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Cancer Treatment Reviews Jul 2021Children and adolescents and young adults (AYAs) with cancer are often treated with a multidisciplinary approach. This includes use of radiotherapy, which is important... (Review)
Review
Children and adolescents and young adults (AYAs) with cancer are often treated with a multidisciplinary approach. This includes use of radiotherapy, which is important for local control, but may also cause adverse events in the long term, including second cancer. The risks for limited growth and development, endocrine dysfunction, reduced fertility and second cancer in children and AYAs are reduced by proton beam therapy (PBT), which has a dose distribution that decreases irradiation of normal organs while still targeting the tumor. To define the outcomes and characteristics of PBT in cancer treatment in pediatric and AYA patients, this document was developed by the Japanese Society for Radiation Oncology (JASTRO) and the Japanese Society of Pediatric Hematology/Oncology (JSPHO).
Topics: Adolescent; Adult; Child; Humans; Neoplasms; Practice Guidelines as Topic; Proton Therapy; Societies, Medical; Young Adult
PubMed: 33984606
DOI: 10.1016/j.ctrv.2021.102209 -
Physics in Medicine and Biology Apr 2015The physics of proton therapy has advanced considerably since it was proposed in 1946. Today analytical equations and numerical simulation methods are available to... (Review)
Review
The physics of proton therapy has advanced considerably since it was proposed in 1946. Today analytical equations and numerical simulation methods are available to predict and characterize many aspects of proton therapy. This article reviews the basic aspects of the physics of proton therapy, including proton interaction mechanisms, proton transport calculations, the determination of dose from therapeutic and stray radiations, and shielding design. The article discusses underlying processes as well as selected practical experimental and theoretical methods. We conclude by briefly speculating on possible future areas of research of relevance to the physics of proton therapy.
Topics: Humans; Proton Therapy; Protons; Radiation Dosage
PubMed: 25803097
DOI: 10.1088/0031-9155/60/8/R155 -
Chinese Clinical Oncology Aug 2016Proton beam radiotherapy of uveal melanoma and other malignant and benign ocular tumors has shown tremendous development and success over the past four decades. Proton... (Review)
Review
Proton beam radiotherapy of uveal melanoma and other malignant and benign ocular tumors has shown tremendous development and success over the past four decades. Proton beam is associated with the lowest overall risk of local tumor recurrence in uveal melanoma, compared with other eye-conserving forms of primary treatment. Proton beam is also utilized for other malignant and benign tumors as primary, salvage, or adjuvant treatment with combined modality therapy. The physical characteristics of proton therapy allows for uniform dose distribution, minimal scatter, and sharp dose fall off making it an ideal therapy for ocular tumors in which critical structures lay in close proximity to the tumor. High radiation doses can be delivered to tumors with relative sparing of adjacent tissues from collateral damage. Proton beam therapy for ocular tumors has resulted in overall excellent chances for tumor control, ocular conservation, and visual preservation.
Topics: Eye; Eye Neoplasms; Humans; Melanoma; Proton Therapy; Uveal Neoplasms
PubMed: 27558251
DOI: 10.21037/cco.2016.07.06 -
The British Journal of Radiology Mar 2020Range uncertainty is a much discussed topic in proton therapy. Although a very real aspect of proton therapy, its magnitude and consequences are sometimes misunderstood... (Review)
Review
Range uncertainty is a much discussed topic in proton therapy. Although a very real aspect of proton therapy, its magnitude and consequences are sometimes misunderstood or overestimated. In this article, the sources and consequences of range uncertainty are reviewed, a number of myths associated with the effect discussed with the aim of putting range uncertainty into clinical context and attempting to de-bunk some of the more exaggerated claims made as to its consequences.
Topics: Absorption, Radiation; Humans; Neoplasms, Radiation-Induced; Patient Positioning; Photons; Proton Therapy; Radiotherapy Dosage; Treatment Outcome; Uncertainty; Water
PubMed: 31778317
DOI: 10.1259/bjr.20190582 -
International Journal of Radiation... May 2016Radiation dose escalation has been shown to improve local control and survival in patients with non-small cell lung cancer in some studies, but randomized data have not... (Review)
Review
Radiation dose escalation has been shown to improve local control and survival in patients with non-small cell lung cancer in some studies, but randomized data have not supported this premise, possibly owing to adverse effects. Because of the physical characteristics of the Bragg peak, proton therapy (PT) delivers minimal exit dose distal to the target volume, resulting in better sparing of normal tissues in comparison to photon-based radiation therapy. This is particularly important for lung cancer given the proximity of the lung, heart, esophagus, major airways, large blood vessels, and spinal cord. However, PT is associated with more uncertainty because of the finite range of the proton beam and motion for thoracic cancers. PT is more costly than traditional photon therapy but may reduce side effects and toxicity-related hospitalization, which has its own associated cost. The cost of PT is decreasing over time because of reduced prices for the building, machine, maintenance, and overhead, as well as newer, shorter treatment programs. PT is improving rapidly as more research is performed particularly with the implementation of 4-dimensional computed tomography-based motion management and intensity modulated PT. Given these controversies, there is much debate in the oncology community about which patients with lung cancer benefit significantly from PT. The Particle Therapy Co-operative Group (PTCOG) Thoracic Subcommittee task group intends to address the issues of PT indications, advantages and limitations, cost-effectiveness, technology improvement, clinical trials, and future research directions. This consensus report can be used to guide clinical practice and indications for PT, insurance approval, and clinical or translational research directions.
Topics: Carcinoma, Non-Small-Cell Lung; Clinical Trials as Topic; Consensus; Humans; Lung Neoplasms; Movement; Organ Sparing Treatments; Organs at Risk; Proton Therapy; Radiation Injuries; Radiotherapy Planning, Computer-Assisted; Radiotherapy, Intensity-Modulated; Scattering, Radiation; Tumor Burden
PubMed: 27084663
DOI: 10.1016/j.ijrobp.2016.01.036 -
The British Journal of Radiology Sep 2015Proton radiography and tomography have long promised benefit for proton therapy. Their first suggestion was in the early 1960s and the first published proton radiographs... (Review)
Review
Proton radiography and tomography have long promised benefit for proton therapy. Their first suggestion was in the early 1960s and the first published proton radiographs and CT images appeared in the late 1960s and 1970s, respectively. More than just providing anatomical images, proton transmission imaging provides the potential for the more accurate estimation of stopping-power ratio inside a patient and hence improved treatment planning and verification. With the recent explosion in growth of clinical proton therapy facilities, the time is perhaps ripe for the imaging modality to come to the fore. Yet many technical challenges remain to be solved before proton CT scanners become commonplace in the clinic. Research and development in this field is currently more active than at any time with several prototype designs emerging. This review introduces the principles of proton radiography and tomography, their historical developments, the raft of modern prototype systems and the primary design issues.
Topics: Algorithms; History, 20th Century; History, 21st Century; Humans; Proton Therapy; Radiotherapy Planning, Computer-Assisted; Tomography, X-Ray Computed
PubMed: 26043157
DOI: 10.1259/bjr.20150134 -
Medical Physics Dec 2022Challenges in proton therapy include identifying patients most likely to benefit; ensuring consistent, high-quality plans as its adoption becomes more widespread; and...
PURPOSE
Challenges in proton therapy include identifying patients most likely to benefit; ensuring consistent, high-quality plans as its adoption becomes more widespread; and recognizing biological uncertainties that may be related to increased relative biologic effectiveness driven by linear energy transfer (LET). Knowledge-based planning (KBP) is a domain that may help to address all three.
METHODS
Artificial neural networks were trained using 117 unique treatment plans and associated dose and dose-weighted LET (LET ) distributions. The data set was split into training (n = 82), validation (n = 17), and test (n = 18) sets. Model performance was evaluated on the test set using dose- and LET -volume metrics in the clinical target volume (CTV) and nearby organs at risk and Dice similarity coefficients (DSC) comparing predicted and planned isodose lines at 50%, 75%, and 95% of the prescription dose.
RESULTS
Dose-volume metrics significantly differed (α = 0.05) between predicted and planned dose distributions in only one dose-volume metric, D to the CTV. The maximum observed root mean square (RMS) difference between corresponding metrics was 4.3 Gy (8% of prescription) for D to optic chiasm. DSC were 0.90, 0.93, and 0.88 for the 50%, 75%, and 95% isodose lines, respectively. LET -volume metrics significantly differed in all but one metric, L of the brainstem. The maximum observed difference in RMS differences for LET metrics was 1.0 keV/μm for L to brainstem.
CONCLUSIONS
We have devised the first three-dimensional dose and LET -prediction model for cranial proton radiation therapy has been developed. Dose accuracy compared favorably with that of previously published models in other treatment sites. The agreement in LET supports future investigations with biological doses in mind to enable the full potential of KBP in proton therapy.
Topics: Humans; Proton Therapy; Radiotherapy Dosage; Linear Energy Transfer; Radiotherapy Planning, Computer-Assisted; Relative Biological Effectiveness; Neural Networks, Computer
PubMed: 36227617
DOI: 10.1002/mp.16043 -
Acta Oncologica (Stockholm, Sweden) Nov 2017The relative biological effectiveness (RBE) for particle therapy is a complex function of particle type, radiation dose, linear energy transfer (LET), cell type,... (Review)
Review
The relative biological effectiveness (RBE) for particle therapy is a complex function of particle type, radiation dose, linear energy transfer (LET), cell type, endpoint, etc. In the clinical practice of proton therapy, the RBE is assumed to have a fixed value of 1.1. This assumption, along with the effects of physical uncertainties, may mean that the biologically effective dose distributions received by the patient may be significantly different from what is seen on treatment plans. This may contribute to unforeseen toxicities and/or failure to control the disease. Variability of Proton RBE: It has been shown experimentally that proton RBE varies significantly along the beam path, especially near the end of the particle range. While there is now an increasing acceptance that proton RBE is variable, there is an ongoing debate about whether to change the current clinical practice. Clinical Evidence: A rationale against the change is the uncertainty in the models of variable RBE. Secondly, so far there is no clear clinical evidence of the harm of assuming proton RBE to be 1.1. It is conceivable, however, that the evidence is masked partially by physical uncertainties. It is, therefore, plausible that reduction in uncertainties and their incorporation in the estimation of dose actually delivered may isolate and reveal the variability of RBE in clinical practice. Nevertheless, clinical evidence of RBE variability is slowly emerging as more patients are treated with protons and their response data are analyzed. Modelling and Incorporation of RBE in the Optimization of Proton Therapy: The improvement in the knowledge of RBE could lead to better understanding of outcomes of proton therapy and in the improvement of models to predict RBE. Prospectively, the incorporation of such models in the optimization of intensity-modulated proton therapy could lead to improvements in the therapeutic ratio of proton therapy.
Topics: Humans; Neoplasms; Proton Therapy; Radiobiology
PubMed: 28826292
DOI: 10.1080/0284186X.2017.1348621 -
Chinese Clinical Oncology Apr 2016The treatment of nasopharyngeal carcinoma (NPC) has traditionally included a multimodality approach including radiotherapy (RT) and systemic chemotherapy. RT has long... (Review)
Review
The treatment of nasopharyngeal carcinoma (NPC) has traditionally included a multimodality approach including radiotherapy (RT) and systemic chemotherapy. RT has long been favored as the mainstay of local treatment for disease in this challenging anatomic location owing to the morbidity of extensive surgical resection in the nasopharynx. However, NPC presents a unique treatment challenge for radiation oncologists because such tumors typically involve complex anatomic structures near several critical organ structures such as the brainstem, spinal cord, temporal lobes, salivary glands, cochleae, oral cavity, mandible and optic structures. Thus, radiation is not without toxicity, and critical organs in these areas clearly benefit from the use of conformal and precise treatment delivery. The unique physical properties of proton radiotherapy (PRT) make it especially well-suited for treating tumors in this anatomically complex area and offer promising potential for acute and chronic toxicity reduction while maintaining excellent disease control.
Topics: Carcinoma; Humans; Immobilization; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Proton Therapy; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted; Treatment Outcome
PubMed: 27121885
DOI: 10.21037/cco.2016.03.05 -
Radiation Oncology (London, England) Dec 2021This study presents an analysis (efficacy and toxicity) of outcomes in patients with skull-base chordomas or chondrosarcomas treated with a fixed horizontal pencil...
AIM
This study presents an analysis (efficacy and toxicity) of outcomes in patients with skull-base chordomas or chondrosarcomas treated with a fixed horizontal pencil proton beam.
BACKGROUND
Chordomas (CAs) and chondrosarcomas (CSAs) are rare tumours that are usually located near the base of the skull and very close to the brain's most critical structures. Proton therapy (PT) is often considered the best radiation treatment for these diseases, but it is still a limited resource. Active scanning PT delivered via a fixed pencil beamline might be a promising option.
METHODS
This is a single-centre experience describing the results of proton therapy for 31 patients with CA (n = 23) or CSA (n = 8) located near the base of the skull. Proton therapy was utilized by a fixed pencil beamline with a chair to position the patient between May 2016 and November 2020. Ten patients underwent resection (32.2%), 15 patients (48.4%) underwent R2 resection, and 6 patients had unresectable tumours (19.4%). In 4 cases, the tumours had been previously irradiated. The median PT dose was 70 GyRBE (relative biological efficacy, 1.1) [range, 60 to 74] with 2.0 GyRBE per fraction. The mean GTV volume was 25.6 cm [range, 4.2-115.6]. Patient demographics, pathology, treatment parameters, and toxicity were collected and analysed. Radiation-induced reactions were assessed according to the Common Terminology Criteria for Adverse Events (CTCAE) v 4.0.
RESULTS
The median follow-up time was 21 months [range, 4 to 52]. The median overall survival (OS) was 40 months. The 1- and 2-year OS was 100%, and the 3-year OS was 66.3%. Four patients died due to non-cancer-related reasons, 1 patient died due to tumour progression, and 1 patient died due to treatment-related injuries. The 1-year local control (LC) rate was 100%, the 2-year LC rate was 93.7%, and the 3-year LC rate was 85.3%. Two patients with CSA exhibited progression in the neck lymph nodes and lungs. All patients tolerated PT well without any treatment interruptions. We observed 2 cases of ≥ grade 3 toxicity, with 1 case of grade 3 myelitis and 1 case of grade 5 brainstem injury.
CONCLUSION
Treatment with a fixed proton beam shows promising disease control and an acceptable toxicity rate, even the difficult-to-treat subpopulation of patients with skull-base chordomas or chondrosarcomas requiring dose escalation.
Topics: Adult; Aged; Chondrosarcoma; Chordoma; Female; Humans; Male; Middle Aged; Organs at Risk; Proton Therapy; Radiotherapy Dosage; Radiotherapy, Intensity-Modulated; Skull Base Neoplasms
PubMed: 34930352
DOI: 10.1186/s13014-021-01961-9