Proton Beam Therapy for Pediatric Malignancies

Doyle-Lindrud, Susan

doi:10.1188/15.cjon.521-523

Cited by 3 publications

(3 citation statements)

References 13 publications

(24 reference statements)

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“…Proton beam therapy is a globally emerging cancer treatment modality which utilises highly energetic positively charged particles to kill the cancer cells [25]. About fifty years after the discovery of X-rays, Robert Wilson, a physicist and the first director of Fermilab, proposed the use of protons for cancer treatment in 1946.…”

Section: History and Principle Of Proton Beam Therapymentioning

confidence: 99%

“…Therefore, it is taking longer to have widely-available proton beam therapy centers. However, it has specifically gained attention of media and patients in the last 8 years [25,29] and a number of hospitalbased proton therapy facilities are now available worldwide. As of July 2017, there were 75 particle therapy centers at international level, with 41 others under construction [30].…”

Section: History and Principle Of Proton Beam Therapymentioning

confidence: 99%

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Range uncertainty and dose uniformity in proton therapy in the presence of inhomogeneities in tissue and phantom materials

Nazir¹

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Proton therapy is an emerging modality for providing radiation treatment to cancer pa-tients. The principal advantages of proton therapy are the reduced total dose deposited into the patient as compared to conventional photon therapy and the finite range of the proton beam. It is considered as a more favorable option for optimum treatment outcomes in terms of maximising tumor control probability and minimising normal tissue complications. The depth dose distribution of the proton beam adds an additional degree of freedom to treat-ment planning. The range in tissue is associated with substantial uncertainties triggered by imaging, patient set-up, beam delivery and dose calculations. Therefore, reduction in uncer-tainties would allow to minimise the treatment volume and thus allow a better usage of the protons. However, the presence of sub-millimeter sized heterogeneities, such is pronounced in trabecular bone and lung parenchyma, in the path of the proton beam can cause the Bragg peak degradation with a widening to the distal fall-o˙. Additionally, the restricted resolution of a classic CT scan used in treatment planning cannot fully resolve such fine structures, potentially leading to inaccuracy in determination of the range.This work aims to investigate the presence of range uncertainties in proton therapy beams when they penetrate through the sub-millimeter sized heterogeneities. The e˙ect of Bragg peak degradation has been demonstrated in bone models with the FLUKA Monte Carlo code and experimental measurements with a 36 MeV proton beam. The bone-substitute material, SAWBONES®, ranging in density from 0.088 to 0.48 g/cc, was used to simulate bone heterogeneities. Micro-CT images were obtained of the SAWBONES® material and used to construct Monte Carlo models of realistic proton radiotherapy treatments and to benchmark experimental studies. Broadening of the Bragg peak and shifts in the range, as defined by the d20% depth-dose parameter were observed both experimentally and in Monte Carlo models, indicating that such e˙ects are in principle, clinically relevant in certain circumstances.Furthermore, a FLUKA Monte Carlo model is benchmarked against the Eclipse treatment planning system (TPS) golden data for proton beam therapy. This project is designed to obtain the proton dose distributions from TPS for a 10 ×10 × 10 cm3 water-filled box. A Monte Carlo analytical model is developed by utilising the information from the TPS to recalculate the dose distribution which are then compared to find any di˙erences (if present) for di˙erent phantom materials. Due to the lack of any experimental information to measure the normalized depth dose as a function of energy, considering the general behaviour of a monitor chamber, it has been assumed that the treatment planning system has a built-in relationship between the monitor units (MU) and dose delivered. A mathematical formula is developed to find the relationship between monitor units (MU) and dose (E). MU α 1/Ea.The value of a is varied from 0 to 1. It has been observed that the beam non-uniformity calculated by using the relationship " MU = E−0.5 " is only 0.15 % for water and 0.43 % for graphite. This non-uniformity in graphite is not severe and it is actually clinically acceptable. This modeling has suggested that the planned dose distributions for water can also be replaced by graphite to a reasonably acceptable standard.

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Section: History and Principle Of Proton Beam Therapymentioning

confidence: 99%

Section: History and Principle Of Proton Beam Therapymentioning

confidence: 99%

Range uncertainty and dose uniformity in proton therapy in the presence of inhomogeneities in tissue and phantom materials

Nazir¹

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“…The notion of using high energy positive charge particles to treat cancer patients was introduced in 1946 (83). The first treatment using protons took place in Berkeley National Laboratory in 1954 (84).…”

Section: Proton Therapymentioning

confidence: 99%

Monte Carlo Modelling for Photon and Proton Therapy in Heterogenous Tissue and Prosthesis Material

Abbas

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Treatment outcomes in radiotherapy can be improved by reducing uncertainties in patient set-up, beam delivery and dose distribution. Clarification of arrangements can minimize the dose distributed to normal tissues, and facilitate dose escalation. However, heterogeneity can increase any ambiguities associated with dose distribution. The treatment planning system (TPS) cannot effectively calculate dose distribution in complex heterogeneous areas, which increases uncertainty. This research aims to study microscopic dose distribution in temporal bone, cochlea and pancreatic stents as applicable to modern radiotherapy treatments. To achieve this aim a multiscale approach will be used, as it provides essential information about differences in dose distribution between TPS/clinical CT and Monte Carlo (MC)/Micro CT for photons and protons.In the first part of this study, two DICOM series of pancreatic cancer patients were used with an inserted stent. A new model includes the atomic composition of the stent material, and new stent contouring was introduced to overcome a CT artefact. A PRIMO Monte Carlo model was tuned and compared with the TPS dose distribution and a one-beam volume-modulated arc therapy (VMAT) plan was created. A significant dose difference was observed when comparing the new model and TPS, suggesting increased uncertainty of the dose distribution in clinical practice.An open-access DICOM format of the data for the resected temporal bone and cochlea tissue was used with the FLUKA MC code to imitate potential high-dose scenarios associated with VMAT using the FLOOD option. Twenty-three photon and proton energy levels ranging from 0.055 to 5.5 MeV for photons and 37.59 to 124.83 MeV for protons were simulated separately to calculate dose distribution. Micro CT data shows three density levels in the temporal bone and cochlea. The photon distribution in the low energy range 0.055-0.09 MeV, the largest proportion of the dose (48.8%) was deposited within high-density bone, whereas above 0.125 MeV, the change on dose distribution started to occur where there was greater deposition in low-density tissue, reaching 53%. The dose distribution in the soft bone's intermediate density was 26.4% at 0.07 MeV and dropped to 19.7% at 2.5 MeV. There is a 29% percentage difference in dose distribution on the soft bone between the low and high energy. The dose distribution did not change significantly in proton between the low, intermediate and high-density areas. The dose distribution in 37.59 MeV shows 54.86% in low density, 19.75% in intermediate density and 25.39% in high density. A similar outcome was observed in high energy 124.83 MeV, a dose distribution was 54.21% in low density, 19.79% intermediate density and 26% in high density.An advanced model was created to connect the results to a clinical routine when treating brain tumours using the VMAT technique. Cases were selected from 280 data sets of patients diagnosis with gliomas. Eleven different scenarios were identified. The advanced model shows five cases with a...

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The Evolution of Radiation Therapy in Treating Cancer

Abshire¹,

Lang²

2018

Seminars in Oncology Nursing

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Proton Beam Therapy for Pediatric Malignancies

Cited by 3 publications

References 13 publications

Range uncertainty and dose uniformity in proton therapy in the presence of inhomogeneities in tissue and phantom materials

Range uncertainty and dose uniformity in proton therapy in the presence of inhomogeneities in tissue and phantom materials

Monte Carlo Modelling for Photon and Proton Therapy in Heterogenous Tissue and Prosthesis Material

The Evolution of Radiation Therapy in Treating Cancer

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