Leaf Open Time Sinogram (LOTS): A novel approach for Patient specific quality assurance of Total marrow irradiation

Abstract There is no ideal detector-phantom combination to perform patient specific quality assurance (PSQA) for total marrow (TMI) and Lymphoid (TMLI) irradiation plan. In this study, 3D dose reconstruction using mega voltage computed tomography detectors measured leaf open time sinogram (LOTS) was investigated for PSQA of TMI/TMLI patients in helical tomotherapy. The feasibility of this method was first validated for ten non-TMI/TMLI patients, by comparing reconstructed dose with a) ion-chamber (IC) and helical detector array (ArcCheck) measurement and b) planned dose distribution using 3Dγ analysis for 3%@3mm and dose to 98%(D98%) and 2%(D2%) of PTVs. Same comparison was extended for ten treatment plans from five TMI/TMLI patients. In all non-TMI/TMLI patients, reconstructed absolute dose was within ±1.8% of planned and IC measurement. The planned dose distribution agrees with reconstructed and ArcCheck measured dose with mean(SD) 3Dγ of 98.7%(1.57%) and 2Dγ of 99.48%(0.81%). The deviation in D98% and D2% were within 1.71% and 4.1% respectively. In all 25 measurement locations from TMI/TMLI patients, planned and IC measured absolute dose agrees within ±1.2%. Although sectorial fluence verification using ArcCHECK measurement for PTVs chest from five upper body TMI/TMLI plans showed mean±SD 2Dγ of 97.82%±1.27%, the reconstruction method resulted poor mean(SD) 3Dγ of 92.00%(±5.83%), 64.80%(±28.28%), 69.20%(±30.46%), 60.80%(±19.37%) and 73.2% (±20.36%) for PTVs brain, chest, torso, limb and upper body respectively. The corresponding deviation in median D98% and D2% of all PTVs were <3.8% and 9.5%. Re-optimization of all upper body TMI/TMLI plans with new pitch and modulation factor of 0.3 and 3 leads significant improvement with 3Dγ of 100% for all PTVs and median D98% and D2% <1.6%. LOTS based PSQA for TMI/TMLI is accurate, robust and efficient. A field width, pitch and modulation factor of 5cm, 0.3 and 3 for upper body TMI/TMLI plan is suggested for better dosimetric outcome and PSQA results.

Download Full-text

Leaf Open Time Sinogram (LOTS): A novel approach for Patient specific quality assurance of Total marrow irradiation

10.21203/rs.3.rs-25426/v1 ◽

2020 ◽

Author(s):

Rajesh Thiyagarajan ◽

Dayananda Shamurailatpam Sharma ◽

Suryakant Kaushik ◽

Mayur Sawant ◽

Ganapathy Krishnan ◽

...

Keyword(s):

Quality Assurance ◽

Dose Distribution ◽

Upper Body ◽

Patient Specific ◽

Reconstruction Method ◽

Ion Chamber ◽

Modulation Factor ◽

Novel Approach ◽

Open Time ◽

Total Marrow Irradiation

Download Full-text

Leaf open time sinogram (LOTS): a novel approach for patient specific quality assurance of total marrow irradiation

Radiation Oncology ◽

10.1186/s13014-020-01669-2 ◽

2020 ◽

Vol 15 (1) ◽

Author(s):

Rajesh Thiyagarajan ◽

Dayananda Shamurailatpam Sharma ◽

Suryakant Kaushik ◽

Mayur Sawant ◽

K. Ganapathy ◽

...

Keyword(s):

Quality Assurance ◽

Dose Distribution ◽

Upper Body ◽

Patient Specific ◽

Reconstruction Method ◽

Ion Chamber ◽

Modulation Factor ◽

Novel Approach ◽

Open Time ◽

Total Marrow Irradiation

Abstract There is no ideal detector-phantom combination to perform patient specific quality assurance (PSQA) for Total Marrow (TMI) and Lymphoid (TMLI) Irradiation plan. In this study, 3D dose reconstruction using mega voltage computed tomography detectors measured Leaf Open Time Sinogram (LOTS) was investigated for PSQA of TMI/TMLI patients in helical tomotherapy. The feasibility of this method was first validated for ten non-TMI/TMLI patients, by comparing reconstructed dose with (a) ion-chamber (IC) and helical detector array (ArcCheck) measurement and (b) planned dose distribution using 3Dγ analysis for 3%@3mm and dose to 98% (D98%) and 2% (D2%) of PTVs. Same comparison was extended for ten treatment plans from five TMI/TMLI patients. In all non-TMI/TMLI patients, reconstructed absolute dose was within ± 1.80% of planned and IC measurement. The planned dose distribution agreed with reconstructed and ArcCheck measured dose with mean (SD) 3Dγ of 98.70% (1.57%) and 2Dγ of 99.48% (0.81%). The deviation in D98% and D2% were within 1.71% and 4.10% respectively. In all 25 measurement locations from TMI/TMLI patients, planned and IC measured absolute dose agreed within ± 1.20%. Although sectorial fluence verification using ArcCHECK measurement for PTVs chest from the five upper body TMI/TMLI plans showed mean ± SD 2Dγ of 97.82% ± 1.27%, the reconstruction method resulted poor mean (SD) 3Dγ of 92.00% (± 5.83%), 64.80% (± 28.28%), 69.20% (± 30.46%), 60.80% (± 19.37%) and 73.2% (± 20.36%) for PTVs brain, chest, torso, limb and upper body respectively. The corresponding deviation in median D98% and D2% of all PTVs were < 3.80% and 9.50%. Re-optimization of all upper body TMI/TMLI plans with new pitch and modulation factor of 0.3 and 3 leads significant improvement with 3Dγ of 100% for all PTVs and median D98% and D2% < 1.6%. LOTS based PSQA for TMI/TMLI is accurate, robust and efficient. A field width, pitch and modulation factor of 5 cm, 0.3 and 3 for upper body TMI/TMLI plan is suggested for better dosimetric outcome and PSQA results.

Download Full-text

Development of a time-resolved mirrorless scintillation detector

PLoS ONE ◽

10.1371/journal.pone.0246742 ◽

2021 ◽

Vol 16 (2) ◽

pp. e0246742

Author(s):

Wonjoong Cheon ◽

Hyunuk Jung ◽

Moonhee Lee ◽

Jinhyeop Lee ◽

Sung Jin Kim ◽

...

Keyword(s):

Quality Assurance ◽

Dose Rate ◽

Dose Distribution ◽

Scintillation Detector ◽

Image Sensor ◽

Geometric Distortion ◽

Patient Specific ◽

Rate Dependency ◽

Time Resolved ◽

Dose Profile

Purpose We developed a compact and lightweight time-resolved mirrorless scintillation detector (TRMLSD) employing image processing techniques and a convolutional neural network (CNN) for high-resolution two-dimensional (2D) dosimetry. Methods The TRMLSD comprises a camera and an inorganic scintillator plate without a mirror. The camera was installed at a certain angle from the horizontal plane to collect scintillation from the scintillator plate. The geometric distortion due to the absence of a mirror and camera lens was corrected using a projective transform. Variations in brightness due to the distance between the image sensor and each point on the scintillator plate and the inhomogeneity of the material constituting the scintillator were corrected using a 20.0 × 20.0 cm2 radiation field. Hot pixels were removed using a frame-based noise-reduction technique. Finally, a CNN-based 2D dose distribution deconvolution model was applied to compensate for the dose error in the penumbra region and a lack of backscatter. The linearity, reproducibility, dose rate dependency, and dose profile were tested for a 6 MV X-ray beam to verify dosimeter characteristics. Gamma analysis was performed for two simple and 10 clinical intensity-modulated radiation therapy (IMRT) plans. Results The dose linearity with brightness ranging from 0.0 cGy to 200.0 cGy was 0.9998 (R-squared value), and the root-mean-square error value was 1.010. For five consecutive measurements, the reproducibility was within 3% error, and the dose rate dependency was within 1%. The depth dose distribution and lateral dose profile coincided with the ionization chamber data with a 1% mean error. In 2D dosimetry for IMRT plans, the mean gamma passing rates with a 3%/3 mm gamma criterion for the two simple and ten clinical IMRT plans were 96.77% and 95.75%, respectively. Conclusion The verified accuracy and time-resolved characteristics of the dosimeter may be useful for the quality assurance of machines and patient-specific quality assurance for clinical step-and-shoot IMRT plans.

Download Full-text

Evaluation of Delta4DVH Anatomy in 3D Patient-Specific IMRT Quality Assurance

Technology in Cancer Research & Treatment ◽

10.1177/1533033820945816 ◽

2020 ◽

Vol 19 ◽

pp. 153303382094581

Author(s):

Du Tang ◽

Zhen Yang ◽

Xunzhang Dai ◽

Ying Cao

Keyword(s):

Quality Assurance ◽

Treatment Planning ◽

Treatment Plan ◽

Planning System ◽

Treatment Planning System ◽

Patient Specific ◽

Pencil Beam ◽

Ion Chamber ◽

Passing Rate ◽

Gamma Passing Rate

Purpose: To evaluate the performance of Delta4DVH Anatomy in patient-specific intensity-modulated radiotherapy quality assurance. Materials and Methods: Dose comparisons were performed between Anatomy doses calculated with treatment plan dose measured modification and pencil beam algorithms, treatment planning system doses, film doses, and ion chamber measured doses in homogeneous and inhomogeneous geometries. The sensitivity of Anatomy doses to machine errors and output calibration errors was also investigated. Results: For a Volumetric Modulated Arc Therapy (VMAT) plan evaluated on the Delta4 geometry, the conventional gamma passing rate was 99.6%. For a water-equivalent slab geometry, good agreements were found between dose profiles in film, treatment planning system, and Anatomy treatment plan dose measured modification and pencil beam calculations. Gamma passing rate for Anatomy treatment plan dose measured modification and pencil beam doses versus treatment planning system doses was 100%. However, gamma passing rate dropped to 97.2% and 96% for treatment plan dose measured modification and pencil beam calculations in inhomogeneous head & neck phantom, respectively. For the 10 patients’ quality assurance plans, good agreements were found between ion chamber measured doses and the planned ones (deviation: 0.09% ± 1.17%). The averaged gamma passing rate for conventional and Anatomy treatment plan dose measured modification and pencil beam gamma analyses in Delta4 geometry was 99.6% ± 0.89%, 98.54% ± 1.60%, and 98.95% ± 1.27%, respectively, higher than averaged gamma passing rate of 97.75% ± 1.23% and 93.04% ± 2.69% for treatment plan dose measured modification and pencil beam in patients’ geometries, respectively. Anatomy treatment plan dose measured modification dose profiles agreed well with those in treatment planning system for both Delta4 and patients’ geometries, while pencil beam doses demonstrated substantial disagreement in patients’ geometries when compared to treatment planning system doses. Both treatment planning system doses are sensitive to multileaf collimator and monitor unit (MU) errors for high and medium dose metrics but not sensitive to the gantry and collimator rotation error smaller than 3°. Conclusions: The new Delta4DVH Anatomy with treatment plan dose measured modification algorithm is a useful tool for the anatomy-based patient-specific quality assurance. Cautions should be taken when using pencil beam algorithm due to its limitations in handling heterogeneity and in high-dose gradient regions.

Download Full-text

Patient-specific quality assurance for proton depth dose distribution using a multi-layer ionization chamber in a single-ring wobbling method

Radiological Physics and Technology ◽

10.1007/s12194-019-00524-8 ◽

2019 ◽

Vol 12 (3) ◽

pp. 305-311 ◽

Cited By ~ 1

Author(s):

Takahiro Kato ◽

Kazuhiro Arai ◽

Tatsuhiko Sagara ◽

Ryohei Kato ◽

Yuhei Yamazaki ◽

...

Keyword(s):

Quality Assurance ◽

Dose Distribution ◽

Ionization Chamber ◽

Patient Specific ◽

Depth Dose ◽

Single Ring ◽

Depth Dose Distribution

Download Full-text

A management method for the statistical results of patient-specific quality assurance for intensity-modulated radiation therapy

Journal of Radiation Research ◽

10.1093/jrr/rrw107 ◽

2016 ◽

Vol 58 (4) ◽

pp. 572-578

Author(s):

Satoshi Nakamura ◽

Hiroyuki Okamoto ◽

Akihisa Wakita ◽

Rei Umezawa ◽

Kana Takahashi ◽

...

Keyword(s):

Quality Assurance ◽

Intensity Modulated Radiation Therapy ◽

Tolerance Limit ◽

Patient Specific ◽

Ion Chamber ◽

Intensity Modulated ◽

Patient Specific Qa ◽

Management Method ◽

Statistical Results ◽

Dose Difference

Abstract There are many reports concerning patient-specific quality assurance (QA) for intensity-modulated radiation therapy (IMRT). However, reports about the statistical results of QA are lacking. Management methods for the results of the QA are needed, even though we have the ESTRO group recommendation that a tolerance limit of 1.96 standard deviation (SD) be established in each institution. The purpose of this study was to establish a management method for determining the tolerance limit and to report the statistical results of patient-specific QA. From April 2006 to March 2015, five linacs in the National Cancer Center, Tokyo, Japan, were used to treat 1185 patients with IMRT. Patient-specific QA was performed using an ion chamber, films, and some detectors. To establish a management method for the results, differences between the measured and calculated doses in the ion chamber were analyzed for each linac, each phantom, and each treatment site. The overall mean dose difference was 0.5 ± 1.3%, and the mean dose difference in each linac was 0.6 ± 1.2%, 0.9 ± 1.3%, −0.4 ± 1.4%, −0.1 ± 1.2% and −0.1 ± 0.9%. The difference between linacs and between treatment sites was significant (P < 0.001 and 0.01, respectively). The proportion of the dose difference within ±3% was 97.7%, and that was improved from 2006 to 2014. The results of the patient-specific QA should be managed for each linac and each treatment site in order to decide the suitable tolerance limit. Reports of statistical results will be helped if a new tolerance limit and action level will be considered.

Download Full-text