Scattered Dose Calculations and Measurements in a Life-Like Mouse Phantom

Welch, David; Turner, Leah; Speiser, M.; Randers-Pehrson, Gerhard; Brenner, David J.

doi:10.1667/rr004cc.1

Cited by 14 publications

(28 citation statements)

References 42 publications

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“…Dr. Welch and colleagues previously published their phantom design. [9] In brief, two separate mouse-like phantoms were created using similar densities to soft tissue and bone to simulate the mouse anatomy, one in the axial orientation and one in the sagittal orientation (Figure 3 and 4). A representative MRI T1-post contrast scan of a mouse 11 days after tumor cell injection was used to fuse with a CBCT performed on each of the phantom.…”

Section: Resultsmentioning

confidence: 99%

“…The phantoms (one in the axial orientation and one in the sagittal orientation) are made using materials which mimic the characteristics of tissue, lung, and bone for radiation dosimetry studies. [9] These phantoms are useful in examining the accuracy and precision of radiation delivery of the SARRP. The phantom allows for: 1) Assessing the accuracy and precision of the treatment field 2) Calculating the dose delivered to radiochromic film factoring differences in tissue density, and 3) Allowing analysis of dose fall off in the non-targeted region.…”

Section: Discussionmentioning

confidence: 99%

“…[9,13] One mouse-like phantom is in the sagittal arrangement and a second one is in the coronal arrangement. The brain of the coronal mouse-like phantom was placed in the axial spatial arrangement and will be referred to as the axial mouse-like phantom thereafter in this manuscript.…”

Section: Materials Methodsmentioning

confidence: 99%

“…We used radiochromic film with the mouse-like phantom system established by Welch and colleagues to verify the treatment plan. [9] Outcomes for this study included tumor volume at 7 days after SRS and overall survival.…”

Section: Introductionmentioning

confidence: 99%

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Quality Assessment of Stereotactic Radiosurgery of a Melanoma Brain Metastases Model Using a Mouselike Phantom and the Small Animal Radiation Research Platform

Chaudhary

et al. 2017

International Journal of Radiation Oncology*Biology*Physics

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Purpose/Objective To establish a novel preclinical model for stereotactic radiosurgery with combined mouse-like phantom quality assurance in the setting of brain metastases. Material Methods C57B6 mice underwent intracranial injection of B16-F10 melanoma cells. T1-post contrast MRI was performed on Day 11 after injection. The MRI images were fused with cone beam computed tomography (CBCT) images using the SARRP. Gross tumor volume (GTV) was contoured using the MRI. A single sagittal arc utilizing the 3×3 mm2 collimator was used to deliver 18 Gy prescribed to the isocenter. MRI was performed 7 days after radiation treatment and the dose delivered to the mice was confirmed using two mouse-like anthropomorphic phantoms: one in the axial and the other in the sagittal orientation. SARRP output was measured using a PTW Farmer type ionization chamber as per AAPM TG-61 and the H-D curve was generated up to a max dose of 30 Gy. Irradiated films were analyzed based on optical density distribution and H-D curve. Results The tumor volume at Day 11, before intervention, was 2.48±1.37 mm3 in the no SRS arm versus 3.75±1.19 mm3 in the SRS arm (NS). In the SRS arm, GTV Dose max (Dmax) and mean dose were 2048±207 and 1785±14 cGy. Using the mouse-like phantoms, the radiochromic film showed close precision as compared with projected isodose lines with a Dmax of 1903.4 and 1972.7 cGy, the axial and sagittal phantom respectively. Tumor volume 7 days post-treatment was 7.34±8.24 mm3 in the SRS arm and 60.20±40.4 mm3 in the no SRS arm (p=0.009). No mice in the control group survived more than 22 days after implantation with a median overall survival (mOS) of 19 days. mOS was not reached in the SRS group with one death noted. Conclusion Single fraction SRS of 18 Gy delivered in a single arc can be delivered accurately with MRI T1-post contrast based treatment planning. The mouse-like phantom allows for verification of dose delivery and accuracy.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Materials Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Quality Assessment of Stereotactic Radiosurgery of a Melanoma Brain Metastases Model Using a Mouselike Phantom and the Small Animal Radiation Research Platform

Chaudhary

et al. 2017

International Journal of Radiation Oncology*Biology*Physics

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“…Welch et al. and Wu et al . accomplished this by using materials that closely mimicked the physical properties of the corresponding anatomy and precise micromachining techniques; unfortunately, the proposed methodology remained laborious and costly.…”

Section: Introductionmentioning

confidence: 99%

Technical Note: Manufacturing of a realistic mouse phantom for dosimetry of radiobiology experiments

2019

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Purpose The goal of this work was to design a realistic mouse phantom as a useful tool for accurate dosimetry in radiobiology experiments. Methods A subcutaneous tumor‐bearing mouse was scanned in a microCT scanner, its organs manually segmented and contoured. The resulting geometries were converted into a stereolithographic file format (STL) and sent to a multimaterial 3D printer. The phantom was split into two parts to allow for lung excavation and 3D‐printed with an acrylic‐like material and consisted of the main body (mass density ρ=1.18 g/cm3) and bone (ρ=1.20 g/cm3). The excavated lungs were filled with polystyrene (ρ=0.32 g/cm3). Three cavities were excavated to allow the placement of a 1‐mm diameter plastic scintillator dosimeter (PSD) in the brain, the center of the body and a subcutaneous tumor. Additionally, a laser‐cut Gafchromic film can be placed in between the two phantom parts for 2D dosimetric evaluation. The expected differences in dose deposition between mouse tissues and the mouse phantom for a 220‐kVp beam delivered by the small animal radiation research platform (SARRP) were calculated by Monte Carlo (MC). Results MicroCT scans of the phantom showed excellent material uniformity and confirmed the material densities given by the manufacturer. MC dose calculations revealed that the dose measured by tissue‐equivalent dosimeters inserted into the phantom in the brain, abdomen, and subcutaneous tumor would be underestimated by 3–5%, which is deemed to be an acceptable error assuming the proposed 5% accuracy of radiobiological experiments. Conclusions The low‐cost mouse phantom can be easily manufactured and, after a careful dosimetric characterization, may serve as a useful tool for dose verification in a range of radiobiology experiments.

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Preclinical dose verification using a 3D printed mouse phantom for radiobiology experiments

Esplen¹,

Therriault‐Proulx²,

Beaulieu³

et al. 2019

Medical Physics

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Purpose: Dose verification in preclinical radiotherapy is often challenged by a lack of standardization in the techniques and technologies commonly employed along with the inherent difficulty of dosimetry associated with small-field kilovoltage sources. As a consequence, the accuracy of dosimetry in radiobiological research has been called into question. Fortunately, the development and characterization of realistic small-animal phantoms has emerged as an effective and accessible means of improving dosimetric accuracy and precision in this context. The application of three-dimensional (3D) printing, in particular, has enabled substantial improvements in the conformity of representative phantoms with respect to the small animals they are modeled after. In this study, our goal was to evaluate a fully 3D printed mouse phantom for use in preclinical treatment verification of sophisticated therapies for various anatomical targets of therapeutic interest. Methods: An anatomically realistic mouse phantom was 3D printed based on segmented microCT data of a tumor-bearing mouse. The phantom was modified to accommodate both laser-cut EBT3 radiochromic film within the mouse thorax and a plastic scintillator dosimeter (PSD), which may be placed within the brain, abdomen, or 1-cm flank subcutaneous tumor. Various treatments were delivered on an image-guided small-animal irradiator in order to determine the doses to isocenter using a PSD and validate lateral-and depth-dose distributions using film dosimeters. On-board cone-beam CT imaging was used to localize isocenter to the film plane or PSD active element prior to irradiation. The PSD irradiations comprised a 3 9 3 mm 2 brain arc, 5 9 5 mm 2 parallel-opposed pair (POP), and 5-beam 10 9 10 mm 2 abdominal coplanar arrangement while two-dimensional (2D) film dose distributions were acquired using a 3 9 3 mm 2 arc and both 5 9 5 and 10 9 10 mm 2 3-beam coplanar plans. A validated Monte Carlo (MC) model of the source was used as to verify the accuracy of the film and PSD dose measurements. computer-aided design (CAD) geometries for the mouse phantom and dosimeters were imported directly into the MC code to allow for highly accurate reproduction of the physical experiment conditions. Experimental and MC-derived film data were co-registered and film dose profiles were compared for points above 90% of the dose maximum. Point dose measurements obtained with the PSD were similarly compared for each of the candidate (brain, abdomen, and tumor) treatment sites. Results: For each treatment configuration and anatomical target, the MC-calculated and measured doses met the proposed 5% agreement goal for dose accuracy in radiobiology experiments. The 2D film and MC dose distributions were successfully registered and mean doses for lateral profiles were found to agree to within 2.3% in all cases. Isocentric point-dose measurements taken with the PSD were similarly consistent, with a maximum percentage deviation of 3.2%. Conclusions: Our study confirms the utility of 3D printed phantom design ...

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Scattered Dose Calculations and Measurements in a Life-Like Mouse Phantom

Cited by 14 publications

References 42 publications

Quality Assessment of Stereotactic Radiosurgery of a Melanoma Brain Metastases Model Using a Mouselike Phantom and the Small Animal Radiation Research Platform

Quality Assessment of Stereotactic Radiosurgery of a Melanoma Brain Metastases Model Using a Mouselike Phantom and the Small Animal Radiation Research Platform

Technical Note: Manufacturing of a realistic mouse phantom for dosimetry of radiobiology experiments

Preclinical dose verification using a 3D printed mouse phantom for radiobiology experiments

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