Clinical assessment of the use of the Sonarray system for daily prostate localization

doi:10.1016/j.radonc.2006.08.027

Radiotherapy and Oncology

Volume 81, Issue 2, November 2006, Pages 176-178

https://doi.org/10.1016/j.radonc.2006.08.027 Get rights and content

Abstract

The Sonarray ultrasound system is a non-invasive technique allowing real-time prostate localization. Since 2003, it has been used in our department before intensity modulated radiation therapy for prostate cancer. We reported both setup errors and organ motion detected by Sonarray system and the accuracy of this ultrasound imaging dedicated to radiotherapy.

Section snippets

Patient and treatment characteristics

From april 2003 until september 2004, 37 consecutive patients with clinically localized prostate cancer were treated by intensity modulated radiation therapy.

All patients first underwent a planning CT scan with a 2.5 mm slice thickness in supine position with knee and ankle supports. They were asked to maintain the same bladder filling during simulation and treatment sessions. Protocol was written to replicate bladder filling: patients had to pass water 1 h before CT scan or irradiation and then

Ultrasound image quality

The localization process and positioning adjustment was completed in less than 10 min. Of the 37 patients, Sonarray system provided high quality images in 35 patients. The interfaces between prostate and rectum and prostate and bladder were sufficiently demarcated and allowed confident patient positioning. Ultrasound images were judged to be of poor quality for two patients excluded from the study, one for inability to maintain the same bladder filling over the treatment and large body habitus

Discussion

On our knowledge, this report is one of the first obtained with the Sonarray system. Results are robust and comparable to series using the BAT system. The standard deviation of shift distribution obtained with BAT ranged from 2.1 to 3.9 mm in the lateral dimension, 2.8–6.4 mm in the longitudinal dimension and 2.7–6.4 mm in the vertical dimension [2], [5], [7], [8], [10], [14], [15]. In our study, a systematic error was measured in the SI and AP axis similar as reported by Morr and Van den Heuvel

Conclusion

Ultrasound imaging is a feasible noninvasive method that allows real time localization of the target volume and provides high image quality. The Sonarray system induced small prostate displacements due to the probe pressure and detects both setup error and prostate motion. Consequently, it can be implemented as part of a daily setup routine.

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Cited by (23)

Ultrasound versus Cone-beam CT image-guided radiotherapy for prostate and post-prostatectomy pretreatment localization
2015, Physica Medica
Citation Excerpt :
Finally, for prostate patients, the results obtained in the present study were in agreement with those previously reported, with LOA values close to 10 mm in all directions, and larger discrepancies observed in the AP direction [7,9,10]. Several publications have raised concerns about the accuracy of inter-modality US devices [12,13]. Among the suggested reasons are user variability, the impact of probe pressure on prostate localization [22,25], the speed of sound aberration on 3D-US reconstruction [26], and the differences in the prostate delineation between CT and US modalities [27].
To evaluate the accuracy of an intra-modality trans-abdominal ultrasound (TA-US) device against soft-tissue based Cone-Beam Computed tomography (CBCT) registration for prostate and post-prostatectomy pre-treatment positioning.
The differences between CBCT and US shifts were calculated on 25 prostate cancer patients (cohort A) and 11 post-prostatectomy patients (cohort B), resulting in 284 and 106 paired shifts for cohorts A and B, respectively. As a second step, a corrective method was applied to the US registration results to decrease the systematic shifts observed between TA-US and CBCT results. This method consisted of subtracting the mean difference obtained between US and CBCT registration results during the first 3 sessions from the US registration results of the subsequent sessions. Inter-operator registration variability (IOV) was also investigated for both modalities.
After initial review, about 20% of the US images were excluded because of insufficient quality. The average differences between US and CBCT were: 2.8 ± 4.1 mm, −0.9 ± 4.2 mm, 0.4 ± 3.4 mm for cohort A and 1.3 ± 5.0 mm, −2.3 ± 4.6 mm, 0.5 ± 2.9 mm for cohort B, in the anterior-posterior (AP), superior-inferior (SI) and lateral (LR) directions, respectively. After applying the corrective method, only the differences in the AP direction remained significant (p < 0.05). The IOV values were between 0.6–2.0 mm and 2.1–3.5 mm for the CBCT and TA-US modalities, respectively.
Based on the obtained results and on the image quality, the TA-US imaging modality is not safely interchangeable with CBCT for pre-treatment repositioning. Treatment margins adaptation based on the correction of the systematic shifts should be considered.
Stereotactic ultrasound for target volume definition in a patient with prostate cancer and bilateral total hip replacement
2015, Practical Radiation Oncology
Citation Excerpt :
Data regarding workflow, accuracy, and limitations of US systems for daily image guidance have been extensively published for the BAT (BestNomos) or similar US systems such as Sonarray (Varian) or ExacTrac US Module (Brainlab). Precision, user-dependence, and accuracy of these systems have been discussed controversially.10,14-20 Concerns about accuracy have mainly regarded methodological issues.
Target-volume definition for prostate cancer in patients with bilateral metal total hip replacements (THRs) is a challenge because of metal artifacts in the planning computed tomography (CT) scans. Magnetic resonance imaging (MRI) can be used for matching and prostate delineation; however, at a spatial and temporal distance from the planning CT, identical rectal and vesical filling is difficult to achieve. In addition, MRI may also be impaired by metal artifacts, even resulting in spatial image distortion. Here, we present a method to define prostate target volumes based on ultrasound images acquired during CT simulation and online-matched to the CT data set directly at the planning CT.
A 78-year-old patient with cT2cNxM0 prostate cancer with bilateral metal THRs was referred to external beam radiation therapy. T2-weighted MRI was performed on the day of the planning CT with preparation according to a protocol for reproducible bladder and rectal filling. The planning CT was obtained with the immediate acquisition of a 3-dimensional ultrasound data set with a dedicated stereotactic ultrasound system for online intermodality image matching referenced to the isocenter by ceiling-mounted infrared cameras. MRI (offline) and ultrasound images (online) were thus both matched to the CT images for planning. Daily image guided radiation therapy (IGRT) was performed with transabdominal ultrasound and compared with cone beam CT.
Because of variations in bladder and rectal filling and metal-induced image distortion in MRI, soft-tissue–based matching of the MRI to CT was not sufficient for unequivocal prostate target definition. Ultrasound-based images could be matched, and prostate, seminal vesicles, and target volumes were reliably defined. Daily IGRT could be successfully completed with transabdominal ultrasound with good accordance between cone beam CT and ultrasound.
For prostate cancer patients with bilateral THRs causing artifacts in planning CTs, ultrasound referenced to the isocenter of the CT simulator and acquired with intermodal online coregistration directly at the planning CT is a fast and easy method to reliably delineate the prostate and target volumes and for daily IGRT.
Image-guided IMRT for localized prostate cancer with daily repositioning: Inferring the difference between planned dose and delivered dose distribution
2014, Physica Medica
To investigate the dosimetric impact of daily on-line repositioning during a full course of IMRT for prostate cancer.
Twenty patients were treated with image-guided IMRT. Each pre-treatment plan (Plan A) was compared with a post-treatment plan sum (Plan B) based on couch shifts measured. The delivered dose to the prostate without a daily repositioning was inferred by considering each daily couch shift during the whole course of image-guided IMRT (i.e. plan B). Dose metrics were compared for prostate CTV (P-CTV) and PTV (P-PTV) and for organs at risk. Ten patients were treated with a 5 mm margin and 10 patients with a 10 mm margin.
For plan A vs plan B: the average D95, D98, D50, D mean and EUD were: 76.4 Gy vs 73.9 Gy (p = 0.0007), 75.4 Gy vs 72.3 Gy (p = 0.001), 78.9 Gy vs 78.4 Gy (p = 0.014), 78.7 Gy vs 77.8 Gy (p = 0.003) and 78.1 Gy vs 75.9 Gy (p = 0.002), respectively for P-CTV, and 73.2 Gy vs 69.3 Gy (p = 0.0006), 70.7 Gy vs 66.0 Gy (p = 0.0008), 78.3 Gy vs 77.5 Gy (p = 0.001), 77.8 Gy vs 76.4 Gy (p = 0.0002) and 74.4 Gy vs 69.2 Gy (p = 0.003), respectively for P-PTV. Margin comparison showed no differences in dose metrics between the two plans except for D98 of the rectum in plan B which was significantly higher with a 10 mm margin.
The absence of daily image-guided IMRT resulted in a significantly less uniform and less homogeneous dose distribution to the prostate. A reduction in PTV margin showed neither a lower target coverage nor a better spare of OAR with and without daily image-guided IMRT.
Task sharing with radiotherapy technicians in image-guided radiotherapy
2013, Cancer/Radiotherapie
Le développement des systèmes d’imagerie embarquée sur les accélérateurs permet désormais de recaler au mieux les volumes cibles au moment de l’irradiation (radiothérapie guidée par l’image ou image-guided radiotherapy [IGRT]). Cependant, ces avancées technologiques en matière de contrôle du repositionnement ont conduit à une multiplication des tâches pour chaque acteur en radiothérapie et à une augmentation du temps imparti au traitement, que ce soit pour les manipulateurs en électroradiologie médicale ou les oncologues radiothérapeutes. Alors qu’il n’y a pas encore de cadre réglementaire explicite sur la radiothérapie guidée par l’image, certaines expériences institutionnelles montrent qu’un transfert des tâches est possible entre oncologues radiothérapeutes et manipulateurs en électroradiologie médicale pour la vérification en temps réel des images de positionnement. Une formation initiale adaptée à chaque technique et la rédaction de procédures et modes opératoires au sein des établissements permettront d’améliorer la qualité de la vérification en diminuant les variations interindividuelles.
The development of accelerators with on-board imaging systems now allows better target volumes reset at the time of irradiation (image-guided radiotherapy [IGRT]). However, these technological advances in the control of repositioning led to a multiplication of tasks for each actor in radiotherapy and increase the time available for the treatment, whether for radiotherapy technicians or radiation oncologists. As there is currently no explicit regulatory framework governing the use of IGRT, some institutional experiments show that a transfer is possible between radiation oncologists and radiotherapy technicians for on-line verification of image positioning. Initial training for every technical and drafting procedures within institutions will improve audit quality by reducing interindividual variability.
Image-guided radiotherapy in prostate cancer: Concepts and implications
2012, Cancer/Radiotherapie
La radiothérapie conformationnelle avec modulation d’intensité (RCMI) et la radiothérapie guidée par l’image sont deux évolutions technologiques qui, appliquées au modèle des cancers prostatiques, ont permis de voir diminuer significativement la toxicité et les séquelles digestives et urinaires de la radiothérapie conformationnelle tridimensionnelle. Le bénéfice clinique majeur de ces techniques sur la diminution de la toxicité digestive et urinaire est indiscutable puisque les séquelles observées à dix ans sont devenues rares avec ces techniques (2 % de cas de toxicité digestive de grade 2 et 1 % de grade 3, 11 % de cas de toxicité urinaire de grade 2 et 5 % de grade 3). Si ces deux techniques sont conjuguées, la toxicité tardive génito-urinaire s’en trouve encore réduite. En l’absence de radiothérapie adaptative, les protocoles de radiothérapie guidée par l’image et les techniques de repositionnement sont multiples et doivent imposer une rigueur importante dans chaque étape du processus : installation et système de contention, technique de repositionnement avec ou sans repères fiduciels, type d’imagerie de repositionnement, définition des marges inhérentes à chaque technique (prostate, vésicules séminales et/ou ganglions pelviens), fréquence de repositionnement au cours du traitement, règles diététiques avec ou sans lavement rectal. Pour ces raisons, chaque centre pratiquant la radiothérapie guidée par l’image doit évaluer avec attention et rigoureusement les incertitudes de repositionnement liées à sa technique. Dans cette revue, nous avons fait une analyse des données de la littérature basées sur les études dosimétriques et l’impact clinique prouvé répondant aux différentes questions se posant aux oncologues radiothérapeutes à chaque étape du processus de radiothérapie guidée par l’image des cancers de la prostate. Des recommandations sont faites sur des protocoles de repositionnement en fonction des techniques de repositionnement les plus répandues : repères fiduciels ou tissus mous, tomographie conique de basse (kV) ou haute (MV) énergie, échographie tridimensionnelle.
Intensity modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT) are technological developments, which when applied in a model of prostate cancer, led to a significant reduction in the toxicity and digestive and urinary sequelae of 3D conformational radiotherapy. The major clinical benefits of these techniques with regard to reduced digestive and urinary toxicity are unequivocal since very few sequelae have been reported at 10 years (2% of grade 2 and 1% of grade 3 digestive toxicity; 11% of grade 2 and 5% of grade 3 urinary toxicity). Even when these two techniques are combined, IG–IMRT significantly diminishes late genitourinary toxicity. In the absence of adaptive radiotherapy, there are many IGRT protocols and repositioning techniques, and every step in the IGRT process must be carried out with extreme rigor: installing the patient and contention system, repositioning technique with or without fiduciary markers, type of repositioning imaging, definition of margins inherent in each technique (prostate, seminal vesicles and/or pelvic lymph nodes), frequency of repositioning during treatment, dietary constraints with or without rectal lavage. For these reasons, every centre that performs IGRT must carefully and rigorously assess the uncertainties of repositioning linked to the IGRT technique. In this review, we analyzed data from the literature based on dosimetric studies and the proven clinical impact in order to answer the different questions asked by radiation oncologists at every step of the IGRT process for cancer of the prostate. Recommendations are made for the repositioning protocols according to the most widely used repositioning techniques: fiduciary markers or soft tissues, kV-CBCT or MV-CBCT, 3D ultrasonography.
Clinical impact of margin reduction on late toxicity and short-term biochemical control for patients treated with daily on-line image guided IMRT for prostate cancer
2012, Radiotherapy and Oncology
To evaluate the impact of PTV reduction when delivering image-guided IMRT (IG-IMRT) for patients with prostate cancer. Between 2001 and 2007, 165 men were treated with daily IG-IMRT using a 3D ultrasound-based system. Median dose prescribed to the prostate was 78 Gy [74 Gy–78 Gy]. Patients were stratified regarding the CTV to the PTV margin: group A (n = 87) = 5 mm or group B (n = 78) = 10 mm. Late toxicity was scored using the CTC v3.0 scale. Biochemical progression-free survival (bPFS) was calculated using the Phoenix definition. Grade 2 genitourinary toxicity was 7.0% for group A and 6.6% for group B (p = 1.00). Grade 2 gastrointestinal toxicity was 1.2% and 2.6% (p = 0.38). With a median follow-up of 38.3 months [5.25–87.3], bPFS at 3 years was 92.5% [82.4%–96.9%] in group A and 94.3% [85.5%–97.8%] in group B (p = 0.84). IG-IMRT yielded very low rates of late toxicity. Margin had impact neither on short-term bPFS nor late toxicity.

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Prostate radiotherapyClinical assessment of the use of the Sonarray system for daily prostate localization

Abstract

Section snippets

Patient and treatment characteristics

Ultrasound image quality

Discussion

Conclusion

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Prostate radiotherapy
Clinical assessment of the use of the Sonarray system for daily prostate localization