Estimation of patient-specific imaging dose for real-time tumour monitoring in lung patients during respiratory-gated radiotherapy

Shiinoki, Takehiro; Onizuka, Ryota; Kawahara, Daisuke; Suzuki, Tatsuro; Yuasa, Yuki; Fujimoto, Kiyoshige; Uehara, Takuya; Hanazawa, Hideki; Shibuya, Kazuhiko

doi:10.1088/1361-6560/aab242

Cited by 9 publications

(8 citation statements)

References 26 publications

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“…Onimaru et al. reported that the PTV dose increases by 1.9% due to the radiation exposure caused by tracking during radiation using SyncTraX [ 28 ]. When converted to whole breast irradiation, the radiation exposure was calculated as approximately 90 mGy.…”

Section: Discussionmentioning

confidence: 99%

Development of deep-inspiration breath-hold system that monitors the position of the chest wall using infrared rangefinder

Oshima

Shikama

Usui

et al. 2022

Journal of Radiation Research

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We conducted a prospective study to quantitatively evaluate the movement of the chest wall to establish the simple and reproducible deep-inspiration breath-hold (DIBH) method. The left nipple position was monitored to confirm the inspiratory state. Planning computed tomography (CT) was performed under DIBH and free-breath. We conducted radiation plans with DIBH and free-breath CT and evaluated organ at risk (OAR) and target doses according to two different plans. The relationship between positioning errors of the chest wall and patient factors was evaluated using univariate analysis and fixed-effects models. Twenty-three patients aged ≤ 60 years were enrolled during January–August 2021; 358 daily radiation treatments were evaluated. The median time of treatment room occupancy was 16 minutes (interquartile range, 14–20). The area of the planning target volume (PTV) surrounded by the 95% isodose line was more extensive in DIBH than in free breathing (71.6% vs 69.5%, P < 0.01), whereas the cardiac and left anterior descending (LAD) artery doses were lower (both P < 0.01). In the fixed-effects model analysis, the occupation time of the treatment room was correlated with positioning error. The difference between the planned and irradiated dose was the largest in the LAD branch of the coronary artery (−2.5 Gy), although the OAR dose decreased owing to positional error. The current DIBH method, wherein a single point on the chest wall is monitored to confirm that the patient is in an inspiratory state, allows radiation to be performed in a short time with a small dose error.

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Section: Discussionmentioning

confidence: 99%

Development of deep-inspiration breath-hold system that monitors the position of the chest wall using infrared rangefinder

Oshima

Shikama

Usui

et al. 2022

Journal of Radiation Research

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“…In this case the validated MC simulation could be advantageous and used to obtain patient specific 3D dose to estimate the target and OARs dose received from both treatment and continuous intra-fraction imaging. Imaging dose for these applications may need to be included in treatment planning systems for planning optimizations to deliver correct dose to target while sparing normal tissues (Ding et al 2018, Shiinoki et al 2018. The dose values are plotted for all available kVps in figure 10 from 60 kVp to 140 kVp, since the clinical protocols in table 1 do not include all available kVps.…”

Section: Discussionmentioning

confidence: 99%

Comprehensive characterization of ExacTrac stereoscopic image guidance system using Monte Carlo and Spektr simulations

Darvish-Molla¹,

Spurway²,

Sattarivand³

2020

Phys. Med. Biol.

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The purpose of this work is to develop accurate computational methods to comprehensively characterize and model the clinical ExacTrac imaging system, which is used as an image guidance system for stereotactic treatment applications. The Spektr toolkit was utilized to simulate the spectral and imaging characterization of the system. Since Spektr only simulates the primary beam (ignoring scatter), a full model of ExacTrac was also developed in Monte Carlo (MC) to characterize the imaging system. To ensure proper performance of both simulation models, Spektr and MC data were compared to the measured spectral and half value layers (HVLs) values. To validate the simulation results, x-ray spectra of the ExacTrac system were measured for various tube potentials using a CdTe spectrometer with multiple added narrow collimators. The raw spectra were calibrated using a 57Co source and corrected for the escape peaks and detector efficiency. HVLs in mm of Al for various energies were measured using a calibrated RaySafe detector. Spektr and MC HVLs were calculated and compared to the measured values. The patient surface dose was calculated for different clinical imaging protocols from the measured air kerma and HVL values following the TG-61 methodology. The x-ray focal spot was measured by slanted edge technique using gafchromic films. ExacTrac imaging system beam profiles were simulated for various energies by MC simulation and the results were benchmarked by experimentally acquired beam profiles using gafchromic films. The effect of 6D IGRT treatment couch on beam hardening, dynamic range of the flat panel detector and scatter effect were determined using both Spektr simulation and experimental measurements. The measured and simulated spectra (of both MC and Spektr) for various kVps were compared and agreed within acceptable error. As another validation, the measured HVLs agreed with the Spektr and MC simulated HVLs on average within 1.0% for all kVps. The maximum and minimum patient surface doses were found to be 1.06 mGy for shoulder (high) and 0.051 mGy for cranial (low) imaging protocols, respectively. The MC simulated beam profiles were well matched with experimental results and replicated the penumbral slopes, the heel effect, and out-of-field regions. Dynamic range of detector (in terms of air kerma at detector surface) was found to be in the range of [6.1 × 10−6, 5.3 × 10−3] mGy. Accurate MC and Spektr models of the ExacTrac image guidance system were successfully developed and benchmarked via experimental validation. While patient surface dose for available imaging protocols were reported in this study, the established MC model may be used to obtain 3D imaging dose distribution for real patient geometries.

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“…Although it has been reported that the imaging dose for IGRT is smaller than that for treatment, its impact to normal tissue is not negligible . The imaging dose of IGRT devices has been reported previouly . In particular, the imaging dose for CBCT acquisition is larger than that for other imaging devices.…”

Section: Introductionmentioning

confidence: 99%

Estimation of effective imaging dose and excess absolute risk of secondary cancer incidence for four‐dimensional cone‐beam computed tomography acquisition

Yuasa

Shiinoki

Onizuka

et al. 2019

J Applied Clin Med Phys

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This study was conducted to estimate the organ equivalent dose and effective imaging dose for four‐dimensional cone‐beam computed tomography (4D‐CBCT) using a Monte Carlo simulation, and to evaluate the excess absolute risk (EAR) of secondary cancer incidence. The EGSnrc/BEAMnrc were used to simulate the on‐board imager (OBI) from the TrueBeam linear accelerator. Specifically, the OBI was modeled based on the percent depth dose and the off‐center ratio was measured using a three‐dimensional (3D) water phantom. For clinical cases, 15 lung and liver cancer patients were simulated using the EGSnrc/DOSXYZnrc. The mean absorbed doses to the lung, stomach, bone marrow, esophagus, liver, thyroid, bone surface, skin, adrenal glands, gallbladder, heart, intestine, kidney, pancreas and spleen, were quantified using a treatment planning system, and the equivalent doses to each organ were calculated. Subsequently, the effective dose was calculated as the weighted sum of the equivalent dose, and the EAR of the secondary cancer incidence was determined for each organ with the use of the biologic effects of ionizing radiation (BEIR) VII model. The effective doses were 3.9 ± 0.5, 15.7 ± 2.0, and 7.3 ± 0.9 mSv, for the lung, and 4.2 ± 0.6, 16.7 ± 2.4, and 7.8 ± 1.1 mSv, for the liver in the respective cases of the 3D‐CBCT (thorax, pelvis) and 4D‐CBCT modes. The lung EARs for males and females were 7.3 and 10.7 cases per million person‐years, whereas the liver EARs were 9.9 and 4.5 cases per million person‐years. The EAR increased with increasing time since radiation exposure. In clinical studies, we should use 4D‐CBCT based on consideration of the effective dose and EAR of secondary cancer incidence.

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Estimation of patient-specific imaging dose for real-time tumour monitoring in lung patients during respiratory-gated radiotherapy

Cited by 9 publications

References 26 publications

Development of deep-inspiration breath-hold system that monitors the position of the chest wall using infrared rangefinder

Development of deep-inspiration breath-hold system that monitors the position of the chest wall using infrared rangefinder

Comprehensive characterization of ExacTrac stereoscopic image guidance system using Monte Carlo and Spektr simulations

Estimation of effective imaging dose and excess absolute risk of secondary cancer incidence for four‐dimensional cone‐beam computed tomography acquisition

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