Spatial distribution of bremsstrahlung in a dual electron beam used in total skin electron treatments: Errors due to ionization chamber cable irradiation

Das, Indra J.; Copeland, J.F.; Bushe, Harry

doi:10.1118/1.597215

Cited by 18 publications

(28 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As such, great effort needs to be taken to either shield the cable from the electron beam or otherwise reduce the amount of cabling exposed to radiation. 198 Ongoing quality assurance may be accomplished through a simplified setup, e.g., with a lateral gantry setting to perform routine constancy with an appropriate dosimeter and phantom. A large volume ion chamber can be useful for daily constancy checks, since polarity effects are greatly reduced.…”

Section: Viiik5 Quality Assurancementioning

confidence: 99%

Recommendations for clinical electron beam dosimetry: Supplement to the recommendations of Task Group 25

et al. 2009

View full text Add to dashboard Cite

The goal of Task Group 25 (TG-25) of the Radiation Therapy Committee of the American Association of.Physicists in Medicine (AAPM) was to provide a methodology and set of procedures for a medical physicist performing clinical electron beam dosimetry in the nominal energy range of 5-25 MeV. Specifically, the task group recommended procedures for acquiring basic information required for acceptance testing and treatment planning of new accelerators with therapeutic electron beams. Since the publication of the TG-25 report, significant advances have taken place in the field of electron beam dosimetry, the most significant being that primary standards laboratories around the world have shifted from calibration standards based on exposure or air kerma to standards based on absorbed dose to water. The AAPM has published a new calibration protocol, TG-51, for the calibration of high-energy photon and electron beams. The formalism and dosimetry procedures recommended in this protocol are based on the absorbed dose to water calibration coefficient of an ionization chamber at 60Co energy, N60Co(D,w), together with the theoretical beam quality conversion coefficient k(Q) for the determination of absorbed dose to water in high-energy photon and electron beams. Task Group 70 was charged to reassess and update the recommendations in TG-25 to bring them into alignment with report TG-51 and to recommend new methodologies and procedures that would allow the practicing medical physicist to initiate and continue a high quality program in clinical electron beam dosimetry. This TG-70 report is a supplement to the TG-25 report and enhances the TG-25 report by including new topics and topics that were not covered in depth in the TG-25 report. These topics include procedures for obtaining data to commission a treatment planning computer, determining dose in irregularly shaped electron fields, and commissioning of sophisticated special procedures using high-energy electron beams. The use of radiochromic film for electrons is addressed, and radiographic film that is no longer available has been replaced by film that is available. Realistic stopping-power data are incorporated when appropriate along with enhanced tables of electron fluence data. A larger list of clinical applications of electron beams is included in the full TG-70 report available at http://www.aapm.org/pubs/reports. Descriptions of the techniques in the clinical sections are not exhaustive but do describe key elements of the procedures and how to initiate these programs in the clinic. There have been no major changes since the TG-25 report relating to flatness and symmetry, surface dose, use of thermoluminescent dosimeters or diodes, virtual source position designation, air gap corrections, oblique incidence, or corrections for inhomogeneities. Thus these topics are not addressed in the TG-70 report.

show abstract

Section: Viiik5 Quality Assurancementioning

confidence: 99%

Recommendations for clinical electron beam dosimetry: Supplement to the recommendations of Task Group 25

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Figure 5 shows the effect of cable length in the radiation beam for various types of cables from different manufacturers. The amount of cable in the beam could be a serious matter in electron beam which was discussed by Das et al 86 Special precaution is needed when large amount of cable is kept in the radiation beam. Prior to scanning, one should inspect the cable length for kinks and nicks in the jacket, particularly the length near the detector where it will be submerged.…”

Section: Iiia2 Cables Connectors and Adaptersmentioning

confidence: 99%

Accelerator beam data commissioning equipment and procedures: Report of the TG‐106 of the Therapy Physics Committee of the AAPM

Das

Cheng

Watts³

et al. 2008

Medical Physics

Self Cite

422

424

View full text Add to dashboard Cite

For commissioning a linear accelerator for clinical use, medical physicists are faced with many challenges including the need for precision, a variety of testing methods, data validation, the lack of standards, and time constraints. Since commissioning beam data are treated as a reference and ultimately used by treatment planning systems, it is vitally important that the collected data are of the highest quality to avoid dosimetric and patient treatment errors that may subsequently lead to a poor radiation outcome. Beam data commissioning should be performed with appropriate knowledge and proper tools and should be independent of the person collecting the data. To achieve this goal, Task Group 106 (TG-106) of the Therapy Physics Committee of the American Association of Physicists in Medicine was formed to review the practical aspects as well as the physics of linear accelerator commissioning. The report provides guidelines and recommendations on the proper selection of phantoms and detectors, setting up of a phantom for data acquisition (both scanning and no-scanning data), procedures for acquiring specific photon and electron beam parameters and methods to reduce measurement errors (<1%), beam data processing and detector size convolution for accurate profiles. The TG-106 also provides a brief.discussion on the emerging trend in Monte Carlo simulation techniques in photon and electron beam commissioning. The procedures described in this report should assist a qualified medical physicist in either measuring a complete set of beam data, or in verifying a subset of data before initial use or for periodic quality assurance measurements. By combining practical experience with theoretical discussion, this document sets a new standard for beam data commissioning.

show abstract

“…During the profile measurements, care should be taken of the currents created in the chamber cable, connector, and extension cable. (12,13,14,15) For electron fields, the cable effect is directly proportional with the irradiated cable length and leakage current predominates. (13) At each measurement point the readouts taken with positive and negative chamber polarity have been averaged.…”

Section: B Moving Gantry Methodsmentioning

confidence: 99%

Moving gantry method for electron beam dose profile measurement at extended source‐to‐surface distances

Faludi

Fodor

Pesznyák

2015

J Applied Clin Med Phys

View full text Add to dashboard Cite

A novel method has been put forward for very large electron beam profile measurement. With this method, absorbed dose profiles can be measured at any depth in a solid phantom for total skin electron therapy. Electron beam dose profiles were collected with two different methods. Profile measurements were performed at 0.2 and 1.2 cm depths with a parallel plate and a thimble chamber, respectively. 108 cm×108 cm and 45 cm×45 cm projected size electron beams were scanned by vertically moving phantom and detector at 300 cm source‐to‐surface distance with 90° and 270° gantry angles. The profiles collected this way were used as reference. Afterwards, the phantom was fixed on the central axis and the gantry was rotated with certain angular steps. After applying correction for the different source‐to‐detector distances and incidence of angle, the profiles measured in the two different setups were compared. Correction formalism has been developed. The agreement between the cross profiles taken at the depth of maximum dose with the ‘classical’ scanning and with the new moving gantry method was better than 0.5 % in the measuring range from zero to 71.9 cm. Inverse square and attenuation corrections had to be applied. The profiles measured with the parallel plate chamber agree better than 1%, except for the penumbra region, where the maximum difference is 1.5%. With the moving gantry method, very large electron field profiles can be measured at any depth in a solid phantom with high accuracy and reproducibility and with much less time per step. No special instrumentation is needed. The method can be used for commissioning of very large electron beams for computer‐assisted treatment planning, for designing beam modifiers to improve dose uniformity, and for verification of computed dose profiles.PACS numbers: 87.53.Bn, 87.53.Jw, 87.56.jf

show abstract

Spatial distribution of bremsstrahlung in a dual electron beam used in total skin electron treatments: Errors due to ionization chamber cable irradiation

Cited by 18 publications

References 0 publications

Recommendations for clinical electron beam dosimetry: Supplement to the recommendations of Task Group 25

Recommendations for clinical electron beam dosimetry: Supplement to the recommendations of Task Group 25

Accelerator beam data commissioning equipment and procedures: Report of the TG‐106 of the Therapy Physics Committee of the AAPM

Moving gantry method for electron beam dose profile measurement at extended source‐to‐surface distances

Contact Info

Product

Resources

About