Quantifying the dosimetric influences of radiation coverage and brachytherapy implant placement uncertainty on eye plaque size selection

Gagne, Nolan L.; Rivard, Mark J.

doi:10.1016/j.brachy.2012.09.006

Cited by 30 publications

(30 citation statements)

References 30 publications

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“…However, a recent study has shown that following these recommendations, COMS eye plaque tumor coverage is a sensitive function of both prescription depth and assumed plaque placement uncertainty, and that D 95% may be as low as 68% of D Rx for certain lesions [26]. Nonetheless, the present study assumes that the plaque is placed perfectly coaxial above a cylindrically-symmetric tumor; likewise the tumor dimension and plaque size combinations in the present study also ensure adequate dose volumetric coverage.…”

Section: Resultsmentioning

confidence: 99%

Keeping an eye on the ring: COMS plaque loading optimization for improved dose conformity and homogeneity

Gagne¹,

Cutright²,

Rivard³

2012

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PurposeTo improve tumor dose conformity and homogeneity for COMS plaque brachytherapy by investigating the dosimetric effects of varying component source ring radionuclides and source strengths.Material and methodsThe MCNP5 Monte Carlo (MC) radiation transport code was used to simulate plaque heterogeneity-corrected dose distributions for individually-activated source rings of 14, 16 and 18 mm diameter COMS plaques, populated with 103Pd, 125I and 131Cs sources. Ellipsoidal tumors were contoured for each plaque size and MATLAB programming was developed to generate tumor dose distributions for all possible ring weighting and radionuclide permutations for a given plaque size and source strength resolution, assuming a 75 Gy apical prescription dose. These dose distributions were analyzed for conformity and homogeneity and compared to reference dose distributions from uniformly-loaded 125I plaques. The most conformal and homogeneous dose distributions were reproduced within a reference eye environment to assess organ-at-risk (OAR) doses in the Pinnacle3 treatment planning system (TPS). The gamma-index analysis method was used to quantitatively compare MC and TPS-generated dose distributions.ResultsConcentrating > 97% of the total source strength in a single or pair of central 103Pd seeds produced the most conformal dose distributions, with tumor basal doses a factor of 2-3 higher and OAR doses a factor of 2-3 lower than those of corresponding uniformly-loaded 125I plaques. Concentrating 82-86% of the total source strength in peripherally-loaded 131Cs seeds produced the most homogeneous dose distributions, with tumor basal doses 17-25% lower and OAR doses typically 20% higher than those of corresponding uniformly-loaded 125I plaques. Gamma-index analysis found > 99% agreement between MC and TPS dose distributions.ConclusionsA method was developed to select intra-plaque ring radionuclide compositions and source strengths to deliver more conformal and homogeneous tumor dose distributions than uniformly-loaded 125I plaques. This method may support coordinated investigations of an appropriate clinical target for eye plaque brachytherapy.

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Section: Resultsmentioning

confidence: 99%

Keeping an eye on the ring: COMS plaque loading optimization for improved dose conformity and homogeneity

Gagne¹,

Cutright²,

Rivard³

2012

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“…A case by case defined planning target volume (PTV), extra safety margin can be added by the radiation oncologist in case of uncertainties in tumor delineation and/or plaque localization [24,25]. …”

Section: Step 1 Multidisciplinary Tumor Board: a Case Presentation Amentioning

confidence: 99%

INTERACTS (INTErventional Radiotherapy ACtive Teaching School) guidelines for quality assurance in choroidal melanoma interventional radiotherapy (brachytherapy) procedures

Tagliaferri¹,

Pagliara²,

Boldrini³

et al. 2017

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Eye plaque brachytherapy represents a safe and effective therapeutic approach for choroidal melanoma, combining clinical outcomes with an eye and visual preservation.As it represents a complex procedure, a specific quality assurance program is strongly suggested to improve patients and operators safety, and to reduce possible complications linked to surgical procedure and radiation exposure.The aim of this paper is to describe the INTERACTS (Interventional Radiotherapy Active Teaching School) guidelines for quality assurance in choroidal melanoma interventional radiotherapy (brachytherapy) used in our institution.

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“…The dose rate correction has been applied for different dose rates [19]. We included a lateral safety margin of 2 mm around the tumor base [20]. Using 5-0 Mersilene sutures, plaques were secured to the sclera for the duration of calculated radiation time.…”

Section: Surgical Proceduresmentioning

confidence: 99%

Ruthenium-106 brachytherapy for thick uveal melanoma: reappraisal of apex and base dose radiation and dose rate

Naseripour¹,

Jaberi²,

Sedaghat³

et al. 2016

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Purpose: To evaluate the outcomes of ruthenium-106 ( 106 Ru) brachytherapy in terms of radiation parameters in patients with thick uveal melanomas.Material and methods: Medical records of 51 patients with thick (thickness ≥ 7 mm and < 11 mm) uveal melanoma treated with 106 Ru brachytherapy during a ten-year period were reviewed. Radiation parameters, tumor regression, best corrected visual acuity (BCVA), and treatment-related complications were assessed.Results: Fifty one eyes of 51 consecutive patients including 25 men and 26 women with a mean age of 50.5 ± 15.2 years were enrolled. Patients were followed for 36.1 ± 26.5 months (mean ± SD). Mean radiation dose to tumor apex and to sclera were 71 (± 19.2) Gy and 1269 (± 168.2) Gy. Radiation dose rates to tumor apex and to sclera were 0.37 (± 0.14) Gy/h and 6.44 (± 1.50) Gy/h. Globe preservation was achieved in 82.4%. Preoperative mean tumor thickness of 8.1 (± 0.9) mm decreased to 4.5 (± 1.6) mm, 3.4 (± 1.4) mm, and 3.0 (± 1.46) mm at 12, 24, and 48 months after brachytherapy (p = 0.03). Four eyes that did not show regression after 6 months of brachytherapy were enucleated. Secondary enucleation was performed in 5 eyes because of tumor recurrence or neovascular glaucoma. Tumor recurrence was evident in 6 (11.8%) patients. Mean Log MAR (magnification requirement) visual acuity declined from 0.75 (± 0.63) to 0.94 (± 0.5) (p = 0.04). Best corrected visual acuity of 20/200 or worse was recorded in 37% of the patients at the time of diagnosis and 61.7% of the patients at last exam (p = 0.04). Non-proliferative and proliferative radiation-induced retinopathy was observed in 20 and 7 eyes.Conclusions: Thick uveal melanomas are amenable to 106 Ru brachytherapy with less than recommended apex radiation dose and dose rates.

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Quantifying the dosimetric influences of radiation coverage and brachytherapy implant placement uncertainty on eye plaque size selection

Cited by 30 publications

References 30 publications

Keeping an eye on the ring: COMS plaque loading optimization for improved dose conformity and homogeneity

Keeping an eye on the ring: COMS plaque loading optimization for improved dose conformity and homogeneity

INTERACTS (INTErventional Radiotherapy ACtive Teaching School) guidelines for quality assurance in choroidal melanoma interventional radiotherapy (brachytherapy) procedures

Ruthenium-106 brachytherapy for thick uveal melanoma: reappraisal of apex and base dose radiation and dose rate

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