• Title, Summary, Keyword: dose calculation

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Optimal Density Assignment to 2D Diode Array Detector for Different Dose Calculation Algorithms in Patient Specific VMAT QA

  • Park, So-Yeon;Park, Jong Min;Choi, Chang Heon;Chun, Minsoo;Han, Ji Hye;Cho, Jin Dong;Kim, Jung-in
    • Journal of Radiation Protection and Research
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    • v.42 no.1
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    • pp.9-15
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    • 2017
  • Background: The purpose of this study is to assign an appropriate density to virtual phantom for 2D diode array detector with different dose calculation algorithms to guarantee the accuracy of patient-specific QA. Materials and Methods: Ten VMAT plans with 6 MV photon beam and ten VMAT plans with 15 MV photon beam were selected retrospectively. The computed tomography (CT) images of MapCHECK2 with MapPHAN were acquired to design the virtual phantom images. For all plans, dose distributions were calculated for the virtual phantoms with four different materials by AAA and AXB algorithms. The four materials were polystyrene, 455 HU, Jursinic phantom, and PVC. Passing rates for several gamma criteria were calculated by comparing the measured dose distribution with calculated dose distributions of four materials. Results and Discussion: For validation of AXB modeling in clinic, the mean percentages of agreement in the cases of dose difference criteria of 1.0% and 2.0% for 6 MV were $97.2%{\pm}2.3%$, and $99.4%{\pm}1.1%$, respectively while those for 15 MV were $98.5%{\pm}0.85%$ and $99.8%{\pm}0.2%$, respectively. In the case of 2%/2 mm, all mean passing rates were more than 96.0% and 97.2% for 6 MV and 15 MV, respectively, regardless of the virtual phantoms of different materials and dose calculation algorithms. The passing rates in all criteria slightly increased for AXB as well as AAA when using 455 HU rather than polystyrene. Conclusion: The virtual phantom which had a 455 HU values showed high passing rates for all gamma criteria. To guarantee the accuracy of patent-specific VMAT QA, each institution should fine-tune the mass density or HU values of this device.

Quality Assurance on Dose Distribution of Ir-192 Line Source (Ir-192 선 선원의 선량분포에 관한 품질보증)

  • Kim, Jong-Eon
    • Journal of radiological science and technology
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    • v.30 no.1
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    • pp.33-38
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    • 2007
  • The propose of this study is a verification of the correct calculation of the dose around source and the prescription dose of Ir-192 source in the plato treatment planning system. The source and orthogonal coordinates for lateral direction and those for the anterior posterior direction were drawn on a A4 paper and then input into the system. The prescription dose was prescribed to two points with radius 1 cm in the direction of polar angle $90^{\circ} and $270^{\circ} from the center of the source. The doses of prescription point and dose points acquired from the treatment planning system were compared with those from manual calculation using the geometry function formalism derived by Paul King et al. In this analysis, the doses of prescription point were exactly consistent with each other and those of dose points were obtained within the error point of 1.85%. And the system of accuracy was evaluated within 2% of tolerance error. Therefore, this manual dose calculation used for the geometry function formalism is considered to be useful in clinics due to its convenience and high quality assurance.

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AN ASSESSMENT OF THE RADIATION DOSE RATE DUE TO AN OCCURRENCE OF THE DEFECT ON THE SPENT NUCLEAR FUEL ROD

  • Lee, Sang-Hun;Moon, Joo-Hyun
    • Journal of Radiation Protection and Research
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    • v.34 no.3
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    • pp.144-150
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    • 2009
  • This study examines how much the radiation dose rate around it varies if a crack occurs on the spent nuclear fuel rod. The spent nuclear fuel rod to be examined is that of Kori unit 3&4. The source terms are evaluated using the ORIGEN-ARP that is part of the version 5.1 of the SCALE package. The radiation dose rate is assessed using the TORT. To check if the structure of a fuel rod is appropriately modeled in the TORT calculation, the calculation results by the TORT are compared with those by the ANISN for the same case. From the code simulation, it is known that if a crack occurs on the spent nuclear fuel rod, the neutron dose rate varies depending on what material is the crack filled with, but the gamma dose rate varies irrespective of type of the material that the crack is filled with.

The patient dose calculation model on the Exell program (촬영조건에 의한 환자 피폭선량의 자동계산 프로그램)

  • Kim, Jung-Min;Seok, Jin-Yong
    • Journal of radiological science and technology
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    • v.25 no.2
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    • pp.35-38
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    • 2002
  • Recently, They are usually recording the patient information on the Hospital Information System. In the department of Radiology, For the purpose of assuming patient exposed dose, Authors contrived the mathematical calculation model by use of x-ray out put data on the Excel program, if they in put the exposure factors (kVp, mAs, thickness), the program could automatically calculate the patient Skin dose. The assuming data by three dimensional equation has average errors within ${\pm}5%$, there for We could make good use of clinical field in department of radiology.

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Dosimetric Effects of Low Dose 4D CT Using a Commercial Iterative Reconstruction on Dose Calculation in Radiation Treatment Planning: A Phantom Study

  • Kim, Hee Jung;Park, Sung Yong;Park, Young Hee;Chang, Ah Ram
    • Progress in Medical Physics
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    • v.28 no.1
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    • pp.27-32
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    • 2017
  • We investigated the effect of a commercial iterative reconstruction technique (iDose, Philips) on the image quality and the dose calculation for the treatment plan. Using the electron density phantom, the 3D CT images with five different protocols (50, 100, 200, 350 and 400 mAs) were obtained. Additionally, the acquired data was reconstructed using the iDose with level 5. A lung phantom was used to acquire the 4D CT with the default protocol as a reference and the low dose (one third of the default protocol) 4D CT using the iDose for the spine and lung plans. When applying the iDose at the same mAs, the mean HU value was changed up to 85 HU. Although the 1 SD was increased with reducing the CT dose, it was decreased up to 4 HU due to the use of iDose. When using the low dose 4D CT with iDose, the dose change relative to the reference was less than 0.5% for the target and OARs in the spine plan. It was also less than 1.1% in the lung plan. Therefore, our results suggests that this dose reduction technique is applicable to the 4D CT image acquisition for the radiation treatment planning.

A Study on Measurement of Output Dose in X-ray Unit (X-선장치에서 출력선량 측정에 관한 연구)

  • Kim, Jong Eon;Lee, Sang Hun
    • Journal of the Korean Society of Radiology
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    • v.14 no.3
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    • pp.289-294
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    • 2020
  • In order to control the quality of X-ray images and patient exposure, it is necessary to document the output dose(air absorption dose(mGy)) output from the X-ray unit from the measurement. The purpose of this study is to find an equation that can calculate the output dose from the measurement of the output dose and output factor(Of) of the X-ray Unit. The output dose and output factors of the X-beam irradiated from the X-ray unit were measured using an XR multi-detector. The output dose calculation formula was obtained by fitting the measured output dose divided by the tube current-exposure time product(mAs) and the set tube voltage with Allometric1. The final output dose calculation formula was obtained by multiplying this formula with the output factor. It is considered that the obtained final output dose calculation formula will be useful for all tube voltages, tube currents, exposure times, field sizes, and distances.

Improvement of the Dose Calculation Accuracy Using MVCBCT Image Processing (Megavoltage Cone-Beam CT 영상의 변환을 이용한 선량 계산의 정확성 향상)

  • Kim, Min-Joo;Cho, Woong;Kang, Young-Nam;Suh, Tae-Suk
    • Progress in Medical Physics
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    • v.23 no.1
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    • pp.62-69
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    • 2012
  • The dose re-calculation process using Megavoltage cone-beam CT images is inevitable process to perform the Adaptive Radiation Therapy (ART). The purpose of this study is to improve dose re-calculation accuracy using MVCBCT images by applying intensity calibration method and three dimensional rigid body transform and filtering process. The three dimensional rigid body transform and Gaussian smoothing filtering process to MVCBCT Rando phantom images was applied to reduce image orientation error and the noise of the MVCBCT images. Then, to obtain the predefined modification level for intensity calibration, the cheese phantom images from kilo-voltage CT (kV CT), MVCBCT was acquired. From these cheese phantom images, the calibration table for MVCBCT images was defined from the relationship between Hounsfield Units (HUs) of kV CT and MVCBCT images at the same electron density plugs. The intensity of MVCBCT images from Rando phantom was calibrated using the predefined modification level as discussed above to have the intensity of the kV CT images to make the two images have the same intensity range as if they were obtained from the same modality. Finally, the dose calculation using kV CT, MVCBCT with/without intensity calibration was applied using radiation treatment planning system. As a result, the percentage difference of dose distributions between dose calculation based on kVCT and MVCBCT with intensity calibration was reduced comparing to the percentage difference of dose distribution between dose calculation based on kVCT and MVCBCT without intensity calibration. For head and neck, lung images, the percentage difference between kV CT and non-calibrated MVCBCT images was 1.08%, 2.44%, respectively. In summary, our method has quantitatively improved the accuracy of dose calculation and could be a useful solution to enhance the dose calculation accuracy using MVCBCT images.

A Study on Dose Calculation in Intracavitary Radiotherapy of the Carcinoma of the Uterine Cervix with TAO Applicator (TAO Applicator를 이용한 자궁경암 강내조사시의 선양계산에 관한 고찰)

  • Kim, Chul-Soo;Kim, Jung-Jin
    • Radiation Oncology Journal
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    • v.2 no.1
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    • pp.101-106
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    • 1984
  • Various methods are available for determination of exposure time in intracavitary radiotherapy of the carcinoma of the uterine cervix. To determine the accuracy of dose calculation with isodose curve for TAO applicator, comparison with results calculated by computer for radiotherapy treatment Planning was done in 24 procedures done in 12 consecutive patients with the carcinoma of the uterine cervix from May to December, 1983. The results are as follows: 1. The average dose rate Per hour of Point A was 87.70 rad, being 89.91 rad ana 85.49 rad in left and right, respectively. 2. The average percentage of dose rate of point A calculated by isodose curve method over that by computer was $101.28\%$ and the difference was less than $5\%$ in 17 Procedures and over $10\%$ in only 3 procedures. 3. The average percentage in case of point B was $108.67\%$. In conclusion, in most cases the difference was less than 200 rad for point A and less than 100 rad for point B during 2 courses of intracavitary radiotherapy. And so the dose rate calculation with isodose curve for TAO applicator is comparatively accurate.

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Safety Assessment of Nuclear Waste Incineration Process by Estimating Radiation Dose of Workers and Residential Individuals (원자력폐기물 소각공정에서의 작업자 및 인근주민의 피폭선량에 따른 안전성 평가)

  • 서용칠
    • Journal of the Korean Society of Safety
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    • v.8 no.4
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    • pp.165-174
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    • 1993
  • For the safety assessment of the demonstration-scale incineration plant for treating the combustible radioactive wastes, radiation doses of a worker and a residential individual were estimated. The demonstration plant showed a good performance of trial-burn tests using non-radioactive tracers with resulting In high mass reduction of around 40 times and very low emmission of dusts through a stack, which promised a high decontamination factor in an order of 10$^{7}$ . Based on the result s obtained from the trial-burns in the process, the estimation of radiation dose for workers and general publics near the plant was made using dose pathway calculation theories. The parametric values for calculation were selected from design and operational results of the process and from more conservative conditions In reference data. The estimated annual doses for workers and residential indivisuals were 3.07 $\times$ 10$^{-4}$ and 4.35 X 10$^{-8}$ $\mu$Sv/y, respectively, which were high enough to operate the process when comparing with the allowable dose limit in the regulation. The dose calculation models were quite applicable with showing an excellent safety for the process.

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