Justus Adamson

Overview:

Radiosurgery and SBRT
Image Guided Radiation Therapy (IGRT)
Quality Assurance (QA) in Radiation Therapy
3D Dosimetry

Positions:

Associate Professor of Radiation Oncology

Radiation Oncology
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

Ph.D. 2009

Wayne State University

Research Assistant

William Beaumont Hospital Royal Oak

Postdoctoral Associate/Medical Physicist Residency Program, Radiation Oncology Physics Division

Duke University School of Medicine

Publications:

Evaluation of UVA emission from x-ray megavoltage-irradiated tissues and phantoms.

RECA (Radiotherapy enhanced with Cherenkov photo-activation) is a proposed treatment where the anti-cancer drug psoralen is photo-activated in situ by UVA (Ultraviolet A, 320-400 nm) Cherenkov light (CL) produced directly by the treatment beam itself. In this study, we develop a UVA-imaging technique to quantify relative UVA CL produced by bulk tissues and other phantoms upon clinical x-ray megavoltage irradiation. UVA CL emission (320-400 nm) was quantified in tissue samples of porcine and poultry and in two kinds of solid waters (SW): brown (Virtual Waters, Standard Imaging, WI) and white (Diagnostic Therapy, CIRS, VA), and in 1% agarose gels variously doped with absorbing dye. Quantification was achieved through cumulative imaging of the samples placed in a dark, light-blocking chamber during irradiation on a Varian 21 EX accelerator. UVA imaging required a specialized high-sensitivity cooled camera equipped with UVA lenses and a filter. At 15 MV, white SW emitted [Formula: see text], [Formula: see text] and [Formula: see text] less UVA than chicken breast, pork loin and pork belly, respectively. Similar under-response was observed at 6 MV. Brown SW had [Formula: see text] less UVA emission than white SW at 15 MV, and negligible emission at 6 MV. Agarose samples (1% by weight) doped with 250 ppm India ink exhibited equivalent UVA CL emission to chicken breast (within 8%). The results confirm that for the same absorbed dose, SW emits less UVA light than the tissue samples, indicating that prior in vitro studies utilizing SW as the CL-generating source may have underestimated the RECA therapeutic effect. Agarose doped with 250 ppm India ink is a convenient tissue-equivalent phantom for further work.
Authors
Jain, S; Yoon, SW; Zhang, X; Adamson, J; Floyd, S; Oldham, M
MLA Citation
Jain, Sagarika, et al. “Evaluation of UVA emission from x-ray megavoltage-irradiated tissues and phantoms..” Phys Med Biol, vol. 64, no. 22, Nov. 2019. Pubmed, doi:10.1088/1361-6560/ab4333.
URI
https://scholars.duke.edu/individual/pub1409900
PMID
31505474
Source
pubmed
Published In
Phys Med Biol
Volume
64
Published Date
Start Page
225017
DOI
10.1088/1361-6560/ab4333

Feasibility of radiosurgery dosimetry using NIPAM 3D dosimeters and x-ray CT

© Published under licence by IOP Publishing Ltd. We investigated the feasibility of using N-isopropylacrylamide (NIPAM) dosimeters with x-ray CT to verify radiosurgery dose. Dosimeters were prepared at one facility and shipped to a second facility for irradiation. A simulation CT was acquired and plans prepared for a 4 field box, and a 4 arc VMAT radiosurgery plan to 6 targets with 1cm diameter. Each dosimeter was aligned via CBCT and irradiated, followed by 5 diagnostic CTs acquired after >24 hours, which were averaged for analysis. Absolute dose calibration was applied and dose evaluated for both plans. Hounsfield Units were proportional to dose above 10-12Gy. For the 4-field box, mean difference between measured and predicted dose >10Gy was -0.13Gy -1.69Gy and gamma index was <1 for 72% and 65% of voxels using a 5% / 1mm and 3% / 2mm criteria, respectively (threshold = 15Gy, global dose criteria). For the multifocal SRS case, mean dose within each target was within -0.14Gy- 0.55Gy of the expected value, and gamma index was < 1 for 94.0% and 99.5% of voxels, respectively (threshold = 15Gy). NIPAM based 3D dosimetry with x-ray CT is well suited for validating radiosurgery spatial alignment, as well as dose distributions when dose is above 10-12Gy.
Authors
Adamson, J; Carroll, J; Trager, M; Yoon, P; Kodra, J; Yin, FF; Maynard, E; Hilts, M; Oldham, M; Jirasik, A
MLA Citation
Adamson, J., et al. “Feasibility of radiosurgery dosimetry using NIPAM 3D dosimeters and x-ray CT.” Journal of Physics: Conference Series, vol. 1305, no. 1, 2019. Scopus, doi:10.1088/1742-6596/1305/1/012004.
URI
https://scholars.duke.edu/individual/pub1417159
Source
scopus
Published In
Journal of Physics: Conference Series
Volume
1305
Published Date
DOI
10.1088/1742-6596/1305/1/012004

Predicting intracranial progression following stereotactic radiosurgery for brain metastases: Implications for post SRS imaging

© 2019 Old City Publishing, Inc. Purpose: Follow-up imaging after stereotactic radiosurgery (SRS) is crucial to identify salvageable brain metastases (BM) recurrence. As optimal imaging intervals are poorly understood, we sought to build a predictive model for time to intracranial progression. Methods: Consecutive patients treated with SRS for BM at three institutions from January 1, 2002 to June 30, 2017 were retrospectively reviewed. We developed a model using stepwise regression that identified four prognostic factors and built a predictive nomogram. Results: We identified 755 patients with primarily non-small cell lung, breast, and melanoma BMs. Factors such as number of BMs, histology, history of prior whole-brain radiation, and time interval from initial cancer diagnosis to metastases were prognostic for intracranial progression. Per our nomogram, risk of intracranial progression by 3 months post-SRS in the high-risk group was 21% compared to 11% in the low-risk group; at 6 months, it was 43% versus 27%. Conclusion: We present a nomogram estimating time to BM progression following SRS to potentially personalize surveillance imaging.
Authors
Natarajan, BD; Rushing, CN; Cummings, MA; Jutzy, JMS; Choudhury, KR; Moravan, MJ; Fecci, PE; Adamson, J; Chmura, SJ; Milano, MT; Kirkpatrick, JP; Salama, JK
MLA Citation
Natarajan, B. D., et al. “Predicting intracranial progression following stereotactic radiosurgery for brain metastases: Implications for post SRS imaging.” Journal of Radiosurgery and Sbrt, vol. 6, no. 3, Jan. 2019, pp. 179–87.
URI
https://scholars.duke.edu/individual/pub1410083
Source
scopus
Published In
Journal of Radiosurgery and Sbrt
Volume
6
Published Date
Start Page
179
End Page
187

The effect of MLC leaf width in single-isocenter multi-target radiosurgery with volumetric modulated arc therapy.

Purpose: Single-isocenter multi-target (SIMT) volumetric modulated arc therapy (VMAT) is primarily limited to linear accelerators utilizing 2.5 mm leaf width MLCs. We explore feasibility of applying this technique to linear accelerators utilizing MLCs with leaf width of 5 mm. Methods: Twenty patients with 3-10 intracranial brain metastases originally treated with 2.5 mm MLCs were re-planned using 5 mm MLCs and relevant dosimetric indices were compared. We also evaluated various strategies of adding VMAT arcs to mitigate degradations of dose quality values. Results: Wider MLCs caused small changes in total MUs (5827 ± 2334 vs 5572 ± 2220, p = 0.006), and conformity index (CI) (2.22% ± 0.05%, p = 0.045), but produced more substantial increases in brain V30%[%] and V50%[%] (27.75% ± 0.16% and 20.04% ± 0.13% respectively, p < 0.001 for both), and V12Gy[cc] (16.91% ± 0.12%, p < 0.001). Conclusion: SIMT radiosurgery delivered via VMAT using 5 mm wide MLCs can achieve similar CI compared to that using 2.5 mm leaf width MLCs but with moderately increased isodose spill, which can be only partially mitigated by increasing the number of VMAT arcs.
Authors
Abisheva, Z; Floyd, SR; Salama, JK; Kirkpatrick, J; Yin, F-F; Moravan, MJ; Giles, W; Adamson, J
MLA Citation
Abisheva, Zhanerke, et al. “The effect of MLC leaf width in single-isocenter multi-target radiosurgery with volumetric modulated arc therapy..” J Radiosurg Sbrt, vol. 6, no. 2, 2019, pp. 131–38.
URI
https://scholars.duke.edu/individual/pub1410134
PMID
31641549
Source
pubmed
Published In
J Radiosurg Sbrt
Volume
6
Published Date
Start Page
131
End Page
138

Is a single isocenter sufficient for volumetric modulated arc therapy radiosurgery when multiple itracranial metastases are spatially dispersed?

Previous work demonstrated improved dosimetry of single isocenter volumetric modulated arc therapy (VMAT) of multiple intracranial targets when they are located ≤ 4cm from isocenter because of narrower multileaf collimators (MLCs). In follow-up, we sought to determine if decreasing isocenter-target distance (diso) by using 2 to 3 isocenters would improve dosimetry for spatially dispersed targets. We also investigated the effect of a maximum dose constraint during VMAT optimization, and the dosimetric effect of the number of VMAT arcs used for a larger number of targets (i.e., 7 to 9). We identified radiosurgery cases that had multiple intracranial targets with diso of at least 1 target > 5cm. A single isocenter VMAT plan was created using a standardized 4-arc technique with 18Gy per target. Each case was then replanned (1) using 2 to 3 isocenters, (2) including a maximum dose constraint per target, and in the case of 7 to 9 targets, (3) using 3 to 6 arcs. Dose evaluation included brain V6Gy and V12Gy, and conformity index (CI), gradient index (GI), and heterogeneity index (HI) per target. Two isocenters were sufficient to limit diso to ≤ 4cm and ≤ 5cm for 11/15 and 13/15 cases, respectively; after replanning with 2 to 3 isocenters, diso decreased from 5.8 ± 2.8cm (2.3 14.9) to 2.5 ± 1.4cm (0 5.2). All dose statistics improved on average, albeit modestly: V6Gy = 6.9 ± 7.1%, V12Gy = 0.9% ± 4.4%, CI = 2.6% ± 4.6%, GI = 0.9% ± 12.7%, and HI = 2.6% ± 5.2%; however, the number of arcs doubled and monitor units increase by nearly 2-fold. A maximum dose constraint had a negative effect on all dose indices, increasing V12Gy by 9.7 ± 6.9%. For ≥ 7 targets, increasing number of arcs to > 3 improved CI, V12Gy, and V6Gy. A single isocenter is likely sufficient for VMAT radiosurgery of multiple intracranial metastases. Optimal treatment plan quality is achieved when no constraint is placed on the maximum target dose; for cases with many targets at least 4 arcs are needed for optimal plan quality.
Authors
Morrison, J; Hood, R; Yin, F-F; Salama, JK; Kirkpatrick, J; Adamson, J
MLA Citation
Morrison, Jay, et al. “Is a single isocenter sufficient for volumetric modulated arc therapy radiosurgery when multiple itracranial metastases are spatially dispersed?.” Medical Dosimetry : Official Journal of the American Association of Medical Dosimetrists, vol. 41, no. 4, Dec. 2016, pp. 285–89. Epmc, doi:10.1016/j.meddos.2016.06.007.
URI
https://scholars.duke.edu/individual/pub1145746
PMID
27614790
Source
epmc
Published In
Medical Dosimetry
Volume
41
Published Date
Start Page
285
End Page
289
DOI
10.1016/j.meddos.2016.06.007