Intensity-modulated proton therapy decreases dose to organs at risk in low-grade glioma patients: results of a multicentric in silico ROCOCO trial

Purpose: To investigate the role of intensity-modulated proton therapy (IMPT) for hepatocellular carcinoma (HCC) patients to be treated with stereotactic body radiation therapy (SBRT) in a risk-adapted dose prescription regimen. Methods: A cohort of 30 patients was retrospectively selected as “at-risk” of dose de-escalation due to the proximity of the target volumes to dose-limiting healthy structures. IMPT plans were compared to volumetric modulated arc therapy (VMAT) RapidArc (RA) plans. The maximum dose prescription foreseen was 75 Gy in 3 fractions. The dosimetric analysis was performed on several quantitative metrics on the target volumes and organs at risk to identify the relative improvement of IMPT over VMAT and to determine if IMPT could mitigate the need of dose reduction and quantify the consequent potential patient accrual rate for protons. Results: IMPT and VMAT plans resulted in equivalent target dose distributions: both could ensure the required coverage for CTV and PTV. Systematic and significant improvements were observed with IMPT for all organs at risk and metrics. An average gain of 9.0 ± 11.6, 8.5 ± 7.7, 5.9 ± 7.1, 4.2 ± 6.4, 8.9 ± 7.1, 6.7 ± 7.5 Gy was found in the near-to-maximum doses for the ribs, chest wall, heart, duodenum, stomach and bowel bag respectively. Twenty patients violated one or more binding constraints with RA, while only 2 with IMPT. For all these patients, some dose de-intensification would have been required to respect the constraints. For photons, the maximum allowed dose ranged from 15.0 to 20.63 Gy per fraction while for the 2 proton cases it would have been 18.75 or 20.63 Gy. Conclusion: The results of this in-silico planning study suggests that IMPT might result in advantages compared to photon-based VMAT for HCC patients to be treated with ablative SBRT. In particular, the dosimetric characteristics of protons may avoid the need for dose de-escalation in a risk-adapted prescription regimen for those patients with lesions located in proximity of dose-limiting healthy structures. Depending on the selection thresholds, the number of patients eligible for treatment at the full dose can be significantly increased with protons.

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Comparison of intensity modulated photon therapy and intensity modulated proton therapy plans for prostate cancer

Science and Technology Development Journal ◽

10.32508/stdj.v18i3.825 ◽

2015 ◽

Vol 18 (3) ◽

pp. 93-100

Author(s):

Tu Thi Cam Nguyen ◽

Nhon Van Mai ◽

Binh Thai Nguyen

Keyword(s):

At Risk ◽

Proton Therapy ◽

Organs At Risk ◽

X Rays ◽

Work Intensity ◽

Normal Tissues ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

Dose Volume ◽

Treatment Plans

Nowadays, traditional radiation therapy using x-rays is still the most common type of external exposure in curing cancer. However, the persisting problem is that significant dose delivered to normal tissues because of the characteristics of interaction of photons with matter even with the most advanced delivery techniques such as IMRT, IGRT, etc. Proton therapy is not only the technique producing better conformity to target but also better sparing to organs at risk. In this work, intensity modulated proton therapy (IMPT) and intensity modulated photon therapy (IMRT) plans are generated for a prostate patient. The evaluation and comparison of the two treatment plans were performed in term of physical quantity based on Dose Volume Histogram (DVH) and dose statistics for both target and organs at risk. The results of our study show that IMPT could be beneficial compared to IMRT with 5 fields. The doses to intestine and bladder are low resulting in possibly reducing side effects and second malignancies

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

Technology in Cancer Research & Treatment ◽

10.1177/1533033820985866 ◽

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.

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Intensity modulated proton therapy planning study for organ at risk sparing in rectal cancer re-irradiation

Acta Oncologica ◽

10.1080/0284186x.2021.1953139 ◽

2021 ◽

pp. 1-4

Author(s):

H. S. Rønde ◽

J. F. Kallehauge ◽

C. J. S. Kronborg ◽

L. Nyvang ◽

B. L. Rekstad ◽

...

Keyword(s):

At Risk ◽

Rectal Cancer ◽

Proton Therapy ◽

Therapy Planning ◽

Planning Study ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

Organ At Risk

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Impact of Breast Size on Dosimetric Indices in Proton Versus X-ray Radiotherapy for Breast Cancer

Journal of Personalized Medicine ◽

10.3390/jpm11040282 ◽

2021 ◽

Vol 11 (4) ◽

pp. 282

Author(s):

Lisa Cunningham ◽

Scott Penfold ◽

Eileen Giles ◽

Hien Le ◽

Michala Short

Keyword(s):

Breast Cancer ◽

At Risk ◽

Proton Therapy ◽

Organs At Risk ◽

Patient Specific ◽

Breast Size ◽

X Ray ◽

Intensity Modulated ◽

Dosimetric Indices ◽

The Impact

Deep inspiration breath hold (DIBH) radiotherapy is a technique used to manage early stage left-sided breast cancer. This study compared dosimetric indices of patient-specific X-ray versus proton therapy DIBH plans to explore differences in target coverage, radiation doses to organs at risk, and the impact of breast size. Radiotherapy plans of sixteen breast cancer patients previously treated with DIBH radiotherapy were re-planned with hybrid inverse-planned intensity modulated X-ray radiotherapy (h-IMRT) and intensity modulated proton therapy (IMPT). The total prescribed dose was 40.05 Gy in 15 fractions for all cases. Comparisons between the clinical, h-IMRT, and IMPT evaluated doses to target volumes, organs at risk, and correlations between doses and breast size. Although no differences were observed in target volume coverage between techniques, the h-IMRT and IMPT were able to produce more even dose distributions and IMPT delivered significantly less dose to all organs at risk than both X-ray techniques. A moderate negative correlation was observed between breast size and dose to the target in X-ray techniques, but not IMPT. Both h-IMRT and IMPT produced plans with more homogeneous dose distribution than forward-planned IMRT and IMPT achieved significantly lower doses to organs at risk compared to X-ray techniques.

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Intensity Modulated Proton Therapy for Craniospinal Irradiation: Organ-at-Risk Exposure and a Low-Gradient Junctioning Technique

International Journal of Radiation Oncology*Biology*Physics ◽

10.1016/j.ijrobp.2014.07.003 ◽

2014 ◽

Vol 90 (3) ◽

pp. 637-644 ◽

Cited By ~ 15

Author(s):

Joshua B. Stoker ◽

Jonathan Grant ◽

X. Ronald Zhu ◽

Rajesh Pidikiti ◽

Anita Mahajan ◽

...

Keyword(s):

At Risk ◽

Proton Therapy ◽

Craniospinal Irradiation ◽

Risk Exposure ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

Organ At Risk

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Intensity Modulated Radiation Therapy (IMRT) Versus Intensity Modulated Proton Therapy (IMPT) in Low-Grade Gliomas: A Dosimetric Study

International Journal of Radiation Oncology*Biology*Physics ◽

10.1016/j.ijrobp.2013.06.658 ◽

2013 ◽

Vol 87 (2) ◽

pp. S253 ◽

Cited By ~ 2

Author(s):

D. Amelio ◽

S. Lorentini ◽

M. Giri ◽

G. Meliadò ◽

G. Fava ◽

...

Keyword(s):

Radiation Therapy ◽

Proton Therapy ◽

Intensity Modulated Radiation Therapy ◽

Low Grade ◽

Low Grade Gliomas ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

Dosimetric Study

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Assessment of Knowledge-Based Planning for Prostate Intensity Modulated Proton Therapy

International Journal of Particle Therapy ◽

10.14338/ijpt-20-00088.1 ◽

2021 ◽

Author(s):

Yihang Xu ◽

Nellie Brovold ◽

Jonathan Cyriac ◽

Elizabeth Bossart ◽

Kyle Padgett ◽

...

Keyword(s):

Prostate Cancer ◽

At Risk ◽

Proton Therapy ◽

Volumetric Modulated Arc Therapy ◽

Model Quality ◽

Intensity Modulated Proton Therapy ◽

Intensity Modulated ◽

Knowledge Based ◽

Knowledge Based Planning ◽

Organ At Risk

Abstract Purpose To assess the performance of a proton-specific knowledge based planning (KBPP) model in creation of robustly optimized intensity-modulated proton therapy (IMPT) plans for treatment of patients with prostate cancer. Materials and Methods Forty-five patients with localized prostate cancer, who had previously been treated with volumetric modulated arc therapy, were selected and replanned with robustly optimized IMPT. A KBPP model was generated from the results of 30 of the patients, and the remaining 15 patient results were used for validation. The KBPP model quality and accuracy were evaluated with the model-provided organ-at-risk regression plots and metrics. The KBPP quality was also assessed through comparison of expert and KBPP-generated IMPT plans for target coverage and organ-at-risk sparing. Results The resulting R2 (mean ± SD, 0.87 ± 0.07) between dosimetric and geometric features, as well as the χ2 test (1.17 ± 0.07) between the original and estimated data, showed the model had good quality. All the KBPP plans were clinically acceptable. Compared with the expert plans, the KBPP plans had marginally higher dose-volume indices for the rectum V65Gy (0.8% ± 2.94%), but delivered a lower dose to the bladder (−1.06% ± 2.9% for bladder V65Gy). In addition, KBPP plans achieved lower hotspot (−0.67Gy ± 2.17Gy) and lower integral dose (−0.09Gy ± 0.3Gy) than the expert plans did. Moreover, the KBPP generated better plans that demonstrated slightly greater clinical target volume V95 (0.1% ± 0.68%) and lower homogeneity index (−1.13 ± 2.34). Conclusions The results demonstrated that robustly optimized IMPT plans created by the KBPP model are of high quality and are comparable to expert plans. Furthermore, the KBPP model can generate more-robust and more-homogenous plans compared with those of expert plans. More studies need to be done for the validation of the proton KBPP model at more-complicated treatment sites.

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