A Novel Proton Pencil Beam Scanning FLASH RT Delivery Method Enables Optimal OAR Sparing and Ultra-High Dose Rate Delivery: A Comprehensive Dosimetry Study for Lung Tumors

Purpose: While transmission proton beams have been demonstrated to achieve ultra-high dose rate FLASH therapy delivery, they are unable to spare normal tissues distal to the target. This study aims to compare FLASH treatment planning using single energy Bragg peak proton beams versus transmission proton beams in lung tumors and to evaluate Bragg peak plan optimization, characterize plan quality, and quantify organ-at-risk (OAR) sparing. Materials and Methods: Both Bragg peak and transmission plans were optimized using an in-house platform for 10 consecutive lung patients previously treated with proton stereotactic body radiation therapy (SBRT). To bring the dose rate up to the FLASH-RT threshold, Bragg peak plans with a minimum MU/spot of 1200 and transmission plans with a minimum MU/spot of 400 were developed. Two common prescriptions, 34 Gy in 1 fraction and 54 Gy in 3 fractions, were studied with the same beam arrangement for both Bragg peak and transmission plans (n = 40 plans). RTOG 0915 dosimetry metrics and dose rate metrics based on different dose rate calculations, including average dose rate (ADR), dose-averaged dose rate (DADR), and dose threshold dose rate (DTDR), were investigated. We then evaluated the effect of beam angular optimization on the Bragg peak plans to explore the potential for superior OAR sparing. Results: Bragg peak plans significantly reduced doses to several OAR dose parameters, including lung V7.4Gy and V7Gy by 32.0% (p < 0.01) and 30.4% (p < 0.01) for 34Gy/fx plans, respectively; and by 40.8% (p < 0.01) and 41.2% (p < 0.01) for 18Gy/fx plans, respectively, compared with transmission plans. Bragg peak plans have ~3% less in DADR and ~10% differences in mean OARs in DTDR and DADR relative to transmission plans due to the larger portion of lower dose regions of Bragg peak plans. With angular optimization, optimized Bragg peak plans can further reduce the lung V7Gy by 20.7% (p < 0.01) and V7.4Gy by 19.7% (p < 0.01) compared with Bragg peak plans without angular optimization while achieving a similar 3D dose rate distribution. Conclusion: The single-energy Bragg peak plans achieve superior dosimetry performances in OARs to transmission plans with comparable dose rate performances for lung cancer FLASH therapy. Beam angle optimization can further improve the OAR dosimetry parameters with similar 3D FLASH dose rate coverage.

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FP08.03 Outcomes With Multi-Disciplinary Management of Central Lung Tumors Treated With Percutaneous High-Dose-Rate Brachytherapy

Journal of Thoracic Oncology ◽

10.1016/j.jtho.2021.08.233 ◽

2021 ◽

Vol 16 (10) ◽

pp. S958-S959

Author(s):

S. Yoon ◽

R. Suh ◽

F. Abtin ◽

D. Moghanaki ◽

S. Genshaft ◽

...

Keyword(s):

Dose Rate ◽

Lung Tumors ◽

High Dose Rate ◽

High Dose ◽

High Dose Rate Brachytherapy

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High-dose rate brachytherapy (HDR-BT): A prospective randomized trial of two fractionation schedules in the palliative treatment of central lung tumors

International Journal of Radiation Oncology*Biology*Physics ◽

10.1016/s0360-3016(00)80261-8 ◽

2000 ◽

Vol 48 (3) ◽

pp. 233-234 ◽

Cited By ~ 1

Author(s):

B Poellinger ◽

R.M Huber ◽

R Fischer ◽

H Hautmann ◽

A Siefert ◽

...

Keyword(s):

Randomized Trial ◽

Dose Rate ◽

Palliative Treatment ◽

Lung Tumors ◽

High Dose Rate ◽

Prospective Randomized Trial ◽

High Dose ◽

High Dose Rate Brachytherapy ◽

Fractionation Schedules

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The value of systematic contouring of the bowel for treatment plan optimization in image-guided cervical cancer high-dose-rate brachytherapy

Brachytherapy ◽

10.1016/j.brachy.2017.01.008 ◽

2017 ◽

Vol 16 (3) ◽

pp. 579-585 ◽

Cited By ~ 1

Author(s):

Antonio L. Damato ◽

Ivan Buzurovic ◽

Mandar S. Bhagwat ◽

Robert A. Cormack ◽

Phillip M. Devlin ◽

...

Keyword(s):

Cervical Cancer ◽

Dose Rate ◽

Treatment Plan ◽

High Dose Rate ◽

High Dose ◽

High Dose Rate Brachytherapy ◽

Image Guided ◽

Plan Optimization ◽

Treatment Plan Optimization

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Outcomes with multi-disciplinary management of central lung tumors with CT-guided percutaneous high dose rate brachyablation

Radiation Oncology ◽

10.1186/s13014-021-01826-1 ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Stephanie M. Yoon ◽

Robert Suh ◽

Fereidoun Abtin ◽

Drew Moghanaki ◽

Scott Genshaft ◽

...

Keyword(s):

Adverse Events ◽

Dose Rate ◽

Pulmonary Hemorrhage ◽

Lung Tumors ◽

High Dose Rate ◽

High Dose ◽

Median Dose ◽

Management Options ◽

Ct Guided

Abstract Background Centrally located lung tumors present treatment challenges given their proximity to mediastinal structures including the central airway, esophagus, major vessels, and heart. Therapeutic options can be limited for medically inoperable patients, particularly if they have received previous thoracic radiotherapy. High dose rate (HDR) brachyablation was developed to improve the therapeutic ratio for patients with central lung tumors. The purpose of this study is to report initial safety and efficacy outcomes with this treatment for central lung malignancies. Methods From September 2015 to August 2019, a total of 25 patients with 37 pulmonary tumors were treated with percutaneous HDR brachyablation. Treatment was delivered by a multi-disciplinary team of interventional radiologists, pulmonologists, and radiation oncologists. Twenty-three patients received a median dose of 21.5 Gy (range 15–27.5) in a single fraction, whereas two patients received median dose of 24.75 Gy (range 24–25.5) over 2–3 fractions. Tumor local control (LC) was evaluated by Response Evaluation Criteria in Solid Tumors v1.1. Treatment-related toxicities were graded by Common Terminology Criteria for Adverse Events v5.0, with adverse events less than 90 days defined as acute, and those occurring later were defined as late. LC, progression-free survival (PFS), and overall survival (OS) rates were estimated by the Kaplan–Meier method. Results Of 37 treated tumors, 88% were metastatic. Tumor location was central and ultra-central in 24.3% and 54.1%, respectively. Average tumor volume was 11.6 cm3 (SD 12.4, range 0.57–62.8). Median follow-up was 19 months (range 3–48). Two–year LC, PFS, and OS were 96.2%, 29.7%, and 65.5%, respectively. Thirteen of 39 (33.3%) catheter implantation procedures were associated with trace minor pneumothorax requiring no intervention, 1 (2.5%) procedure with minor radiographic pulmonary hemorrhage, and 4 (10.3%) with major pneumothorax requiring chest tube insertions. All procedural complications resolved within 24 h from treatment. Acute grade 1–2 toxicity was identified in 4 patients, whereas none developed late toxicity beyond 90 days of follow-up. Conclusion Percutaneous HDR brachyablation is a safe and promising treatment option for centrally located primary and metastatic lung tumors. Future comparisons with stereotactic body radiotherapy and other ablative techniques are warranted to expand multi-disciplinary management options.

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Radiobiology Experiments With Ultra-high Dose Rate Laser-Driven Protons: Methodology and State-of-the-Art

Frontiers in Physics ◽

10.3389/fphy.2021.624963 ◽

2021 ◽

Vol 9 ◽

Author(s):

Pankaj Chaudhary ◽

Giuliana Milluzzo ◽

Hamad Ahmed ◽

Boris Odlozilik ◽

Aaron McMurray ◽

...

Keyword(s):

Dose Rate ◽

Biological Effects ◽

Therapeutic Index ◽

High Dose Rate ◽

High Dose ◽

Particle Accelerators ◽

Dose Rates ◽

Normal Tissues ◽

Multiple Pulses ◽

Tissue Sparing

The use of particle accelerators in radiotherapy has significantly changed the therapeutic outcomes for many types of solid tumours. In particular, protons are well known for sparing normal tissues and increasing the overall therapeutic index. Recent studies show that normal tissue sparing can be further enhanced through proton delivery at 100 Gy/s and above, in the so-called FLASH regime. This has generated very significant interest in assessing the biological effects of proton pulses delivered at very high dose rates. Laser-accelerated proton beams have unique temporal emission properties, which can be exploited to deliver Gy level doses in single or multiple pulses at dose rates exceeding by many orders of magnitude those currently used in FLASH approaches. An extensive investigation of the radiobiology of laser-driven protons is therefore not only necessary for future clinical application, but also offers the opportunity of accessing yet untested regimes of radiobiology. This paper provides an updated review of the recent progress achieved in ultra-high dose rate radiobiology experiments employing laser-driven protons, including a brief discussion of the relevant methodology and dosimetry approaches.

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Clinical and endoscopic response to high dose rate endobronchial brachytherapy in malignant lung tumors: A single centre experience

South Asian Journal of Cancer ◽

10.4103/sajc.sajc_29_18 ◽

2018 ◽

Vol 07 (04) ◽

pp. 267-269

Author(s):

Sneha Dhillon ◽

Saurabh Bansal ◽

Girish Sindhwani ◽

Meenu Gupta ◽

Vipul Nautiyal ◽

...

Keyword(s):

Dose Rate ◽

Lung Tumors ◽

High Dose Rate ◽

P Value ◽

High Dose ◽

Hdr Brachytherapy ◽

Single Centre ◽

Short Term ◽

Single Centre Experience ◽

Promising Treatment

Abstract Purpose: The aim of the study was to evaluate the short-term clinical, endoscopic response, and acute toxicities in endobronchial cancer treated with high-dose-rate endobronchial brachytherapy (HDR-EB). Materials and Methods: Thirty patients of advanced endobronchial cancers were treated with HDR-EB. Brachytherapy was delivered at a depth of 1 cm from the source axis at weeks 1, 2, and 3 with 7 Gy per fraction. All patients were evaluated before treatment and at 1 month after completion of therapy. Using Speiser's scoring criteria, the severity of symptoms (dyspnea, cough, hemoptysis, and postobstructive pneumonia) and degree of obstruction were graded. Results: Symptomatic response for cough, dyspnea, and hemoptysis was seen in 88%, 75%, and 96%, respectively, with a significant P value (<0.05). Obstructive pneumonia was resolved in 94% of patients. Endoscopic response in terms of degree of obstruction was seen in 84% of patients. Acute toxicities in the form of radiation bronchitis were seen in 32% of patients, whereas 8% of patients experienced esophagitis. Bronchospasm was seen in one patient during treatment. Conclusion: HDR brachytherapy is a highly effective, safe, convenient therapy in alleviating symptoms of endobronchial obstruction with endoscopic response in the majority of cases. Thus, HDR-BT is a promising treatment for palliation of patients presenting with symptoms of endobronchial obstruction with an acceptable rate of complications.

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