Novel low-kVp beamlet system for choroidal melanoma

Carlos Esquivel, Clifton D. Fuller, Robert G. Waggener, Adrian Wong, Martin Meltz, Melissa Blough, Tony Y. Eng, Charles R. Thomas

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Background: Treatment of choroidal melanoma with radiation often involves placement of customized brachytherapy eye-plaques. However, the dosimetric properties inherent in source-based radiotherapy preclude facile dose optimization to critical ocular structures. Consequently, we have constructed a novel system for utilizing small beam low-energy radiation delivery, the Beamlet Low-kVp X-ray, or "BLOKX" system. This technique relies on an isocentric rotational approach to deliver dose to target volumes within the eye, while potentially sparing normal structures. Methods: Monte Carlo N-Particle (MCNP) transport code version 5.0(14) was used to simulate photon interaction with normal and tumor tissues within modeled right eye phantoms. Five modeled dome-shaped tumors with a diameter and apical height of 8 mm and 6 mm, respectively, were simulated distinct positions with respect to the macula iteratively. A single fixed 9 × 9 mm2 beamlet, and a comparison COMS protocol plaque containing eight I-125 seeds (apparent activity of 8 mCi) placed on the scleral surface of the eye adjacent to the tumor, were utilized to determine dosimetric parameters at tumor and adjacent tissues. After MCNP simulation, comparison of dose distribution at each of the 5 tumor positions for each modality (BLOKX vs. eye-plaque) was performed. Results: Tumor-base doses ranged from 87.1-102.8 Gy for the BLOKX procedure, and from 335.3-338.6 Gy for the eye-plaque procedure. A reduction of dose of at least 69% to tumor base was noted when using the BLOKX. The BLOKX technique showed a significant reduction of dose, 89.8%, to the macula compared to the episcleral plaque. A minimum 71.0% decrease in dose to the optic nerve occurred when the BLOKX was used. Conclusion: The BLOKX technique allows more favorable dose distribution in comparison to standard COMS brachytherapy, as simulated using a Monte Carlo iterative mathematical modeling. Future series to determine clinical utility of such an approach are warranted.

Original languageEnglish (US)
Article number36
JournalRadiation Oncology
Volume1
Issue number1
DOIs
StatePublished - Sep 11 2006

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Melanoma
Neoplasms
Brachytherapy
Radiation
Monte Carlo Method
Optic Nerve
Photons
Seeds
Radiotherapy
X-Rays

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Medicine(all)

Cite this

Esquivel, C., Fuller, C. D., Waggener, R. G., Wong, A., Meltz, M., Blough, M., ... Thomas, C. R. (2006). Novel low-kVp beamlet system for choroidal melanoma. Radiation Oncology, 1(1), [36]. https://doi.org/10.1186/1748-717X-1-36

Novel low-kVp beamlet system for choroidal melanoma. / Esquivel, Carlos; Fuller, Clifton D.; Waggener, Robert G.; Wong, Adrian; Meltz, Martin; Blough, Melissa; Eng, Tony Y.; Thomas, Charles R.

In: Radiation Oncology, Vol. 1, No. 1, 36, 11.09.2006.

Research output: Contribution to journalArticle

Esquivel, C, Fuller, CD, Waggener, RG, Wong, A, Meltz, M, Blough, M, Eng, TY & Thomas, CR 2006, 'Novel low-kVp beamlet system for choroidal melanoma', Radiation Oncology, vol. 1, no. 1, 36. https://doi.org/10.1186/1748-717X-1-36
Esquivel C, Fuller CD, Waggener RG, Wong A, Meltz M, Blough M et al. Novel low-kVp beamlet system for choroidal melanoma. Radiation Oncology. 2006 Sep 11;1(1). 36. https://doi.org/10.1186/1748-717X-1-36
Esquivel, Carlos ; Fuller, Clifton D. ; Waggener, Robert G. ; Wong, Adrian ; Meltz, Martin ; Blough, Melissa ; Eng, Tony Y. ; Thomas, Charles R. / Novel low-kVp beamlet system for choroidal melanoma. In: Radiation Oncology. 2006 ; Vol. 1, No. 1.
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abstract = "Background: Treatment of choroidal melanoma with radiation often involves placement of customized brachytherapy eye-plaques. However, the dosimetric properties inherent in source-based radiotherapy preclude facile dose optimization to critical ocular structures. Consequently, we have constructed a novel system for utilizing small beam low-energy radiation delivery, the Beamlet Low-kVp X-ray, or {"}BLOKX{"} system. This technique relies on an isocentric rotational approach to deliver dose to target volumes within the eye, while potentially sparing normal structures. Methods: Monte Carlo N-Particle (MCNP) transport code version 5.0(14) was used to simulate photon interaction with normal and tumor tissues within modeled right eye phantoms. Five modeled dome-shaped tumors with a diameter and apical height of 8 mm and 6 mm, respectively, were simulated distinct positions with respect to the macula iteratively. A single fixed 9 × 9 mm2 beamlet, and a comparison COMS protocol plaque containing eight I-125 seeds (apparent activity of 8 mCi) placed on the scleral surface of the eye adjacent to the tumor, were utilized to determine dosimetric parameters at tumor and adjacent tissues. After MCNP simulation, comparison of dose distribution at each of the 5 tumor positions for each modality (BLOKX vs. eye-plaque) was performed. Results: Tumor-base doses ranged from 87.1-102.8 Gy for the BLOKX procedure, and from 335.3-338.6 Gy for the eye-plaque procedure. A reduction of dose of at least 69{\%} to tumor base was noted when using the BLOKX. The BLOKX technique showed a significant reduction of dose, 89.8{\%}, to the macula compared to the episcleral plaque. A minimum 71.0{\%} decrease in dose to the optic nerve occurred when the BLOKX was used. Conclusion: The BLOKX technique allows more favorable dose distribution in comparison to standard COMS brachytherapy, as simulated using a Monte Carlo iterative mathematical modeling. Future series to determine clinical utility of such an approach are warranted.",
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N2 - Background: Treatment of choroidal melanoma with radiation often involves placement of customized brachytherapy eye-plaques. However, the dosimetric properties inherent in source-based radiotherapy preclude facile dose optimization to critical ocular structures. Consequently, we have constructed a novel system for utilizing small beam low-energy radiation delivery, the Beamlet Low-kVp X-ray, or "BLOKX" system. This technique relies on an isocentric rotational approach to deliver dose to target volumes within the eye, while potentially sparing normal structures. Methods: Monte Carlo N-Particle (MCNP) transport code version 5.0(14) was used to simulate photon interaction with normal and tumor tissues within modeled right eye phantoms. Five modeled dome-shaped tumors with a diameter and apical height of 8 mm and 6 mm, respectively, were simulated distinct positions with respect to the macula iteratively. A single fixed 9 × 9 mm2 beamlet, and a comparison COMS protocol plaque containing eight I-125 seeds (apparent activity of 8 mCi) placed on the scleral surface of the eye adjacent to the tumor, were utilized to determine dosimetric parameters at tumor and adjacent tissues. After MCNP simulation, comparison of dose distribution at each of the 5 tumor positions for each modality (BLOKX vs. eye-plaque) was performed. Results: Tumor-base doses ranged from 87.1-102.8 Gy for the BLOKX procedure, and from 335.3-338.6 Gy for the eye-plaque procedure. A reduction of dose of at least 69% to tumor base was noted when using the BLOKX. The BLOKX technique showed a significant reduction of dose, 89.8%, to the macula compared to the episcleral plaque. A minimum 71.0% decrease in dose to the optic nerve occurred when the BLOKX was used. Conclusion: The BLOKX technique allows more favorable dose distribution in comparison to standard COMS brachytherapy, as simulated using a Monte Carlo iterative mathematical modeling. Future series to determine clinical utility of such an approach are warranted.

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