SU-E-T-196: Comparative Analysis of Surface Dose Measurements Using MOSFET Detector and Dose Predicted by Eclipse - AAA with Varying Dose Calculation Grid Size

2015 ◽  
Vol 42 (6Part15) ◽  
pp. 3377-3377
Author(s):  
R Badkul ◽  
S Nejaiman ◽  
D Pokhrel ◽  
H Jiang ◽  
P Kumar
Keyword(s):  
Comparative Analysis ◽  
Dose Calculation ◽  
Grid Size ◽  
Surface Dose ◽  
Mosfet Detector ◽  
Dose Measurements ◽  
Calculation Grid

scholarly journals Study on the ability of the three-dose-volume-histogram-gamma (3DVH-γ) analysis and bio-mathematical model in detecting dose changes caused by dose-calculation-grid-size (DCGS)

2020 ◽  
Author(s):  
Han Bai ◽  
Sijin Zhu ◽  
Xingrao Wu ◽  
Xuhong Liu ◽  
Feihu Chen ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Cervical Cancer ◽  
Dose Distribution ◽  
Measurement Data ◽  
Dose Calculation ◽  
Grid Size ◽  
Dose Effect ◽  
P Value ◽  
Data Set ◽  
Calculation Grid

Abstract Objective : To explore the efficacy and sensitivity of 3DVH-γanalysis and bio-mathematical model for cervical cancer in detecting dose changes caused by dose-calculation-grid-size(DCGS). Methods： 17 patients’ plans for cervical cancer were enrolled（Pinnacle TPS，VMAT）, and the DCGS was changed from 2.0mm to 5.0mm to calculate the planned dose respectively. The dose distribution calculated by DCGS = 2.0mm as the “ reference ” data set (RDS) , the dose distribution calculated by the rest DCGS as the“measurement”data set (MDS), the 3DVH-γ passing rates and the (N)TCPs of the all structures under different DCGS were obtained , and then analyze the ability of 3DVH-γ analysis and (N)TCP model in detecting dose changes and what factors affect this ability. Results: The effect of DCGS on planned dose was obvious. When the γ-standard was 1.0mm, 1.0% and 10.0%, the difference of the results of the DCGS on dose-effect could be detected by 3DVH-γ analysis ( p s<0.05). With the decline of the standard, 3DVH-γ analysis’ ability to detect this difference shows weaker. When the standard was 1.0mm, 3.0% and 10.0%, the p value of >0.05 accounted for the majority. With DCGS=2.0mm being RDS, ∆γ-passing-rate presented the same trend with ∆(N)TCPs of all structures except for the femurs only when the 1.0mm, 1.0% and 10.0% standards were adopted for the 3DVH-γ analysis. Conclusions: The 3DVH-γ analysis and bio-mathematical model can be used to analyze the effect of DCGS on the planned dose. For comparison, the former’s detection ability has a lot to do with the designed standard, and the latter’s capability is related to the parameters and calculated accuracy instrinsically.

Evaluation of Dose Volume and Radiobiological Indices by the Dose Calculation Grid Size in Nasopharyngeal Cancer VMAT

2020 ◽  
Vol 43 (4) ◽  
pp. 265-272
Author(s):  
Dong-Jin Kang ◽  
◽  
Jae-Yong Jung ◽  
Young-Joo Shin ◽  
Jung-Whan Min ◽  
...  
Keyword(s):  
Nasopharyngeal Cancer ◽  
Dose Calculation ◽  
Grid Size ◽  
Dose Volume ◽  
Calculation Grid

scholarly journals Study on the ability of 3D gamma analysis and bio-mathematical model in detecting dose changes caused by dose-calculation-grid-size (DCGS)

2020 ◽  
Author(s):  
Han Bai ◽  
Sijin Zhu ◽  
Xingrao Wu ◽  
Xuhong Liu ◽  
Feihu Chen ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Cervical Cancer ◽  
Dose Distribution ◽  
Measurement Data ◽  
Dose Calculation ◽  
Grid Size ◽  
Dose Effect ◽  
Data Set ◽  
Gamma Analysis ◽  
Calculation Grid

Abstract Objective: To explore the efficacy and sensitivity of 3D gamma analysis and bio-mathematical model for cervical cancer in detecting dose changes caused by dose-calculation-grid-size (DCGS).Methods：17 patients’ plans for cervical cancer were enrolled (Pinnacle TPS，VMAT), and the DCGS was changed from 2.0mm to 5.0mm to calculate the planned dose respectively. The dose distribution calculated by DCGS = 2.0mm as the “reference” data set (RDS), the dose distribution calculated by the rest DCGS as the“measurement”data set (MDS), the 3D gamma passing rates and the (N)TCPs of the all structures under different DCGS were obtained, and then analyze the ability of 3D gamma analysis and (N)TCP model in detecting dose changes and what factors affect this ability.Results: The effect of DCGS on planned dose was obvious. When the gamma standard was 1.0mm, 1.0% and 10.0%, the difference of the results of the DCGS on dose-effect could be detected by 3D gamma analysis (all p value < 0.05). With the decline of the standard, 3D gamma analysis’ ability to detect this difference shows weaker. When the standard was 1.0mm, 3.0% and 10.0%, the p value of > 0.05 accounted for the majority. With DCGS=2.0mm being RDS, ∆gamma-passing-rate presented the same trend with ∆(N)TCPs of all structures except for the femurs only when the 1.0mm, 1.0% and 10.0% standards were adopted for the 3D gamma analysis.Conclusions: The 3D gamma analysis and bio-mathematical model can be used to analyze the effect of DCGS on the planned dose. For comparison, the former’s detection ability has a lot to do with the designed standard, and the latter’s capability is related to the parameters and calculated accuracy instrinsically.

scholarly journals Surface and Buildup Region Dose Measurements with Markus Parallel-Plate Ionization Chamber, GafChromic EBT3 Film, and MOSFET Detector for High-Energy Photon Beams

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Ugur Akbas ◽  
Nazmiye Donmez Kesen ◽  
Canan Koksal ◽  
Hatice Bilge
Keyword(s):  
Ionization Chamber ◽  
Parallel Plate ◽  
Incident Radiation ◽  
High Energy ◽  
Field Size ◽  
Surface Dose ◽  
Photon Beams ◽  
Radiation Beam ◽  
Mosfet Detector ◽  
Dose Measurements

The aim of the study was to investigate surface and buildup region doses for 6 MV and 15 MV photon beams using a Markus parallel-plate ionization chamber, GafChromic EBT3 film, and MOSFET detector for different field sizes and beam angles. The measurements were made in a water equivalent solid phantom at the surface and in the buildup region of the 6 MV and 15 MV photon beams at 100 cm source-detector distance for 5 × 5, 10 × 10, and 20 × 20 cm2field sizes and 0°, 30°, 60°, and 80° beam angles. The surface doses using 6 MV photon beams for 10 × 10 cm2field size were found to be 20.3%, 18.8%, and 25.5% for Markus chamber, EBT3 film, and MOSFET detector, respectively. The surface doses using 15 MV photon beams for 10 × 10 cm2field size were found to be 14.9%, 13.4%, and 16.4% for Markus chamber, EBT3 film, and MOSFET detector, respectively. The surface dose increased with field size for all dosimeters. As the angle of the incident radiation beam became more oblique, the surface dose increased. The effective measurement depths of dosimeters vary; thus, the results of the measurements could be different. This issue can lead to mistakes at surface and buildup dosimetry and must be taken into account.

Dosimetric effects of dose calculation grid size on the epidural space dose

2020 ◽  
Vol 45 (4) ◽  
pp. 327-333
Author(s):  
Hidetoshi Shimizu ◽  
Koji Sasaki ◽  
Hiroshi Tanaka ◽  
Takahiro Aoyama ◽  
Hiroyuki Tachibana ◽  
...  
Keyword(s):  
Epidural Space ◽  
Dose Calculation ◽  
Grid Size ◽  
Calculation Grid

scholarly journals Rectal and Bladder Dose Measurements in the Intracavitary Applications of Cervical Cancer Treatment with HDR Afterloading System: Comparison of TPS Data with MOSFET Detector

2019 ◽  
Author(s):  
N Singh ◽  
Sh Ahamed ◽  
A Sinha ◽  
Sh Srivastava ◽  
N K Painuly ◽  
...  
Keyword(s):  
High Dose Rate ◽  
In Vivo Dosimetry ◽  
Intracavitary Brachytherapy ◽  
High Dose ◽  
Gradient Fields ◽  
Calculated Dose ◽  
Mosfet Detector ◽  
Dose Measurements

Background: Intracavitary brachytherapy plays a major role in management of cervical carcinoma. Assessment of dose received by OAR’s therefore becomes crucial for the estimation of radiation toxicities in high dose rate brachytherapy.Objective: The purpose of this study is to evaluate the role of in vivo dosimetry in HDR brachytherapy and to compare the actual doses delivered to OAR’s with those calculated during treatment planning.Materials and Methods: A total of 50 patients were treated with Microselectron HDR. Out of 50 patients, 26 were treated with a dose of 7 Gy and 24 with a dose of 9 Gy, prescribed to point A. Brachytherapy planning and evaluation of dose to the bladder and rectum was done on TPS & in vivo dosimetry was performed using portable MOSFET.Results: The calibration factors calculated for both the dosimeters are almost equal and are 0.984 cGy/mV and 1.0895 cGy/mV. For bladder, dose deviation was found to be within +/- 5% in 28 patients, +/- 5-10% in 14 patients, +/- 10-15% in 4 patients. The deviation between the TPS-calculated dose and the dose measured by MOSFET for rectum was within +/- 5% in 31 patients, +/- 5–10% in 8 patients, and +/- 10–15% in 7 patients.Conclusion: TPS calculated doses were slightly higher than that measured by MOSFET. The use of a small size of MOSFET dosimeter is an efficient method for accurately measuring doses in high-dose gradient fields typically seen in brachytherapy. Therefore, to reduce risk of large errors in the dose delivery, in vivo dosimetry can be done in addition to TPS computations.

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