Film dosimetry of clinical electron beams

Battum, L.J. van; Huizenga, H.

doi:10.1016/0360-3016(90)90269-p

Cited by 29 publications

(10 citation statements)

References 11 publications

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“…Therefore several methods are being developed to measure the dose in many points simultaneously, preferably in two or three dimensions. Examples of presently considered methods are: a linear array of diodes 2 ͑1D͒, film, 3 and electronic portal imaging systems 4 ͑2D͒, and MRI gel dosimetry 5,6 ͑3D͒.…”

Section: Introductionmentioning

confidence: 99%

Fast 2D phantom dosimetry for scanning proton beams

et al. 1998

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A quality control system especially designed for dosimetry in scanning proton beams has been designed and tested. The system consists of a scintillating screen (Gd2O2S:Tb), mounted at the beam-exit side of a phantom, and observed by a low noise CCD camera with a long integration time. The purpose of the instrument is to make a fast and accurate two-dimensional image of the dose distribution at the screen position in the phantom. The linearity of the signal with the dose, the noise in the signal, the influence of the ionization density on the signal, and the influence of the field size on the signal have been investigated. The spatial resolution is 1.3 mm (1 s.d.), which is sufficiently smaller than typical penumbras in dose distributions. The measured yield depends linearly on the dose and agrees within 5% with the calculations. In the images a signal to noise ration (signal/1 s.d.) of 10(2) has been found, which is in the same order of magnitude as expected from the calculations. At locations in the dose distribution possessing a strong contribution of high ionization densities (i.e., in the Bragg peak), we found some quenching of the light output, which can be described well by existing models if the beam characteristics are known. For clinically used beam characteristics such as a Spread Out Bragg peak, there is at most 8% deviation from the NACP ionization chamber measurements. The conclusion is that this instrument is a useful tool for quick and reliable quality control of proton beams. The long integration-time capabilities of the system make it worthwhile to investigate its applicability in scanning proton beams and other dynamic treatment modalities.

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Section: Introductionmentioning

confidence: 99%

Fast 2D phantom dosimetry for scanning proton beams

et al. 1998

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“…These differences are markedly larger than the values mentioned by some groups, 8,21 but in agreement with the strong dependence of shape of sensitivity curves on the production batch, as reported by others. 12,22 This difference in observation with II. Differences in optical density OD, for a dose of 50 cGy, of films for different institutions.…”

Section: A Batch Compositionmentioning

confidence: 85%

Interinstitutional variations of sensitometric curves of radiographic dosimetric films

Bos¹,

Danciu²,

Cheng³

et al. 2002

Medical Physics

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Depth and field size dependence of the sensitometric curves of radiographic films have been studied by various groups. Limited information is, however, available on the magnitude of the variations in sensitometric curves applied in clinical practice in different institutions. In this study we assessed in a systematic way the effect of the various parameters influencing the shape of the sensitometric curve: batch composition, irradiation conditions, film processing, and film scanning. Two types of film, Kodak X-Omat V and CEA TVS, were irradiated, processed, and analyzed in three different institutions. The interinstitutional variation of the sensitometric curves, expressed as the OD variation at 50 cGy, can be up to 32% and is mainly caused by differences in film processing and to a lesser degree to differences in batch composition, film scanning, and irradiation conditions. For the Kodak films, the average OD difference at 50 cGy between the three institutions is 17% as a result of differences in batch composition and 25% due to differences in processing conditions. For the CEA films these data are 6% and 24%, respectively. The long-term variation of the sensitometric curves of KODAK films in one institution was smaller than the differences in batch composition between the three institutions. The sensitometric curves of CEA films showed in one institution a large variation with time; the shape gradually varied from sigmoidal to quasilinear. By using relative OD values rather than absolute OD values, variations in sensitometric curves of KODAK films can be reduced to 2%. Consequently, one sensitometric curve is sufficient to derive relative dose values. If processing conditions are well controlled, it might therefore be advantageous to determine the absolute OD only at one or two dose values, in combination with a "universal" relative sensitometric curve.

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“…The choice of this dosimeter was due to the impossibility of using the ionization chamber for absolute measurements [1] owing to the high dose per pulse and, in case of mechanical scanning irradiation, owing to the small dimension of the beam. Furthermore, it was also due to the necessity of evaluating the composition of the small beams.…”

Section: Methodsmentioning

confidence: 99%

Preliminary Studies for Clinical Applications of Novac7, A Robotic Mobile Intraoperative Electron Beam Therapy Unit

Zonca

Fossati

Ricci

et al. 1997

Frontiers of Radiation Therapy and Oncology

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To solve logistic problems in the method of transporting the anesthetized patient from the surgical theater to the radiation department, a new linear accelerator, named Novac7, was developed in order to enable its use in the operating room.In this paper some interesting features concerning the practice of a Novac7 unit, in the conventional way of irradiation, are presented: (1) preliminary study of medical and nursing staff radioprotection is evaluated; (2) measurements of beam intensity reproducibility have been performed; (3) isodose distributions, carried out by a radiation field analyzer using diodes and water phantom, and beam dosimetry carried out by gafchromic MD55 films in acrylic phantom to solve problems due to the high-dose-rate output of the machine are described. Materials and MethodsNovac7 is a new compact medical linear accelerator, produced by Hitesys SpA. The accelerator is designed to produce an electron beam of 9 MeV maximum nominal energy, with a maximum beam current of 3 mA.

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Film dosimetry of clinical electron beams

Cited by 29 publications

References 11 publications

Fast 2D phantom dosimetry for scanning proton beams

Fast 2D phantom dosimetry for scanning proton beams

Interinstitutional variations of sensitometric curves of radiographic dosimetric films

Preliminary Studies for Clinical Applications of Novac7, A Robotic Mobile Intraoperative Electron Beam Therapy Unit

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