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Stereotactic radiosurgery (SRS) using the single-isocenter-multiple-target (SIMT) technique by volumetric modulated arc therapy is increasingly popular for treating multiple brain metastases. However, the complex nature of SIMT SRS necessitates rigorous patient-specific quality assurance (PSQA). This study presents a multi-institutional dosimetric commissioning of a high-resolution complementary metal oxide semiconductor (CMOS) 2D detector array, the myQA SRS device for SIMT SRS PSQA. Basic dosimetric properties such as dose-rate, field-size, energy and angular dependencies were characterized for the CMOS detectors. Additionally, gamma index analyses were performed between the measured dose and the films for nine simulated and clinical plans. The results showed that the CMOS detector was dose-rate, field-size, energy and beam-angle dependent. Specific to SIMT SRS, angular dependence on gantry rotations was invariant to couch rotations but was sensitive to off-isocenter distances. With appropriate dose calibration and angular corrections, myQA SRS showed a high dosimetric correlation with films. The average gamma index pass rates were 99.9 ± 0.03% and 99.2 ± 1.1% at 3%/2 mm/10%thr(global) and 1 mm/1%/10%thr(local) criteria, respectively. The average dose difference between myQA SRS and films was 0.4 ± 1.3%. In conclusion, the CMOS 2D detector array has demonstrated its potential as a reliable tool for PSQA for SIMT SRS. The excellent dosimetric agreement with the films was consistent in multiple institutions, further validating the dosimetric accuracy and reproducibility. It provides a timely alternative to film dosimetry for commissioning and quality assurance. [ABSTRACT FROM AUTHOR]

Objective: To investigate the feasibility of standardizing RT simulation CT scanner protocols between vendors using target‐based image quality (IQ) metrics. Method and materials: A systematic assessment process in phantom was developed to standardize clinical scan protocols for scanners from different vendors following these steps: (a) images were acquired by varying CTDIvol and using an iterative reconstruction (IR) method (IR: iDose and model‐based iterative reconstruction [IMR] of CTp‐Philips Big Bore scanner, SAFIRE of CTs‐Siemens biograph PETCT scanner), (b) CT exams were classified into body and brain protocols, (c) the rescaled noise power spectrum (NPS) was calculated, (d) quantified the IQ change due to varied CTDIvol and IR, and (e) matched the IR strength level. IQ metrics included noise and texture from NPS, contrast, and contrast‐to‐noise ratio (CNR), low contrast detectability (d′). Area under curve (AUC) of the receiver operation characteristic curve of d′ was calculated and compared. Results: The level of change in the IQ ratio was significant (>0.6) when using IMR. The IQ ratio change was relatively low to moderate when using either iDose in CTp (0.1–0.5) or SAFIRE in CTs (0.1–0.6). SAFIRE‐2 in CTs showed a closer match to the reference body protocol when compared to iDose‐3 in CTp. In the brain protocol, iDose‐3 in CTp could be matched to the low to moderate level of SAFIRE in CTs. The AUC of d′ was highest when using IMR in CTp with lower CTDIvol, and SAFIRE in CTs performed better than iDose in CTp Conclusion: It is possible to use target‐based IQ metrics to evaluate the performance of the system and operations across various scanners in a phantom. This can serve as an initial reference to convert clinical scanned protocols from one CT simulation scanner to another. [ABSTRACT FROM AUTHOR]

Purpose: Although notched Collaborative Ocular Melanoma Study (COMS) plaques have been widely used, optic disc dose reduction by notched COMS plaques has not been discussed in the literature. Therefore, this study investigated optic disc dose reduction in ocular brachytherapy using 125I notched COMS plaques in comparison with optic disc dose for 125I standard COMS plaques. Methods: For this simulation study, an in‐house brachytherapy dose calculation program was developed using MATLAB software by incorporating the American Association of Physicists in Medicine Task Group‐43 Update (AAPM TG‐43U1) dosimetry formalism with a line source approximation in a homogeneous water medium and COMS seed coordinates in the AAPM TG 129. Using this program, optic disc doses for standard COMS plaques (from 12 to 22 mm in diameter in 2 mm increments) and notched COMS plaques with one seed removed (Case #1, from 12 to 22 mm) and with two seeds removed (Case #2, from 14 to 22 mm) were calculated as a function of tumor margin‐to‐optic disc distance (DT) for various tumor basal dimensions (BDs) for prescription depths from 1 to 10 mm in 1 mm intervals. A dose of 85 Gy for an irradiation time of 168 h was prescribed to each prescription depth. Then absolute and relative optic disc dose reduction by notched COMS plaques (Cases #1 and #2) was calculated for all prescription depths. Results: Optic disc dose reduction by notched COMS plaques (Cases #1 and #2) had five unique trends related to maximum optic disc dose reduction and corresponding optimal DT for each BD in each plaque. It increased with increasing prescription depth. Conclusions: The results presented in this study would enable the clinician to choose an adequate plaque type among standard and notched 125I COMS plaques and a prescription depth to minimize optic disc dose. [ABSTRACT FROM AUTHOR]

Purpose: The precise dosimetric and geometric characteristics of small animal irradiators are essential to achieving reproducible dose delivery, especially in cases where image‐guidance is utilized. Currently, radiochromic film is the established measurement tool used to evaluate beam characteristics for these systems. However, only 2D information can be acquired with film. This study characterized both the dosimetric and geometric properties of the small animal research radiation platform (SARRP, Xstrahl) for commissioning purposes using a 3D radiochromic dosimetry system with a submillimeter resolution optical computed tomography (OCT) scanner. Methods: Like a modern clinical linear accelerator, the SARRP features both a beam delivery system and a cone beam computed tomography (CBCT) imaging system. Dosimetric and geometric characteristics of the SARRP were studied using EBT3 radiochromic film and 3D PRESAGE dosimeters. Dosimetric measurements included percent depth dose (PDD) curves and beam profiles. For geometric evaluation, the isocenter sizes of the treatment stage and gantry rotations as well as their coincidence were measured using star shot patterns. A commercial Epson Expression 11000XL flatbed scanner was used for readout of irradiated EBT3 films at 300 dpi resolution. Each irradiated PRESAGE dosimeter was scanned using a submillimeter resolution single laser beam OCT scanner. Acquired data were reconstructed with a resolution of 0.3 mm/pixel. Results: PDD data measured from films and 3D dosimeters agree to within ±3% for depths up to 5 cm, for both 3 × 3 and 10 × 10 mm2 fixed collimation. Profiles were analyzed at 10, 20, and 30 mm depth for 3 × 3 mm2 and 10 × 10 mm2 fields. The FWHM measurements for both dosimeters agreed to within 0.01 mm, and the penumbras agreed to within 0.1 mm for 3 × 3 mm2 and 0.5 mm for 10 × 10 mm2. Gantry and treatment stage isocenter sizes were determined to be 0.21 and 0.43 mm using EBT3 film, and 1.72 and 0.75 mm using PRESAGE dosimeters. Absolute isocenter shifts, evaluated with 3D phantoms, were 0.80 mm for the gantry rotation isocenter (treatment isocenter) with respect to the laser‐defined setup isocenter, and 0.71 mm for the gantry rotation isocenter relative to treatment stage rotation isocenter (CBCT isocenter). The difference between CBCT isocenter and laser‐defined setup isocenter was 0.68 mm. Conclusions: This study demonstrated that 3D PRESAGE dosimeters can be used for verification of precise targeting for the SARRP. This 3D dosimetry system can be utilized to obtain information on both geometric and dosimetric properties, as well as acquire beam data parameters for the purpose of commissioning image‐guided small animal irradiator systems. [ABSTRACT FROM AUTHOR]

Objectives: To investigate accumulated mental stress according to the concept of the meridians of Traditional Chinese Medicine (TCM). This stress was quantified by using pulse spectrum analysis of finger-tip photoplethysmography (PPG). Stress accumulation is one of the main causes of cardiovascular disease and depression in humans, resulting in chronic physiologic malfunctions; however, few studies have thoroughly assessed the quantitative evaluation of accumulative stress using the concept of TCM. Design: This study investigated accumulated mental stress from the perspective of TCM based on an 8-day experiment. The theory of organ resonance was integrated into the proposed PPG sensing instrument to capture the nine harmonics of TCM. Participants were given daily mental arithmetic tasks over 1 week to simulate stress accumulation, and trends in the proportion of the nine harmonics of TCM were extracted over several days and analyzed to identify the affective factors related to cumulative stress. Results: The experimental results showed that the kidney harmonic proportion (C2) and stomach harmonic proportion (C5) were significant only on the first few days because of a physiologic phenomenon of temporary stimulation. Most important, the trend of the liver harmonic proportion (C1) from days 3 to 8 dramatically increased and became gradually saturated because of the influence of accumulated mental stress. Conclusions: The results strongly suggest that pulse spectrum analysis of the PPG signal provides physiologically and pathologically important information on accumulated mental stress and can be useful for TCM analysis. [ABSTRACT FROM AUTHOR]

A case-control trial enrolled 70 high-risk domestic violence (DV) offenders under protective orders and court-ordered batterer treatment (study group) and 231 low-medium risk DV offenders under protective orders only. Recidivism was defined as any recurrence of violence by the offenders. These acts of violence included both physical and verbal violence, which were measured by interviewing the victims by telephone at three, six, and nine months after mandatory treatment for the study group or after adjudication of the protective order for the control group. There were no significant differences between the groups in terms of overall DV recidivism rate at the six-month and nine-month assessments, and no difference in physical violence at any assessment stage. However, the treated offenders showed greater reductions in the percentage of physical violence from the three-month to the six-month and the six-month to the nine-month follow-ups than non-treated offenders (43.0% vs. 35.1%, and 37.5% vs. 10%, respectively). Alcohol use was a significant variable in predicting recidivism. Thus the treated offenders demonstrated reductions in the rate of physical violence compared to the control group. As high-risk offenders are thought to be at risk of recidivism and more severe forms of DV, the authors suggest increasing resources and modifying treatment programs to suit the offenders' needs to prevent further violence, especially by those who abuse alcohol. [ABSTRACT FROM AUTHOR]

Background: It has been reported that proximity of the tumor to the optic disc and macula, and radiation dose to the critical structures are substantial risk factors for vision loss following plaque brachytherapy. However, there is little dosimetry data published on this. In this study, therefore, the relationship between distance from tumor margin and radiation dose to the optic disc and macula in ocular brachytherapy using 125I Collaborative Ocular Melanoma Study (COMS) plaques was comprehensively investigated. From the information, this study aimed to allow for estimation of optic disc dose and macula dose without treatment planning.Methods: An in-house brachytherapy dose calculation program utilizing the American Association of Physicists in Medicine Task Group-43 U1 formalism with a line source approximation in a homogenous water phantom was developed and validated against three commercial treatment planning systems (TPS). Then optic disc dose and macula dose were calculated as a function of distance from tumor margin for various tumor basal dimensions for seven COMS plaques (from 10 mm to 22 mm in 2 mm increments) loaded with commercially available 125I seeds models (IAI-125A, 2301 and I25.S16). A prescribed dose of 85 Gy for an irradiation time of 168 h was normalized to a central-axis depth of 5 mm. Dose conversion factors for each seed model were obtained by taking ratios of total reference air kerma per seed at various prescription depths (from 1 mm to 10 mm in 1 mm intervals) to that at 5 mm.Results: The in-house program demonstrated relatively similar accuracy to commercial TPS. Optic disc dose and macula dose decreased as distance from tumor margin and tumor basal dimension increased. Dose conversion factors increased with increasing prescription depth. There existed dose variations (<8%) among three 125I seed models. Optic disc dose and macula dose for each COMS plaque and for each seed model are presented in a figure format. Dose conversion factors for each seed model are presented in a tabular format.Conclusions: The data provided in this study would enable clinicians in any clinic using 125I COMS plaques to estimate optic disc dose and macula dose without dose calculations. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this study is to compare optic disc dose (ODD) between 125 I and 103 Pd Collaborative Ocular Melanoma Study (COMS) plaques in ocular brachytherapy. Methods A previously validated in-house brachytherapy dose calculation program was used for ODD calculations. ODD was calculated as a function of tumor margin-to-optic disc distance (DT) up to 5 mm for various tumor basal dimensions (BDs), for a prescription depth of 5 mm, and for standard and notched COMS plaques loaded with  125 I (model: IAI-125A) and  103 Pd (model: IAPd-103A) seeds. ODD calculations were repeated for prescription depths from 2 mm to 10 mm in 1 mm intervals. A prescribed dose of 85 Gy (irradiation time: 120 hours) was normalized to each prescription depth. Dose conversion factors (DCFs) for each prescription depth were calculated by taking a ratio of [total reference air kerma (TRAK) per seed] prescription   depth  to [TRAK per seed] 5 mm . ODD reduction by notched COMS plaques was calculated for each prescription depth by subtracting ODD for notched COMS plaques from ODD for standard COMS plaques. Results Trends of ODD as a function of DT for various BDs are similar between the two seed types in both standard and notched COMS plaques. However, due to the energy difference, there exists a transition distance (d t ) for each BD in each plaque at which ODD for 125 I COMS plaques equals that for 103 Pd COMS plaques. For small BDs, at DT t , ODD for 103 Pd COMS plaques is higher than that for 125 I COMS plaques while at DT >d t , the opposite is observed. For the largest 1-3 BD(s), contrarily, d t occurs within the tumor, and thus, ODD for 125 I COMS plaquesis always higher. Trends of ODD reduction by notched COMS plaques as a function of DT for various BDs are the same for the two seed types except that maximum ODD reduction by 103 Pd COMS notched plaques is larger. DCF increases with increasing prescription depth for both seed types. Conclusions There exist ODD differences between 125 I and 103 Pd COMS plaques and the differences depend on DT, BD, plaque size, and prescription depth., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2021, Lee et al.)

Purpose: Although notched Collaborative Ocular Melanoma Study (COMS) plaques have been widely used, optic disc dose reduction by notched COMS plaques has not been discussed in the literature. Therefore, this study investigated optic disc dose reduction in ocular brachytherapy using 125 I notched COMS plaques in comparison with optic disc dose for 125 I standard COMS plaques., Methods: For this simulation study, an in-house brachytherapy dose calculation program was developed using MATLAB software by incorporating the American Association of Physicists in Medicine Task Group-43 Update (AAPM TG-43U1) dosimetry formalism with a line source approximation in a homogeneous water medium and COMS seed coordinates in the AAPM TG 129. Using this program, optic disc doses for standard COMS plaques (from 12 to 22 mm in diameter in 2 mm increments) and notched COMS plaques with one seed removed (Case #1, from 12 to 22 mm) and with two seeds removed (Case #2, from 14 to 22 mm) were calculated as a function of tumor margin-to-optic disc distance (DT) for various tumor basal dimensions (BDs) for prescription depths from 1 to 10 mm in 1 mm intervals. A dose of 85 Gy for an irradiation time of 168 h was prescribed to each prescription depth. Then absolute and relative optic disc dose reduction by notched COMS plaques (Cases #1 and #2) was calculated for all prescription depths., Results: Optic disc dose reduction by notched COMS plaques (Cases #1 and #2) had five unique trends related to maximum optic disc dose reduction and corresponding optimal DT for each BD in each plaque. It increased with increasing prescription depth., Conclusions: The results presented in this study would enable the clinician to choose an adequate plaque type among standard and notched 125 I COMS plaques and a prescription depth to minimize optic disc dose., (© 2020 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)

In recent years, small animal image-guided irradiators have been widely utilized in preclinical studies involving rodent models. However, the dosimetry commissioning of such equipment involving kilovoltage small-field dosimetry has not received as much interest as the megavoltage small-field dosimetry used clinically. To date, a paucity of measured kilovoltage beam data, especially for field sizes less than 3 mm, can be found in the literature. For improvement of rodent treatments in the future, this work aims to provide comprehensive and accurate beam data for the small animal radiation research platform (SARRP, Xstrahl) using EBT3 Gafchromic films and Monte Carlo calculation, with submillimeter resolution and accuracy. This work includes three primary tasks: (1) establish an optimized film measurement protocol for small field dosimetry of kilovoltage photon beam. (2) Acquire dosimetric data including (a) depth dose curves from the surface to 6 cm depth (b) beam profiles, (c) penumbra, (d) cone factors and (e) 2D dose distribution. These tasks were undertaken for a 220 kVp photon beam with five different small field widths and 33 cm source to surface distance (0.5 mm and 1 mm circular fields, 3  ×  3 mm 2 , 5  ×  5 mm 2 , 10  ×  10 mm 2 square fields). Beam data was measured with EBT3 films. (3) Provide comparative dosimetry for film measurements, Monte Carlo calculations, and the dose calculations performed with the SARRP treatment planning system, Muriplan. For the majority of parameters, film measurement agreed with Monte Carlo simulation within 1%. There were, however, discrepancies between measured beam data and Muriplan treatment planning data. Specifically, for PDD, Muriplan underestimates the dose for field sizes of 0.5 mm and 1 mm. For beam profiles comparisons, the calculation from Muriplan predicts a smaller lateral distance between the 50% isodose lines compared to film measurement. There is a difference of 0.18, 0.72, 0.6 mm between Muriplan and film for field sizes of 3, 5, 10 mm, respectively. This work demonstrates that accurate and precise kilovoltage small-field dosimetry can be conducted using EBT3 Gafchromic film with an optimized protocol. In addition, discrepancies between measured beam data and Muriplan were identified.