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Effect of using different U/S probe Standoff materials in image geometry for interventional procedures: the example of prostate.

Diamantopoulos S, Milickovic N, Butt S, Katsilieri Z, Kefala V, Zogal P, Sakas G, Baltas D - J Contemp Brachytherapy (2011)

Bottom Line: The shift deforms also the PTV (prostate in our case) and other organs at risk (OARs) in the same way leading to overestimation of volume and underestimation of the dose.The use of EA 4015 Silicone Standoff kit for image acquisition, leads to erroneous contouring of PTV and OARs and reconstruction and placement of catheters, which results to incorrect dose calculation during prostate brachytherapy.Moreover, the reliability of QA procedures lies mostly in the right temperature of the water used for accurate simulation of real conditions of transrectal ultrasound imaging.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Physics & Engineering, Klinikum Offenbach GmbH, Offenbach am Main, Germany.

ABSTRACT

Purpose: This study investigates the distortion of geometry of catheters and anatomy in acquired U/S images, caused by utilizing various stand-off materials for covering a transrectal bi-planar ultrasound probe in HDR and LDR prostate brachytherapy, biopsy and other interventional procedures. Furthermore, an evaluation of currently established water-bath based quality assurance (QA) procedures is presented.

Material and methods: Image acquisitions of an ultrasound QA setup were carried out at 5 MHz and 7 MHz. The U/S probe was covered by EA 4015 Silicone Standoff kit, or UA0059 Endocavity balloon filled either with water or one of the following: 40 ml of Endosgel(®), Instillagel(®), Ultraschall gel or Space OAR™ gel. The differences between images were recorded. Consequently, the dosimetric impact of the observed image distortion was investigated, using a tissue equivalent ultrasound prostate phantom - Model number 053 (CIRS Inc., Norfolk, VA, USA).

Results: By using the EA 4015 Silicone Standoff kit in normal water with sound speed of 1525 m/s, a 3 mm needle shift was observed. The expansion of objects appeared in radial direction. The shift deforms also the PTV (prostate in our case) and other organs at risk (OARs) in the same way leading to overestimation of volume and underestimation of the dose. On the other hand, Instillagel(®) and Space OAR™ "shrinks" objects in an ultrasound image for 0.65 mm and 0.40 mm, respectively.

Conclusions: The use of EA 4015 Silicone Standoff kit for image acquisition, leads to erroneous contouring of PTV and OARs and reconstruction and placement of catheters, which results to incorrect dose calculation during prostate brachytherapy. Moreover, the reliability of QA procedures lies mostly in the right temperature of the water used for accurate simulation of real conditions of transrectal ultrasound imaging.

No MeSH data available.


Related in: MedlinePlus

Fused images (BiopSee® 0.9.14 software): reference image (acquisition made using an Endocavity balloon filled with water) and image from acquisition made utilizing a Silicone Standoff kit at reference plane at 5 MHz
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Figure 0005: Fused images (BiopSee® 0.9.14 software): reference image (acquisition made using an Endocavity balloon filled with water) and image from acquisition made utilizing a Silicone Standoff kit at reference plane at 5 MHz

Mentions: Using a Silicone Standoff kit, we observed a radial needle shift of about 3 mm (Tables 3 and 4) at both frequencies (Figs. 5 and 6). Experimentally evaluated shift was in a good agreement with theoretical estimation, as displayed in Table 3. In addition, we found out that the needle displacement was independent from its distance from the probe and depended only on the wall thickness of the Silicone Standoff kit (Fig. 7). This was precisely what was expected theoretically (see the appendix).


Effect of using different U/S probe Standoff materials in image geometry for interventional procedures: the example of prostate.

Diamantopoulos S, Milickovic N, Butt S, Katsilieri Z, Kefala V, Zogal P, Sakas G, Baltas D - J Contemp Brachytherapy (2011)

Fused images (BiopSee® 0.9.14 software): reference image (acquisition made using an Endocavity balloon filled with water) and image from acquisition made utilizing a Silicone Standoff kit at reference plane at 5 MHz
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3551363&req=5

Figure 0005: Fused images (BiopSee® 0.9.14 software): reference image (acquisition made using an Endocavity balloon filled with water) and image from acquisition made utilizing a Silicone Standoff kit at reference plane at 5 MHz
Mentions: Using a Silicone Standoff kit, we observed a radial needle shift of about 3 mm (Tables 3 and 4) at both frequencies (Figs. 5 and 6). Experimentally evaluated shift was in a good agreement with theoretical estimation, as displayed in Table 3. In addition, we found out that the needle displacement was independent from its distance from the probe and depended only on the wall thickness of the Silicone Standoff kit (Fig. 7). This was precisely what was expected theoretically (see the appendix).

Bottom Line: The shift deforms also the PTV (prostate in our case) and other organs at risk (OARs) in the same way leading to overestimation of volume and underestimation of the dose.The use of EA 4015 Silicone Standoff kit for image acquisition, leads to erroneous contouring of PTV and OARs and reconstruction and placement of catheters, which results to incorrect dose calculation during prostate brachytherapy.Moreover, the reliability of QA procedures lies mostly in the right temperature of the water used for accurate simulation of real conditions of transrectal ultrasound imaging.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Physics & Engineering, Klinikum Offenbach GmbH, Offenbach am Main, Germany.

ABSTRACT

Purpose: This study investigates the distortion of geometry of catheters and anatomy in acquired U/S images, caused by utilizing various stand-off materials for covering a transrectal bi-planar ultrasound probe in HDR and LDR prostate brachytherapy, biopsy and other interventional procedures. Furthermore, an evaluation of currently established water-bath based quality assurance (QA) procedures is presented.

Material and methods: Image acquisitions of an ultrasound QA setup were carried out at 5 MHz and 7 MHz. The U/S probe was covered by EA 4015 Silicone Standoff kit, or UA0059 Endocavity balloon filled either with water or one of the following: 40 ml of Endosgel(®), Instillagel(®), Ultraschall gel or Space OAR™ gel. The differences between images were recorded. Consequently, the dosimetric impact of the observed image distortion was investigated, using a tissue equivalent ultrasound prostate phantom - Model number 053 (CIRS Inc., Norfolk, VA, USA).

Results: By using the EA 4015 Silicone Standoff kit in normal water with sound speed of 1525 m/s, a 3 mm needle shift was observed. The expansion of objects appeared in radial direction. The shift deforms also the PTV (prostate in our case) and other organs at risk (OARs) in the same way leading to overestimation of volume and underestimation of the dose. On the other hand, Instillagel(®) and Space OAR™ "shrinks" objects in an ultrasound image for 0.65 mm and 0.40 mm, respectively.

Conclusions: The use of EA 4015 Silicone Standoff kit for image acquisition, leads to erroneous contouring of PTV and OARs and reconstruction and placement of catheters, which results to incorrect dose calculation during prostate brachytherapy. Moreover, the reliability of QA procedures lies mostly in the right temperature of the water used for accurate simulation of real conditions of transrectal ultrasound imaging.

No MeSH data available.


Related in: MedlinePlus