MLC-based penumbra softener of EDW borders to reduce junction inhomogeneities.
Abstract Junctions of fields are known to be susceptible to developing cold or hot spots in the presence of even small geometrical misalignments. Reduction of these dose inhomogeneities can be accomplished through decreasing the dose gradients in the penumbra, but currently it cannot be done for enhanced dynamic wedges (EDW). An MLC-based penumbra softener was developed in the developer mode of TrueBeam linacs to reduce dose gradients across the side border of EDWs. The movement of each leaf was individually synchronized with the movement of the dynamic Y jaw to soften the penumbra in the same manner along the ent...
Source: Journal of Applied Clinical Medical Physics - April 19, 2017 Category: Physics Authors: Szpala S, Kohli K Tags: J Appl Clin Med Phys Source Type: research

Comparability of three output prediction models for a compact passively double-scattered proton therapy system.
Abstract The purpose of this study was to investigate comparability of three output prediction models for a compact double-scattered proton therapy system. Two published output prediction models are commissioned for our Mevion S250 proton therapy system. Model A is a correction-based model (Sahoo et al., Med Phys, 2008;35(11):5088-5097) and model B is an analytical model which employs a function of r = (R'-M')/M' (Kooy et al., Phys Med Biol, 2005;50:5487-5456) where R' is defined as depth of distal 100% dose with straggling and M' is the width between distal 100% dose and proximal 100% dose wit...
Source: Journal of Applied Clinical Medical Physics - April 19, 2017 Category: Physics Authors: Ferguson S, Chen Y, Ferreira C, Islam M, Keeling VP, Lau A, Ahmad S, Jin H Tags: J Appl Clin Med Phys Source Type: research

AAPM Spring Clinical Meeting - Program 2017 AAPM Spring Clinical Meeting March 18 - 21, 2017 New Orleans, LA.
Authors: PMID: 28422414 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 19, 2017 Category: Physics Tags: J Appl Clin Med Phys Source Type: research

Results of a 10-year survey of workload for 10 treatment vaults at a high-throughput comprehensive cancer center.
In this study, we report on the workload for 10 treatment vaults in terms of dose to isocenter (cGy), monitor units delivered (MUs), number of treatment sessions (Txs), as well as, use factors (U) and modulation factors (CI) for different treatment techniques. The survey was performed for the years between 2006 and 2015 and included 16 treatment machines which represent different generations of Varian linear accelerators (6EX, 600C, 2100C, 2100EX, and TrueBeam) operating at different electron and x-ray energies (6, 9, 12, 16 and 20 MeV electrons and, 6 and 15 MV x-rays). An institutional review board (IRB) approval was acq...
Source: Journal of Applied Clinical Medical Physics - April 19, 2017 Category: Physics Authors: Saleh ZH, Jeong J, Quinn B, Mechalakos J, St Germain J, Dauer LT Tags: J Appl Clin Med Phys Source Type: research

AAPM Spring Clinical Meeting - Abstract SATURDAY, MARCH 18.
Authors: PMID: 28422430 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 19, 2017 Category: Physics Tags: J Appl Clin Med Phys Source Type: research

Evaluation of the truebeam machine performance check (MPC): mechanical and collimation checks.
Abstract Machine performance check (MPC) is an automated and integrated image-based tool for verification of beam and geometric performance of the TrueBeam linac. The aims of the study were to evaluate the performance of the MPC geometric tests relevant to beam collimation (MLC and jaws) and mechanical systems (gantry and collimator). Evaluation was performed by comparing MPC to QA tests performed routinely in the department over a 4-month period. The MPC MLC tests were compared to an in-house analysis of the Picket Fence test. The jaw positions were compared against an in-house EPID-based method, against the trad...
Source: Journal of Applied Clinical Medical Physics - April 17, 2017 Category: Physics Authors: Barnes MP, Greer PB Tags: J Appl Clin Med Phys Source Type: research

Evaluation of stability of stereotactic space defined by cone-beam CT for the Leksell Gamma Knife Icon.
In this study, we used an in-house built marker tool to evaluate the stability of the CBCT-based stereotactic space and its agreement with the standard frame-based stereotactic space. We imaged the tool with a CT indicator box using our CT-simulator at the beginning, middle, and end of the study period (6 weeks) for determining the frame-based stereotactic space. The tool was also scanned with the Icon's CBCT on a daily basis throughout the study period, and the CBCT images were used for determining the CBCT-based stereotactic space. The coordinates of each marker were determined in each CT and CBCT scan using the Leksell ...
Source: Journal of Applied Clinical Medical Physics - April 17, 2017 Category: Physics Authors: AlDahlawi I, Prasad D, Podgorsak MB Tags: J Appl Clin Med Phys Source Type: research

Dosimetric impacts of endorectal balloon in CyberKnife stereotactic body radiation therapy (SBRT) for early-stage prostate cancer.
CONCLUSIONS: Significant reductions of dose to the rectum using ERB were observed. This may lead to improvement of the rectal toxicity profiles in prostate SBRT. PMID: 28407345 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 13, 2017 Category: Physics Authors: Xiang HF, Lu HM, Efstathiou JA, Zietman AL, Armas R, Harris K, Bloch BN, Qureshi MM, Keohan S, Hirsch AE Tags: J Appl Clin Med Phys Source Type: research

Insight gained from responses to surveys on reference dosimetry practices.
CONCLUSIONS: The results of these surveys offer insight on clinical reference dosimetry practices and will be useful in identifying current and future needs for reference dosimetry. PMID: 28397396 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 11, 2017 Category: Physics Authors: Muir B, Culberson W, Davis S, Kim GY, Huang Y, Lee SW, Lowenstein J, Sarfehnia A, Siebers J, Tolani N Tags: J Appl Clin Med Phys Source Type: research

Development of a novel low-radiation-absorbent lok-bar to reduce X-ray scattering and absorption in RapidArc( ®) treatment planning and dose delivery.
Development of a novel low-radiation-absorbent lok-bar to reduce X-ray scattering and absorption in RapidArc(®) treatment planning and dose delivery. J Appl Clin Med Phys. 2017 Apr 06;: Authors: Monzen H, Kubo K, Tamura M, Hayakawa M, Nishimura Y Abstract We developed a novel low-radiation-absorbent lok-bar (HM-bar) that is used to secure the immobilizers to the couch. The aim of this study was to investigate the X-ray scattering and absorption properties of the HM-bar in computed tomography (CT) simulation and radiotherapy dose delivery using the Varian Exact™ lok-bar (VL-bar) as a benchmar...
Source: Journal of Applied Clinical Medical Physics - April 6, 2017 Category: Physics Authors: Monzen H, Kubo K, Tamura M, Hayakawa M, Nishimura Y Tags: J Appl Clin Med Phys Source Type: research

Effect of beam profile measurement on arc therapy plan quality assurance: a case study.
We present an example when profile measurement and modeling of an Elekta Agility multileaf collimator (MLC) had a large effect specifically on arc therapy plan quality assurance (QA) results using ArcCheck. ArcCheck absolute dose measurements of these plans were systematically lower than planned by 3-10%. Failing QA results were seen even with unmodulated static and conformal arcs. Furthermore, the effect was found to be dependent on collimator angle, with worse results associated with near-zero collimator angles. In contrast, step-and-shoot QA results were not affected. Changing the beam model to match steeper profile mea...
Source: Journal of Applied Clinical Medical Physics - March 29, 2017 Category: Physics Authors: Kim LH, Malajovich I, Reyhan ML, Xue J, Park JH Tags: J Appl Clin Med Phys Source Type: research

Validation of a GPU-Based 3D dose calculator for modulated beams.
Abstract A superposition/convolution GPU-accelerated dose computation algorithm (the Calculator) has been recently incorporated into commercial software. The algorithm requires validation prior to clinical use. Three photon energies were examined: conventional 6 MV and 15 MV, and 10 MV flattening filter free (10 MVFFF). For a set of IMRT and VMAT plans based on four of the five AAPM Practice Guideline 5a downloadable datasets, ion chamber (IC) measurements were performed on the water-equivalent phantoms. The average difference between the Calculator and IC was -0.3 ± 0.8% (1SD). The same plans were projecte...
Source: Journal of Applied Clinical Medical Physics - March 29, 2017 Category: Physics Authors: Ahmed S, Hunt D, Kapatoes J, Hayward R, Zhang G, Moros EG, Feygelman V Tags: J Appl Clin Med Phys Source Type: research

Optimization of intra-voxel incoherent motion measurement in diffusion-weighted imaging of breast cancer.
CONCLUSION: IVIM-derived diffusion and perfusion parameter maps depend highly on the choice of threshold b-value. Using the methodology developed in this work, and with the optimized threshold b-value, the diffusion and perfusion parameters of breast tissues can be accurately assessed, making IVIM MRI a technique of choice for differential diagnosis of breast cancer. PMID: 28349630 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - March 27, 2017 Category: Physics Authors: Chen W, Zhang J, Long D, Wang Z, Zhu JM Tags: J Appl Clin Med Phys Source Type: research

Evaluation of the truebeam machine performance check (MPC) geometric checks for daily IGRT geometric accuracy quality assurance.
Abstract Machine Performance Check (MPC) is an automated and integrated image-based tool for verification of beam and geometric performance of the TrueBeam linac. The aims of the study were to evaluate the performance of the MPC geometric tests relevant to OBI/CBCT IGRT geometric accuracy. This included evaluation of the MPC isocenter and couch tests. Evaluation was performed by comparing MPC to QA tests performed routinely in the department over a 4-month period. The MPC isocenter tests were compared against an in-house developed Winston-Lutz test and the couch compared against routine mechanical QA type procedur...
Source: Journal of Applied Clinical Medical Physics - March 22, 2017 Category: Physics Authors: Barnes MP, Greer PB Tags: J Appl Clin Med Phys Source Type: research

Evaluation of dose calculation accuracy of treatment planning systems at hip prosthesis interfaces.
Abstract There are an increasing number of radiation therapy patients with hip prosthesis. The common method of minimizing treatment planning inaccuracies is to avoid radiation beams to transit through the prosthesis. However, the beams often exit through them, especially when the patient has a double-prosthesis. Modern treatment planning systems employ algorithms with improved dose calculation accuracies but even these algorithms may not predict the dose accurately at high atomic number interfaces. The current study evaluates the dose calculation accuracy of three common dose calculation algorithms employed in tw...
Source: Journal of Applied Clinical Medical Physics - March 20, 2017 Category: Physics Authors: Paulu D, Alaei P Tags: J Appl Clin Med Phys Source Type: research

Experimental verification of Advanced Collapsed-cone Engine for use with a multichannel vaginal cylinder applicator.
Abstract Model-based dose calculation algorithms have recently been incorporated into brachytherapy treatment planning systems, and their introduction requires critical evaluation before clinical implementation. Here, we present an experimental evaluation of Oncentra(®) Brachy Advanced Collapsed-cone Engine (ACE) for a multichannel vaginal cylinder (MCVC) applicator using radiochromic film. A uniform dose of 500 cGy was specified to the surface of the MCVC using the TG-43 dose formalism under two conditions: (a) with only the central channel loaded or (b) only the peripheral channels loaded. Film measurements ...
Source: Journal of Applied Clinical Medical Physics - March 20, 2017 Category: Physics Authors: Cawston-Grant B, Morrison H, Menon G, Sloboda RS Tags: J Appl Clin Med Phys Source Type: research

Individual volume-based 3D gamma indices for pretreatment VMAT QA.
Abstract Although gamma analysis is still a widely accepted quantitative tool to analyze and report patient-specific QA for intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), the correlation between the 2D percentage gamma passing rate (%GP), and the clinical dosimetric difference for IMRT and VMAT has been questioned. The purpose of this study was to investigate the feasibility of individual volume-based 3D gamma indices for pretreatment VMAT QA. Percentage dosimetric errors (%DE) of dose-volume histogram metrics (includes target volumes and organ at risks) between the treatment ...
Source: Journal of Applied Clinical Medical Physics - March 20, 2017 Category: Physics Authors: Yi J, Han C, Zheng X, Zhou Y, Deng Z, Xie C, Jin X, Jin F Tags: J Appl Clin Med Phys Source Type: research

J Appl Clin Med Phys; +281 new citations
281 new pubmed citations were retrieved for your search. Click on the search hyperlink below to display the complete search results: J Appl Clin Med Phys These pubmed results were generated on 2017/03/17PubMed comprises more than millions of citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites. (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - March 17, 2017 Category: Physics Tags: Report Source Type: research

State of the JACMP: Thoughts on our transition and a fond farewell to Multimed
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Source: Journal of Applied Clinical Medical Physics - November 18, 2016 Category: Physics Source Type: research

The Diagnosis of Prostate Cancer
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Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Implementation of quality medical physics training in a low-middle income country — sharing experience from a tertiary care JCIA-accredited university hospital
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Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

The feasibility of using Microsoft Kinect v2 sensors during radiotherapy delivery
Consumer-grade distance sensors, such as the Microsoft Kinect devices (v1 and v2), have been investigated for use as marker-free motion monitoring systems for radiotherapy. The radiotherapy delivery environment is challenging for such sen ­sors because of the proximity to electromagnetic interference (EMI) from the pulse forming network which fires the magnetron and electron gun of a linear accelerator (linac) during radiation delivery, as well as the requirement to operate them from the control area. This work investigated whether using Kinect v2 sensors as motion monitors was feasible during radiation delivery. Three...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

An innovative method to acquire the location of point A for cervical cancer treatment by HDR brachytherapy
Brachytherapy of local cervical cancer is generally accomplished through film-based treatment planning with the prescription directed to point A, which is invisible on images and is located at a high-dose gradient area. Through a standard reconstruction method by digitizing film points, the location error for point A would be 3mm with a condition of 30 ° curvature tandem, which is 10° away from the gantry rotation axis of a simulator, and has an 8.7 cm interval between the flange and the isocenter. To reduce the location error of the reconstructed point A, this paper proposes a method and demonstrates its accuracy....
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Evaluation of kidney motion and target localization in abdominal SBRT patients
The purpose of this study was to evaluate bilateral kidney and target translational/rotational intrafraction motion during stereotactic body radiation therapy treatment delivery of primary renal cell carcinoma and oligometastatic adrenal lesions for patients immobilized in the Elekta BodyFIX system. Bilateral kidney motion was assessed at midplane for 30 patients immobilized in a full-body dual-vacuum-cushion system with two patients immobilized via abdominal compression. Intrafraction motion was assessed for 15 patients using kilovoltage cone-beam computed tomography (kV-CBCT) datasets (n = 151) correlated to the planning...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Accuracy of automatic matching of Catphan 504 phantom in cone-beam computed tomography for tube current –exposure time product
The purpose of this study is to evaluate the accuracy of automatic matching in cone-beam computed tomography (CBCT) images relative to the reduction of total tube current –exposure time product (mAs) for the X-ray imaging (XI) system. The CBCT images were acquired with the Catphan 504 phantom various total mAs ratios such as 1.00, 0.83, 0.67, 0.57, and 0.50. For studying the automatic match­ing accuracy, the phantom images were acquired with a six-dimensional shif ting table. The image quality and correction of automatic matching were compared. With a decreasing total mAs ratio, the noise of the images increased ...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

A survey on table tolerances and couch overrides in radiotherapy
The purpose of this study was to survey current departmental policies on treatment couch overrides and the values of table tolerances used clinically. A 25-question electronic survey on couch overrides and tolerances was sent to full members of the American Association of Physicists in Medicine (AAPM). The first part of the survey asked participants if table overrides were allowed at their institution, who was allowed to perform these overrides, and if imaging was required with overrides. The second part of the survey asked individuals to provide table tolerance data for the following treatment sites: brain/head and neck (...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Evaluation of dose-area product of common radiographic examinations towards establishing a preliminary diagnostic reference levels (PDRLs) in Southwestern Nigeria
In Nigeria, a large number of radiographic examinations are conducted yearly for various diagnostic purposes. However, most examinations carried out do not have records of doses received by the patients, and the employed exposure parameters used are not documented; therefore, adequate radiation dose management is hin ­dered. The aim of the present study was to estimate the dose-area product (DAP) of patients examined in Nigeria, and to propose regional reference dose levels for nine common examinations (chest PA, abdomen AP, pelvis AP, lumbar AP, skull AP, leg AP, knee AP, hand AP, and thigh AP) undertaken in N igeria....
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Deriving detector-specific correction factors for rectangular small fields using a scintillator detector
The goal of this study was to investigate small field output factors (OFs) for flat ­tening filter-free (FFF) beams on a dedicated stereotactic linear accelerator-based system. From this data, the collimator exchange effect was quantified, and detector-specific correction factors were generated. Output factors for 16 jaw-collimated small fields (from 0.5 to 2 cm) were measured usi ng five different detectors including an ion chamber (CC01), a stereotactic field diode (SFD), a diode detector (Edge), Gafchromic film (EBT3), and a plastic scintillator detector (PSD, W1). Chamber, diodes, and PSD measurements were performe...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Comparison of the low contrast detectability of two ultrasound systems using a greyscale phantom
The purpose of the present study was to evaluate the relevance of using a phantom to simulate a clinical situation where small low contrast objects are embedded in relatively homogeneous organs in order to discriminate between different ultrasound machines, taking into account human observer variability. One high-end and one general ultrasound machine using the same probe were included. Images containing 4 and 6.4-mm objects of four different contrasts were collected from a greyscale phantom at different depths. Six observers participated in a 4-alternative forced choice study based on 960 images. Variability was determine...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Development of a universal medical X-ray imaging phantom prototype
Diagnostic X-ray imaging depends on the maintenance of image quality that allows for proper diagnosis of medical conditions. Maintenance of image quality requires quality assurance programs on the various X-ray modalities, which consist of pro ­jection radiography (including mobile X-ray units), fluoroscopy, mammography, and computed tomography (CT) scanning. Currently a variety of modality-specific phantoms are used to perform quality assurance (QA) tests. These phantoms are not only expensive, but suitably trained personnel are needed to successfully use them and interpret the results. The question arose as to whethe...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Evaluation of digital radiography practice using exposure index tracking
Some digital radiography (DR) detectors and software allow for remote download of exam statistics, including image reject status, body part, projection, and exposure index (EI). The ability to have automated data collection from multiple DR units is conducive to a quality control (QC) program monitoring institutional radiographic exposures. We have implemented such a QC program with the goal to identify outliers in machine radiation output and opportunities for improvement in radiation dose levels. We studied the QC records of four digital detectors in greater detail on a monthly basis for one year. Although individual pat...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Dose reduction in CT urography and vasculature phantom studies using model-based iterative reconstruction
To evaluate the feasibility of radiation dose reduction using model-based iterative reconstruction (MBIR) for evaluating the ureters and vasculature in a phantom, a tissue-equivalent CT dose phantom was scanned using a 64-channel CT scan ­ner. Tubes of varying diameters filled with different dilutions of a contrast agent, simulating ureters or vessels, were inserted into the center of the phantom. Each combination was scanned using an existing renal protocol at 140 kVp or 120 kVp, yielding a display volumetric CT dose index (CTDIvo l) of 24 mGy. The scans were repeated using reduced scan techniques to achieve lower rad...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

A comprehensive evaluation of adaptive daily planning for cervical cancer HDR brachytherapy
This study included 22 cervical cancer patients who underwent 5 fractions of HDR-BT. Regions of interest (ROIs) including high-risk clinical tumor vo lume (HR-CTV) and organs at risk (OARs) were manually contoured on daily CT images. All patients were clinically treated with adaptive daily plans (ADP), which involved ROI delineation and dose optimization at each treatment fraction. Single treatment plans (SP) were retrospectively generated by app lying the first treatment fraction’s dwell times adjusted for decay and dwell positions of the applicator to subsequent treatment fractions. Various existing similarity metr...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Gafchromic EBT-XD film: Dosimetry characterization in high-dose, volumetric-modulated arc therapy
Radiochromic films are important tools for assessing complex dose distributions. Gafchromic EBT-XD films have been designed for optimal performance in the 40 –4,000 cGy dose range. We investigated the dosimetric characteristics of these films, including their dose-response, postexposure density growth, and dependence on scanner orientation, beam energy, and dose rate with applications to high-dose volumetric-modulated arc therapy (VMAT) verification. A 10 MV beam from a TrueBeam STx linear accelerator was used to irradiate the films with doses in the 0–4,000 cGy range. Postexposure coloration was analyzed at po...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Real-time in vivo dosimetry for SBRT prostate treatment using plastic scintillating dosimetry embedded in a rectal balloon: a case study
A novel FDA approvedin vivodosimetry device system using plastic scintillating detectors placed in an endorectal balloon to provide real-timein vivodosimetry for prostatic rectal interface was tested for use with stereotactic body radiotherapy (SBRT). The system was used for the first time ever to measure dose during linear accelerator based SBRT. A single patient was treated with a total dose of 36.25 Gy given in 5 fractions. Delivered dose was measured for each treatment with the detectors placed against the anterior rectal wall near the prostate rectal interface. Measured doses showed varying degrees of agreement with c...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

EPID-based dosimetry to verify IMRT planar dose distribution for the aS1200 EPID and FFF beams
We proposed to perform a basic dosimetry commissioning on a new imager sys ­tem, the Varian aS1200 electronic portal imaging device (EPID) and TrueBeam 2.0 linear accelerator for flattened (FF) and flattening filter-free (FFF) beams, then to develop an image-based quality assurance (QA) model for verification of the system delivery accuracy for intensity-modulated radiati on therapy (IMRT) treat­ments. For dosimetry testing, linearity of dose response with MU, imager lag, and effectiveness of backscatter shielding were investigated. Then, an image-based model was developed to convert images to planar dose onto a vi...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Volumetric-modulated arc therapy using multicriteria optimization for body and extremity sarcoma
This study evaluates the implementation of volumetric-modulated arc therapy (VMAT) using multicriteria optimization (MCO) in the RayStation treatment planning system (TPS) for complex sites, namely extremity and body sarcoma. The VMAT-MCO algorithm implemented in RayStation is newly developed and requires an integrated, comprehensive analysis of plan generation, delivery, and treatment efficiency. Ten patients previously treated by intensity-modulated radiation therapy (IMRT) with MCO were randomly selected and replanned using VMAT-MCO. The plan quality was compared using homogeneity index (HI) and conformity index (CI) of...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

The dose penumbra of a custom-made shield used in hemibody skin electron irradiation
We report our technique for hemibody skin electron irradiation with a custom-made plywood shield. The technique is similar to our clinical total skin electron irradiation (TSEI), performed with a six-pair dual field (Stanford technique) at an extended source-to-skin distance (SSD) of 377 cm, with the addition of a plywood shield placed at 50 cm from the patient. The shield is made of three layers of stan ­dard 5/8’’ thick plywood (total thickness of 4.75 cm) that are clamped securely on an adjustable-height stand. Gafchromic EBT3 films were used in assessing the shield’s transmission factor and the ex...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Development and evaluation of a clinical model for lung cancer patients using stereotactic body radiotherapy (SBRT) within a knowledge-based algorithm for treatment planning
The purpose of this study was to describe the development of a clinical model for lung cancer patients treated with stereotactic body radiotherapy (SBRT) within a knowledge-based algorithm for treatment planning, and to evaluate the model performance and applicability to different planning techniques, tumor locations, and beam arrangements. 105 SBRT plans for lung cancer patients previously treated at our institution were included in the development of the knowledge-based model (KBM). The KBM was trained with a combination of IMRT, VMAT, and 3D CRT techniques. Model performance was validated with 25 cases, for both IMRT an...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Dosimetric comparison of intensity-modulated radiotherapy and volumetric-modulated arc radiotherapy in patients with prostate cancer: a meta-analysis
Intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) are two main radiotherapy techniques. The aim of this study is to explore which is the preferred technique in prostate treatment through the related publica ­tions and meta-analysis. Two authors independently identified all relevant articles available regarding eligibility criteria on PubMed, Embase, and Cochrane Library databases until December 2015. Publication bias was evaluated with funnel plot, and statistical analyses were performed with Stata so ftware.P
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

A comparison of methods for monitoring photon beam energy constancy
We examined changes in these energy metrics when photon energies were changed to ± 5% and ± 10% from their nominal energies: 1) an attenuation-based metric (the percent depth dose at 10 cm depth, PDD(10)) and, 2) profile-based metrics, including flatness (Flat) and off-axis ratios (OARs) measured on the orthogonal axes or on the diagonals (diagonal normalized flatness, FDN). P rofile-based metrics were measured near dmax and also near 10 cm depth in water (using a 3D scanner) and with ioniza­tion chamber array (ICA). PDD(10) was measured only in water. Changes in PDD, OAR, and FDN were nearly linear to th...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Experimental evaluation of a GPU-based Monte Carlo dose calculation algorithm in the Monaco treatment planning system
A new GPU-based Monte Carlo dose calculation algorithm (GPUMCD), devel ­oped by the vendor Elekta for the Monaco treatment planning system (TPS), is capable of modeling dose for both a standard linear accelerator and an Elekta MRI linear accelerator. We have experimentally evaluated this algorithm for a standard Elekta Agility linear accelerator. A beam model was deve loped in the Monaco TPS (research version 5.09.06) using the commissioned beam data for a 6 MV Agility linac. A heterogeneous phantom representing several scenarios — tumor-in-lung, lung, and bone-in-tissue — was designed and built. Dose calcu...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Investigation of dosimetric differences between the TMR 10 and convolution algorithm for Gamma Knife stereotactic radiosurgery
Since its inception, doses applied using Gamma Knife Radiosurgery (GKR) have been calculated using a simple TMR algorithm, which assumes the patient ’s head is of even density, the same as water. This results in a significant approximation of the dose delivered by the Gamma Knife. We investigated how GKR dose cal­culations varied when using a new convolution algorithm clinically available for GKR planning that takes into account density varia tions in the head compared with the established calculation algorithm. Fifty-five patients undergoing GKR and harboring 85 lesions were voluntarily and prospectively enrolle...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

The dosimetric impact of control point spacing for sliding gap MLC fields
Dynamic sliding gap multileaf collimator (MLC) fields are used to model MLC properties within the treatment planning system (TPS) for dynamic treatments. One of the key MLC properties in the Eclipse TPS is the dosimetric leaf gap (DLG) and precise determination of this parameter is paramount to ensuring accurate dose delivery. In this investigation, we report on how the spacing between control points (CPs) for sliding gap fields impacts the dose delivery, MLC positioning accuracy, and measurement of the DLG. The central axis dose was measured for sliding gap MLC fields with gap widths ranging from 2 to 40 mm. It was found ...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Application programming in C# environment with recorded user software interactions and its application in autopilot of VMAT/IMRT treatment planning
An autopilot scheme of volumetric-modulated arc therapy (VMAT)/intensity-modulated radiation therapy (IMRT) planning with the guidance of prior knowl ­edge is established with recorded interactions between a planner and a commercial treatment planning system (TPS). Microsoft (MS) Visual Studio Coded UI is applied to record some common planner-TPS interactions as subroutines. The TPS used in this study is a Windows-based Eclipse system. The inter actions of our application program with Eclipse TPS are realized through a series of subrou­tines obtained by prerecording the mouse clicks or keyboard strokes of a planner...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Treatment planning for metals using an extended CT number scale
This study investigated dose calculation based directly on extended CT scale images for different metals and geometries. The aim was to evaluate extended CT accuracy as a suitable alternative to standard CT methods in the presence of high-Z materials and artifacts, despite the reduced HU resolution of extended CT. Gafchromic film measurements were made for comparison to calculated doses. The method of direct dose calculation on extended CT scale was compared to our institution ’s standard method of manually contouring and assigning metal values on saturated CT images for each of the metal samples. Clinical patient pl...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Validation of an improved helical diode array and dose reconstruction software using TG-244 datasets and stringent dose comparison criteria
The original helical ArcCHECK (AC) diode array and associated software for 3D measurement-guided dose reconstruction were characterized and validated; however, recent design changes to the AC required that the subject be revisited. The most important AC change starting in 2014 was a significant reduction in the overresponse of diodes to scattered radiation outside of the direct beam, accom-plished by reducing the amount of high-Z materials adjacent to the diodes. This change improved the diode measurement accuracy, but in the process invalidated the dose reconstruction models that were assembled based on measured data acqu...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Rounded leaf end modeling in Pinnacle VMAT treatment planning for fixed jaw linacs
During volume-modulated arc therapies (VMAT), dosimetric errors are introduced by multiple open dynamic leaf gaps that are present in fixed diaphragm linear accelerators. The purpose of this work was to develop a methodology for adjusting the rounded leaf end modeling parameters to improve out-of-field dose agreement in SmartArc VMAT treatment plans delivered by fixed jaw linacs where leaf gap dose is not negligible. Leaf gap doses were measured for an Elekta beam modulator linac with 0.4 cm micro-multileaf collimators (MLC) using an A16 micro-ionization chamber, a MatriXX ion chamber detector array, and Kodak EDR2 film do...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Clinically relevant investigation of flattening filter-free skin dose
This study conveyed the magnitude of surface dose in a clinically meaning ­ful manner by reporting results normalized to 10 cm depth dose instead of depth of dose maximum. (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research

Production and quality control 177Lu (NCA) —DOTMP as a potential agent for bone pain palliation
Skeletal uptake of radiolabeled-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetramethylene phosphoric acid (e.g., 177Lu-DOTMP) complex, is used for bone pain palliation. The moderate energy of β-emitting 177Lu (T½ = 6.7 d, Eβmax = 497keV) has been considered as a potential radionuclide for development of the bone-seeking radiopharmaceutical. Since the specific activity of the radiolabeled carrier molecules should be high, the “no-carrier-added radionuclides” have sig­nificant role s in nuclear medicine. Many researchers illustrated no-carrier-added 177Lu production; among these separation...
Source: Journal of Applied Clinical Medical Physics - November 8, 2016 Category: Physics Source Type: research