Dimensional Dose Distributions Research Articles

Creation of waterproof, TLD probes for dose measurements to validate image-based radiopharmaceutical therapy dosimetry workflow

Voxel-level dosimetry based on nuclear medicine images offers patient-specific personalization of radiopharmaceutical therapy (RPT) treatments. Clinical evidence is emerging demonstrating improvements in treatment precision in patients when voxel-level dosimetry is used compared to MIRD. Voxel-level dosimetry requires absolute quantification of activity concentrations in the patient, but images from SPECT/CT scanners are not quantitative and require calibration using nuclear medicine phantoms. While phantom studies can validate a scanner’s ability to recover activity concentrations, these studies provide only a surrogate for the true metric of interest: absorbed doses. Measurements using thermoluminescent dosimeters (TLDs) are a versatile and accurate method of measuring absorbed dose. In this work, a TLD probe was manufactured that can fit into currently available nuclear medicine phantoms for the measurement of absorbed dose of RPT agents. Next, 748 MBq of I-131 was administered to a 16 ml hollow source sphere placed in a 6.4 L Jaszczak phantom in addition to six TLD probes, each holding 4 TLD-100 1 × 1 × 1 mm TLD-100 (LiF:Mg,Ti) microcubes. The phantom then underwent a SPECT/CT scan in accordance with a standard SPECT/CT imaging protocol for I-131. The SPECT/CT images were then input into a Monte Carlo based RPT dosimetry platform named RAPID and a three dimensional dose distribution in the phantom was estimated. Additionally, a GEANT4 benchmarking scenario (denoted ‘idealized’) was created using a stylized representation of the phantom. There was good agreement for all six probes, the differences between measurement and RAPID ranged between −5.5% and 0.9%. The difference between the measured and the idealized GEANT4 scenario was calculated and ranged from −4.3% and −20.5%. This work demonstrates good agreement between TLD measurements and RAPID. In addition, it introduces a novel TLD probe that can be easily introduced into clinical nuclear medicine workflows to provide QA of image-based dosimetry for RPT treatments.

Dosimetric verification of stereotactic body radiotherapy treatment plan via ArcCHECK-3DVH system.

To study the feasibility of ArcCHECK-3DVH system in dosimetric verification for stereotactic body radiaotherapy (SBRT) with flattening filter free (FFF) model. SBRT treatment plans for 57 patients were introduced into ArcCHECK phantom and recalculated. The calculated dose distribution of treatment planning system and the measured dose distribution of ArcCHECK phantom were compared by γ analysis. Then the 3 dimensional dose distribution of target and organs at risk was reconstructed by 3DVH software. The reconstructed dose and calculated dose with treatment planning system (TPS) were compared, and the dose volume γ pass rate and deviation of dose volume parameters to the target and organs at risk were quantitatively valuated. Based on the threshold criteria (3%, 3 mm, 10%), namely the deviation of measuring points between the planned value and the measured value was less than 3%, and the proportion of points with similar values in the plane or sphere with the center of the point and the radius of 3 mm was 10%, the relative and absolute dose pass rates of SBRT treatment plans in ArcCHECK system via γ analysis were greater than 95%. Based on the stricter threshold criteria (2%, 2 mm, 10%), the relative and absolute dose pass rates of SBRT treatment plan in ArcCHECK system via γ analysis were about 93%. In 3DVH dose verification, the γ pass rate of target and organs at risk was exceed 97%, and the deviations in 3DVH of the target and organs at risk were less than ±5%. The ArcCHECK-3DVH system in dose verification can provide more comprehensive dose distribution information to reasonably evaluate the SBRT plan, with more significance for guiding clinical treatment.

Investigation of Verification Methods of Field Matching Using Polymer Gel Dosimeter in Proton Therapy

In our proton beam therapy center, we use imaging plates (IP) for dose verification of field matching in irradiation (called patch-field technique). In this study, a polymer gel dosimeter, which can perform three- dimensional dose distribution measurement, was used as a new tool for the verification of the patch field irradiation method corresponding to the rectangular irradiation. The results of measurements of the PAGAT gel dosimeter to irradiate to two rectangular fields called as patch irradiation fields, which were created using the treatment planning system, were evaluated and compared to the results of IP and plan in profiles near the boundary of two fields. In the case of no gap between the two fields, the relative dose using the gel dosimeter was 10.1% higher compared to that measured with the IP in the midpoint of two fields. In case of overlap (called hot region), the result of gels was 6.3% higher than that of IP. In the case of space (called cold region), the result of gels was 14.9% higher than that of IP. The results of the difference between gel and plan in the midpoint of two fields were 14.2% (no gap), -5.0% (hot), and 10.5% (cold). We found that the gel dosimeter was a 3-D dosimetric tool and possibility method for dose verification of patch fields. In this study, the results were preliminary and included several error factors. In the future, it is necessary to develop a dosimeter with improved and more precise measurements.

Study of Analysis the Sensitivity of the Computational Environment for Radiological Research Field Size Based on Two Dimensional Dose Distribution for Water Phantom Cases

Purpose This study analysed the sensitivity of the field size from variations in the target volume dimensions, depth, and position. The variations in the target volume analysis were used to determine the width of the field size. Thus, the quality control of the radiation beam can be obtained. Materials and Methods The computed tomography (CT) image of the IBA Dose 1 type of water phantom consists of 350 slices. Variations in the dimension of the target volume were modelled in 10×10×10 cm3, 10×12×10 cm3 , 10.2×10×10.2 cm3, and 15×15×15 cm3. Beam parameters use one beam of irradiation on the central axis 0°, 6 MV energy, 100 cm source-skin distance (SSD), beamlet delta x, and y set to 0.1 cm. Dose distribution in the form of the XZ isodose curve and dose profile was used to observe the field size. Results In this study, the isodose curve was successfully displayed in the XZ isodose curve. The field size’s sensitivity has been successfully reviewed from variations of the target volume, depth, and position. The target X and Z direction analysis is used in determining the width and length of the field size. Conclusion The analysis related to the field size sensitivity study was obtained from a relatively valid calculation. The field size was evaluated with variations in depth of 1.5 cm, 5 cm, 10 cm, and variations in positions of 10 cm, 12 cm, 14 cm, 18 cm, and 20 cm. This study will be used as a reference to validate the distribution of computational environment for radiotherapy research (CERR) dose in the future. Thus, the accuracy of the dose calculation can be obtained.

A novel investigation of the effect of different concentrations of methacrylic acid on the dose response of MAGAT gel dosimeter in intraoperative radiotherapy

PurposeHigh dose prescription in one treatment session of intraoperative radiotherapy (IORT) requires precise monitoring of the delivered dose. Methacrylic acid, gelatin and tetrakis phosphonium chloride (MAGAT) gel with superior dose sensitivity and dose resolution seems to be a suitable tool for 3 dimensional dose verification of IORT. In the current study, the dose response of MAGAT gel dosimeter with varying concentrations of methacrylic acid (MAA) was investigated. Finally, the MAGAT with optimal concentration was subjected to dose rate and energy dependency measurements. MethodsMAGAT gel with different concentrations of 3, 5, 6, 8 and 10% was manufactured and irradiated with 50 keV produced by IORT. Gel vials were read out by MRI and R2 responses were plotted against dose. Dose rate and energy dependency of optimum MAGAT gel were assessed by irradiation by a VARIAN linear accelerator using various dose rates of 30, 40 and 50 cGy/min and diverse photon energies of 6 and 18 MV as well as 50 keV of IORT. ResultsMAGAT with a concentration of 8% MAA, exhibited a high-dose response and dose sensitivity of 5.16 Gy−1 s−1 in irradiation by IORT. Moreover, its response was independent of low dose rates (30, 40 and 50 cGy/min) and mega-voltage energies (p > 0.05). However, there was a significant difference between the R2-dose response of MAGAT irradiated by mega-voltage (6 and 18 MV) and 50 keV energy of IORT. ConclusionMAGAT is an effective tool to investigate three dimensional dose distributions of IORT independent of dose rates used in X-ray IORT. Moreover, its response is energy independent over mega-voltage energies.

Feasibility study of using polyacrylamide gel dosimeter as brain equivalent material in therapeutic energy range of X-rays

In this paper the feasibility study of using polyacrylamide gels as a brain equivalent material has been performed. Thus, the parameters of mass energy absorption coefficient (μen/ρ), mass stopping power (S/ρ), effective atomic number (Zeff), mass attenuation coefficient (μeff/ρ) and absorbed dose delivered to polyacrylamide gel (D) were determined for this gel using analytical and Monte Carlo methods and were compared with brain reference material. The calculation results reveal that the relative difference between the calculated μen/ρ, S/ρ, Zeff, μeff/ρ and D for polyacrylamide gel and those for brain are 1.32%, less than 1%, less than 2%, less than 4% and less than 1%, respectively in therapeutic energy range. Consequently, like water, polyacrylamide gel can be also used for designing and construction of head and neck phantoms applied for validation of medical algorithms used in treatment planning systems. The advantage of using polyacrylamide gel as a brain equivalent material in comparison to water is that this gel is a reliable X and gamma rays dosimeter applicable for three dimensional dose distribution determination. Also, other advantages of this gel are its low price, availability and forming it in different sizes and shapes. These properties of the polyacrylamide gel make it beneficial as brain equivalent material in designing and construction of head and neck phantoms.

Film dosimetry studies for patient specific quality assurance in microbeam radiation therapy

Microbeam radiation therapy (MRT) uses synchrotron arrays of X-ray microbeams to take advantage of the spatial fractionation effect for normal tissue sparing. In this study, radiochromic film dosimetry was performed for a treatment where MRT is introduced as a dose boost in a hypofractionated stereotactic radiotherapy (SRT) scheme. The isocenter dose was measured using an ionization chamber and two dimensional dose distributions were determined using radiochromic films. To compare the measured dose distribution to the MRT treatment plan, peak and valley were displayed in separate dosemaps. The measured and computed isocenter doses were compared and a two-dimensional 2%/2 mm normalized γ-index analysis with a 90% passing rate criterion was computed. For SRT, a difference of 2.6% was observed in the dose at the isocenter from the treatment plan and film measurement, with a passing rate of 96% for the γ-index analysis. For MRT, peak and valley doses differences of 25.6% and 8.2% were observed, respectively but passing rates of 96% and 90% respectively were obtained from the normalized γ-index maps. The differences in isocenter doses measured in MRT should be further investigated. We present the methodology of patient specific quality assurance (QA) for studying MRT dose distributions and discuss ideas to improve absolute dosimetry. This patient specific QA will be used for large animal trials quality assurance where MRT will be administered as a dose boost in conventional SRT. The observed remaining discrepancies should be studied against approximations in the TPS phantom materials, beams characteristics or film read-out procedures.

The effect of gel homogeneity on dose response in a low-density polymer gel dosimeter for radiation therapy.

The human body consists of a variety of tissues and cavities with different physical and radiological properties. The most important among these are tissues and cavities including lungs, oral cavities, teeth, nasal passages, sinuses, and bones. Thus, the dose distribution in these tissues cannot be verified with soft tissue equivalent polymer gel dosimeters. This study is conducted to evaluate the effect of homogeneity on dose response of an anoxic low-density polymer gel dosimeter for radiation therapy. The low-density polymer gel dosimeter is composed of 12% gelatin, 5% methacrylic acid, 0.15% sodium dodecyl sulfate, 10 mm tetrakis (hydroxymethyl) phosphonium chloride, and 83% ultrapure deionized water. The time between irradiation and scanning for all gels experiments was 18 h. The gel dosimeters were imaged using a 1.5 T clinical magnetic resonance imaging scanner in a transmitter/receiver head coil. The low-density gels had a mass density between 0.35 g/cm 3 and 0.45 g/cm 3 and the computed tomography (CT) values varied from approximately -650 to -750 Hounsfield units. It is clear that the CT numbers of the fabricated gel are close to those of the normal human lung tissue, which ranges from -770 to -875 Hounsfield units. Findings of the present study showed that if the density and homogeneity of the low-density polymer gel dosimeters are equal to those of the normal lung tissue, it may be used to measure the three dimensional dose distributions in lung tissue during radiation therapy.

The feasibility of direct treatment planning via contrast-enhanced computed tomography: an evaluation of dose differences based on the dimensional dose distribution comparison method

The feasibility of direct treatment planning via contrast-enhanced computed tomography: an evaluation of dose differences based on the dimensional dose distribution comparison method

Evaluation of Three Dimensional Dose Distributions by Using Polymer Gel Dosimeters Based on HPC Gel Sheets

We have proposed a novel polymer gel dosimeter containing of 2-hydroxyethyl methacrylate (HEMA), nonaethylene glycol dimethacrylate (9G), and tetrakis (hydroxymethyl) phosphonium chloride (THPC) with radiation-crosslinked hydroxypropyl cellulose (HPC) gel sheet. The transparent sheet-type dosimeters became white and cloudy by irradiation with gamma-rays and heavy ions such as He ions (150 MeV/u), C ions (290 MeV/u), Fe ions (500 MeV/u). The cloudiness increased with increasing dose. The cloudiness distribution with the sheet-type dosimeter was obtained by using a flatbed scanner to evaluate the dose distribution. Recently, we prepared a three-dimensional dosimeter by putting the gel sheets on top of another in the glass vessel. Three-dimensional dose distribution of the dosimeter irradiated with C ions was evaluated by the reconstruction of the data of each layer.

Evaluation of Absorbed Dose by MRI Read-Out

Three dimensional dose distribution by gel dosimeters is often read out by an MRI scanner, which is readily available in most hospitals. Both the T1 and T2 relaxation rates are used to evaluate the absorbed dose. This paper will describe the principle of the imaging sequences (spin echo, multiple spin echo, and inversion recovery methods) to measure the relaxation rate and the factors to affect the precision (signal noise ratio, temperature during scanning, coil, imaging artefact). Additionally, the magnetization transfer method will be mentioned as an alternative for low-density foam gel dosimeters.

Percentage depth dose (PDD) and Beam profile measurements using CT based MAGAT gel dosimetry system and Monte Carlo calculation


 
 
 Abstract
 The aim of this project is to develop and to evaluate the CT based MAGAT (methacrylic acid, gelatine and tetrakis phosphonium chloride) polymer gel dosimetry for measuring 3D dose distributions in radiation treatment. The MAGAT gel was prepared based on the formulation proposed in the literature. The percentage depth dose (PDD) and beam profile of 8 x 8 cm2 field size photon beam from a 6 MV linear accelerator were measured. Monte Carlo simulation was carried out to calculate PDD and beam profiles in the simulated MAGAT gel phantom to verify the data measured using MAGAT gel dosimetry for the 8 x 8 cm2 field size. The PDD and beam profile calculated using simulated MAGAT gel phantom agreed very well with that measured using MAGAT gel dosimetry. However, there were some differences between the simulated PDD with that measured at the surface region due to the electron contamination at the surface of the simulated phantom. In conclusion, the results showed that the CT based MAGAT gel dosimetry system is promising method to measure three- dimensional dose distribution based on PDD and Beam profile measurement.
 Keywords: MAGAT gel, CT, Monte Carlo simulation
 
 

Introducing a Novel Method for Three Dimensional Dose Map by Optical Computed Tomography

Background: Radiochromic gel is recently introduced as a three dimensional dosimeter that exhibits color changes by being exposed to ionizing radiation. Therefore, the read-out system of this dosimeter should be based on radiochromic response. Objectives: The aim of this study was to introduce a novel design of machine called optical computed tomography (OCT) and acquire the three dimensional dose distribution of ionizing radiation by using the Radon transform image reconstruction technique. Materials and Methods: By assembling red light-emitting diode as a light source, two lenses, charge-coupled device (CCD) camera, step motor, matching liquid, radiochromic gel, and a base frame, a novel design of OCT was manufactured. Then a sample of radiochromic gel was irradiated and scanned by novel OCT. The acquired images were then reconstructed by using the Radon transform algorithm and consequently the dose distribution was mapped. Finally the results of this device were verified by an ion chamber. Results: By setting up the required accessories, a new design of OCT was constructed. The verification test showed that the results of novel OCT could be reliable by almost ± 3% deviations. Conclusion: The results of this study confirmed that not only the Radon transform algorithm could be used for reconstructing computed tomography (CT) images, but also this technique could be applied for imaging the dose map of ionizing radiation obtained by OCT. Moreover, novel OCT- radiochromic gel could be considered as a proper system for acquiring three dimensional dose distribution of ionizing radiation.

Comparison of dosimetry gels prepared by agar and bovine gelatine

Gel dosimeters are unique materials capable of showing three dimensional (3D) dose distributions of therapeutic or diagnostic exposures. Fricke gel dosimeters can be considered as chemical dosimeters that rely on a radiation-induced chemical reaction. Dose distribution of Fricke solutions containing Fe+2 ions determines the transformation of acidic, oxygen saturated Fe+2 ions to Fe+3 ions by the ionizing radiation in aqueous solutions. In this study we produced two different types of gel dosimeters using agar and bovine gelatin with similar fabrication methods. We compared the magnetic resonance (MR) T1 imaging responses of these two gel dosimeters to acquire a dose dependency of MR intensities. In conclusion agar gel dosimeters found to be produced easily and more consistent.

A Monte Carlo evaluation for effects of probable dimensional uncertainties of low dose rate brachytherapy seeds on dose

The aim of this study is to determine effects of size deviations of brachytherapy seeds on two dimensional dose distributions around the seed. Although many uncertainties are well known, the uncertainties which stem from geometric features of radiation sources are weakly considered and predicted. Neither TG-43 report which is not completely in common consensus, nor individual scientific MC and experimental studies include sufficient data for geometric uncertainties. Sizes of seed and its components can vary in a manufacturing deviation. This causes geometrical uncertainties, too. In this study, three seeds which have different geometrical properties were modeled using EGSnrc-Code Packages. Seeds were designed with all their details using the geometry package. 5% deviations of seed sizes were assumed. Modified seeds were derived from original seed by changing sizes by 5%. Normalizations of doses which were calculated from three kinds of brachytherapy seed and their derivations were found to be about 3%–20%. It was shown that manufacturing differences of brachytherapy seed cause considerable changes in dose distribution.

SU‐E‐T‐243: MonteCarlo Simulation Study of Polymer and Radiochromic Gel for Three‐Dimensional Proton Dose Distribution

Purpose:To estimate the three dimensional dose distributions in a polymer gel and a radiochromic gel by comparing with the virtual water phantom exposed to proton beams by applying Monte Carlo simulation.Methods:The polymer gel dosimeter is the compositeness material of gelatin, methacrylic acid, hydroquinone, tetrakis, and distilled water. The radiochromic gel is PRESAGE product. The densities of polymer and radiochromic gel were 1.040 and 1.0005 g/cm3, respectively. The shape of water phantom was a hexahedron with the size of 13 × 13 × 15 cm3. The proton beam energies of 72 and 116 MeV were used in the simulation. Proton beam was directed to the top of the phantom with Z‐axis and the shape of beam was quadrangle with 10 × 10 cm2 dimension. The Percent depth dose and the dose distribution were evaluated for estimating the dose distribution of proton particle in two gel dosimeters, and compared with the virtual water phantom.Results:The Bragg‐peak for proton particles in two gel dosimeters was similar to the virtual water phantom. Bragg‐peak regions of polymer gel, radiochromic gel, and virtual water phantom were represented in the identical region (4.3 cm) for 72 MeV proton beam. For 116 MeV proton beam, the Bragg‐peak regions of polymer gel, radiochromic gel, and virtual water phantom were represented in 9.9, 9.9 and 9.7 cm, respectively. The dose distribution of proton particles in polymer gel, radiochromic gel, and virtual water phantom was approximately identical in the case of 72 and 116 MeV energies. The errors for the simulation were under 10%.Conclusion:This work indicates the evaluation of three dimensional dose distributions by exposing proton particles to polymer and radiochromic gel dosimeter by comparing with the water phantom. The polymer gel and the radiochromic gel dosimeter show similar dose distributions for the proton beams.

SU-C-12A-05: Radiation Dose in High-Pitch Pediatric Cardiac CTA: Correlation Between Lung Dose and CTDIvol, DLP, and Size Specific Dose Estimates (SSDE)

Purpose: To investigate the radiation dose for pediatric high pitch cardiac CTA Methods: A total of 14 cases were included in this study, with mean age of 6.2 years (ranges from 2 months to 15 years). Cardiac CTA was performed using a dual-source CT system (Definition Flash, Siemens). Tube voltage (70, 80 and 100kV) was chosen based on patient weight. All patients were scanned using a high-pitch spiral mode (pitch ranges from 2.5 to 3) with tube current modulation technique (CareDose4D, Siemens). For each case, the three dimensional dose distributions were calculated using a Monte Carlo software package (IMPACT-MC, CT Image GmbH). Scanning parameters of each exam, including tube voltage, tube current, beamshaping filters, beam collimation, were defined in the Monte Carlo calculation. Tube current profile along projection angles was obtained from projection data of each tube, which included data within the over-scanning range along z direction. The volume of lungs was segmented out with CT images (3DSlicer). Lung doses of all patients were calculated and compared with CTDIvol, DLP, and SSDE. Results: The average (range) of CTDIvol, DLP and SSDE of all patients was 1.19 mGy (0.58 to 3.12mGy), 31.54 mGy*cm (12.56 to 99 mGy*cm), 2.26 mGy (1.19 to 6.24 mGy), respectively. Radiation dose to the lungs ranged from 0.83 to 4.18 mGy. Lung doses correlated with CTDIvol, DLP and SSDE with correlation coefficients(k) at 0.98, 0.93, and 0.99. However, for the cases with CTDIvol less than 1mGy, only SSDE preserved a strong correlation with lung doses (k=0.83), while much weaker correlations were found for CTDIvol (k=0.29) and DLP (k=-0.47). Conclusion: Lung doses to pediatric patients during Cardiac CTA were estimated. SSDE showed the most robust correlation with lung doses in contrast to CTDIvol and DLP.

The Advantages of Two Dimensional Techniques (2D) in Pituitary Adenoma Treatment

The purpose of the study is to evaluate the two dimensional dose distribution techniques in pituitary adenoma patient treatment in order to provide 2D dose coverage to the target volume while sparing organs at risk (OARs). The CT simulator was used to radiograph 300 patients of pituitary adenomas to conform 2D dose distribution planning inside the tumour bed , and its structures were delineated; including gross target volume (GTV), clinical target volume (CTV), and planning target volume (PTV)), as well as organs at risks (OARs) . Dose distribution analysis was edited to provide 2D dose coverage to the target while sparing organs at risk. The main results of the study were, 2D dose distribution plans increases the unnecessary dose to the critical organs according to their geographical location from the pituitary adenoma site, and the present study , concludes that when the tumour dose increases from 45 to 55 Gy there is a linear proportional increment of dose to the organs at risks, and when the dose is about 60 Gy in 2D, the increment of unnecessary dose to temporal lobe is 0.31 Gy, and to eye is0.34Gy, and to optic chiasm is 0.42 Gy respectively .New techniques, which will lessen the unnecessary dose to OARs, needed to be developed .

SU‐E‐T‐355: A Novel Ophthalmic Applicator Design for Brachytherapy for Conjunctival Melanoma

Purpose: To design and construct a novel ophthalmic brachytherapy applicator for the treatment of conjunctival melanoma using I‐125 radioactive seed sources to overcome the dosimetric limitations of the commonly used standard Collaborative Ocular Melanoma Study (COMS) plaques. Methods: A commercially available polymethylmethacrylate conformer (Gulden Ophtalmics, Elkins Park, PA) was employed to hold a total of 12 low dose I‐125 seeds (model IAI‐125A, IsoAid, LLC, Port Richey, FL) distributed along the periphery of the conformer. Three dimensional dose distribution was calculated using the Plaque Simulator software (EyePhysics, LLC, Los Alamitos, CA) to optimize seed distribution pattern. The AAPM TG‐43 dose calculation formulism was utilized within the software. Results: The seed distribution pattern was designed in a way that dose would be delivered to the conjunctival tissue,while limiting the dose to the cornea and lens. Once the design was finalized, each slot for the seed was fabricated using a 6‐axis computer numerical control (CNC) machine available at our institution. The slots were milled into the convex side of the conformer to minimize any patient discomfort and to protect the cornea from direct contact with the seeds. Conclusion: The difficulty of treating conjunctival melanomas with COMS eyeplaques due to its unique anatomical distribution called for a custom design brachytherapy applicator. The applicator designed in the current study can effectively deliver radiation dose to affected area while minimizing the dose to the centrally located unaffected tissues.

SU-E-T-111: Estimation of Characteristics for Dose Distribution in Polymer Gel by Means of Monte Carlo Simulation

Purpose: To estimate the three dimensional dose distributions for proton, proton induced gamma rays and proton induced neutron particles, in case of exposing the proton beam to a polymer gel dosimeter and a water phantom. Methods: The polymer gel dosimeter was compositeness material of gelatin, methacrylic acid, hydroquinone, tetrakis and distilled water. The density of the gel dosimeter was 1.04g/cm3 which density was similar to water. The proton beam energies of 72 and 116 MeV were used in the simulation. Proton beam was directed to the top of a cylindrical phantom which radius was 5 cm and height was 12.2 cm for covering the proton Bragg‐peak (on X‐axis). The proton beam interacted with the nuclei of the phantom and the nuclei in excited states emitted prompt gamma rays and proton induced neutron particles during the process of de‐excitation. The proton particles, gamma prays and induced neutron were detected by the gel dosimeter and water phantom, respectively. The gap of the X‐axis was 2 mm. Results: The Bragg‐peak for proton particles in the gel dosimeter was similar to water phantom. The dose distribution for proton and prompt gamma rays in the gel dosimeter and water phantom was approximately identical in case of 72 and 116 MeV for proton beam. However, in case of proton induced neutron particles for 72 and 116 MeV proton beam, particles were not detected in the gel dosimeter, while the water phantom absorbed neutron. Conclusion: For the evaluation of proton dose distribution, the gel dosimeter was valuable tools for three dimensional measurements. This work indicates the evaluation for dose distribution of proton, induced gamma, and neutron in the gel dosimeter compared with the water phantom. Considering the Result data, the gel dosimeter which was developed in the normoxic state attentively detected the dose distribution for proton beam exposure except neutron particles.