APPARATUS FOR PERFORMING IN VIVO DOSIMETRY

• US 20080191141A1
• Filed: 12/28/2007
• Published: 08/14/2008
• Est. Priority Date: 05/06/2002
• Status: Abandoned Application

• Current Assignee: 4D-S Pty, Ltd., Dow Corning GMBH (Dow, Inc.)
• Original Assignee: Dow Corning GMBH (Dow, Inc.)
• Inventors: Nilsson, Gorgen
• Application Number:
  US11/966,383
• Publication Number:
  US 20080191141A1
• Time in Patent Office: Days
• US Class Current: 250/393
• CPC Class Codes: A61N 2005/1076 using a dummy object placed in the radiation field, e.g. phantom
• CPC Class Codes: A61N 5/1042 with spatial modulation of the radiation beam within the treatment head
• CPC Class Codes: A61N 5/1048 Monitoring, verifying, controlling systems and methods
• CPC Class Codes: A61N 5/1071 for verifying the dose delivered by the treatment plan

Abstract

The present invention relates to a device enabling quantification of dose delivery in radiotherapy treatment during patient-specific treatment of the patient utilising measurements in predefined time-intervals with information means positioned in the radiation beam, between the patient and the source and converting the readings to corresponding measures in a phantom.

Claims

1. An apparatus for quantifying dose delivery in radiotherapy treatment, characterized in that it is configured for:

irradiating a phantom,

obtaining fluency measurements in said phantom, and wherein it comprises electronic circuitry configured for;

collecting information regarding the irradiation by information means arranged between the phantom and the radiation source, wherein said measurements are divided in time-intervals,

processing data from the measurements, and

obtaining at each time-interval information regarding the relationship between the measurements in the phantom and the information collected by said information means arranged between the phantom and the treatment source, which relationship information is to be used as verification of the treatment of a patient.

2. The apparatus in claimed in claim 1, wherein the electronic circuitry is configured for gathering information about the position of Multi Leaf Collimator (MLC) leafs arranged for shaping the irradiating beam of the radiation source.

3. The apparatus as claimed in claim 2, characterized in that the measurements in the phantom and a determination of the positions of Multi Leaf Collimator leafs are performed simultaneously.

4. The apparatus as claimed in claim 1, characterized in that it comprises detectors (ExtDet).

5. The apparatus as claimed in claim 4, wherein the electronic circuitry is configured for performing measurements in the phantom and with detectors (ExtDet) simultaneously.

6. The apparatus as claimed in any of claims 2 to 5, wherein the electronic circuitry is configured for calculating calibration factors from the obtained relationship information as the ratio of the reading from information from the information means and the measurements along the radiation ray in the phantom.

7. The apparatus as claimed in any of claims 1 to 5, characterized in the further step of storing the data for each specific time-interval both for measurements in the phantom and information between the patient and the treatment source.

9. The apparatus as claimed in claim 4, characterized in that it comprises detectors (ExtDet) positioned on the surface of the phantom.

10. The apparatus as claimed in claim 4, characterized in that it comprises detectors (ExtDet) positioned between the radiation source and the surface of the phantom.

11. The apparatus as claimed in claim 4, wherein the detector setup allows for detectors (ExtDet) to be placed inside the phantom.

13. The apparatus as claimed in any of claims 1 to 5 and 9 to 11, wherein it is configured to be capable of storing in its memory a patient specific treatment plan during irradiation of the phantom, and verifying the accuracy of the irradiation of the phantom comparing the measured dose in the phantom with the treatment plan.

14. The apparatus as claimed in claim 2 or 3, wherein the electronic circuitry is configured to, during treatment of the patient, utilize the same positions of the MLCs as during the irradiation of the phantom.

15. The apparatus as claimed in claim 4, wherein the electronic circuitry is configured to, during treatment of the patient, utilize ExtDet in the same lateral positions between the patient and the treatment source as during the irradiation of the phantom.

16. The apparatus as claimed in claim 15, wherein the electronic circuitry is configured to, during treatment of patient, convert the readings from ExtDet to dose using calculated calibration factors for each time-interval.

17. The apparatus as claimed in claim 16, wherein the readings are converted according to:

D_{seg-n,f,p,t(i),t(i+1)}=S_{n,f,t(i),t(i+1)}/Cal_{n,f,seg-n,f,p,t(i),t(i+1)}

20. The apparatus as claimed in any of the claims 16 to 17, wherein the electronic circuitry is configured to totalize the readings from all time-intervals for each specific dose point in order to obtain the total dose.

21. The apparatus according to claim 20, wherein the totalization is obtained according to:

$\begin{array}{c}{D}_{\mathrm{seg}<br><br>\text{-}<br><br>n,f,p}=\underset{i=0<br><br><br><br>\mathrm{to}<br><br><br><br>T}{\overset{}{\sum <br><br>}}<br><br>D_{\mathrm{seg}<br><br>\text{-}<br><br>n,f,p,t<br><br>\left(i\right),t<br><br>\left(i+1\right)})\\ =\underset{i=0<br><br><br><br>\mathrm{to}<br><br><br><br>T}{\overset{}{\sum <br><br>}}<br><br>\left(S_{n,f,t<br><br>\left(i\right),t<br><br>\left(i+1\right)}/{\mathrm{Cal}}_{n,f,\mathrm{seg}<br><br>\text{-}<br><br>n,f,p,t<br><br>\left(i\right),t<br><br>\left(i+1\right)}\right)\end{array}$

23. The apparatus as claimed in claim 4, wherein it is configured to determine the position of the ExtDet in the transversal plane using the projection of the detectors or markers well defined to the ExtDet utilising an image from an image device downstream the phantom e.g. EPID or radiographic film.

24. The apparatus as claimed in any of claims 1-5, 9-11, 15-17 and 23, wherein the electronic circuitry is configured to calculate the dose distribution using measurement of the patient anatomy and delivered dose, using the dose distribution in a patient at one treatment fraction or accumulated for several treatment fractions, and to modify the subsequent treatments due to previous treatments in order to adapt the intended dose distribution.

8. An apparatus for enabling quantification of dose delivery in radiotherapy treatment, characterized in that it is configured for:

irradiating a phantom,

obtaining measurements in said phantom during irradiation of said phantom

collecting information regarding the irradiation by information means arranged between the phantom and the radiation source, wherein said measurements are divided in time-intervals, characterized in that the information means comprises detectors (ExtDet),

analysing the measurements,

obtaining at each time-interval information regarding the relationship between the measurements in the phantom and the information collected by said information means arranged between the phantom and the treatment source, which relationship information is to be used as verification of the treatment of a patient, and

calculating calibration factors from the obtained relationship information as the ratio of the reading from information from the information means and the measurements along the radiation ray in the phantom, characterized in that the calibration factors are calculated according to,

Cal_{n,f,seg-n,f,p,t(i),t(i+1)}=S_{n,f,t(i),t(i+1)}/(D_{seg-n,f,p,t(i),t(i+1)})

where

D_{seg-n,f,p,t(i),t(i+1)} The dose in point p in the phantom-segment defined by the DetExt detector-element, n and the field (projection), f integrated from time t(i) until t(i+1)

S_{n,f,t(i),t(i+1)} The signal from the ExtDet detector-element, n, in the field, f, integrated from time t(i) until t(i+1)

Cal_{n,f, seg-n,f,p,t(i),t(i+1)} The calibration factor to be used with ExtDet detector-element n, in the field, f, to convert the signal integrated from time t(i) until t(i+1) to achieve the dose in the point p in the phantom-segment defined by the DetExt detector-element, n and the field (projection), f integrated from time t(i) until t(i+1).

25. The apparatus as claimed in claim 8, wherein the electronic circuitry is configured so that measurements in the phantom and with detectors (ExtDet) can be performed simultaneously.

12. An apparatus for enabling quantification of dose delivery in radiotherapy treatment, characterized in that it is configured to:

irradiate a phantom,

obtain measurements in said phantom during irradiation of said phantom,

collect information regarding the irradiation by information means arranged between the phantom and the radiation source, wherein said measurements are divided in time-intervals, characterized in that the information means comprises the position of Multi Leaf Collimator leafs (MLC) arranged for shaping the irradiating beam of the radiation source,

analyze the measurements,

obtain information regarding the relationship between the measurements in the phantom and the information collected by said information means arranged between the phantom and the treatment source at each time-interval, which relationship information is to be used as verification of the treatment of a patient, and

calculate calibration factors from the obtained relationship information as the ratio of the reading from information from the information means and the measurements along the radiation ray in the phantom, characterized in that the calibration factors are calculated according to

Cal_{n,f,p,t(i),t(i+1)}=F_{n,f,t(i),t(i+1)}/(D_{f,p,t(i),t(i+1)})

where

D_{f,p,t(i),t(i+1)} The dose in point p in the phantom at the field (projection), f integrated from time t(i) until t(i+1)

F_{n,f,t(i),t(i+1)} The radiation fluency in the field, f, between the patient and the source along the ray that intersects point p in the phantom integrated from time t(i) until t(i+1)

Cal_{n,f,p,t(i),t(i+1)} The calibration factor describing the relation between the fluency between the patient and the source and the dose in the phantom.

18. The apparatus as claimed in claim 12, wherein the electronic circuitry is configured to, during treatment of the patient, convert the information from the positions of the MLC'"'"'s to dose using said calibration factors for each time-interval.

19. The apparatus as claimed in claim 18, wherein the readings are converted according to:

D_{f,p,t(i),t(i+1)}=F_{n,f,t(i),t(i+1)}/Cal_{n,f,p,t(i),t(i+1)}

22. The apparatus as claimed in any of claims 18-19, wherein the electronic circuitry is configured to totalize the readings from all time-intervals for each specific dose point in order to obtain the total dose, wherein the totalization is obtained according to:

$\begin{array}{c}{D}_{f,p}=\underset{i=0<br><br><br><br>\mathrm{to}<br><br><br><br>T}{\overset{}{\sum <br><br>}}<br><br>D_{f,p,t<br><br>\left(i\right),t<br><br>\left(i+1\right)}\\ =\underset{i=0<br><br><br><br>\mathrm{to}<br><br><br><br>T}{\overset{}{\sum <br><br>}}<br><br>F_{n,f,t<br><br>\left(i\right),t<br><br>\left(i+1\right)}/{\mathrm{Cal}}_{n,f,p,t<br><br>\left(i\right),t<br><br>\left(i+1\right)}\end{array}$

26. The apparatus as claimed in claim 12, wherein the electronic circuitry is configured to enable measurements in the phantom and a determination of the positions of Multi Leaf Collimator leafs to be performed simultaneously.