Alanine Detectors Research Articles

STUDY OF DOSIMETRY POSSIBILITIES USING ELECTRON PARAMAGNETIC RESONANCE ON ALANINE FOR ILU-10 ACCELERATOR INP RK

Experimental studying possibilities of the electron paramagnetic resonance (EPR) method application for the dose control using alanine deteectors in the process of technological irradiations with brake radiation at the accelerator ILU-10 INP RK has been carried out. The EPR signal stability and sensitivity of original alanine detectors have been studied, serviceability in standard modes was shown in the range of small doses of brake irradiation (0,005–1 kGy); for dose estimation the calibration on gamma-irrdiation was used. The obtained data confirmed the promise of alanine EPR dosimetry at the ILU-10 accelerator INP RK.

Characterization and implementation of the L-alanine detector for quality control of lung SBRT treatments with the VMAT technique

New treatments in radiotherapy have some difficulties, among them, the geometric and dosimetric characterization of the radiation beam and the use of small radiation fields. Determination of the prescribed dose in the target volume in cases of small fields is difficult due to the absence of lateral electronic equilibrium and the sharp dose gradient at the edges of the fields. In this way, the choice of the radiation detector becomes relevant when performing the dosimetry of small fields. Alanine dosimeters have proven to be a good option for measurements of high radiation doses in these field sizes. This work aims to characterize the alanine detector through dosimetric tests for the VMAT (Volumetric Modulated Arc Therapy) technique in cases of SBRT (Stereotactic Body Radiation Therapy) to demonstrate the feasibility of using the alanine dosimetric system for use in quality control. End-to-End test was performed in a phantom, simulating two situations: homogeneous and heterogeneous regions. The response of L-alanine showed a strong linear correlation with dose (R2 = 0.99997), and insignificant dependence to dose rate. In the End-to-End test for a planned dose of 18 Gy, the doses obtained in alanine presented expanded uncertainty of 4.60% at 95% confidence level. Therefore, this work demonstrated that alanine dosimeter is suitable for quality control of SBRT with the VMAT technique in routine applications.

Numerical analysis of the alanine response using Monte Carlo: Correlation with experimental results

International centers based on research reactors (ICERR) project supported by IAEA, offers training and research in the application of advanced nuclear reactor technology. In this context of the project, alanine dosimeters were irradiated under mixed neutron/gamma irradiation in the core of the MINERVE research reactor at the CEA Cadarache. The integrated dose of the alanine was measured by electron spin resonance spectrometry with reference to an absorbed dose in water from a 60Co gamma-ray beam. Neutron and gamma dose components were calculated using the MCNP code. The neutron dose and relative effectiveness (REn) for neutrons was evaluated using FLUKA code and Track Structure Theory (TST) formulations of alanine response towards irradiations with ions produced by neutron interactions with alanine. REn values were found to be between 0.516 and 0.538. The measured dose was compared to the calculation results. The best agreement between the alanine integral measurements and model predictions (0.4%) was obtained by using the Cucinotta alanine detector response model.

Characterization of passive dosimeters in proton pencil beam scanning - A EURADOS intercomparison for mailed dosimetry audits in proton therapy centres.

The lack of mailed dosimetry audits of proton therapy centres in Europe has encouraged researchers of EURADOS Working Group 9 (WG9) to compare response of several existing passive detector systems in therapeutic pencil beam scanning. Alanine Electron Paramagnetic Resonance dosimetry systems from 3 different institutes (ISS, Italy; UH, Belgium and IFJ PAN, Poland), natLiF:Mg, Ti (MTS-N) and natLiF:Mg, Cu, P (MCP-N) thermoluminescent dosimeters (TLDs), GD-352M radiophotoluminescent glass dosimeters (RPLGDs) and Al2O3:C optically stimulated dosimeters (OSLDs) were evaluate. Dosimeter repeatability, batch reproducibility and response in therapeutic Pencil Beam Scanning were verified for implementation as mail auditing system. Alanine detectors demonstrated the lowest linear energy transfer (LET) dependence with an agreement between measured and treatment planning system (TPS) dose below 1%. The OSLDs measured on average a 6.3% lower dose compared to TPS calculation, with no significant difference between varying modulations and ranges. Both GD-352M and MCP-N measured a lower dose than the TPS and luminescent response was dependent on the LET of the therapeutic proton beam. Thermoluminescent response of MTS-N was also found to be dependent on the LET and a higher dose than TPS was measured with the most pronounced increase of 11%. As alanine detectors are characterized by the lowest energy dependence for different parameters of therapeutic pencil beam scanning they are suitable candidates for mail auditing in proton therapy. The response of luminescence detector systems have shown promises even though more careful calibration and corrections are needed for its implementation as part of a mailed dosimetry audit system.

P206] Gafchromic and alanine detectors for verification of field junctions in craniospinal proton irradiation

Purpose Radiotherapy is one of essential methods of treatment for medulloblastoma – a primitive neuroectodermal tumor growing in cerebellum. Proton craniospinal irradiations are recommended because of sparing of intermediate-to-low-dose to healthy tissues and reduction of side effects, including secondary cancers. Two laterally opposed cranial fields and several posterior spine fields are usually used for irradiation in medulloblastoma as well in conventional radiotherapy as in proton one. In this field configuration a potential dose inhomogeneity at the field junctions can appear. We have investigated the dose homogeneity in the junction areas using Gafchromic films and alanine detectors. Methods A clinical plan for an anthropomorphic phantom of a 5-year-old child have been prepared. There were two opposed lateral brain fields and 2 posterior spine fields. Therefore two field junctions were investigated. Then the phantom was equipped with alanine detectors and Gafchromic films at chosen positions mainly in junction areas and irradiated. Alanine doses were assessed using proton beam calibration (5–20 Gy). The calibration curve was designed upon developed protocol based on ISO/WD 15566.1 document. Alanine doses were then compared with doses in the treatment plan. Gafchromic films were analyzed using in-house developed AnalyseGafchromic software allowing to calculate dose based on triple channel calibration and apply corrections on scanner spatial inhomogeneity and scan-to-scan instability. Finally, the measured 2D dose distributions were compared with dose planes exported from TPS (Treatment Planning System) using gamma index analysis. Results The compatibility of alanine doses and TPS doses was at the level of 1%. For all the dose planes measured with Gafchromic passing rates of gamma index test (3%/3 mm) was higher than 95%. Conclusions Patients with medulloblastoma may benefit greatly from proton radiotherapy, however the main condition for a successful treatment is a careful and accurate field junctions, where all the uncertainties of beam model in TPS, CT calibration curve and Patient Positioning may affect the dose delivered to the patient. We have proved that Gafchromic films and alanine detectors can be successfully used for complex system check for ability to irradiate the target with sufficient accuracy.

End-to-end tests using alanine dosimetry in scanned proton beams

This paper describes end-to-end test procedures as the last fundamental step of medical commissioning before starting clinical operation of the MedAustron synchrotron-based pencil beam scanning (PBS) therapy facility with protons.One in-house homogeneous phantom and two anthropomorphic heterogeneous (head and pelvis) phantoms were used for end-to-end tests at MedAustron. The phantoms were equipped with alanine detectors, radiochromic films and ionization chambers. The correction for the ‘quenching’ effect of alanine pellets was implemented in the Monte Carlo platform of the evaluation version of RayStation TPS. During the end-to-end tests, the phantoms were transferred through the workflow like real patients to simulate the entire clinical workflow: immobilization, imaging, treatment planning and dose delivery. Different clinical scenarios of increasing complexity were simulated: delivery of a single beam, two oblique beams without and with range shifter. In addition to the dose comparison in the plastic phantoms the dose obtained from alanine pellet readings was compared with the dose determined with the Farmer ionization chamber in water.A consistent systematic deviation of about 2% was found between alanine dosimetry and the ionization chamber dosimetry in water and plastic materials. Acceptable agreement of planned and delivered doses was observed together with consistent and reproducible results of the end-to-end testing performed with different dosimetric techniques (alanine detectors, ionization chambers and EBT3 radiochromic films).The results confirmed the adequate implementation and integration of the new PBS technology at MedAustron. This work demonstrates that alanine pellets are suitable detectors for end-to-end tests in proton beam therapy and the developed procedures with customized anthropomorphic phantoms can be used to support implementation of PBS technology in clinical practice.

Characterization of the ESR response of alanine dosimeters to low-energy Cu-target X-tube photons

This article describes Electron Spin Resonance (ESR) response measurements of Kodak BioMax alanine films exposed to low-energy X-rays from a Cu-target tube operating at 20 kV. Commercial alanine detectors were used to ensure maximum reproducibility of the results, while the choice of a film was due the low penetration of the soft X-rays. X-ray energy spectra and fluences were determined with an innovative digital semiconductor detector system. These data were used to quantify the irradiation of the alanine films in terms of absorbed dose to water. The alanine films were found to present a stable response, highly linear with dose. To our knowledge, these data have not been previously reported and they may be extremely relevant, e.g., when mapping the high-gradient treatment fields used in microbeam radiation therapy (MRT) with synchrotron radiation.

Perturbation correction for alanine dosimeters in different phantom materials in high-energy photon beams

In modern radiotherapy the verification of complex treatments plans is often performed in inhomogeneous or even anthropomorphic phantoms. For dose verification small detectors are necessary and therefore alanine detectors are most suitable. Though the response of alanine for a wide range of clinical photon energies in water is well know, the knowledge about the influence of the surrounding phantom material on the response of alanine is sparse. Therefore we investigated the influence of twenty different surrounding/phantom materials for alanine dosimeters in clinical photon fields via Monte Carlo simulations. The relative electron density of the used materials was in the range up to 1.69, covering almost all materials appearing in inhomogeneous or anthropomorphic phantoms used in radiotherapy. The investigations were performed for three different clinical photon spectra ranging from 6 to 25 MV-X and Co-60 and as a result a perturbation correction depending on the environmental material was established. The Monte Carlo simulation show, that there is only a small dependence of on the phantom material and the photon energy, which is below ±0.6%. The results confirm the good suitability of alanine detectors for in-vivo dosimetry.

Application of alanine dosimetry in dose assessment for ocular melanoma patients undergoing proton radiotherapy – preliminary results

Abstract Basing on alanine solid state/electron paramagnetic resonance (EPR) dosimetry, a supplementary method of cumulatively recording the therapeutic dose received by ocular cancer patients undergoing fractionated proton radiotherapy is proposed. By applying alanine dosimetry during the delivery of consecutive fractions, the dose received within each fraction can be read out by EPR spectrometry and a final permanent cumulative record of the total dose delivered obtained. The dose response of the alanine detector was found to be practically independent on its position within the extended proton Bragg peak region. Dose measurements based on entrance dose recorded in proton beams individually formed for each patient are presented. The described method will be applied as a complementary Quality Assurance procedure for patients undergoing proton radiotherapy at the Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland (IFJ PAN).

SU‐E‐T‐608: Perturbation Corrections for Alanine Dosimeters in Different Phantom Materials in High‐Energy Photon Beams

Purpose:Alanine dosimeters are often used for in‐vivo dosimetry purposes in radiation therapy. In a Monte Carlo study the influence of 20 different surrounding/phantom materials for alanine dosimeters was investigated. The investigations were performed in high‐energy photon beams, covering the whole range from 60Co up to 25 MV‐X. The aim of the study is the introduction of a perturbation correction kenv for alanine dosimeters accounting for the environmental material.Methods:The influence of different surrounding materials on the response of alanine dosimeters was investigated with Monte Carlo simulations using the EGSnrc code. The photon source was adapted with BEAMnrc to a 60Co unit and an Elekta (Enom=6, 10, 25 MV‐X) linear accelerator. Different tissue‐equivalent materials ranging from cortical bone to lung were investigated. In addition to available phantom materials, some material compositions were taken and scaled to different electron densities. The depth of the alanine detectors within the different phantom materials corresponds to 5 cm depth in water, i.e. the depth is scaled according to the electron density (ne/ne,w) of the corresponding phantom material. The dose was scored within the detector volume once for an alanine/paraffin mixture and once for a liquid water voxel. The relative response, the ratio of the absorbed dose to alanine to the absorbed dose to water, was calculated and compared to the corresponding ratio under reference conditions. Results: For each beam quality the relative response r and the correction factor for the environment kenv was calculated. kenv=0.9991+0.0049 *((ne/ne,w)−0.7659)3Conclusion:A perturbation correction factor kenv accounting for the phantom environment has been introduced. The response of the alanine dosimeter can be considered independent of the surrounding material for relative electron densities (ne/ne,w) between 1 and 1.4. For denser materials such as bone or much less dense surroundings such as lung, a small correction would be appropriate.

The comparison of the proton dose distribution calculated with the treatment planning system and measured with alanine detectors in the eye phantom irradiated under therapeutic conditions

The paper describes the applicability of commercially available alanine detectors produced by Synergy Health for verification of the dose distribution calculated by the treatment planning system (TPS) used in proton eye radiotherapy – Eclipse Ocular Proton Planning (EOPP) program, version 8.9.06, Varian Medical Systems. The TPS-planned dose distribution at selected points in the eye phantom is compared to the dose registered by alanine detectors at these points during a simulated therapeutic irradiation at the proton eye radiotherapy facility in the Henryk Niewodniczanski Institute of Nuclear Physics (IFJ PAN), Krakow, Poland. The phantom was irradiated to obtain, a typical for choroidal melanoma, fraction dose of 15 CGE (13,64 Gy) at the tumor location. The dose registered with alanine pellets located inside the simulated tumor volume demonstrates a good agreement with the TPS-planned dose. The typical for proton radiotherapy, steep dose fall-off outside the treated area is registered by the alanine pellets however, it is difficult to assess it quantitatively, because the dose related EPR signal is registered from the entire pellet volume.

Applicability of EPR/alanine dosimetry for quality assurance in proton eye radiotherapy.

A new quality assurance and quality control method for proton eye radiotherapy based on electron paramagnetic resonance (EPR)/alanine dosimetry has been developed. It is based on Spread-Out Bragg Peak entrance dose measurement with alanine detectors. The entrance dose is well correlated with the dose at the facility isocenter, where, during the therapeutic irradiation, the tumour is placed. The unique alanine detector features namely keeping the dose record in a form of stable radiation-induced free radicals trapped in the material structure, and the non-destructive read-out makes this type of detector a good candidate for additional documentation of the patient's exposure over the therapy course.

SU‐F‐BRE‐01: A Rapid Method to Determine An Upper Limit On a Radiation Detector's Correction Factor During the QA of IMRT Plans

Purpose:Discrepancies in the verification of the absorbed dose to water from an IMRT plan using a radiation dosimeter can be wither caused by 1) detector specific nonstandard field correction factors as described by the formalism of Alfonso et al. 2) inaccurate delivery of the DQA plan. The aim of this work is to develop a simple/fast method to determine an upper limit on the contribution of composite field correction factors to these discrepancies.Methods:Indices that characterize the non‐flatness of the symmetrised collapsed delivery (VSC) of IMRT fields over detector‐specific regions of interest were shown to be correlated with IMRT field correction factors. The indices introduced are the uniformity index (UI) and the mean fluctuation index (MF). Each one of these correlation plots have 10 000 fields generated with a stochastic model. A total of eight radiation detectors were investigated in the radial orientation. An upper bound on the correction factors was evaluated by fitting values of high correction factors for a given index value.Results:These fitted curves can be used to compare the performance of radiation dosimeters in composite IMRT fields. Highly water‐equivalent dosimeters like the scintillating detector (Exradin W1) and a generic alanine detector have been found to have corrections under 1% over a broad range of field modulations (0 – 0.12 for MF and 0 – 0.5 for UI). Other detectors have been shown to have corrections of a few percent over this range. Finally, a full Monte Carlo simulations of 18 clinical and nonclinical IMRT field showed good agreement with the fitted curve for the A12 ionization chamber.Conclusion:This work proposes a rapid method to evaluate an upper bound on the contribution of correction factors to discrepancies found in the verification of DQA plans.

TU‐F‐BRE‐03: Application of a Novel Mass‐Density Compensation Optimization Method to Improve the Response of a Liquid‐Filled Ionization Chamber in Nonstandard Fields

Purpose:To improve the response of the microLion detector (PTW 31018) in small field conditions by optimizing the density of the detector's non‐sensitive components using a novel method based on the detector's dose response function.Methods:The central values h(0,0) of the perturbation functions for the microLion detector and a volume of water equivalent to its sensitive volume were calculated using the Monte Carlo user code egs_chamber by scoring the dose absorbed by a 6 MV photon pencil beam incident on their centroids. Values of h(0,0) were plotted as a function of the density of the microLion's graphite electrode with the detector placed in the axial orientation. The optimized density was found by finding the minimal value of h(0,0).Results:A density of 1.37 g/cm3 was found to minimize the perturbation function of the microLion detector. The modified microLion's response was then evaluated in small square fields with sides in the range of 5 – 40 mm and found to be consistent with highly watere‐quivalent detectors such as a scintillating detector (Exradin W1) and a generic alanine detector in both axial and radial orientations.Conclusion:This work illustrates a novel method which can used to optimize the design of radiation detectors in small fields. This method should also work with other optimization parameters (e.g. thickness of electrode). Density‐compensated detectors have the potential to eliminate the need to evaluate nonstandard field correction factors as described by the IAEA‐AAPM formalism (Alfonso et al.) and simplify future dosimetry protocols for SRS/SBRT modalities. Finally, we also expect an improvement in the response of density‐compensated detectors for composite IMRT fields.

Dosimetry auditing procedure with alanine dosimeters for light ion beam therapy

In the next few years the number of facilities providing ion beam therapy with scanning beams will increase. An auditing process based on an end-to-end test (including CT imaging, planning and dose delivery) could help new ion therapy centres to validate their entire logistic chain of radiation delivery. An end-to-end procedure was designed and tested in both scanned proton and carbon ion beams, which may also serve as a dosimetric credentialing procedure for clinical trials in the future. The developed procedure is focused only on physical dose delivery and the validation of the biological dose is out of scope of the current work. The audit procedure was based on a homogeneous phantom that mimics the dimension of a head (20 × 20 × 21 cm(3)). The phantom can be loaded either with an ionisation chamber or 20 alanine dosimeters plus 2 radiochromic EBT films. Dose verification aimed at measuring a dose of 10Gy homogeneously delivered to a virtual-target volume of 8 × 8 × 12 cm(3). In order to interpret the readout of the irradiated alanine dosimeters additional Monte Carlo simulations were performed to calculate the energy dependent detector response of the particle fluence in the alanine detector. A pilot run was performed with protons and carbon ions at the Heidelberg Ion Therapy facility (HIT). The mean difference of the absolute physical dose measured with the alanine dosimeters compared with the expected dose from the treatment planning system was -2.4 ± 0.9% (1σ) for protons and -2.2 ± 1.1% (1σ) for carbon ions. The measurements performed with the ionisation chamber indicate this slight underdosage with a dose difference of -1.7% for protons and -1.0% for carbon ions. The profiles measured by radiochromic films showed an acceptable homogeneity of about 3%. Alanine dosimeters are suitable detectors for dosimetry audits in ion beam therapy and the presented end-to-end test is feasible. If further studies show similar results, this dosimetric audit could be implemented as a credentialing procedure for clinical proton and carbon beam delivery.

Experimental determination of the energy response of alanine pellets in the high dose rate 192Ir spectrum

An experimental determination of the energy correction factor for alanine/paraffin pellets in the 192Ir spectrum at varying distances from the source is presented. Alanine dosimeters were irradiated in water under full scatter conditions with a high dose rate (HDR) 192Ir source (Flexisource), using a dedicated holder. Up to six line sources (catheters) fit in a regular pattern at fixed radial distances from the holder axis, the alanine detector being placed at the centre of the holder. The HDR source was stepping every 0.5 cm within a trocar needle within ± 3.0 cm around the medial plane through the detector in order to achieve dose homogeneity within the detector volume. The energy correction factor of alanine/paraffin pellets in 192Ir relative to 60Co was experimentally determined as the inverse ratio of the dose to water measured in water around the 192Ir source to the dose to water calculated in water using the TG-43 formalism. The pellets were read out with a Bruker EMXmicro spectrometer (X-band). The amplitude of the central line in the alanine absorption spectrum from pellets irradiated within the 192Ir spectrum was directly compared with the amplitude from 60Co-irradiated pellets. The energy correction factors of Harwell pellets irradiated in the 192Ir spectrum are 1.029 ± 0.02, 1.027 ± 0.02 and 1.045 ± 0.02 at a mean weighted source–detector distance of 2.0, 2.9 and 5.3 cm, respectively. The experimentally obtained values for the energy response are 1.3% lower compared to the theoretical values for radial distances smaller than 3 cm.

Dose determination using alanine detectors in a mixed neutron and gamma field for boron neutron capture therapy of liver malignancies

Boron Neutron Capture Therapy for liver malignancies is being investigated at the University of Mainz. One important aim is the set-up of a reliable dosimetry system. Alanine dosimeters have previously been applied for dosimetry of mixed radiation fields in antiproton therapy, and may be suitable for measurements in mixed neutron and gamma fields. Material and methods. Two experiments have been carried out in the thermal column of the TRIGA Mark II reactor at the University of Mainz. Alanine dosimeters have been irradiated in a phantom and in liver tissue. Results. For the interpretation and prediction of the dose for each pellet, beside the results of the measurements, calculations with the Monte Carlo code FLUKA are presented here. For the phantom, as well as for the liver tissue, the measured and calculated dose and flux values are in good agreement. Discussion. Alanine dosimeters, in combination with flux measurements and Monte Carlo calculations with FLUKA, suggest that it is possible to establish a system for monitoring the dose in a mixed neutron and gamma field for BNCT and other applications in radiotherapy.

Amorphous track predictions in ‘libamtrack’ for alanine relative effectiveness in ion beams

Abstract Solid state dosimetry in therapeutic ion beams is seriously hampered by ionisation density effects. In most cases the use of empirical corrections is limited and therefore model predictions, especially from amorphous track models (ATMs), play a major role. Due to its high saturation dose and simple dose response, the alanine detector can help to study fundamental assumptions and accuracy in amorphous track modelling. The libamtrack project enabled recently to directly compare various flavours of ATMs. We therefore present here the potential of predictions for alanine from two libamtrack ATMs with experimental data as first part of a greater study. We find very good agreement for protons, helium and carbon ions for thin targets. For thick targets, however, the two compared algorithms show differences, with one generally better matching the data. Additional assumptions which have to be made on particle transport and stopping powers hinders a thorough interpretation of the deviation found and stress the necessity for a broader data base at lower particle energies.

SU-E-T-728: TG-51A: Part 1: An Alternative Secondary Standard for Medical Linear Accelerators Using Alanine Dosimeters

Purpose: To demonstrate the suitability of the use of alanine dosimeters as a supplement or alternative to TG51 as an acceptable secondary calibration method for high energy photons beams from a medical linear accelerator. Methods: Alanine dosimiters were irradiated at three radiation treatment facilities and compared to dose/mu determined by TG51 using ionization chambers calibrated at ADCL. The ionization chamber was positioned in a Scanditronix Wellhoffer water phantom with dimensions 42 cm × 36 cm × 36 cm and at a dept of 5.0 cm. The volume of the ionization chamber was 0.6 cc. A polystyrene holder containing two alanine dosimeters was placed at the same point. Each alanine dosimeter is cylindrical in shape with a diameter of 5 mm and a length of 3 mm (volume = 0.25 cc). Ten sets of alanine detectors (20) were irradiated to 20 Gy in sequential exposures. An independent ionization chamber was used to normalize the exposures for any variation in accelerator output for every measurement. For one beam energy the alanine detectors were returned to a national standards laboratory for conversion to dose based on the same primary standard used for ionization chambers. The remaining dosimeters was evaluated on a Bruker EMX EPR spectrometer at the Armed Forces Radiobiology Research Institute which is directly traceable to NIST based on calibrated alanine dosimeters. Results: The average normalized dose per mu for all data is within expected experimental uncertainty. The uncertainty of each measurement technique is believed to be approximately 2% and will be discussed in detail. Conclusion: Analysis of the intercomparison measurements establishes that the alanine dosimeters are a valid method to establish the dose per mu for a medical linear accelerator that is traceable to the primary standard at a national standards laboratory in the same manner as used in TG51.

Dose response of alanine detectors irradiated with carbon ion beams

The dose response of the alanine detector shows a dependence on particle energy and type when irradiated with ion beams. The purpose of this study is to investigate the response behavior of the alanine detector in clinical carbon ion beams and compare the results to model predictions. Alanine detectors have been irradiated with carbon ions with an energy range of 89-400 MeV/u. The relative effectiveness of alanine has been measured in this regime. Pristine and spread out Bragg peak depth-dose curves have been measured with alanine dosimeters. The track structure based alanine response model developed by Hansen and Olsen has been implemented in the Monte Carlo code FLUKA and calculations were compared to experimental results. Calculations of the relative effectiveness deviate less than 5% from the measured values for monoenergetic beams. Measured depth-dose curves deviate from predictions in the peak region, most pronounced at the distal edge of the peak. The used model and its implementation show a good overall agreement for quasi-monoenergetic measurements. Deviations in depth-dose measurements are mainly attributed to uncertainties of the detector geometry implemented in the Monte Carlo simulations.