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© copyright Image Guided Radiation Therapy Dr. Mark Fisher School of Computing Sciences UEA Norwich UK.

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Presentation on theme: "© copyright Image Guided Radiation Therapy Dr. Mark Fisher School of Computing Sciences UEA Norwich UK."— Presentation transcript:

1 © copyright Image Guided Radiation Therapy Dr. Mark Fisher School of Computing Sciences UEA Norwich UK

2 © copyright Plan Introduction/Motivation Background State of the Art Current Research Conclusions

3 © copyright Introduction/Motivation

4 © copyright Introduction Cancer is currently the cause of 12% of all deaths world wide; 10 million new cases diagnosed annually. Within the European union over 1,5 million new cancer cases are diagnosed every year and over 920000 people die of cancer. Most scientists are confident that in the long term significant improvement in cancer cure will come from systematic treatments such as immunotherapy and/or gene therapy and drug targeting. For the time being the surgical removal of the tumour tissue followed by radiotherapy remains the main method of treatment. Source: MAESTRO 2004

5 © copyright New cases and deaths from cancer - US 2004 Source: American Cancer Society, 2005

6 © copyright Radiation treatment equipment per million population

7 © copyright Background

8 © copyright Background Ionising Electromagnetic Radiation interacts with cells destroying their DNA None-malignant cells can repair themselves but high doses of radiation to healthy tissue can induce secondary malignancies. Both malignant and non- malignant tissue is destroyed BUT...

9 © copyright Aim of Radiotherapy Treatment I To deliver a high dose of Radiation to the tumour while and a low dose to healthy tissue and organs at risk. –Possible through the use of multiple treatment fields (beams).

10 © copyright Radiation Therapy Treatment Delivery 1895 Wilhelm Conrad Roentgen saw the bones of his own hand when held between cathode tube and fluorescent screen.

11 © copyright The Coolidge Tube. William Coolidge of GE with his "hot" cathode tube, The Coolidge tubes also made possible the development of orthovoltage kV X-ray therapy. 1912 Radiation Therapy Treatment Delivery

12 © copyright 1937 Varian brothers develop first klystron tube, initially used in Radar Radiation Therapy Treatment Delivery

13 © copyright 1953 Mullard (Philips) 4 MV double gantry linac. First installed at Newcastle Hospital, This unit featured a nearly isocentric mount, a 1 meter traveling wavetube, MV magnetron, and a false floor. Radiation Therapy Treatment Delivery

14 © copyright Varian Clinac treatment unit, Today's integrated medical linac has been enhanced by computerized controls and easier operation in the quest for optimal treatment in cancer. 1990s Radiation Therapy Treatment Delivery

15 © copyright Radiation Therapy Treatment Planning In the early days of radiotherapy, the X-ray beams were rectangular or square in shape and were directed at the tumor from two to four different angles. –Since the dosages delivered were uniform in strength there was some damage to healthy tissue. In the 1970’s conformal RT was developed. This approach used lead-alloy blocks to shape the beam. –The dose was ‘conformed’ to the shape of the tumour, healthy tissue is spared.

16 © copyright ICRU 50/62 ICRU 50 (1993) and ICRU 62 (1999) define relationships and margins between treatment volumes Report of BIR working party (2003), established in 1999 following initial work by Euen Thompson, NNH

17 © copyright State-of-the-Art

18 © copyright Intensity Modulated Radiotherapy Treatment (IMRT) Conceptualised in 1980’s Uses Multi-leaf collimator to vary the dose density within the treatment volume. Allows for much higher dose delivery to malignant tissue. Needs higher precision volumetric planning systems Currently the most widely deployed method in clinical use.

19 © copyright Beam shaping using MLC

20 © copyright treatment planning software with inverse treatment planning capability Total Cost approx. £3M each system To treat each patient a medical linac with a multi-leaf collimator ($1.6M) simulation devices and software for establishing patient positioning as well as pre-testing and refining treatment plans

21 © copyright Comparisons between IMRT and 3D-CRT Treatment Costs

22 © copyright Source: Alison Vinall, HHUH

23 © copyright Source: NNUH Data Acquisition

24 © copyright Treatment Planning

25 © copyright Computer Planning

26 © copyright Plan Simulation/Verification

27 © copyright Five field IMRT beam arrangement for treating prostate

28 © copyright Treatment Delivery Treatment is delivered over 30-40 fractions Patient makes several visits to hospital over a period of weeks

29 © copyright Accounting For Organ Movement “Most of the development of IMRT has taken place assuming that the organs don't move from fraction to fraction and are well represented by their positions determined from some pre-planning 3D imaging study, be it x-ray CT, MR or functional imaging. As the ability to conform to the target has now reached near perfection, attention is now turning to not accepting this limitation and attempting to quantitate organ movement and account for it in IMRT planning and delivery”. “IMRT of the moving patient is like completing a jigsaw on a jelly” Prof. Steve Webb, Royal Marsden Hosp.

30 © copyright Types of Motion Patient set-up errors –Position-related organ motion which can be minimised if the patient's planning scan is performed while the patient is immobilised and in the treatment position. Inter-fraction motion –i.e. motion that occurs when the target volume changes from day to day. This is a problem for organs that are close to or part of the digestive/excretory system. This work is collated under various headings: gynaecological tumours, prostate (the largest group), bladder and rectum. Intra-fraction –generally due to respiratory and cardiac functions which disturb other organs. This work is collated under headings: liver, diaphragm, kidneys, pancreas, lung tumours and prostate.

31 © copyright Patient Set-up Errors Stereotactic surgery uses mechanical fixations implanted in the skull to ensure alignment. Gold markers may be implanted in soft tissue

32 © copyright Passive infra-red reflective marker block used to track chest wall motion during data acquisition, simulation, and treatment. Intra-Fraction Motion: Current Approaches

33 © copyright Varian RPM respiratory gating

34 © copyright Gated 4D CT

35 © copyright Beam’s Eye Views of gated and non-gated treatment volumes

36 © copyright Gated 4-D CT Movie showing Lung Motion

37 © copyright MotionView™: addresses intra-fraction deformation This offers particular advantages for targeting lung tumors which move and deform during respiration. Flat panel Amorphous Silicon Detector

38 © copyright Traditionally, imaging technology has been used to produce three-dimensional scans of the patient’s anatomy to identify the exact location of the cancer tumor prior to treatment. However, difficulty arises when trying to administer the radiation, since cancer tumors are constantly moving within the body IGRT combines a new form of scanning technology, which allows planar or X-ray Volume Imaging (XVI), with IMRT. This enables physicians to adjust the radiation beam based on the position of the target tumor and critical organs, while the patient is in the treatment position. Inter-fraction Motion: Current Approaches Image Guided Radiation Therapy (IGRT)

39 © copyright Elekta Synergy™ Source: Elekta

40 © copyright Elekta Synergy™ Synergy allows for co- registration of Cone- Beam CT and RTP data in real-time immediately before treatment delivery

41 © copyright

42 © copyright “For the first time the cone beam system lets us see what we want to hit with our treatment by giving us a continuous set of detailed 3-D X-ray images of the patient when the patient is lying down on the treatment couch. This means we can even move towards better cure rates by safely increasing the doses we deliver in radiotherapy.” (Professor Chris Moore, Consultant Physicist, Christie Hospital) Available from August 2004

43 © copyright Current Research

44 © copyright “The future is motion” - Varian annual report 2003 Even when patients are placed in precisely the same position for their daily treatments, some tumors can shift by as much as two to three centimeters over six to eight weeks of therapy. In addition, normal physiological processes like breathing cause some organs and tumors to move significantly during a daily treatment session. As we understand more about tumor motion, we have had to realize that we cannot position patients just on the basis of marks or tattoos on their external anatomy. As the treatments have become more conformal, and as we try to confine the high dose area much more strictly just to where the tumor is, we have to be all the more diligent in knowing exactly where the tumor is, every day.

45 © copyright

46 © copyright

47 © copyright MAESTRO WP1.3 - Dynamic RT Objective –To compensate for intra-fraction organ motion by dynamically shaping the beam in real-time (UEA + UCLM). Currently researchers are able to track implanted gold markers © Harvard Medical School

48 © copyright Portal Video: Respiratory Motion WP1.3 Aims to infer motion without using markers

49 © copyright Ultimately we hope to simulate Dynamic MLC Control

50 © copyright ASM: Motion Tracking © Yu Su, School of Computing Sciences, UEA

51 © copyright Building & Fitting ASM Models © Yanong Zhu, School of Computing Sciences, UEA

52 © copyright Image Registration via Graph Matching © Muhannad Al-Hasan, School of Computing Sciences, UEA

53 © copyright Conclusions Several Studies have shown IMRT improves quality of RT –IMRT showed a 92 percent three-year survival rate for early stage prostate patients and a better than 80 percent three-year survival rate for those with an initially unfavorable prognosis. Set-up error and organ motion interferes with the accuracy of radiotherapy, –The important goal of shrinking the treatment margin can only be achieved with better patient positioning techniques. Improvements in electronic portal image devices are needed before widespread use of Dynamic Image Guided RT is possible –WP1.3 should demonstrate it is feasible in a limited number of cases e.g Lung

54 © copyright Acknowledgements Alison Vinall - Head of Radiotherapy Physics, NNUH Dr. Yu Su, Computing Sciences, UEA Yanong Zhu, Computing Sciences UEA Muhannad Al-Hasan, Computing Sciences, UEA MAESTRO

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