Verification of Dose Plans Using Film Dosimetry for Quality Assurance in Radiosurgery

Mack, Andreas; Mack, G.; Weltz, Dirk; Czempiel, H; Kreiner, H.J.

doi:10.1159/000062344

Cited by 9 publications

(10 citation statements)

References 4 publications

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“…14). Stripes of radiochromic films (GAFCHROMIC ® MD 55 II) were embedded between the hemispheres and the outer shell of the phantom and the results by film dosimetry 8,9 compared to the ones given by the superposition model.…”

Section: Methodsmentioning

confidence: 99%

“…(8) Here every u means a 1D convolution which can be solved by methods of FFT. This approach can reduce the calculation time proportional to N ·log 2 N with the restriction that the kernel has to be taken as invariant and can not be scaled and adjusted as described previously [41][42][43] .…”

Section: Speed Versus Accuracymentioning

confidence: 99%

“…IMRT techniques 4,5 ). High dose gradients are common to all of these stereotactically guided irradiation fields, regardless of their shape, thus precise algorithms are required having to be verified in terms of precise dosimetric measurements [6][7][8][9] .…”

Section: Introductionmentioning

confidence: 99%

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Development of a 3-D convolution / superposition algorithm for precise dose calculation in the skull

Mack

Weltz²,

Scheib

et al. 2006

Australas. Phys. Eng. Sci. Med.

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In this paper an algorithm for calculating 3-D dose distributions within the brain is introduced and adapted to the demands of modem radiosurgery. The dose calculation with this model is based on a 3-D distribution of the primary photon intensity which is calculated with a ray casting algorithm. A prelocated matrix takes into account field sizes as well as modifying elements as collimator positions (MLC), blocks, wedges and compensators. Monte Carlo precalculated monoenergetic kernels from 0.1 MeV to 50 MeV were at our disposal. The components of the spectrum were either determined by deconvoluting depth dose curves measured in water or analyzed with a Ge-Li detector system in the case of 60Co. The calculated fluence distribution has to be superposed to the complete kernel containing the spatial energy deposition. Inhomogeneities and tissue interface phenomena (rhoe, Z) have been investigated. The divergence of the rays and the curved surface of the patient are taken into account. Assuming homogenous media, it is possible to shorten the computation time by using the Fast Fourier Transformation (FFT) delivering a first overview within seconds. The algorithm was evaluated and verified under specific conditions of small fields as used in radiosurgery and compared to dose measurements and Monte Carlo calculations. In using both the fast algorithm (FFT) for mainly homogenous conditions on one hand and the very precise superposition for inhomogeneous cases on the other, this algorithm can be a very helpful instrument especially for critical locations in the skull.

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Section: Methodsmentioning

confidence: 99%

Section: Speed Versus Accuracymentioning

confidence: 99%

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Development of a 3-D convolution / superposition algorithm for precise dose calculation in the skull

Mack

Weltz²,

Scheib

et al. 2006

Australas. Phys. Eng. Sci. Med.

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“…After adjusting the coordinates and applying the dose, a stack of embedded fi lms is read and analysed [12][13][14][15] . The resulting measured dose distributions can be compared to the calculated ones.…”

Section: Din 6875-1 -Verifi Cation Of Calculated Dose Calculationsmentioning

confidence: 99%

“…The resulting measured dose distributions ( fi g. 8 c, d) can be compared to the calculated ones ( fi g. 8 b) [12,13] . Several slab thicknesses can be chosen.…”

Section: Verifi Cation Of Calculated Dose Distributionsmentioning

confidence: 99%

Quality Assurance in Stereotactic Radiosurgery/Radiotherapy according to DIN 6875-1

Mack¹,

Mack

Scheib

et al. 2004

Stereotact Funct Neurosurg

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The new DIN (‘Deutsche Industrie-Norm’) 6875-1, which is currently being finalised, deals with quality assurance (QA) criteria and tests methods for linear accelerator and Gamma Knife stereotactic radiosurgery/radiotherapy including treatment planning, stereotactic frame and stereotactic imaging and a system test to check the whole chain of uncertainties. Our existing QA program, based on dedicated phantoms and test procedures, has been refined to fulfill the demands of this new DIN. The radiological and mechanical isocentre corresponded within 0.2 mm and the measured 50% isodose lines were in agreement with the calculated ones within less than 0.5 mm. The measured absorbed dose was within 3%. The resultant output factors measured for the 14-, 8- and 4-mm collimator helmet were 0.9870 ± 0.0086, 0.9578 ± 0.0057 and 0.8741 ± 0.0202, respectively. For 170 consecutive tests, the mean geometrical accuracy was 0.48 ± 0.23 mm. Besides QA phantoms and analysis software developed in-house, the use of commercially available tools facilitated the QA according to the DIN 6875-1 with which our results complied.

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High Precision Radiosurgery and Technical Standards

Scheib

Gianolini

Lomax

et al. 2004

Gamma Knife Radiosurgery

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Verification of Dose Plans Using Film Dosimetry for Quality Assurance in Radiosurgery

Cited by 9 publications

References 4 publications

Development of a 3-D convolution / superposition algorithm for precise dose calculation in the skull

Development of a 3-D convolution / superposition algorithm for precise dose calculation in the skull

Quality Assurance in Stereotactic Radiosurgery/Radiotherapy according to DIN 6875-1

High Precision Radiosurgery and Technical Standards

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