Investigation of dose perturbations and the radiographic visibility of potential fiducials for proton radiation therapy of the prostate

Huang, Jessie Y.; Newhauser, Wayne D.; Zhu, Xiaorong Ronald; Lee, Andrew K.; Kudchadker, Rajat J.

doi:10.1088/0031-9155/56/16/014

Cited by 33 publications

(32 citation statements)

References 24 publications

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“…The evaluation of alternative materials, e.g. zirconium oxide (ZrO 2 )-core carbon-coated markers, revealed a relatively low incidence of artifacts, as seen by other research groups in comparable settings [17]. Furthermore, the carbon marker was clearly visible in kV OBI as well as in the DRRs, making this product a potential candidate for further clinical testing.…”

Section: Discussionmentioning

confidence: 84%

Evaluation of different fiducial markers for image-guided radiotherapy and particle therapy

Habermehl

Henkner

Ecker

et al. 2013

Journal of Radiation Research

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Modern radiotherapy (RT) techniques are widely used in the irradiation of moving organs. A crucial step in ensuring the correct position of a target structure directly before or during treatment is daily image guidance by computed tomography (CT) or X-ray radiography (image-guided radiotherapy, IGRT). Therefore, combinations of modern irradiation devices and imaging, such as on-board imaging (OBI) with X-rays, or in-room CT such as the tomotherapy system, have been developed. Moreover, combinations of linear accelerators and in-room CT-scanners have been designed. IGRT is of special interest in hypofractionated and radiosurgical treatments where high single doses are applied in the proximity of critical organs at risk. Radiographically visible markers in or in close proximity to the target structure may help to reproduce the position during RT and could therefore be used as external surrogates for motion monitoring. Criteria sought for fiducial markers are (i) visibility in the radiologic modalities involved in radiotherapeutic treatment planning and image guidance, such as CT and kilovoltage (kV) OBI), (ii) low production of imaging artifacts, and (iii) low perturbation of the therapeutic dose to the target volume. Photon interaction with interstitial markers has been shown to be not as important as in particle therapy, where interaction of the particle beam, especially with metal markers, can have a significant impact on treatment. This applies especially with a scanned ion beam. Recently we commenced patient recruitment at our institution within the PROMETHEUS trial, which evaluates a hypofractionation regime, starting with 4 x 10 Gy (RBE), for patients with hepatocellular carcinoma. The aim of this work is, therefore, to evaluate potential implantable fiducial markers for enabling precise patient and thus organ positioning in scanned ion beams. To transfer existing knowledge of marker application from photon to particle therapy, we used a range of commercially available markers of different forms and sizes, consisting of carbon and gold materials, and evaluated them for their potential use in the clinical setup with scanned ion beams at our institution. All markers were implanted in a standardized Alderson phantom and were examined using CT scans and orthogonal kV OBI in our clinical routine protocol. Impact on beam perturbation downstream of the markers in the plateau region of a spread-out Bragg peak (SOBP) was estimated by using radiographic films for clinical proton and carbon ion beams of high and low energies. All tested markers achieved good visibility in CT and kV OBI. Disturbances due to artifacts and dose perturbation were highest in the arbitrarily folded gold and the thickest gold marker, but especially low in the carbon marker. Dose perturbation was highest in the arbitrarily folded gold marker. In summary, the analyzed markers offer promising potential for identifying target structures in our treatment setup at HIT and will soon be used in clinical routine. However, a careful choice of marker, d...

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Section: Discussionmentioning

confidence: 84%

Evaluation of different fiducial markers for image-guided radiotherapy and particle therapy

Habermehl

Henkner

Ecker

et al. 2013

Journal of Radiation Research

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“…Another advantage of the proposed candidate materials is their minimal dose perturbation or shadowing. As reported by Cheung et al 2010 and Huang et al 2011, non-gold fiducial makers have the advantage of significantly less dose perturbation compared to gold fiducial makers due to their smaller atomic numbers. The proposed materials (Cu and 68 Zn) have similar atomic numbers to the currently available non-gold fiducials makers and are expected to provide the same benefit.…”

Section: Discussionmentioning

confidence: 85%

Feasibility of proton-activated implantable markers for proton range verification using PET

et al. 2013

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Proton beam range verification using positron emission tomography (PET) currently relies on proton activation of tissue, the products of which decay with a short half-life and necessitate an on-site PET scanner. Tissue activation is, however, negligible near the distal dose fall-off region of the proton beam range due to their high interaction energy thresholds. Therefore Monte Carlo simulation is often supplemented for comparison with measurement; however, this also may be associated with systematic and statistical uncertainties. Therefore, we sought to test the feasibility of using long-lived proton-activated external materials that are inserted or infused into the target volume for more accurate proton beam range verification that could be performed at an off-site PET scanner. We irradiated samples of ≥98% 18O-enriched water, natural Cu foils, and ≥97% 68Zn-enriched foils as candidate materials, along with samples of tissue-equivalent materials including 16O water, heptane (C7H16), and polycarbonate (C16H14O3)n, at 4 depths (ranging from 100% to 3% of center of modulation (COM) dose) along the distal fall-off of a modulated 160-MeV proton beam. Samples were irradiated either directly or after being embedded in Plastic Water® or balsa wood. We then measured the activity of the samples using PET imaging for 20 or 30 min after various delay times. Measured activities of candidate materials were up to 100 times greater than those of the tissue-equivalent materials at the 4 distal dose fall-off depths. The differences between candidate materials and tissue-equivalent materials became more apparent after longer delays between irradiation and PET imaging, due to the longer half-lives of the candidate materials. Furthermore, the activation of the candidate materials closely mimicked the distal dose fall-off with offsets of 1 to 2 mm. Also, signals from the foils were clearly visible compared to the background from the activated Plastic Water® and balsa wood phantoms. These results indicate that markers made from these candidate materials could be used for in vivo proton range verification using an off-site PET scanner.

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“…Up to 6 beam angles may be required to reduce the dose perturbations from the gold fiducial markers to a clinically acceptable level in IMPT. Huang et al 21 evaluated 12 fiducial markers for their potential clinical utility in proton radiation therapy for prostate cancer with the use of a CT and kV imaging system. The dose perturbation caused by each fiducial marker was quantified using radiochromic film and a clinical proton beam.…”

Section: Resultsmentioning

confidence: 99%

Qualitative Evaluation of Fiducial Markers for Radiotherapy Imaging

Chan

Cohen

Deasy

2014

Technol Cancer Res Treat

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Purpose To evaluate visibility, artifacts, and distortions of various commercial markers in magnetic resonance imaging (MRI), computer tomography (CT), and ultrasound imaging used for radiotherapy planning and treatment guidance. Methods We compare 2 solid gold markers, 4 gold coils, and 1 polymer marker from 3 vendors. Imaging modalities used were 3-T and 1.5-T GE MRIs, Siemens Sequoia 512 Ultrasound, Phillips Big Bore CT, Varian Trilogy linear accelerator (cone-beam CT [CBCT], on-board imager kilovoltage [OBI-kV], electronic portal imaging device megavoltage [EPID-MV]), and Medtronic O-ARM CBCT. Markers were imaged in a 30 × 30 × 10 cm3 custom bolus phantom. In one experiment, Surgilube was used around the markers to reduce air gaps. Images were saved in Digital Imaging and Communications in Medicine (DICOM) format and analyzed using an in-house software. Profiles across the markers were used for objective comparison of the markers’ signals. The visibility and artifacts/distortions produced by each marker were assessed qualitatively and quantitatively. Results All markers are visible in CT, CBCT, OBI-kV, and ultrasound. Gold markers below 0.75 mm in diameter are not visible in EPID-MV images. The larger the markers, the more CT and CBCT image artifacts there are, yet the degree of the artifact depends on scan parameters and the scanner itself. Visibility of gold coils of 0.75 mm diameter or larger is comparable across all imaging modalities studied. The polymer marker causes minimal artifacts in CT and CBCT but has poor visibility in EPID-MV. Gold coils of 0.5 mm exhibit poor visibility in MRI and EPID-MV due to their small size. Gold markers are more visible in 3-T T1 gradient-recalled echo than in 1.5-T T1 fast spin-echo, depending on the scan sequence. In this study, all markers are clearly visible on ultrasound. Conclusion All gold markers are visible in CT, CBCT, kV, and ultrasound; however, only the large diameter markers are visible in MV. When MR and EPID-MV imagers are used, the selection of fiducial markers is not straightforward. For hybrid kV/MV image-guided radiotherapy imaging, larger diameter markers are suggested. If using kV imaging alone, smaller sized markers may be used in smaller sized patients in order to reduce artifacts. Only larger diameter gold markers are visible across all imaging modalities.

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Investigation of dose perturbations and the radiographic visibility of potential fiducials for proton radiation therapy of the prostate

Cited by 33 publications

References 24 publications

Evaluation of different fiducial markers for image-guided radiotherapy and particle therapy

Evaluation of different fiducial markers for image-guided radiotherapy and particle therapy

Feasibility of proton-activated implantable markers for proton range verification using PET

Qualitative Evaluation of Fiducial Markers for Radiotherapy Imaging

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