The impact of breathing amplitude on dose homogeneity in intensity modulated proton therapy

Abstract In this review article, we review the 3 important aspects of linear-energy-transfer (LET) in intensity-modulated proton therapy (IMPT) for head and neck (H&N) cancer management. Accurate LET calculation methods are essential for LET-guided plan evaluation and optimization, which can be calculated either by analytical methods or by Monte Carlo (MC) simulations. Recently, some new 3D analytical approaches to calculate LET accurately and efficiently have been proposed. On the other hand, several fast MC codes have also been developed to speed up the MC simulation by simplifying nonessential physics models and/or using the graphics processor unit (GPU)–acceleration approach. Some concepts related to LET are also briefly summarized including (1) dose-weighted versus fluence-weighted LET; (2) restricted versus unrestricted LET; and (3) microdosimetry versus macrodosimetry. LET-guided plan evaluation has been clinically done in some proton centers. Recently, more and more studies using patient outcomes as the biological endpoint have shown a positive correlation between high LET and adverse events sites, indicating the importance of LET-guided plan evaluation in proton clinics. Various LET-guided plan optimization methods have been proposed to generate proton plans to achieve biologically optimized IMPT plans. Different optimization frameworks were used, including 2-step optimization, 1-step optimization, and worst-case robust optimization. They either indirectly or directly optimize the LET distribution in patients while trying to maintain the same dose distribution and plan robustness. It is important to consider the impact of uncertainties in LET-guided optimization (ie, LET-guided robust optimization) in IMPT, since IMPT is sensitive to uncertainties including both the dose and LET distributions. We believe that the advancement of the LET-guided plan evaluation and optimization will help us exploit the unique biological characteristics of proton beams to improve the therapeutic ratio of IMPT to treat H&N and other cancers.

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Robust Optimization for Intensity Modulated Proton Therapy Plans with Multi-Isocenter Large Fields

International Journal of Particle Therapy ◽

10.14338/ijpt-16-00012.1 ◽

2016 ◽

Vol 3 (2) ◽

pp. 305-311 ◽

Cited By ~ 7

Author(s):

Li Liao ◽

Gino J. Lim ◽

Yupeng Li ◽

Juan Yu ◽

Narayan Sahoo ◽

...

Keyword(s):

Robust Optimization ◽

Proton Therapy ◽

Gradient Field ◽

Optimization Approach ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

Treatment Plans ◽

The Impact ◽

Therapy Treatment

Abstract We have developed a robust optimization approach for intensity modulated proton therapy treatment plans with multi-isocenter large fields. The method creates a low-gradient field dose in the junction regions to mitigate the impact caused by misalignment errors and is more efficient than the conventional junction shifting technique.

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Robust optimization to reduce the impact of biological effect variation from physical uncertainties in intensity-modulated proton therapy

Physics in Medicine and Biology ◽

10.1088/1361-6560/aaf5e9 ◽

2019 ◽

Vol 64 (2) ◽

pp. 025004 ◽

Cited By ~ 7

Author(s):

Xuemin Bai ◽

Gino Lim ◽

Hans-Peter Wieser ◽

Mark Bangert ◽

David Grosshans ◽

...

Keyword(s):

Robust Optimization ◽

Proton Therapy ◽

Biological Effect ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

The Impact

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The Impact of Body Weight Change on the Dose Distribution of Intensity Modulated Proton Therapy for Cervical Cancer

International Journal of Radiation Oncology*Biology*Physics ◽

10.1016/j.ijrobp.2014.05.2600 ◽

2014 ◽

Vol 90 (1) ◽

pp. S916-S917 ◽

Cited By ~ 1

Author(s):

D. Wang ◽

S. Bhatia ◽

E. Dinges ◽

B. Gross ◽

J. Buatti ◽

...

Keyword(s):

Cervical Cancer ◽

Body Weight ◽

Proton Therapy ◽

Weight Change ◽

Dose Distribution ◽

Body Weight Change ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

The Impact

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The impact of dose algorithms on tumor control probability in intensity-modulated proton therapy for breast cancer

Physica Medica ◽

10.1016/j.ejmp.2019.04.011 ◽

2019 ◽

Vol 61 ◽

pp. 52-57 ◽

Cited By ~ 1

Author(s):

Xiaoying Liang ◽

Julie A. Bradley ◽

Dandan Zheng ◽

Michael Rutenberg ◽

Raymond Mailhot Vega ◽

...

Keyword(s):

Breast Cancer ◽

Proton Therapy ◽

Tumor Control ◽

Tumor Control Probability ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

The Impact

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Early Clinical Outcomes of Intensity Modulated Radiation Therapy/Intensity Modulated Proton Therapy Combination in Comparison with Intensity Modulated Radiation Therapy Alone in Oropharynx Cancer Patients

Cancers ◽

10.3390/cancers13071549 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1549

Author(s):

Han Gyul Yoon ◽

Yong Chan Ahn ◽

Dongryul Oh ◽

Jae Myoung Noh ◽

Seung Gyu Park ◽

...

Keyword(s):

Radiation Therapy ◽

Proton Therapy ◽

Intensity Modulated Radiation Therapy ◽

Combination Group ◽

Intensity Modulated Proton Therapy ◽

Oropharynx Cancer ◽

Intensity Modulated ◽

Before And After ◽

Grade 3 ◽

Early Clinical Outcomes

Purpose: To report the early clinical outcomes of combining intensity-modulated radiation therapy (IMRT) and intensity-modulated proton therapy (IMPT) in comparison with IMRT alone in treating oropharynx cancer (OPC) patients. Materials and Methods: The medical records of 148 OPC patients who underwent definitive radiotherapy (RT) with concurrent systemic therapy, from January 2016 till December 2019 at Samsung Medical Center, were retrospectively reviewed. During the 5.5 weeks’ RT course, the initial 16 (or 18) fractions were delivered by IMRT in all patients, and the subsequent 12 (or 10) fractions were either by IMRT in 81 patients (IMRT only) or by IMPT in 67 (IMRT/IMPT combination), respectively, based on comparison of adaptive re-plan profiles and availability of equipment. Propensity-score matching (PSM) was done on 76 patients (38 from each group) for comparative analyses. Results: With the median follow-up of 24.7 months, there was no significant difference in overall survival and progression free survival between groups, both before and after PSM. Before PSM, the IMRT/IMPT combination group experienced grade ≥ 3 acute toxicities less frequently: mucositis in 37.0% and 13.4% (p < 0.001); and analgesic quantification algorithm (AQA) in 37.0% and 19.4% (p = 0.019), respectively. The same trends were observed after PSM: mucositis in 39.5% and 15.8% (p = 0.021); and AQA in 47.4% and 21.1% (p = 0.016), respectively. In multivariate logistic regression, grade ≥ 3 mucositis was significantly less frequent in the IMRT/IMPT combination group, both before and after PSM (p = 0.027 and 0.024, respectively). AQA score ≥ 3 was also less frequent in the IMRT/IMPT combination group, both before and after PSM (p = 0.085 and 0.018, respectively). Conclusions: In treating the OPC patients, with comparable early oncologic outcomes, more favorable acute toxicity profiles were achieved following IMRT/IMPT combination than IMRT alone.

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