The water‐equivalence of phantom materials  beta particles

Buckley, Lesley; Thomadsen, Bruce R.; DeWerd, Larry A.

doi:10.1118/1.1376176

Cited by 10 publications

(5 citation statements)

References 10 publications

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“…The addition of calcium and chlorine is intended to increase the scattering power, which would be lower than water due to the high carbon content, without significantly affecting the stopping power. The only data in the literature on Virtual Water™ are from Buckley et al 18 who investigated the material for Sr-90 brachytherapy applications. However, it would appear that Virtual Water™ was used due to its availability rather than because it had been designed for such low energy electrons.…”

Section: Epoxy-resin Materialsmentioning

confidence: 99%

Characterization of the phantom material Virtual Water™ in high‐energy photon and electron beams

McEwen

Niven

2006

Medical Physics

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The material Virtual Water has been characterized in photon and electron beams. Range-scaling factors and fluence correction factors were obtained, the latter with an uncertainty of around 0.2%. This level of uncertainty means that it may be possible to perform dosimetry in a solid phantom with an accuracy approaching that of measurements in water. Two formulations of Virtual Water were investigated with nominally the same elemental composition but differing densities. For photon beams neither formulation showed exact water equivalence-the water/Virtual Water dose ratio varied with the depth of measurement with a difference of over 1% at 10 cm depth. However, by using a density (range) scaling factor very good agreement (<0.2%) between water and Virtual Water at all depths was obtained. In the case of electron beams a range-scaling factor was also required to match the shapes of the depth dose curves in water and Virtual Water. However, there remained a difference in the measured fluence in the two phantoms after this scaling factor had been applied. For measurements around the peak of the depth-dose curve and the reference depth this difference showed some small energy dependence but was in the range 0.1%-0.4%. Perturbation measurements have indicated that small slabs of material upstream of a detector have a small (<0.1% effect) on the chamber reading but material behind the detector can have a larger effect. This has consequences for the design of experiments and in the comparison of measurements and Monte Carlo-derived values.

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Section: Epoxy-resin Materialsmentioning

confidence: 99%

Characterization of the phantom material Virtual Water™ in high‐energy photon and electron beams

McEwen

Niven

2006

Medical Physics

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“…The first medical products to show significant results in a clinical trial for the reduction in in-stent restenosis following balloon angioplasty were intravascular brachytherapy sources, although they were eventually superseded to a great extent by drug-eluting stents. During the development stages of IVBT, the radiation sources used in the coronary vessel clinical trials included seed trains ͑with 16,17 and without [18][19][20][21][22] interseed spacing͒, wires, 23-37 radioactive stents, [38][39][40] radioactive liquid filled balloons, 41-43 radioactive gas filled balloons, 44 and balloons impregnated with radioactivity. 45,46 In addition there were peripheral vascular trials 47 using a HDR…”

Section: Viia1 Backgroundmentioning

confidence: 99%

Off‐label use of medical products in radiation therapy: Summary of the Report of AAPM Task Group No. 121a)

et al. 2010

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Medical products (devices, drugs, or biologics) contain information in their labeling regarding the manner in which the manufacturer has determined that the products can be used in a safe and effective manner. The Food and Drug Administration (FDA) approves medical products for use for these specific indications which are part of the medical product's labeling. When medical products are used in a manner not specified in the labeling, it is commonly referred to as off‐label use. The practice of medicine allows for this off‐label use to treat individual patients, but the ethical and legal implications for such unapproved use can be confusing. Although the responsibility and, ultimately, the liability for off‐label use often rests with the prescribing physician, medical physicists and others are also responsible for the safe and proper use of the medical products. When these products are used for purposes other than which they were approved, it is important for medical physicists to understand their responsibilities. In the United States, medical products can only be marketed if officially cleared, approved, or licensed by the FDA; they can be used if they are not subject to or specifically exempt from FDA regulations, or if they are being used in research with the appropriate regulatory safeguards. Medical devices are either cleared or approved by FDA's Center for Devices and Radiological Health. Drugs are approved by FDA's Center for Drug Evaluation and Research, and biological products such as vaccines or blood are licensed under a biologics license agreement by FDA's Center for Biologics Evaluation and Research. For the purpose of this report, the process by which the FDA eventually clears, approves, or licenses such products for marketing in the United States will be referred to as approval. This report summarizes the various ways medical products, primarily medical devices, can legally be brought to market in the United States, and includes a discussion of the approval process, along with manufacturers’ responsibilities, labeling, marketing and promotion, and off‐label use. This is an educational and descriptive report and does not contain prescriptive recommendations. This report addresses the role of the medical physicist in clinical situations involving off‐label use. Case studies in radiation therapy are presented. Any mention of commercial products is for identification only; it does not imply recom‐mendations or endorsements of any of the authors or the AAPM. The full report, containing extensive background on off‐label use with several appendices, is available on the AAPM website (http://www.aapm.org/pubs/reports/).

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“…Radiochromic film provides an even lower speed, effectively eliminating the problem of source motion complicating the analysis of the film. When used in a tissue-equivalent phantom, radiochromic film can yield dose information, but requires care in the selecting of the phantom, 9 handling the film, 10 and analyzing the result.…”

Section: Dosimetry Accuracymentioning

confidence: 99%

A quality management program in intravascular brachytherapy

Chakri

Thomadsen

2002

Medical Physics

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While simple, intravascular brachytherapy ͑IVB͒ presents a considerable potential for harm to the patient. The medical physicist maintains the responsibility to minimize the likelihood of operational problems or dosimetric errors. The principals for safe operation remain the same as with any radiotherapy treatment: to deliver the correct dose, to the correct location, safety. To develop an effective and comprehensive quality management ͑QM͒ program for IVB, a physicist should utilize proven risk assessment techniques rather than simply thinking of things to check, and follow guidances such as ISO9001:2000. The proposed QM program includes the following: Procedures designed to assure the safety of the patient: Identification of the patient; tests of the integrity and patency for the delivery catheter, operation of the source train, and patency of the catheter in the treatment position; a check for recovery preparations; and verification of source recovery. Procedures to assure positional accuracy of the treatment: Verification of the positioning the catheter in the artery and of the sources in the catheter. Procedures to assure dosimetry accuracy: Acceptance testing of the device, including verification of the source strength and uniformity, and of the treatment duration tables; verification of the treatment prescription and duration for each patient; and control measures that minimize the likelihood of errors removing the source at the correct time.

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The water‐equivalence of phantom materials beta particles

Cited by 10 publications

References 10 publications

Characterization of the phantom material Virtual Water™ in high‐energy photon and electron beams

Characterization of the phantom material Virtual Water™ in high‐energy photon and electron beams

Off‐label use of medical products in radiation therapy: Summary of the Report of AAPM Task Group No. 121a)

A quality management program in intravascular brachytherapy

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