Investigation of source position uncertainties &amp; balloon deformation in MammoSite brachytherapy on treatment effectiveness

Bensaleh, S.; Bezak, Eva

doi:10.1007/s13246-010-0008-6

Cited by 3 publications

(3 citation statements)

References 33 publications

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“…In the DOSXYZnrc code, the

^{192} Ir

brachytherapy source was approximated as a uniformly isotropically radiating parallelepiped source. ( 3 ) The γ‐ray spectrum for the

^{192} Ir

was taken from a published report. ( 18 ) The spectrum consists of 34 energy bins ranging from 0.060 to 0.885 MeV.…”

Section: Methodsmentioning

confidence: 99%

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The impact of uncertainties associated with MammoSite brachytherapy on the dose distribution in the breast

Bensaleh

Bezak

2011

J Applied Clin Med Phys

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The MammoSite radiation therapy system is a novel technique for treatment of patients with early‐stage breast cancer. It was developed to overcome the longer schedules associated with external‐beam radiation therapy. It consists of a small balloon (4 cm in diameter) connected to an inflation channel and a catheter for the passage of a high dose rate 192Ir brachytherapy source. The device is placed into the tumor resection cavity and inflated with a mixture of saline and radiographic contrast agent to a size that fills the cavity. A high dose rate 192Ir source is driven into the balloon center using a remote afterloader to deliver the prescribed dose at a point 1 cm away from the balloon surface. There are several uncertainties that affect the dose distribution in the MammoSite brachytherapy. They include source position deviation, balloon deformation, and the concentration of the contrast medium inside the balloon. The purpose of this study is to investigate the extent of the dose perturbation for various concentrations of the contrast medium in a MammoSite balloon using Monte Carlo simulations and thermoluminescent dosimetry. This study also combines the impact of these uncertainties on the MammoSite treatment efficacy. The current study demonstrates that the combined uncertainties associated with the MammoSite brachytherapy technique — up to the value of 2 mm balloon deformation, 1 mm source deviation, and 15% contrast concentration — have no impact on the tumor control probability.PACS number: 87.53.‐j

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“…In the DOSXYZnrc code, the

^{192} Ir

brachytherapy source was approximated as a uniformly isotropically radiating parallelepiped source. ( 3 ) The γ‐ray spectrum for the

^{192} Ir

was taken from a published report. ( 18 ) The spectrum consists of 34 energy bins ranging from 0.060 to 0.885 MeV.…”

Section: Methodsmentioning

confidence: 99%

“…The impact of these two types of uncertainties on the MammoSite treatment effectiveness was previously investigated. ( 3 ) …”

Section: Introductionmentioning

confidence: 99%

The impact of uncertainties associated with MammoSite brachytherapy on the dose distribution in the breast

Bensaleh

Bezak

2011

J Applied Clin Med Phys

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“…In the literature, the same investigators published two Monte Carlo simulation studies [ 3 , 4 ] regarding dose perturbation due to source positioning uncertainty in HDR balloon brachytherapy of breast cancer. One study [ 3 ] was performed for a single MammoSite patient whose skin spacing was 0.7 cm. The other study [ 4 ] was performed for a phantom with three different sizes of the balloon (4, 5, and 6 cm diameter).…”

Section: Purposementioning

confidence: 99%

Dosimetric impact of source-positioning uncertainty in high-dose-rate balloon brachytherapy of breast cancer

Kim¹

2015

jcb

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PurposeTo evaluate the dosimetric impact of source-positioning uncertainty in high-dose-rate (HDR) balloon brachytherapy of breast cancer.Material and methodsFor 49 HDR balloon patients, each dwell position of catheter(s) was manually shifted distally (+) and proximally (–) with a magnitude from 1 to 4 mm. Total 392 plans were retrospectively generated and compared to corresponding clinical plans using 7 dosimetric parameters: dose (D95) to 95% of planning target volume for evaluation (PTV_EVAL), and volume covered by 100% and 90% of the prescribed dose (PD) (V100 and V90); skin and rib maximum point dose (Dmax); normal breast tissue volume receiving 150% and 200% of PD (V150 and V200).ResultsPTV_EVAL dosimetry deteriorated with larger average/maximum reduction (from ± 1 mm to ± 4 mm) for larger source position uncertainty (p value < 0.0001): from 1.0%/2.5%, 3.3%/5.9%, 6.3%/10.0% to 9.8%/14.5% for D95; from 1.0%/2.6%, 3.1%/5.7%, 5.8%/8.9% to 8.7%/12.3% for V100; from 0.2%/1.5%, 1.0%/4.0%, 2.7%/6.8% to 5.1%/10.3% for V90. ≥ ± 3 mm shift reduced average D95 to < 95% and average V100 to < 90%. While skin and rib Dmax change was case-specific, its absolute change (∣Δ(Value)∣) showed that larger shift and high dose group had larger variation compared to smaller and lower dose group (p value < 0.0001), respectively. Normal breast tissue V150 variation was case-specific and small. Average ∣Δ(V150)∣ was 0.2 cc for the largest shift (± 4 mm) with maximum < 1.7 cc. V200 was increased with higher elevation for larger shift: from 6.4 cc/9.8 cc, 7.0 cc/10.1 cc, 8.0 cc/11.3 cc to 9.2 cc/ 13.0 cc.ConclusionsThe tolerance of ± 2 mm recommended by AAPM TG 56 is clinically acceptable in most clinical cases. However, special attention should be paid to a case where both skin and rib are located proximally to balloon, and the orientation of balloon catheter(s) is vertical to these critical structures. In this case, sufficient dosimetric planning margins are required.

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Dose assessment for brachytherapy with Henschke applicator

Yu¹,

Chao²,

Tung³

et al. 2011

Radiation Measurements

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Investigation of source position uncertainties & balloon deformation in MammoSite brachytherapy on treatment effectiveness

Cited by 3 publications

References 33 publications

The impact of uncertainties associated with MammoSite brachytherapy on the dose distribution in the breast

The impact of uncertainties associated with MammoSite brachytherapy on the dose distribution in the breast

Dosimetric impact of source-positioning uncertainty in high-dose-rate balloon brachytherapy of breast cancer

Dose assessment for brachytherapy with Henschke applicator

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