Tissue Compensators Made of Solid Water or Lead for Megavoltage X-ray Radiotherapy

Constantinou, Christos E.; Harrington, James C.

doi:10.1016/0958-3947(89)90137-4

Cited by 9 publications

(10 citation statements)

References 8 publications

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“…In this section, the calibration from CT Hounsfield units to relative electron densities, using tissue equivalent samples, will be described. To obtain this relationship we have calculated the relative electron densities of various tissue substitutes (ICRU 1989, Constantinou 1974) taking into account their chemical composition (tables 1 and 3) using ρ e = ρN g /ρ water N water g…”

Section: Calibration Of Ct Numbersmentioning

confidence: 99%

The calibration of CT Hounsfield units for radiotherapy treatment planning

1996

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Computer tomographic (CT) scans are used to correct for tissue inhomogeneities in radiotherapy treatment planning. In order to guarantee a precise treatment, it is important to obtain the relationship between CT Hounsfield units and electron densities (or proton stopping powers for proton radiotherapy), which is the basic input for radiotherapy planning systems which consider tissue heterogeneities. A method is described to determine improved CT calibrations for biological tissue (a stoichiometric calibration) based on measurements using tissue equivalent materials. The precision of this stoichiometric calibration and the more usual tissue substitute calibration is determined by a comparison of calculated proton radiographic images based on these calibrations and measured radiographs of a biological sample. It has been found that the stoichiometric calibration is more precise than the tissue substitute calibration.

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Section: Calibration Of Ct Numbersmentioning

confidence: 99%

The calibration of CT Hounsfield units for radiotherapy treatment planning

1996

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“…Compensator devices are fabricated using the moulding and casting process followed by milling, utilising solid water [51], lead [52], tungsten [53], or woods metal (cerrobend) [54] materials for megavoltage x-ray radiotherapy. Similar to wedge filters, these devices are attached close to the primary beam to attenuate beam dose with insignificant effects towards dose scattering within the patient [55].…”

Section: Compensatorsmentioning

confidence: 99%

Additive manufacturing in radiation oncology: a review of clinical practice, emerging trends and research opportunities

Tino

Leary

Yeo

et al. 2020

Int. J. Extrem. Manuf.

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The additive manufacturing (AM) process plays an important role in enabling cross-disciplinary research in engineering and personalised medicine. Commercially available clinical tools currently utilised in radiotherapy are typically based on traditional manufacturing processes, often leading to non-conformal geometries, time-consuming manufacturing process and high costs. An emerging application explores the design and development of patient-specific clinical tools using AM to optimise treatment outcomes among cancer patients receiving radiation therapy. In this review, we: • highlight the key advantages of AM in radiotherapy where rapid prototyping allows for patient-specific manufacture • explore common clinical workflows involving radiotherapy tools such as bolus, compensators, anthropomorphic phantoms, immobilisers, and brachytherapy moulds; and • investigate how current AM processes are exploited by researchers to achieve patient tissue-like imaging and dose attenuations. Finally, significant AM research opportunities in this space are highlighted for their future advancements in radiotherapy for diagnostic and clinical research applications.

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“…26,27 Within the last decade, a number of studies have investigated the use of AM technologies to produce customized patient-specific RPs using different types of in-house and commercially available AM materials including thermoplastics and photopolymer resins. [28][29][30][31][32] To emulate patient-like geometry, it is essential to achieve heterogeneity in terms of electron density, which is often defined by Hounsfield units (HU) in CT imaging 33 ; common methods to vary the density during AM process include controlling the standard Fused Deposition Modelling (FDM) printing parameters such as infilling percentage, infilling pattern, printing temperature, and material extrusion rate. 34 Other methods to increase achievable HU values involve AM material content doping.…”

Section: Introductionmentioning

confidence: 99%

A Systematic Review on 3D-Printed Imaging and Dosimetry Phantoms in Radiation Therapy

Tino

Yeo

Leary

et al. 2019

Technol Cancer Res Treat

109

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Introduction: Additive manufacturing or 3-dimensional printing has become a widespread technology with many applications in medicine. We have conducted a systematic review of its application in radiation oncology with a particular emphasis on the creation of phantoms for image quality assessment and radiation dosimetry. Traditionally used phantoms for quality assurance in radiotherapy are often constraint by simplified geometry and homogenous nature to perform imaging analysis or pretreatment dosimetric verification. Such phantoms are limited due to their ability in only representing the average human body, not only in proportion and radiation properties but also do not accommodate pathological features. These limiting factors restrict the patient-specific quality assurance process to verify image-guided positioning accuracy and/or dose accuracy in “water-like” condition. Methods and Results: English speaking manuscripts published since 2008 were searched in 5 databases (Google Scholar, Scopus, PubMed, IEEE Xplore, and Web of Science). A significant increase in publications over the 10 years was observed with imaging and dosimetry phantoms about the same total number (52 vs 50). Key features of additive manufacturing are the customization with creation of realistic pathology as well as the ability to vary density and as such contrast. Commonly used printing materials, such as polylactic acid, acrylonitrile butadiene styrene, high-impact polystyrene and many more, are utilized to achieve a wide range of achievable X-ray attenuation values from −1000 HU to 500 HU and higher. Not surprisingly, multimaterial printing using the polymer jetting technology is emerging as an important printing process with its ability to create heterogeneous phantoms for dosimetry in radiotherapy. Conclusion: Given the flexibility and increasing availability and low cost of additive manufacturing, it can be expected that its applications for radiation medicine will continue to increase.

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Tissue Compensators Made of Solid Water or Lead for Megavoltage X-ray Radiotherapy

Cited by 9 publications

References 8 publications

The calibration of CT Hounsfield units for radiotherapy treatment planning

The calibration of CT Hounsfield units for radiotherapy treatment planning

Additive manufacturing in radiation oncology: a review of clinical practice, emerging trends and research opportunities

A Systematic Review on 3D-Printed Imaging and Dosimetry Phantoms in Radiation Therapy

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