How Are Fiducial Markers Placed In The Prostate

Growing Preference For Stereotactic Radiation

Since 2019, researchers are touting stereotactic radiation as an effective remedy against several debilitating cancers. These surgeries are highly precision-based, meaning there is minimal damage to surrounding healthy tissues, thus reducing risks of side-effects. This approach is highly effective in patients suffering from oligometastatic diseases.

In a phase II trial to determine the effectiveness of this approach, the primary cancers taken into account were those of the lungs, breasts, prostate gland and colorectal. The test, conducted across 99 patients, revealed that survival rates were over a year and 41 months longer as opposed to 28 months in the standard care group.

Thus, to execute this treatment approach effectively, healthcare providers have increased their investment in high-end equipment which has ultimately provided traction to the fiducial markers market.;

Role Of Fiducial Markers In The Assessment Of Prostate Bed Motion In Post

Published online by Cambridge University Press:;30 October 2019

Department of Radiation Oncology, Ascension Macomb-Oakland Hospital, Warren, MI, USA

Salahuddin Ahmad

Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA

Erika Kennedy

Department of Radiation Oncology, Ascension Macomb-Oakland Hospital, Warren, MI, USA

Amr M. Aref

Department of Radiation Oncology, Ascension Macomb-Oakland Hospital, Warren, MI, USA

Paul J. Chuba

Department of Radiation Oncology, Ascension Macomb-Oakland Hospital, Warren, MI, USA

*

Author for correspondence: Maria T. Vlachaki, Department of Radiation Oncology, Ascension Macomb-Oakland Hospital, Webber Cancer Center, 11800 E 12 Mile Rd, Warren, MI 48093, USA. Tel: 1-586-573-5186. E-mails: ;

Fiducial Numbers And Position

At least three fiducials are recommended to allow triangulation and measurement of position in different planes. Four fiducials are used at some centres to accommodate for fiducial migration or fiducial loss . Marker loss is uncommon, with Deutschmann etâal. reporting 1.4% of patients had lost one of four markers during treatment. Three fiducial markers provide the best alignment, although the use of two fiducials, when in the apex and base, is nearly as effective as three . An example of implanted positions for three fiducials are the left apex, right mid-zone and left base, avoiding the urethra. At least 1âcm spacing is desired, maximal separation is preferred, to allow clear distinction on treatment position verification images . Fiducials are inserted 3â5âmm from the prostate edge, and the mid-zone fiducial is inserted deeper, to maintain triangulation on a sagittal treatment position verification image. Fiducials should be implanted away from calcifications, as this can interfere with image quality and fiducial verification.

Figure 2

Anterior and lateral pelvic X-rays showing three implanted fiducials.

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Rebuttal: Christopher F Njeh Phd

I agree with Dr. Parker that FMs are not superior to noninvasive techniques such as CBCT in the initial setup alignment of prostate patients. Dr. Parker went further to present an argument for an alternative role for FMs whereby they are used to monitor prostate intrafraction motion. However, the data do not justify this. For example, studies have found that intrafraction motion only becomes clinically significant for long duration treatments.- Langen et;al. reported that, from the initial setup, only 13% of patients have displacements above 3;mm by 5;min, rising to 25% by 10;min. Furthermore, such movements are accounted for in the treatment planning margins.

Dr. Parker implied that intrafraction monitoring is critical for hypofractionated regimens because of increased fraction time and the need for reduce treatment margins. The increased fraction time is true with CyberKnife, where prostate treatments typically take up to 45;min per fraction. With the implementation of volumetric modulated arc therapy on traditional linacs; however, the treatment time for prostate cancer has significantly decreased to a mean of 4.6;min. In addition, with flattening filter-free treatment delivery with dose rates up to 2400;MU/min, it possible to deliver hypofractionated doses within a few minutes., Hence, there is not enough time for clinically significant prostate motion.

It is therefore logical to conclude that for prostate cancer radiotherapy, FMs are no longer required.

Fiducials Help Ensure Target Accuracy

Fiducial markers are gold seeds or stainless steel screws that are implanted in and/or around a soft tissue tumor, or within the bony spine, to act as a radiologic landmark, to define the target lesion’s position with millimeter precision. They are typically placed using a CT or other image-guided percutaneous method. There may be other appropriate fiducial placement methods as well, including endoscopic or surgical approaches, if determined best by the participating physicians. To track lesions in 6 degrees , fiducials may be recommended, depending upon the exact circumstance and lesion. Fiducials must be fixed relative to other fiducials and relative to the tumor to ensure targeting accuracy.

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Fiducial Markers In Image

US Oncological Disease

Abstract:

Overview

Fiducial markers are emerging as a standard tool for image-guided radiotherapy . The markers are implantable devices designed to act as reliable surrogates for imaging anatomic structures of interest. Fiducial marker techniques were originally developed in the preconformal radiotherapy era for positional verification of tissues that were not easily visualized using portal X-ray film imaging for patient alignment. Soft tissue structures that were relatively mobile could be more readily seen when radio-opaque seeds or wires were implanted in or near organs of interest. However, since comparatively large margins around target volumes were used, dose delivery limitations overshadowed imaging accuracy. In addition, routine and efficient online implementation of patient set-up error analysis and patient repositioning was problematic in the past.

Article:

As a practical matter, improved dose delivery precision necessitates a higher degree of accuracy in targeting the tumor and aligning the patient so as to reproducibly confirm that the tumor is in the same place in 3-D space as the prescribed conformal dose distribution throughout therapy . However, since even small geometric deviations from the treatment plan may result in substantial changes in dose distribution,2 margin reduction must be matched with IGRT techniques lest margin reduction result in poorer clinical outcomes.3

How Are Prostate Fiducials Placed

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Your doctor will use rectal ultrasound to see your prostate. They will insert tiny needles into your prostate through your perineum, which is the area of skin between your scrotum and anus. Your doctor will place 3 fiducial markers into your prostate through the needles and then will remove the needles.

Secondly, are fiducial markers necessary? Implanted fiducial markers are no longer needed for prostate cancer radiotherapy. Christopher F. Njeh Ph.

Also to know is, where do you put fiducials?

Fiducials are little target registration marks that are printed on PCBs, they are placed on the top copper layer and allow the vision system of the pick and place to recognize where the PCB is at.

How are seeds placed in the prostate?

Permanent prostate brachytherapy involves placing many radioactive seeds within the prostate to treat prostate cancer. During the procedure, an ultrasound probe is placed in the rectum to help guide the placement of seeds. The seeds emit radiation that dissipates over a few months.

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Technical And Treatment Outcomes

The first report of EUS-guided fiducial marker placement was published in 2006 by Pishvaian and colleagues, who successfully deployed fiducial markers in six of seven patients with pancreatic cancer who underwent radiation therapy.31 Later, Varadarajulu and colleagues confirmed the feasibility and safety of EUS-guided fiducial marker placement for the delivery of intensity-modulated radiotherapy .32 Two recent reports have described the utility of fiducials for fluoroscopy-aided intraoperative localization of small pancreatic tumors.35,36 In both reports, the fiducials could be placed successfully without complications and with good operative outcomes.

Ziad F. Issa MD, … Douglas P. Zipes MD, in, 2019

Invasive Nature Of Implants To Restrict Adoption

Fiducial marker placement has several drawbacks. A major shortcoming of this procedure is its invasive nature and thus not applicable to all patients. Furthermore, fiducial markers distort image quality during scanning, rendering tumor delineation a challenge.

An extensive study conducted in 2012 on the efficacy of transrectal fiducial marker insertion for prostate cancer image-guided radiotherapy revealed that out of the 234 patients analyzed, 75 of them develop at least one symptom post-surgery. These manifested into hematuria, rectal bleeding and dysuria.

The study also concluded that 3-4% of the patients experienced shivers and fevers besides pain and obstruction. Such problems are likely to hinder adoption of fiducial markers in the long-run forecast period.

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What Is The Procedure

An ultrasound probe is covered in gel and inserted into your back passage to create an image of the prostate, allowing the seeds to be inserted into the different areas of the prostate with great accuracy.;

Three marker seeds will then be placed within the prostate through ultrasound based needle guidance. The seeds are NOT placed through the rectum, but through the skin on the outside of your body between the scrotum and the rectum . There may also be a brief, sharp pain as the needle is inserted into the prostate gland.

What Is Fiducial Marker Placement

Fiducial marker placement is an image-guided procedure often performed by an interventional radiologist in preparation for certain types of radiation therapy, such as stereotactic radiosurgery and stereotactic body radiotherapy , or proton therapy.

Fiducial markers are small metal spheres, coils or cylinders about the size of a grain of rice that are placed in or near a tumor to help guide the placement of radiation beams during treatment.

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Complete A Health Care Proxy Form

If you havent already completed a Health Care Proxy form, we recommend you complete one now. If youve already completed one or have any other advance directives, bring them to your next appointment.

A health care proxy is a legal document that identifies the person who will speak for you if you cant communicate for yourself. The person you identify is called your health care agent.

Talk with your healthcare provider if youre interested in completing a health care proxy. You can also read the resources Advance Care Planning and How to Be a Health Care Agent for information about health care proxies, other advance directives, and being a health care agent.

Spacer Insertion Technique And Complications

Hatiboglu etâal. has recently described the technique of SpaceOARTM hydrogel injection, and the technique is essentially the same with other spacer material injections . The patient is placed in the lithotomy position, with the TRUS probe inserted and attached to the stepper. The prostate and rectum interface is visualised both on axial and sagittal planes. The injection needle is inserted transperineally into the perirectal fat, posterior to Denonvilliers’ fascia and anterior to the rectal wall. Hydrodissection is performed, a technique that safely dissects the tissue planes using saline, advancing the level to the mid-gland . The needle is aspirated to ensure it is not within a blood vessel, and 10âmL hydrogel solution is then injected into this newly created space. The transperineal route is a familiar technique used by urologists for biopsies, fiducial implants, high-dose rate and low-dose rate seed brachytherapy. This procedure is completed within 20âmin, can be performed under local or general anaesthetic, and antibiotics are commonly administered to reduce infection.

Figure 5

Insertion technique of SpaceOAR Gel. Courtesy of Augmenix, MA, USA.

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High Demand For Precision

As global healthcare advances, the demand for precision-based surgeries is experiencing a steep incline. Precision medicine is imperative to ensure timely treatment and diagnosis of various chronic conditions. In an era of unprecedented data analytics, healthcare providers are finding it easier to implement the same to achieve quicker results.

Oncology is a major beneficiary of advanced imaging modalities. As efforts to reduce mortality rates accelerates, deployment of sophisticated imaging technologies are laying fertile ground for fiducial marker sales in upcoming years.

Significant developments have occurred in fiducial markers for image guided radiotherapy to enhance precision for upper gastrointestinal malignancies. A study on an 89-year-old male patient with localized gastric cancer affirmed the effectiveness of this technology in tumor delineation nearly a decade ago.

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Rebuttal: Brent C Parker Phd

My colleague has made a number of arguments against the use of fiducial markers, and I will address them sequentially.

Trans Rectal Ultrasound And Fiducial Marker Implantation

• South Terrace Urology

Trans Rectal Ultrasound and Fiducial Marker Implantation

Tiny gold seeds that show up on x-ray are now being used by Radiation Oncologists to improve the accuracy of radiation delivery.

This procedure involves the examination of the prostate by an ultrasound inserted into the rectum. After local anaesthetic has been injected three needles are inserted and the gold seed markers are placed within the prostate. This procedure is uncomfortable but not usually painful, similar to the prostate biopsy procedure.

Allow a total appointment time of 30 minutes, although the procedure itself normally takes 10 minutes.

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Clinical Impact Of Prostate Fiducial Marker Image

Many studies demonstrate that the use of FMs improves prostate targeting during image-guided external beam radiotherapy. It is less clear what clinical impact this has in terms of patient-reported toxicity and overall survival and no prospective randomized controlled trials have been performed.

Paluska et al, Cheung et al and Skarsgard et al have all demonstrated the feasibility of reducing PTV margins with the use of FMs. Paluska et al proposed that a 10-mm CTVPTV margin used with daily bone setup could be reduced to 7mm using FMs and daily imaging. Furthermore, they observed better CTV coverage using FMs and reduced margins compared with bony setup plus a 10-mm margin. Toxicity was not reported in this study. However, by further limiting dose to normal surrounding structures, the PTV margin reduction theoretically reduces toxicity, since reducing the volume of rectum receiving 60Gy or more has been shown to be associated with a reduction in rectal toxicity. In addition, reducing the PTV facilitates dose escalation and may improve progression-free survival.

There is convincing evidence that FM IGRT improves the accuracy of prostate targeting and some evidence that using FM IGRT reduces treatment-related toxicity without compromising treatment outcomes; therefore, it is unlikely a prospective randomized control trial comparing FM IGRT with non-FM IGRT will ever be performed.

Using Fiducial Markers To Aid In Prostate Cancer Radiation Treatment

• Study Details

To effectively treat prostate cancer, doctors need an accurate view of the prostate gland during radiation therapy. To help improve this view, doctors may insert gold markers called fiducials into the prostate by placing hollow gold needles through the rectum and moving a fiducial through each needle. The purpose of the study is to determine whether an MRI scan can help doctors improve their placement of these needles.

Prior to their participation in this study, patients will undergo the following evaluations: a physical exam, blood work, urine tests, and, if appropriate, an MRI or bone scan.

Patients with contraindications to MRI:

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

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Note The Time Of Your Procedure

A staff member from the Admitting Office will call you after 2:00 pm the day before your procedure. If your procedure is scheduled for a Monday, theyll call you on the Friday before.

The staff member will tell you what time to arrive at the hospital for your procedure. Theyll also remind you where to go. If you dont get a call by 7:00 pm, call .

Specific Clinical Situations Potentially Requiring Fiducial Placement

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