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Gold Fiducial Markers Are used for soft tissue target volume localization and verification in...

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Page 1: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.
Page 2: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Gold Fiducial MarkersAre used for soft tissue target volume localization and verification in external beam radiation treatment procedures like- IMRT-3D-confomal irradiation- CyberKnife or GammaKnive procedures- or even Brachytherapy

It might be used in organs like- Prostate- Liver - Pancreas- Brain

Page 3: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

e.g. e.g. ProstateProstate EBRT nowadays is seen as one standard treatment for localized and advanced prostate cancer EBRT nowadays is seen as one standard treatment for localized and advanced prostate cancer

patients.patients. Prostate cancer is a multifocal tumor which causes the whole organ to be treated. The organ Prostate cancer is a multifocal tumor which causes the whole organ to be treated. The organ

will be irradiated with homogeneous fields in 3D conformal technique or with IMRT.will be irradiated with homogeneous fields in 3D conformal technique or with IMRT. Toxicity to bladder and rectum are limiting the dose to the organ to 72 Gray with regular Toxicity to bladder and rectum are limiting the dose to the organ to 72 Gray with regular

irradiation procedures.irradiation procedures.

This table shows that higher doses are giving more local control.This table shows that higher doses are giving more local control.

Source: Zelefski, Sloane Kettering CC, NY, NY

5 year survival rate w/o PSA rise depending on applied dose

5 year survival rate (%) w/o PSA rise

Dose 64.8 – 70.2 Gy 75.6 Gy 81 – 86.4 Gy p

Risk Group

Low risk 65 86 96 < 0.01

Intermediate. risk 44 61 87 < 0.01

High risk 22 43 69 < 0.01

Risk factors: ≥ T2, Gleason Score ≥ 7, PSA ≥ 10ng/ml. Low Risk = no risk factor; intermediate. Risk = 1 risk factor; high risk = ≥ 2 risk factors.

Page 4: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Intention

Goal: Goal: High dose to the target volume, low High dose to the target volume, low toxicity to the organs at risk.toxicity to the organs at risk.

But: But: The organs at risk are adjecent to the The organs at risk are adjecent to the target volume.target volume.

Page 5: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

1. Approach to a solution1. Approach to a solutionThe irradiated volume should be similar to the shape of the The irradiated volume should be similar to the shape of the

organ to be treated (conformal).organ to be treated (conformal). 3D – conformal irradiation should be the standard.3D – conformal irradiation should be the standard.

Better but more complex: IMRT Intensity Modulated Radiation TherapyBetter but more complex: IMRT Intensity Modulated Radiation Therapy

Source: Prof. D. Aebersold, Bern

Fast moving leafs made from lead Fast moving leafs made from lead and controlled by a computer and and controlled by a computer and shaping the beam from a LINAC. shaping the beam from a LINAC.

The so called Multi Leaf The so called Multi Leaf Collimator.Collimator.

Whit this system the contour of Whit this system the contour of the beam can be shaped the beam can be shaped according to the shape of the according to the shape of the organ at the respective angle of organ at the respective angle of the radiation fieldthe radiation field..

Conventional 3D conformal IMRT with organ tracking

Page 6: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Motion of the prostate during a 17 days cycleMotion of the prostate during a 17 days cycle

But the main question is: But the main question is:

Where is the Prostate Where is the Prostate ??

Page 7: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Where is the Prostate Where is the Prostate ??Organ motion and therefore geographic miss is a Organ motion and therefore geographic miss is a

major problem when irradiating the prostate. major problem when irradiating the prostate.

Hence a bigger target volume has to be irradiated.Hence a bigger target volume has to be irradiated.But larger sections of the organs at risk will be But larger sections of the organs at risk will be

irradiated as well. irradiated as well. This might lead to increasing toxicity rates.This might lead to increasing toxicity rates.

Page 8: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Field edge variability during several treatment sessions

Setup error of treatment sessions

Page 9: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Motion of the prostateMotion of the prostateMotion of the prostate might be induced by Motion of the prostate might be induced by

- - Tension of the pelvis muscles, Tension of the pelvis muscles, - Bowel and bladder filling - Bowel and bladder filling - Breathing - Breathing A cranial-caudal und ventral-dorsal misplacement of up to A cranial-caudal und ventral-dorsal misplacement of up to 2cm2cm was was observed.observed.

Therefore conventional treatment scemes aks for a 1 – 2 cm Therefore conventional treatment scemes aks for a 1 – 2 cm margin around the organ. margin around the organ.

Aside from that the prostate is shrinking during the treatment.Aside from that the prostate is shrinking during the treatment.

Low margin Low margin low toxicity but at the risk not hitting the whole organ during each low toxicity but at the risk not hitting the whole organ during each fraction fraction local control ?? local control ??

Big margin Big margin organ will be hit easily, but to save bladder and rectum the overall organ will be hit easily, but to save bladder and rectum the overall dose has to be reduced dose has to be reduced

local control ??local control ??

Page 10: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Approach to a solution: IGRTApproach to a solution: IGRTIGRTIGRT Image Guided Radiation Image Guided Radiation

TherapyTherapyRadiation Therapy with image guidance in intended to Radiation Therapy with image guidance in intended to localize and adjust the target volume. The image is localize and adjust the target volume. The image is obtained by an on board imaging system (OBI). Today obtained by an on board imaging system (OBI). Today this can be a flat panel sensor with MV or kV imaging, this can be a flat panel sensor with MV or kV imaging, extra portal imaging or cone beam CT.extra portal imaging or cone beam CT.

BUT:BUT:The prostate itself is hardly seen on x-ray The prostate itself is hardly seen on x-ray

images. images. And bony structures might not be a And bony structures might not be a

reliable aid.reliable aid.Motion of the prostate versus

bony structures

Page 11: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Approach to a Solution: Navigation aid Approach to a Solution: Navigation aid = Marker= Marker

The marker should provide a reliable and The marker should provide a reliable and reproducible localization of the prostate.reproducible localization of the prostate.

The marker should be easily seen with the OBI of The marker should be easily seen with the OBI of the LINAC. the LINAC.

The marker has to be of a radio opaque material. The marker has to be of a radio opaque material. E.g. gold, tungsten, silver etc., sometimes carbon.E.g. gold, tungsten, silver etc., sometimes carbon.

It has to be biocompatible.It has to be biocompatible.

Flouro refrence LINAC OBI

Page 12: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

WhyWhy Gold GoldGold does not react with the body. Gold does not react with the body.

Gold is not causing any allergies.Gold is not causing any allergies.

Gold provides a good visibility under x-ray and Gold provides a good visibility under x-ray and gamma-rays.gamma-rays.

Page 13: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

What is a gold marker and What is a gold marker and how does it look likehow does it look like

Generally gold markers are small cylinders or balls made of Generally gold markers are small cylinders or balls made of gold.gold.

Most commonly used sizes vary from 0,8 to 1,2 mm in Most commonly used sizes vary from 0,8 to 1,2 mm in diameter and 3 to 5 mm in lenght . diameter and 3 to 5 mm in lenght .

Other dimensions might be used in special cases.Other dimensions might be used in special cases.

Goldmarker also can be made of thin goldsprings or small Goldmarker also can be made of thin goldsprings or small beads on a suture. beads on a suture.

Page 14: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Marker KitMarker KitThe marker will be delivered sterile preloaded in a 20 cm needle blocked with bone wax or a synthetic spacer at the front end.It comes in sterile pouch ready for the implant.

Page 15: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Positioning of the Positioning of the MarkerMarker To prevent the marker from migration or To prevent the marker from migration or

dislocation it has to be implanted dislocation it has to be implanted inin the organ. the organ.

Skin marker or patient immobilisation are Skin marker or patient immobilisation are unsufficient means.unsufficient means.

Page 16: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

How many markers are How many markers are neededneeded

Usually three markers will be implantedUsually three markers will be implanted

In some special cases four markers might be In some special cases four markers might be neccessary. This adds extra confidence and might neccessary. This adds extra confidence and might help in case of difficult bony conditions.help in case of difficult bony conditions.

Two markers are insufficient. Two markers are insufficient.

Page 17: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Where to place the Where to place the markersmarkersThree markers will be place likeThree markers will be place like

One at the Base one at the Apex and one most lateral in the One at the Base one at the Apex and one most lateral in the middle of the gland.middle of the gland.

OR: OR: One on the left side at the base, one on the right side of One on the left side at the base, one on the right side of the base and one under the urethra at the apex. the base and one under the urethra at the apex.

The markers have to be placed inside the gland 3 to 5 mm The markers have to be placed inside the gland 3 to 5 mm away from the capsule. away from the capsule. The actual position of the markers is not as important as the The actual position of the markers is not as important as the

positioning at the maximum distance from each other.positioning at the maximum distance from each other.

Page 18: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

ImagesImages

Base – Middle – Apex

Page 19: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

ImagesImages

4 Markers; Base – Base – Middle – Middle

Page 20: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

ImagesImages

Base – Base – Apex

Page 21: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

How will the Markers How will the Markers implantedimplanted..In many places the implant is performed by the Urologist In many places the implant is performed by the Urologist

under Ultrasound conrol. Usually he uses the biopsy channel under Ultrasound conrol. Usually he uses the biopsy channel of the rectal ultrasound probe to insert and visualize the of the rectal ultrasound probe to insert and visualize the needle. The implant is done through the rectal wall. needle. The implant is done through the rectal wall.

Some centers do have the equipment (stand, stepper, Some centers do have the equipment (stand, stepper, template grid) to perform a perineal insertion. This is more template grid) to perform a perineal insertion. This is more accurate but might cause a general anesthesia of the patient.accurate but might cause a general anesthesia of the patient.

Page 22: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Procedure Procedure (one possible scenario)(one possible scenario)

In collaboration with the Urologists there will be a ultrasound guided implant of the Markers one or two weeks before the treatment planning starts.

With the localization of the Markers in the planning CT, the simulation and the daily treatment sessions the actual prostate position can be detected and the LINAC bed coordinates can be adjusted. This is the so called organ tracking.

Before each treatment session a control image is obtained and is matched with the reference image.

Prostate displacement will be compensated by moving the treatment bed according to the calculated geographic miss.

Page 23: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

ProcedureProcedureImplant of the marker Implant of the marker

by the Urologist in the urologists office or hospital.by the Urologist in the urologists office or hospital.

Reference imageReference imagefor treatment planning and aquisition of the marker for treatment planning and aquisition of the marker positionposition

Postioning of the patient Postioning of the patient on the bed of the LINAC on the first treatment day.on the bed of the LINAC on the first treatment day.

Page 24: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

ProcedureProcedureAquisition of the images, Aquisition of the images,

Each day in two orthogonal Each day in two orthogonal planes to detect the planes to detect the geographical miss.geographical miss.

Modern LINACS offer a diagnsotic x-ray unit in a 90° angle to the LINAC. This gives the possibilty to create x-ray images or even CT scans before the treatment starts.

Digitally reconstructed x-ray image as reference for the marker position (A) calculation of the correction with a gold marker image from the LINAC.

Page 25: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

Calculation of the mismatchCalculation of the mismatch Modern systems offer the possibility match the actual Modern systems offer the possibility match the actual

image with the reference image. The actual image will image with the reference image. The actual image will be aligned with the reference image on the computer be aligned with the reference image on the computer monitor and the system generates the coordinates for monitor and the system generates the coordinates for the movement of the patients bed.the movement of the patients bed.

Correction of the bedCorrection of the bed Modern systems do have a remote controlled bed. So Modern systems do have a remote controlled bed. So

compensation of the patient dislocation can be compensation of the patient dislocation can be performed in an easy and fast way. Extra dose for performed in an easy and fast way. Extra dose for imaging stays low.imaging stays low.

IrradiationIrradiation Now the irradiation can start as usual. This localization Now the irradiation can start as usual. This localization

and compensation procedure will be performed each and compensation procedure will be performed each day before each fraction.day before each fraction.

ProcedureProcedure

Mismatch

Match

Page 26: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

ConclusionConclusionThe prostate will be hit safely and reproducible The prostate will be hit safely and reproducible

during each treatment session. during each treatment session. Therefore a preferably high dose can be applied to Therefore a preferably high dose can be applied to

the target volume. the target volume. Increase in local tumor control rate. Increase in local tumor control rate. Decrease in toxicity.Die Nebenwirkungsrate wird Decrease in toxicity.Die Nebenwirkungsrate wird

verringert.verringert.Or: Or: With similar toxicity the local control can be With similar toxicity the local control can be

increased. increased.

Page 27: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

IGRT in picturesIGRT in pictures Increased conformity and better dose distribution by means of IMRT. Excellent match of the 95% iso dose level (blue area) with the target volume (red line). The black arrows show the implanted gold markers.

Quelle: PIRUS GHADJAR, DANIEL M. AEBERSOLD

Gold marker

Page 28: Gold Fiducial Markers Are used for soft tissue target volume localization and verification in external beam radiation treatment procedures like - IMRT.

MRI and CT images with MRI and CT images with gold markersgold markers


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