Three-year follow-up after intracoronary gamma radiation therapy for in-stent restenosis. Original WRIST. Washington Radiation for In-Stent Restenosis Trial

The contemporary use of intracoronary brachytherapy for instent restenosis: A review

In-stent restenosis (ISR) has been a major limitation in interventional cardiology and constitutes nearly 10 % of all percutaneous coronary interventions in the United States. Drug-eluting stent (DES) restenosis proves particularly difficult to manage and poses a high risk of recurrence and repeat intervention. Intra-coronary brachytherapy (IBT) has been traditionally viewed as a potential treatment modality for ISR. However, its use was hindered by procedural complexity, cost, and the advent of newer-generation DES. Recent data suggests promising results regarding IBT for the treatment of resistant DES-ISR. This review addresses the mechanism of action of IBT, procedural details, and associated risks and complications of its use. It will also highlight the available clinical evidence supporting the use of IBT and the future directions of its utilization in the treatment of ISR.

Northwell intracoronary brachytherapy for the treatment of recurrent drug eluting stent in-stent restenosis (NITDI study group)

OBJECTIVE

The purpose of this study is to report on safety, short-term and long-term clinical efficacy following intracoronary brachytherapy (ICBT) for restenosis (ISR) in patients with drug eluting stents (DES).

BACKGROUND

ICBT is an effective treatment for ISR of bare metal stents (BMS) but its utilization has waned due to the advent of DES. ISR following DES occurs at a frequency of 8% or greater.

METHOD

A retrospective analysis was performed on patients treated on an institutional review board (IRB) approved protocol using ICBT for DES ISR between January 2011 and October 2016. All patients were followed for 24 months for procedural complications, mortality, clinical ISR/target lesion revascularization (TLR) and stroke.

RESULTS

A total of 290 patients were identified with a mean age of 66.6 years. All of them had high rates of typical coronary artery disease risk factors. Our primary outcome, composite of in-hospital mortality, myocardial infarction (MI), safety outcomes and procedural failure was noted in 1(0.3%) patient who had a MI. No other secondary outcome was noted in-hospital. At 1-year follow up, 12.4% patients had ISR, 1.7% patients died, and 1 (0.3%) had ischemic stroke. At 2-year, 14.7% had ISR, and total 6 (2.1%) patients had MI.

CONCLUSION

ICBT demonstrates excellent technical success rates for treatment, safety, and reasonable efficacy over 2-years to be free from recurrent clinical ISR. This study represents the largest ICBT data for DES ISR to date among very complex lesion subsets, however, more prospective data will be needed to determine the optimal patient for treatment.

Intracoronary Brachytherapy for Recurrent Drug-Eluting Stent Failure

OBJECTIVES

The study sought to report safety and long-term clinical efficacy of intravascular brachytherapy (VBT) for recurrent drug-eluting stent in-stent restenosis (DES-ISR).

BACKGROUND

Recurrent DES-ISR remains a therapeutic challenge, and VBT has been used selectively in recurrent DES failure.

METHODS

Patients undergoing VBT for recurrent DES-ISR were enrolled from a percutaneous coronary intervention registry. Clinical, procedural, VBT, and outcome data were collected for DES-ISR treated with radiation. Follow-up was obtained by phone call and clinic visits.

RESULTS

A total of 186 patients (283 lesions) were included. Mean age was 65 ± 11 years, and 115 (61.8%) were men. Mean time to failure from last failed DES implantation was 450.65 ± 50 days. Majority (95%) had >2 episodes of target lesion revascularization (TLR). Commonest presentation of DES-ISR was unstable angina (68, 30%). All lesions were treated with balloon angioplasty followed by VBT using Beta-Cath system (Best Vascular Inc., Springfield, Virginia) with a dose of 23 to 25 Gy at 2 mm from source center. Radiation was delivered to site of ISR, without procedural adverse events, in 99% cases. Incidence of TLR was 3.3% at 6 months, 12.1% at 1 year, 19.1% at 2 years, and 20.7% at 3 years. No subacute thrombosis event was noted. One patient had late thrombosis during a 3-year follow-up.

CONCLUSIONS

VBT for recurrent DES-ISR is safe, with low recurrence rates at 12 months post-procedure, and can be safely used as an effective short-term strategy. Overtime, there is a gradual attrition in patency requiring repeat intervention.

Eight-year clinical outcome after radioactive stent implantation: a treatment failure without irreversible long-term clinical sequelae

AIMS

To assess the long-term outcome of patients who underwent radioactive stent (RS) implantation.

METHODS AND RESULTS

The RS study population consisted of 133 consecutive patients who underwent RS implantation between November 1997 and July 2000. They were matched using the propensity score method with 266 patients who underwent bare metal stenting (BMS) in the same span. Long-term survival status and information on MACE (death, non-fatal myocardial infarction or any re-intervention) was retrospectively obtained. Eight-year cumulative survival (90.2% vs. 87.4%, p = 0.57) was similar between the RS and BMS group respectively, while 8-year cumulative MACE-free survival was significantly lower in RS patients (42.1% vs. 64.3%, p < 0.001) due to the difference in events (mainly target lesion revascularisations [TLRs]) during the first year of follow-up (cumulative 1-year MACE-free survival: 59.4% vs. 86.7%, p < 0.001); there was no difference in the MACE rate after the first year (p = 0.71). The TLR rate at six months in the RS group was 29.3%, mainly due to edge restenosis and at one year 36.2% (control group: 9.5%, p < 0.001).

CONCLUSIONS

A high incidence of MACE and re-intervention was observed during the first year following RS implantation, mainly related to TLR for edge restenosis. After the first year, the clinical outcome of RS patients was similar to the control group indicating that there are no late adverse effects related to low dose-rate intracoronary radiation therapy.

A meta-analysis of randomised controlled trials assessing drug-eluting stents and vascular brachytherapy in the treatment of coronary artery in-stent restenosis

OBJECTIVE

We undertook a meta-analysis of randomised trials assessing the outcome of vascular brachytherapy (VBT) or DES for the treatment of coronary artery ISR.

METHODS AND RESULTS

Studies utilising DES or VBT for ISR were identified by a systematic search. Data was pooled and combined overall effect measures were calculated for a random effect model in terms of deaths, myocardial infarctions, revascularisation, binary restenosis, mean late luminal loss and major adverse cardiac events (MACE). Fourteen eligible studies (3103 patients) were included. Neither therapy had any effect on mortality or myocardial infarction rate. VBT reduced the rate of revascularisation (RR 0.59, 95%CI 0.50-0.68), MACE (RR 0.58, 95%CI 0.51-0.67), binary restenosis (RR 0.51, 95%CI 0.44-0.59) and late loss (-0.73 mm, 95%CI -0.91 to -0.55 mm) compared to balloon angioplasty and selective bare metal stents (BMS) alone at intermediate follow-up and MACE (RR 0.72, 95%CI 0.61-0.85) at long-term follow-up. DES reduced the rate of revascularisation (OR 0.51, 95% CI 0.36-0.71), MACE (OR 0.55, 95% CI 0.39-0.79) and binary restenosis (OR 0.57, 95% CI 0.40-0.81) compared to VBT but follow-up was limited to 9 months.

CONCLUSIONS

VBT improves the long-term outcome of angioplasty compared with BMS alone in the treatment of ISR. DES appears to provide similar results to that of VBT during short-term follow-up.

Randomized comparison between intracoronary β-radiation brachytherapy and implantation of paclitaxel-eluting stents for the treatment of diffuse in-stent restenosis

BACKGROUND AND PURPOSE

Intracoronary brachytherapy was the primary therapeutic option for the treatment of in-stent restenosis (ISR) during the last years. Especially for the treatment of diffuse ISR (lesions >10mm), beta-source brachytherapy was significantly superior to singular balloon angioplasty. Despite lacking clinical database, the implantation of drug eluting stents recently became a common procedure for the treatment of ISR. This randomized trial aimed to compare the efficacy of beta-brachytherapy with beta-radioisotopes (90)Sr/(90)Y and paclitaxel-eluting stent implantation for the treatment of diffuse ISR.

MATERIAL AND METHODS

Thirty-seven patients with diffuse ISR were randomly assigned to beta-brachytherapy after balloon angioplasty (Beta-Cath in 17 patients) or paclitaxel-eluting stent implantation (Taxus-Express2 in 20 patients). Six-month clinical follow-up was obtained for all patients, while angiographic follow-up was available for 30 patients.

RESULTS

Binary ISR (restenosis >50%) within target segment was observed in three patients treated with Beta-Cath, of which one needed target segment revascularisation for recurrent ISR, whereas no significant restenosis occurred in the patients treated with Taxus-Express2 (P=0.037). No further major adverse cardiac (target segment revascularisation, myocardial infarction, death) was found in either group (P=NS). Stent implantation was the more time-saving (31+/-11 min versus 60+/-23 min, P<0.001) procedure.

CONCLUSIONS

Although this trial revealed a significant reduction of binary restenosis in the Taxus-Express2 arm, we found no difference in clinical outcome after implantation of paclitaxel-eluting stents for the treatment of diffuse ISR when compared to beta-brachytherapy.

Implementing a best-treatment strategy with intracoronary brachytherapy for in-stent restenosis in patients at high risk for recurrence

BACKGROUND

The deployment of drug-eluting stents (DES) to treat bare-metal stent restenosis [in-stent restenosis (ISR)] has become routine practice, with a consequential decline in the use of intracoronary brachytherapy (ICBT). However, there are concerns as to the long-term safety profile of DES, particularly in terms of late stent thrombosis. In addition, an appropriate treatment strategy for stenosis within DES has not been developed. The aim of this study was to examine the efficacy of best treatment with ICBT for ISR in patients at high risk for future recurrence.

METHODS

Forty-seven consecutive patients with symptomatic ISR with at least one or more increased risk criteria for recurrence were treated with beta-radiation. The patients received best treatment based on avoidance of previously reported procedural risk factors for recurrence (incomplete stent apposition, dissection, geographical miss, and damage to the noninjured vessel segment), deferring ICBT when provisional stenting was performed. A beta-radiation dose of 20 Gy was used, and clopidogrel was prescribed for at least 6 months.

RESULTS

Treatment was successful for all patients without in-hospital complications. ICBT increased the total intervention procedure time by 15+/-10 min. ISR length was 25.4+/-11.5 mm. The angiographic minimal luminal diameter (MLD) was 2.24+/-0.43 mm after ICBT versus 0.75+/-0.58 mm at baseline (P<.05). On 9-month follow-up, the MLD was 1.93+/-0.48 mm (P<.05 vs. baseline). Binary restenosis was detected in six (13%) patients. At 29.7+/-9.3 months of follow-up, target lesion revascularization or target vessel (nonlesion) revascularization was performed in 17 (36%) patients. Only one patient suffered a myocardial infarction, and no deaths were observed.

CONCLUSION

The adoption of a best-practice protocol for the use of ICBT to treat ISR can result in a safe and effective clinical and angiographic outcome. Under these circumstances and with appropriate patient selection, ICBT may continue to be of value despite the popular use of DES.

Long term outcome after intracoronary beta radiation therapy

OBJECTIVES

To determine the long term outcome after intracoronary beta radiation therapy (IRT).

SETTING

Tertiary referral centre.

METHODS

The rate of major adverse cardiac events (MACE) was retrospectively determined in 301 consecutive patients who were treated with IRT. MACE was defined as death, myocardial infarction, or any reintervention. Long term clinical outcome was obtained from an electronic database of hospital records and from questionnaires to the patients and referring physicians. Long term survival status was assessed by written inquiries to the municipal civil registries.

RESULTS

The mean (SD) follow up was 3.6 (1.2) years. The cumulative incidence of MACE at six months was 19.1%, at one year 36.4%, and at four years 58.3%. The target lesion revascularisation (TLR) rate at six months was 12.9%, at one year 28.3%, and at four years 50.4%. From multivariate analysis, dose < 18 Gy was the most significant predictor of TLR. At four years the cumulative incidence of death was 3.8%, of myocardial infarction 13.4%, and of coronary artery bypass surgery 11.3%. Total vessel occlusion was documented in 12.3% of the patients.

CONCLUSIONS

In the long term follow up of patients after IRT, there are increased adverse cardiac events beyond the first six months.

Use of drug-eluting stents for the treatment of in-stent restenosis in routine clinical practice

BACKGROUND

Although target lesion revascularization (TLR) has been dramatically decreased by using drug-eluting stents (DESs) in de-novo lesions, their efficacy for in-stent restenosis (ISR) has not yet been well established.

METHODS

We retrospectively analysed patients treated for ISR with DESs from three referral hospitals.

RESULTS

Eighty-seven consecutive patients, from June 2002 to April 2004, were included, with a mean age of 64+/-11 years; 83% were men, 32% had diabetes, 47% had had a previous myocardial infarction and 16% had low left ventricular ejection fraction. Angiographic characteristics were as follows: mean vessel diameter, 3.05+/-0.4 mm; lesion length, 17.8+/-7.7 mm; diameter stenosis, 84.0+/-10.7%; and complex lesion, 81%. The restenosis was focal in 45%, diffuse/proliferative in 51.3% and total occlusion in 3.7% of the cases. Sirolimus- and paclitaxel-eluting stents were used in 42 and 58% of the patients, respectively. Stent diameter was 3.1+/-0.3 mm and the length was 26.1+/-5.8 mm. Angiographic success was achieved in all patients, with one patient experiencing a post-procedural non-Q-wave myocardial infarction. At 6-month clinical follow-up, two patients had died from non-cardiac deaths, five had experienced a new TLR (5.7%, four percutaneous and one coronary artery bypass graft) and eight (9.2%) had had major adverse cardiac events. A stress test was performed in 60% of the population; target vessel ischemia was observed in one patient (3.3%).

CONCLUSION

In this non-select cohort of patients, the use of DESs is a safe and effective strategy for ISR lesions.

Three-year follow-up after intravascular γ-radiation for in-stent restenosis in saphenous vein grafts

The Washington Radiation for In-Stent Restenosis Trial in Saphenous Vein Grafts (SVG WRIST) demonstrated safety and efficacy of intravascular radiation therapy (IRT) for the treatment of in-stent restenosis (ISR) in SVG at 12 months. In this study, we aimed to examine whether the safety and efficacy of IRT is durable up to 36 months. One hundred twenty patients with diffuse ISR in SVG underwent balloon angioplasty, laser or atherectomy ablation, and/or additional stenting. After successful intervention, patients were randomly assigned in a double-blind fashion to intravascular treatment with a ribbon containing either iridium (Ir)-192 (n = 60) or nonradioactive seeds (n = 60). The prescribed dose at 2 mm from the source was either 14 or 15 Gy in vessels 2.5-4.0 mm or 18 Gy in vessels > 4.0 mm in diameter. At 36 months, target lesion revascularization (TLR; 43% vs. 66%; P = 0.02) and target lesion revascularization-major adverse cardiac event (TLR-MACE; 49% vs. 71%; P = 0.02) rates continued to be lower in the IRT group, but both target vessel revascularization (TVR; 59% vs. 71%; P = 0.17) and TVR-MACE (63% vs. 77%; P = 0.11) rates were not. In SVG WRIST, patients with ISR treated with IRT had a marked reduction in the need for repeat TLR at 36 months, with sustained clinical benefit at 3 years despite late recurrences, which were more pronounced in the radiation group.

Two-year clinical follow-up results of intracoronary radiation therapy with rhenium-188-diethylene triamine penta-acetic acid-filled balloon

We investigated the 2-year clinical follow-up results as well as 6-month angiographic and clinical follow-up results of intracoronary radiation therapy using a rhenium-188-diethylene triamine penta-acetic acid ((188)Re-DTPA)-filled balloon system. The study comprised of 161 patients with significant de novo (83%) or in-stent restenosis (17%) lesions. Irradiation to deliver 17.6 Gy at a depth of 1.0 mm into the vessel wall was carried out after successful intervention. At 6-month follow-up, binary restenosis developed with significantly lower frequency in the radiation group than in the control group (24.3% vs. 46.3%; P = 0.009), although target lesion revascularization rate did not show significant benefit. At 2-year follow-up, cumulative target lesion revascularization rate was not significantly different between radiation group (n = 86) and control group (n = 75; 20.0% vs. 26.0%; P = 0.368). The rate of major adverse cardiac events including death, myocardial infarction, and target lesion revascularization did not show significant difference between two groups either (22.3% vs. 30.1%; P = 0.266). In conclusion, although significant reduction in restenosis rate was noted at 6-month angiographic follow-up, intracoronary radiation therapy mostly in patients with de novo lesion did not show significant clinical benefit in 6-month and 2-year follow-up results. The benefit was noted only in a small subgroup of patients with in-stent restenosis.

Vascular brachytherapy in renal artery restenosis

PURPOSE OF REVIEW

As renal artery stenting becomes more commonly performed, the prevalence of renal artery in-stent restenosis will increase. Intracoronary brachytherapy is the only adjuvant therapy that has been shown to reduce the incidence of recurrent restenosis. This review addresses the mechanisms that make brachytherapy an effective tool for restenosis and its application to renal arteries.

RECENT FINDINGS

To date, the literature on renal artery brachytherapy for restenosis consists of several singular case reports and two case series. The first series of 13 patients had a 20% restenosis rate 1 year after brachytherapy, when Doppler ultrasound was used for follow-up monitoring. A report of a series of 5 patients, published this year, used surrogate markers for assessing efficacy as endpoints and found a similar restenosis rate.

SUMMARY

These series and case reports demonstrate that renal brachytherapy is feasible and safe. Comments on efficacy must await a randomized trial or accumulation of more anecdotal data.

Intracoronary brachytherapy for the prevention of restenosis after percutaneous coronary revascularization

PURPOSE

The purpose of this article is to review the current literature pertaining to intracoronary brachytherapy for the prevention of restenosis after percutaneous coronary revascularization (PCR).

METHODS

English-language articles were identified through a MEDLINE search (January 1984 to January 2003) using the keywords brachytherapy, radioactive stents, and coronary arteries. In addition, pertinent reference citations from relevant articles were reviewed.

RESULTS

Restenosis after PCR is a complex process, thought to be due to a combination of vessel wall remodeling and neointimal proliferation. To date, catheter-based delivery of intracoronary brachytherapy has been found to prevent vessel wall remodeling and causes a reduction in the proliferation of the neointima. Neointimal proliferation, as measured by mean neointimal area, was reduced in all animal studies (range 26%-91%). In contrast, animal studies examining radioactive stents demonstrated an increase in neointimal proliferation, suggesting that they may not be helpful at preventing post-PCR restenosis. All human studies using catheter-based intracoronary brachytherapy for in-stent restenosis have employed either beta (beta) or gamma (gamma) radiation sources with variable doses of radiation (range 7-56 Grays [Gy]). Restenosis occurred in 12% to 40% of patients in nonrandomized studies, and clinical events occurred in 13% to 50% of patients. To date, there have been 7 published randomized trials in humans comparing catheter-based intracoronary brachytherapy to placebo, with a total of 1047 patients. The dose of radiation in the trials ranged from 14 Gy to 30 Gy. During follow-up, 8% to 33% of patients who received brachytherapy had restenosis versus 39% to 64% of patients receiving placebo. Clinical events occurred in 19% to 50% among patients who received brachytherapy versus 29% to 79% among patients receiving placebo. The majority of human studies examining radioactive stents do not demonstrate a reduction in restenosis in patients post-PCR. There are no randomized trials examining radioactive stents in humans.

CONCLUSION

Nonrandomized studies of radioactive stents suggest they are not effective at preventing in-stent restenosis. In contrast, data from animal and human studies suggest that catheter-based intracoronary brachytherapy can prevent in-stent restenosis and reduce clinical events post-PCR.

Five-Year Follow-Up After Intracoronary Gamma Radiation Therapy for In-Stent Restenosis

Background— The Washington Radiation for In-Stent Restenosis Trial is a double-blinded randomized study evaluating the effects of intracoronary radiation therapy (IRT) in patients with in-stent restenosis (ISR).

Methods and Results— One hundred thirty patients with ISR (100 native coronary and 30 vein grafts) underwent percutaneous transluminal coronary angioplasty, laser ablation, rotational atherectomy, or additional stenting (36% of lesions). Patients were randomized to either 192-Iridium IRT or placebo, with a prescribed dose of 15 Gy to a 2-mm radial distance from the center of the source. Angiographic restenosis (27% versus 56%, P =0.002) and target vessel revascularization (26% versus 68%, P <0.001) were reduced at 6 months in patients treated with IRT. Between 6 and 60 months, patients treated with IRT compared with placebo had more target lesion revascularization (IRT, 21.6% versus placebo, 4.7%; P =0.04) and target vessel revascularization (IRT, 21.5% versus placebo, 6.1%; P =0.03). At 5 years, the major adverse cardiac event rate was significantly reduced with IRT (46.2% versus 69.2%, P =0.008).

Conclusions— In the Washington Radiation for In-Stent Restenosis Trial, patients with ISR treated with IRT using 192-Iridium had a reduction in the need for repeat target lesion and vessel revascularization at 6 months and 5 years.

Coronary artery pseudoaneurysm after balloon angioplasty and intracoronary ?-radiation for in-stent restenosis

Intracoronary brachytherapy is an effective method for treating in-stent restenosis. We report a case of coronary artery pseudoaneurysm after balloon angioplasty and intracoronary beta-radiation. The pseudoaneurysm was treated successfully with implantation of two coronary stent grafts.

Impact of radiation dose on late clinical outcome after intracoronary radiation therapy: Three-year follow-up of Long WRIST

To determine the safety and efficacy, including the impact, on the late recurrence rate of an incremental gamma-radiation dose from 15 to 18 Gy, we report the 3-year clinical outcome of Washington Radiation for In-Stent Restenosis Trial for Long Lesions (Long WRIST). One hundred eighty patients with recurrent in-stent restenosis (ISR) were enrolled in the Long WRIST series and treated with (192)Ir with 1 month of antiplatelet therapy. Between 6 months and 3 years, the need for repeat revascularization was low and similar among the three groups. At 3 years, target lesion revascularization (TLR) and major adverse cardiac events (MACE) were less frequent in the 18 Gy group than in the 15 Gy group (P = 0.12 for TLR, P < 0.05 for MACE) and less frequent in the 15 Gy group as compared to the placebo group (P < 0.05 for TLR and MACE). At 3 years, a higher dose of 18 Gy with (192)Ir continues to improve the outcome of patients treated for ISR when compared to patients treated with 15 Gy or placebo.

Intracoronary radiation therapy improves the clinical and angiographic outcomes of diffuse in-stent restenotic lesions: results of the Washington Radiation for In-Stent Restenosis Trial for Long Lesions (Long WRIST) Studies

BACKGROUND

The Washington Radiation for In-Stent Restenosis Trial for long lesions (Long WRIST) was designed to determine the safety and efficacy of vascular brachytherapy for the treatment of diffuse in-stent restenosis.

METHODS AND RESULTS

A total of 120 patients with diffuse in-stent restenosis in native coronary arteries (lesion length, 36 to 80 mm) were randomized for either radiation with 192Ir with 15 Gy at 2 mm from the source axis or placebo. After enrollment, 120 additional patients with the same inclusion criteria were treated with 192Ir with 18 Gy and included in the Long WRIST High Dose registry. Antiplatelet therapy was initially prescribed for 1 month and was extended to 6 months in the last 60 patients of the Long WRIST High Dose registry. At 6 months, the binary angiographic restenosis rate was 73%, 45%, and 38% in the placebo, 15 Gy, and 18 Gy radiated groups, respectively (P<0.05). At 1 year, the primary clinical end point of major cardiac events was 63% in the placebo group and 42% in the radiated group with 15 Gy (P<0.05). The major cardiac event rate was further reduced with 18 Gy (22%; P<0.05 versus 15 Gy). Late thrombosis was 12%, 15%, and 9% in the placebo group, 15 Gy group with 1 month of antiplatelet therapy, and 18 Gy group with 6 months of antiplatelet therapy, respectively.

CONCLUSIONS

Vascular brachytherapy with 192Ir is safe and reduces the rate of recurrent restenosis in diffuse in-stent restenosis. The efficacy of vascular brachytherapy on angiographic and clinical outcomes is enhanced with a radiation dose of 18 Gy and prolonged antiplatelet therapy.

[Brachytherapy for coronary restenosis: state of art in 2003]

Based on therapeutic approach for benign diseases, vascular brachytherapy decreases smooth vascular muscle cells proliferation and multiplication which lead to the formation of the neo-intima. The radioactive positive action affects arterial recoil due to post angioplasty vessel injury. Randomised studies has shown good angiographic results up to 6 months of follow-up, with 50% in-stent restenosis rate decrease and on the analysed segment as well. Decrease on Mace and TLR show statistically significance. Results don't correlate with emitter and bêta emitters had been introduced in France recently. Vascular brachytherapy is actually indicated for in-stent restenosis, there is no evidence to perform this treatment for de novo lesion. Geographic miss, source centering, late thrombosis and pullback procedure may interfere with treatment quality. IVUS allows best target volume determination to a higher quality level. Internationals guidelines such as Eva-Gec-Estro recommendations could increase treatment safety and enable development of an optimal technique.