were performed: 20% (D20) and 99% (D99) with PB-PB plans as reference. Results: Overestimation of the dose to 99% and mean dose of the clinical target volume was observed in all PB-MC compared to PB-PB plans (median: 3.7 Gy(RBE) (5%) (range: 2.3 to 6.9 Gy(RBE)) and 1.8 Gy(RBE) (3%) (0.5 to 4.6 Gy(RBE))). PB-MC scaled plans resulted in significantly higher CTVD2 compared to PB-PB (median difference: −4 Gy(RBE) (−6%) (-5.3 to −2.4 Gy(RBE)), p ≤ .001). The overall median γ pass rates (3%–3 mm) at D20 and D99 were 93.2% (range:62.2–97.5%) and 71.3 (15.4–92.0%). On multivariate analysis, presence of mediastinal disease and absence of range shifters were significantly associated with high γ pass rates. Median D20 and D99 pass rates with these predictors were 96.0% (95.3–97.5%) and 85.4% (75.1–92.0%). MC-MC achieved similar target coverage and doses to OAR compared to PB-PB plans. Conclusion: In the presence of mediastinal involvement and absence of range shifters Raystation ADC may be clinically acceptable in lung IMPT. Otherwise, MC algorithm would be recommended to ensure accuracy of treatment plans. Advances in knowledge: Although MC algorithm is more accurate compared to ADC in lung IMPT, ADC may be clinically acceptable where there is mediastinal involvement and absence of range shifters.

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 Radiotherapy in Osteosarcomas

2018 ◽  
Vol 1 (Supplement) ◽  
pp. 31
Author(s):  
R. Mitrică ◽  
L. Şerbănescu ◽  
O. Trifănescu
Keyword(s):  
Local Control ◽  
Proton Therapy ◽  
Clinical Studies ◽  
Residual Disease ◽  
Lung Metastases ◽  
Current Treatment ◽  
Resection Margins ◽  
First Choice ◽  
Lung Irradiation ◽  
Whole Lung Irradiation

Abstract Osteosarcoma represents a rare primary tumor of the bone, but it ranks 5th among children and adolescents. When diagnosed, many patients already have a disseminated disease at subclinical level. Current treatment includes surgery and chemotherapy. Radiotherapy is not commonly indicated, especially given the radioresistant characteristic of this type of cancer and it is usually administered for residual disease after surgery, inoperable tumors or in palliation, such as whole lung irradiation. The purpose of this paper was to identify the real contribution of radiotherapy in osteosarcomas, with solutions to improve local control and survival. We reviewed clinical studies, starting with the period before chemotherapy, in order to identify treatment techniques related criteria that may influence local control, survival, and secondary toxicity. Modern radiotherapy techniques are outlined with their dosimetric advantages. Following the 1990s, the combination between proper surgery and chemotherapy has eliminated the need for pre-operative radiotherapy. Most clinical studies have used adjuvant radiotherapy for patients with positive resection margins, with good results but hard to dissociate from those of the concurrently administered chemotherapy. Proton therapy is frequently indicated for these patients, due to the healthy tissue sparing characteristics. Studies have pointed out the correlation between radiotherapy response and tumor size, total administered dose, chemo sensitivity. Whole lung irradiation for patients with lung metastases is inferior to chemotherapy. Radiotherapy associated complications include joint fibrosis with reduced functional capabilities, bone fracture, allograft loss and carcinogenic risk. Currently, radiotherapy is not the first choice when treating osteosarcomas, but new evidence is emerging for combining modern techniques, such as proton therapy with surgery and chemotherapy for patients with incomplete resections or inoperable tumors.

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