Dosimetric considerations for catheter-based beta and gamma emitters in the therapy of neointimal hyperplasia in human coronary arteries

Amols, Howard; Zaider, Marco; Weinberger, Judah; Ennis, Ronald D.; Schiff, Peter B.; Reinstein, L. E.

doi:10.1016/s0360-3016(96)00301-x

Cited by 97 publications

(48 citation statements)

References 13 publications

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“…13,14 For instance, the highest prescribed dose in our study was 18 Gy, and the calculated longitudinal dose per millimeter from the 100% isodose boundary is expected to be 15.5Ϯ1.0 Gy at 1 mm, 11.0Ϯ1.0 Gy at 2 mm, 5.5Ϯ0.5 Gy at 3 mm, 2.4Ϯ1.0 Gy at 4 mm, and Ͻ1 Gy at 5 mm.…”

Section: Ivus Image Acquisition Analysis Systemmentioning

confidence: 77%

Three-Dimensional Intravascular Ultrasound Assessment of Noninjured Edges of β-Irradiated Coronary Segments

et al. 2000

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Background-The "edge effect," late lumen loss at the margins of the treated segment, has become an important issue in the field of coronary brachytherapy. The aim of the present study was to assess the edge effect in noninjured margins adjacent to the irradiated segments after catheter-based intracoronary ␤-irradiation. Methods and Results-Fifty-three vessels were assessed by means of 3-dimensional intravascular ultrasound after the procedure and at 6-to 8-month follow-up. Fourteen vessels (placebo group) did not receive radiation (sham source), whereas 39 vessels were irradiated. In the irradiated group, 48 edges (5 mm in length) were identified as noninjured, whereas 18 noninjured edges were selected in the placebo group. We compared the volumetric intravascular ultrasound measurements of the noninjured edges of the irradiated vessels with the fully irradiated nonstented segments (IRS, nϭ27) (26-mm segments received the prescribed 100% isodose) and the noninjured edges of the vessels of the placebo patients. The lumen decreased (6 mm 3 ) in the noninjured edges of the irradiated vessels at follow-up (Pϭ0.001). We observed a similar increase in plaque volume in all segments: noninjured edges of the irradiated group (19.6%), noninjured edges of the placebo group (21.5%), and IRS (21.0%). The total vessel volume increased in the IRS in the 3 groups. No edge segment was subject to repeat revascularization. Conclusions-The edge effect occurs in the noninjured margins of radiation source train in both irradiated and placebo patients. Thus, low-dose radiation may not play an important role in this phenomenon, whereas nonmeasurable device injury may be considered a plausible alternative explanation.

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Section: Ivus Image Acquisition Analysis Systemmentioning

confidence: 77%

Three-Dimensional Intravascular Ultrasound Assessment of Noninjured Edges of β-Irradiated Coronary Segments

et al. 2000

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“…Since most patients treated with brachytherapy have been stented in severely diseased coronary arteries, we were interested in finding out how stents, in combination with various degrees of calcified plaque, affect dosimetry at the level of the adventitia, that is, the most likely target of brachytherapy, for commercially available ␥-and ␤-sources. This topic has been previously addressed by several investigators; however, most of them used Monte Carlo simulation techniques 10,11,16,18,19 or measured the effect of metallic stents only. 15 …”

Section: Discussionmentioning

confidence: 99%

“…The most frequently used ␥-emitters are irdium 192 isotopes ( 192 Ir) and the most frequently used ␤-emitters are strontium/ yttrium 90 sources ( 90 Sr/Y). Many theoretical questions have been raised regarding the effectiveness of both types of emitters in delivering the required dose of 14 to 20 Gy along the vessel wall (in particular the adventitia), such as the importance of accurate source centering 10 and the dose perturbation caused by calcified plaque and/or metallic stents. 11 In animal studies, 14 Gy radiation from a noncentred 90 Sr/Y source was successful in preventing neointima formation only when radiation was performed before rather than after stenting.…”

mentioning

confidence: 99%

Dosimetric Measurements in Isolated Human Coronary Arteries

et al. 2002

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Background-Intravascular brachytherapy is being applied more and more in patients with coronary artery disease for the prevention of restenosis subsequent to balloon angioplasty, in particular after stent implantation. Several radiation sources (␤-and ␥-emitters) are available in clinical routine. It was the purpose of this study to compare the radiation doses at the level of the adventitia in diseased and stented human coronary arteries for 192 Ir and 90 Sr/Y emitters in routine use. In contrast to previously published work, we performed dosimetry instead of calculating depth-dose distribution by use of the Monte Carlo system. Methods and Results-Postmortem calcified human coronary artery segments were stented and placed in an organ bath.Commercially available ␥-emitters ( 192 Ir; Cordis Checkmate) and ␤-emitters ( 90 Sr/Y; Novoste Beta-Cath) were used. Relative dose distributions along the adventitia were measured by a specially designed scintillation detector system. Whereas dose perturbations caused by stents and calcified plaque were negligible for the 192 Ir source, radiation from the beta source was significantly impaired (as much as 40%) at the level of the adventitia (3.0-mm vessel diameter). Dose perturbation was clearly dependent on the extent and severity of calcification, less affected by stent material. Conclusions-Dose perturbation caused by calcified plaque and metallic stents is significant for ␤-sources. This dosimetric difference between ␤-and ␥-emitters in diseased coronary arteries should be considered when calculating doses in intravascular brachytherapy.

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“…While there are several studies comparing beta versus gamma systems (e.g., Amols et al 2 and Li et al 3 ), there are few studies which describe the implications of different geometrical designs. A dosimetric analysis is essential because a randomized study that directly compares these different systems is highly unlikely.…”

Section: Introductionmentioning

confidence: 99%

Wire or coated balloon? Searching for an optimal source for intravascular brachytherapy with β emitters using as an example

Lehmann

King

2003

J Applied Clin Med Phys

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This study identifies basic dosimetric differences between two designs for intravascular brachytherapy (IVBT) in current clinical practice and ongoing trials and their clinical implications within beta emitting systems using P‐32 as an example. The two designs are (i) the wire‐type source, where the radioactive source material is confined to a wirelike structure within the vessel lumen, and (ii) the balloon‐surface source, where the radioactive source material is distributed over a surface area (balloon‐wall) which is brought in close proximity with the vessel wall. Using Monte Carlo simulations with the EGS4 code, the target coverage, the influence of centering errors, and the perturbation of the dose distribution caused by metallic stents have been compared. The radial dose fall‐off in the target region was found to be steeper for balloon surface systems compared with wire systems. The inner lumen wall dose for a balloon surface source was 25% higher than that for a wirelike source (2.5 mm vessel diameter). However, the comparably shallower fall‐off from wire‐type systems is very sensitive to centering uncertainties. A 0.5 mm displacement, for example, will cause the dose to change by a factor of 2 at the inner vessel wall and by a factor of 1.8 at the prescription point. It is shown that the interference from metallic stents is more significant for wire‐type systems than it is for balloon‐surface‐type systems, where double the dose variation beyond the stent at the radial prescription distance may occur. Centering uncertainties dominate the dose perturbation effects for wire‐type systems. Balloon‐surface‐type designs show a more predictable dose distribution that features, however, a higher inner vessel surface dose. Since a direct clinical comparison of systems of both types is not likely, these findings should be considered when interpreting clinical results from treatments with either type of source and, possibly, for future source design. © 2003 American College of Medical Physics. PACS number(s): 87.53.–j, 87.90.+y

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Dosimetric considerations for catheter-based beta and gamma emitters in the therapy of neointimal hyperplasia in human coronary arteries

Cited by 97 publications

References 13 publications

Three-Dimensional Intravascular Ultrasound Assessment of Noninjured Edges of β-Irradiated Coronary Segments

Three-Dimensional Intravascular Ultrasound Assessment of Noninjured Edges of β-Irradiated Coronary Segments

Dosimetric Measurements in Isolated Human Coronary Arteries

Wire or coated balloon? Searching for an optimal source for intravascular brachytherapy with β emitters using as an example

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