DE102009054676A1 - Arrangement for controlling tumor therapy for patient, has combined polyethylene terephthalate/ computed tomography scanner arranged in direct proximity to illumination chambers, and patient table moved between illumination chambers - Google Patents

Abstract

The arrangement has a combined polyethylene terephthalate (PET)/ computed tomography (CT) scanner (2) arranged in direct proximity to illumination chambers, and a patient table (4) moved between the chambers. The scanner is movably and rotatably designed, and a base frame (20) is integrated in an inner ring of the scanner. An upper area of a divan bed is moved between the scanner and the table. The table is moved by a control system and provided for positioning a patient and moved with the scanner. The position of the patient on the table is controlled according to a radiation position.

Description

The subject of this invention is an arrangement with which the control of radiation therapy can be improved and a prescription for the use of the arrangement.

The goal of the radio oncology is the complete destruction of all tumor stem cells of a tumor with maximum protection of the surrounding normal tissue. This requires a tumor-conformant dose distribution. Technical innovations have increased the tumor conformity of the dose application in recent years. The dose distribution of protons and heavier ions is on the one hand due to their advantageous physical and biological properties almost optimally adapted to the tumor. On the other hand, the precision of tumor therapy with conventional irradiation modalities (photons and electrons) has been improved.

By increasing the tumor conformity of the dose distribution, the sensitivity of the treatment result increases to deviations between planned and applied dose. Differences can z. As by uncertainties in patient positioning, by spontaneous or periodic patient movements or by density changes in the irradiated tissue occur. To ensure maximum therapeutic success, the radiation must be controlled.

Radiographic procedures are used to control radiation exposure to check patient position prior to each exposure and to correct any abnormalities that may occur. As a result, intergroup movements, ie differences between the individual fractions of a fractionated irradiation, can be detected and corrected. On the other hand, there may also be deviations during irradiation (intra-fractional changes). In order to be able to quantify and correct these deviations, a three-dimensional method for monitoring the irradiation is necessary. So far, only a non-radiographic in-vivo and in-situ method based on positron emission tomography (PET) exists. The distribution of positron emitters, which are generated directly by the therapy beam, is measured. This activity distribution correlates with the deposited dose so that conclusions can be drawn from the measured activity distribution on the dose distribution. Through the use of positron emission tomography deviations between planned and applied dose can be determined, which can be corrected in the following fractions of a fractionated irradiation. The control of radiotherapy with PET is successful for the therapy with all therapy-relevant ion types from protons to oxygen ions and with high-energy bremsstrahlung, generated by electrons of an energy of at least 20 MeV.

• 1. Der Patient wird bestrahlt und anschließend zu einem entfernt stehenden PET-Scanner transportiert. Die PET-Messung wird nach der Bestrahlung durchgeführt, weshalb diese Methode als off-beam PET bezeichnet wird.
• 2. Wird der PET-Scanner in den Bestrahlungsplatz integriert, kann die erzeugte Aktivität während der Bestrahlung gemessen werden (in-beam PET).

Positron emission tomography for the control of radiotherapy can be technically realized in two ways:

• 1. The patient is irradiated and then transported to a remote PET scanner. The PET measurement is carried out after the irradiation, which is why this method is called off-beam PET.
• 2. If the PET scanner is integrated into the irradiation site, the activity generated during the irradiation can be measured (in-beam PET).

So far, the in-beam PET method has been successfully used in two centers around the world to control ion irradiation: the Ion Therapy Pilot Plant of the Gesellschaft für Schwerionenforschung (GSI) Darmstadt, Germany and the Heavy Ion Medical Accelerator at Chiba ( HIMAC), Japan. The measurement of the generated positron-emitter distribution after proton irradiation with a conventional PET / CT scanner is z. At the Massachusetts General Hospital (MGH) Boston, USA.

A drawback to the use of the in-beam PET method is the high radiation background that occurs during the irradiation. This means that radiation-proof detectors and electronics are required to realize in-beam PET. Furthermore, it is necessary for the in-beam PET scanner to be completely integrated into the irradiation site, resulting in significantly higher costs and making retrofitting into an existing irradiation site more difficult or impossible. In order to ensure integration into the irradiation site, it is not possible to use a full detector ring but a scanner with two detector heads. As a result, the image quality is reduced compared to that in a conventional PET scanner. In addition, specially adapted to the conditions software algorithms are needed. Alternatively, a conventional PET scanner can be used to measure the generated activity after irradiation (off-beam PET). The time difference between the end of irradiation and the beginning of the PET measurement should be minimized in order to reduce the reduction of the generated activity both through physical decay and through biological transport processes. By installing a conventional PET scanner in the immediate vicinity of the irradiation site and thus in the irradiation room, commercially available PET scanners including existing software can be used. State of the art for the control of radiation therapy with PET is the realization in three ways: in-beam (measurement during irradiation), in-room (measurement shortly after irradiation, PET scanner in the irradiation room) or off-line (measurement after irradiation, PET outside the irradiation room). ( KUNATH, Daniela, et al. Comparison of PET Concepts for Dose Delivery Monitoring of Particle Therapy. Medical Physics and Biomedical Engineering World Congress Munich. 07-12th Sept. 2009 .)

A conventional computer tomograph (CT) is already being used clinically for the verification of patient positioning and the position of organs before irradiation. This is located in the irradiation room and is mobile on rails. The patient is initially positioned on the patient table, rotated by a certain angle and the computer tomograph is moved over the patient. After the CT scan, the tomograph is moved back to the parking position, the patient is turned back by a certain angle and the radiation is carried out. The angle through which the patient table is rotated is determined by the angle of the CT scanner and the irradiation site to each other.

Generally, it can be said that PET scanners are used for control during or after the irradiation, and CT scanners for pre-irradiation monitoring as described above. In the known devices, the corresponding devices are available as individual devices partly in different rooms. The methods of using the scanners described above differ from the commonly used radiological and nuclear medicine diagnostic procedures.

The problem to be solved by the invention is to specify a less expensive arrangement for controlling radiotherapy. Their use should provide improved information about the irradiation result compared to existing methods and lead to a time saving.

The object is achieved by the use of the arrangement according to claim 1. In the process, a combined PET / CT scanner is placed in the immediate vicinity of the irradiation site. Advantageous embodiments are specified in the subclaims. An advantageous use of the inventive arrangement is also indicated.

Illustrations are used to illustrate the invention.

represents the schematic representation of the PET / CT scanner with patient and table as an example.

shows the patient before the irradiation in the CT measurement position.

In the patient is in the irradiation area 1 , The PET / CT scanner is in parking position.

shows the patient during the PET measurement.

shows the use of an optional roll stabilization system 20 , This add-on system is fixed in an inner ring of the PET / CT scanner.

shows the rotated by 180 ° PET / CT scanner and the patient in the PET measurement position.

According to the invention, a combined PET / CT scanner is used for optimized control of radiotherapy with high-energy photons, protons or heavier ions. The combined PET / CT scanner is placed close to the irradiation site.

• 1. Der kombinierte PET/CT-Scanner 2 ist in praktikabler Nähe zum Bestrahlungsplatz 1 angeordnet und auf Schienen 3 montiert. Die Normalposition ist die Parkposition. Für die CT- oder die PET-Aufnahme wird die Patientenliege um einen entsprechenden Winkel gedreht, so dass sie senkrecht zur Öffnung des kombinierten PET/CT-Scanners 2 steht. Anschließend wird der kombinierte PET/CT-Scanner 2 über den Patienten, der auf dem Patiententisch 4 positioniert ist, gefahren. Nach der Aufnahme wird der kombinierte PET/CT-Scanner 2 in die Parkposition zurückgefahren und der Patiententisch 4 zurückgedreht.
• 2. Der kombinierte PET/CT-Scanner 2 ist in praktikabler Nähe zum Bestrahlungsplatz 1 angeordnet. Der Patiententisch 4 wird über eine Steuerung bewegt und positioniert. Für die CT- oder die PET-Aufnahme wird die Patientenliege mit dem Patienten manuell oder mit Hilfe einer Steuerung zum kombinierten PET/CT-Scanner 2 und zum Bestrahlungsplatz 1 gefahren.

In the irradiation room is the combined PET / CT scanner 2 and the radiation site 1 arranged. The integration of these two devices can be done as follows:

• 1. The combined PET / CT scanner 2 is in practicable proximity to the irradiation site 1 arranged and on rails 3 assembled. The normal position is the parking position. For CT or PET imaging, the patient bed is rotated by a corresponding angle so that it is perpendicular to the opening of the combined PET / CT scanner 2 stands. Subsequently, the combined PET / CT scanner 2 about the patient on the patient table 4 is positioned, driven. After taking the combined PET / CT scanner 2 moved back to the parking position and the patient table 4 turned back.
• 2. The combined PET / CT scanner 2 is in practicable proximity to the irradiation site 1 arranged. The patient table 4 is moved and positioned via a controller. For CT or PET imaging, the patient bed is placed with the patient manually or by means of a combined PET / CT scanner control 2 and to the radiation site 1 hazards.

The combined PET / CT scanner can be a commercially available PET / CT device. Commercially available PET / CT devices have an X-ray tube detector system for CT scans and a detector ring for PET scans. Alternatively, it is possible to use a combined PET / CT scanner, which consists of only one detector system and can be used for both CT and PET. This arrangement has the advantage over devices with two rings that it will be cheaper and requires less space. Thus, the use of the proposed arrangement is possible even in relatively small spaces.

• 1. Der ausfahrbare Teil des Patiententischs 4 muss so lang sein, dass jeder Bereich eines Patienten bis zu einer definierten Körpergröße (i. d. R. Körper ohne Beine) sowohl mit dem PET-Scanner als auch mit dem CT-Scanner erfasst werden kann.
• 2. Wird der Patiententisch 4 durch die obige Bedingung 1. zu instabil, muss ein Zusatzsystem zur Sicherstellung der Stabilität verwendet werden. Dazu kann eine Unterbaukonstruktion 20 im inneren Ring des PET/CT-Scanners 2 angebracht werden, auf der der Patiententisch 4 z. B. auf Rollen oder Schienen läuft.
• 3. Zur Verhinderung von Stabilitätsproblemen auf Grund der obigen Bedingung 1. kann das PET/CT-System drehbar gelagert werden. Dadurch kann der jeweils benötigte Detektorring in Richtung des Patiententisches gedreht werden.

To ensure that both PET and CT measurements can be performed on areas in the lower part of the body, such as: For example, in the case of prostate irradiation, one of the following conditions must be considered in the design:

• 1. The extendable part of the patient table 4 must be so long that each area of a patient can be detected up to a defined height (usually body without legs) both with the PET scanner and with the CT scanner.
• 2. Will the patient table 4 Too unstable due to the above condition 1. An auxiliary system must be used to ensure stability. This can be a substructure 20 in the inner ring of the PET / CT scanner 2 be attached to the patient table 4 z. B. running on rollers or rails.
• 3. To prevent stability problems due to the above condition 1, the PET / CT system can be rotatably supported. As a result, the respectively required detector ring can be rotated in the direction of the patient table.

• 1. Der Patient wird auf dem Patiententisch positioniert und die Lage mit herkömmlichen Verfahren kontrolliert.
• 2. Der Patiententisch mit dem Patienten wird zu dem kombinierten PET/CT-Scanner bewegt, falls dies erforderlich ist.
• 3. Die CT-Aufnahme wird durchgeführt (siehe ).
• 4. Nach eventuell notwendigen Korrekturen der Lage des Patienten auf dem Patiententisch wird der Patiententisch mit dem Patienten in die Bestrahlungsposition gebracht (siehe ).
• 5. Die Bestrahlung des Patienten verläuft nach Bestrahlungsplan.
• 6. Direkt im Anschluss an die Bestrahlung wird der Patiententisch mit dem Patienten zum kombinierten PET/CT-Scanner bewegt und die im Patienten erzeugte Positronenemitter-Verteilung in einer PET-Aufnahme gemessen.

Radiation therapy using a combined PET / CT scanner can proceed as follows:

• 1. The patient is positioned on the patient table and the situation is checked using conventional procedures.
• 2. The patient table with the patient is moved to the combined PET / CT scanner if necessary.
• 3. The CT scan is performed (see ).
• 4. After any necessary corrections of the position of the patient on the patient table, the patient table is placed with the patient in the irradiation position (see ).
• 5. The patient is irradiated according to the treatment plan.
• 6. Immediately following the irradiation, the patient table is moved with the patient to the combined PET / CT scanner and the positron emitter distribution generated in the patient is measured in a PET scan.

If differences between the planned and applied dose distribution result from the PET measurement, these can be taken into account in the following treatment procedure.

The advantage of using a combined PET / CT scanner to monitor radiotherapy is on the one hand on the economic side, since the cost of a combined device is less than for two individual tomographs. In addition, the space requirement for a combined device is significantly lower than for two devices including the necessary action area. Only one patient table is used for both irradiation and for CT measurement and PET measurement, so the patient only has to be positioned once before the therapy fraction. A repositioning for the PET measurement after the irradiation is not necessary. In contrast to an in-beam PET scanner, a combined PET / CT scanner can be easily integrated into existing irradiation sites.

On the other hand, the use of only one device ensures an exact spatial correlation between the PET and the CT image, so that the positioning of the patient during the irradiation can be clearly determined from the superimposition of both images.

Furthermore, an image data set of the attenuation coefficients for the attenuation and scatter correction is required for PET. This image data set can be taken from the planning CT, on the basis of which radiotherapy is planned. The disadvantage here is that the anatomy of the irradiated area and thus the attenuation coefficients can change during the course of several days of therapy. If a combined PET / CT device is used, the CT scan can be used for attenuation and scatter correction. On the one hand, this CT image is an illustration of the actual anatomy and, on the other hand, it clearly correlates spatially with the PET image.

Integration of the PET / CT scanner into the irradiation room, as opposed to a PET / CT scanner outside the irradiation room, minimizes the time difference between irradiation and PET measurement and thereby maximizes the measurable count rate.

In general, the integration of the PET / CT scanner into the vicinity of the irradiation site leads to a significant time saving for the entire process.

Only with the proposed arrangement can be obtained up-to-date information of the CT on the anatomy before the irradiation as well as the PET, which shows information about the results of the irradiation.

The described arrangement enables automatic or semi-automatic control of patient positioning and movements of the patient Patient table or the combined PET / CT scanner.

LIST OF REFERENCE NUMBERS

1

irradiation station

2

combined PET / CT scanner

3

Rails of the PET / CT scanner

4

patient table

5

Substructure of the patient table

6

Body of the patient (without legs) - maximum measuring range to be measured

7

Head of the patient

8th

CT component of the PET / CT scanner

9

Housing of the PET / CT scanner

10

PET component of the PET / CT scanner

11

Center of the CT component of the PET / CT scanner

12

Center of the PET / CT scanner

13

Center of the PET component of the PET / CT scanner

14

Distance between the end of the patient's body and the center of the CT component

15

Distance between the end of the patient's body and the center of the PET component

16

body length

17

head length

18

Length of the extendable part of the lounger

19

Length of the housing of the PET / CT scanner

20

Stabilization of the patient table in the PET / CT scanner

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• KUNATH, Daniela, et al. Comparison of PET Concepts for Dose Delivery Monitoring of Particle Therapy. Medical Physics and Biomedical Engineering World Congress Munich. 07-12th Sept. 2009 [0007]

Claims (7)

Arrangement for the control of radiotherapy, characterized in that in the immediate vicinity of the irradiation place ( 1 ) a combined PET / CT scanner ( 2 ) and that a patient table ( 3 ) can be moved between the two devices. Arrangement according to claim 1, characterized in that the combined PET / CT scanner is designed to be movable. Arrangement according to claim 1, characterized in that the combined PET / CT scanner is rotatable. Arrangement according to claim 1, characterized in that the patient table on rollers or rails 3 rotatably movably angeordet is. Arrangement according to claim 1, characterized in that in the inner ring of the PET / CT scanner ( 2 ) a substructure ( 20 ), on which the patient table movable between the PET / CT scanner and the irradiation station or its upper area (the couch) can be moved. Arrangement according to claim 1, characterized in that the movement of the patient table can be carried out with a controller. Use of the arrangement according to 1, characterized a) positioning the patient on the patient table and controlling the situation with conventional methods, b) subsequently moving the patient table with the patient to the combined PET / CT scanner or moving the combined PET / CT scanner to the patient table, c) that then the CT scan is performed, d) that after subsequent possibly necessary corrections of the position of the patient on the patient table, the patient table is brought to the patient in the irradiation position, e) that then the irradiation of the patient is carried out according to the treatment plan, f) that immediately after the patient table with the patient to the PET / CT scanner is moved or the combined PET / CT scanner moves to the patient table and the generated positron emitter distribution is measured in a PET recording.

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