This document discusses motion in radiotherapy and strategies for managing organ and tumor motion. It defines different types of motion errors and target volumes used in radiation treatment planning. Techniques described include 4D CT, real-time tumor tracking, gating, abdominal compression, and image-guided radiation therapy. Proton therapy is highlighted as a promising treatment for lung cancer due to its ability to minimize dose to surrounding healthy tissues compared to photon therapy. Early results for proton therapy in early stage non-small cell lung cancer show local control rates of 80-90% with tolerable toxicity.

1. Hadron therapy
Organs motion
Siavash Zare shiraz paramedical university

2. Development of Proton Beam Therapy System
Ability to precisely target the dose of radiation on the cancerous tumor while minimizing the impact on
surrounding organs.
Schematic of dose distribution along a
single line for proton versus X radiation.
Comparative dosimetry for photon (A) versus proton (B). At the high
dose region near the tumor

3. Motion in radiotherapy
Anything that may lead to mismatch between the intended and actual
location of delivery dose.
1. What is motion ?
2. Why is motion important ?
3. Motion in practice
4. Qualitative impact of motion
5. Motion management
Errors of even a few millimeters may have a significant impact on dosimetry
Organ motions:
● Breathing
● Peristalsis
● Swallowing
● Bladder filling
● Rectum filling
● Etc...

4. Subdivision of motion
Systematic versus Random :Measurement errors can be divided into two components: random error and systematic error
Random : are caused by unknown and unpredictable changes in the experiment: electronic noise , heate
Systematic : usually come from the measuring instruments. They may occur because:
1-there is something wrong with the instrument or its data handling system, or
2-because the instrument is wrongly used by the experimenter.

5. Systematic vs Random error
Random error:
-Blur the cumulative dose distribution
-Multiple parts of the tumor underdosed part of the time, correctly dosed most of the time
Systematic error: (worse)
-Shift the cumulative dose distribution
-Same part of the tumor always underdosed

6. Inter-fractional versus Intra-fractional
● Inter-fractional errors:
-Variation between fractions : heartbeat , breathing , rectum filling , bladder filling ...
● Intra-fractional errors:
-Variation within a fraction :Intra-fraction motion is one source of positioning error which contributes to the
design of PTV margins.

7. Qualitative impact of motion

8. Target Volumes
GTV: Macroscopic extent of the tumor.
(Gross Tumor Volume): = 5 cm;
CTV: GTV + surrounding microscopic extension of the tumor(tumor bed).
(Clinical Target Volume): = 6 cm;
ITV: GTV/CTV with an additional margin to account for physiological movement of the tumor or organs.
(Planning Target Volume): = 8 cm;
PTV: A margin given to above to account for uncertainties.
(Planning Target Volume): = 8 cm;

9. PTV
CTV
GTV

10. Biological Target Volume
A target volume that incorporated
data from molecular imaging
techniques
Target volume drawn incorporates
information regarding:
● Cellular metabolism (PET)
● Tumor hypoxia (MRI)
● Tumor proliferation (PET)
● Intrinsic Radioresistance or sensitivity

11. Motion in practice: Target deformation
random & interfractional

12. Motion in practice: breathing motion

13. First step in Motion management
In many cases is
not enough

14. Image Guided Radiation Therapy (IGRT)
IGRT is the use of the image in the actual treatment room as a tool for tracking and
verification of the tumour volume immediately before or during treatment.
Why IGRT?
1-respiration motion effects all tumor, lung tumors can move several cm in any direction during
irradiation.
2-sites in thorax, abdomen , and pelvic. Tumors in the lung, liver, pancreas, esophagus, breast, kidney,
prostate.
3-tumor displacement
4-...
Treatment with IGRT:
● Breast cancer
● Gastrointestinal cancer
● Head and neck cancer
● Lung cancer
● Prostate cancer

15. ON-BOARD Imagers
The accelerator-mounted imaging systems are called
on-board imagers
1-Portal and radiographic imagers
2.In room CT-scanner
3.Cone Beam CT
4.Helical tomotherapy
5.ultrasound

17. What can we do with the IMAGES ?
● Detect systematic errors.
● Position the patient , target or organ at risk.
● Modify the treatment plan or choose an appropriate plan.
● Detect changes in patient tumor size.

18. Management of respiration
4D Computed Tomography Real Time tumor tracking

19. 1-4D computed tomography
Obtain images of the patient during different phases of breathing cycle.
These data used to develop treatment plans.
RPM : is a computer-controlled
video-based system in which a
box with IR reflectors is placed on
a patient surface and the motion
of the box tracked by an IR-
camera

20. Real-time tumor tracking
To detect the respiration motion using radiation beam follow the tumor’s
changing position.
1.Fluoroscopy based tracking system(most available , more radiation exposure)
2.Electromagnetic field tracking system
(RF signal, fast ,Cost)
MRI guided RT

21. Proton Therapy for Lung Cancer
● Lung cancer is the leading cause of cancer death in the USA and worldwide.
● Radiation has played a significant role in the treatment of all types and stages of lung
cancer.
● poor lung tolerance and its location near by critical organs (heart, esophagus, spinal
cord).
● Particle beam therapy is promising due to the ability to spare normal surrounding
tissues from unnecessary collateral radiation.

22. Treatment of lung cancer is challenging due to:
1-Most patients are diagnosed at late stages III or IV.
2-most lung patients are elderly (2/3 patients are 65 years old or older) and often
have co-morbidities.
3-current treatments for lung cancer are difficult to tolerate since they require
radical surgery and/or combined systemic cytotoxic drugs and radiation to the above
organs.
4-lung cancers are radiation-resistant and surrounded by healthy tissues, which are
radiation sensitive, such as the heart, esophagus, and spinal cord.
5-Too much radiation to the lung can cause radiation pneumonitis, which can
decrease lung function.

23. lung cancer has been divided into two major histologic types:
1-small cell lung cancer(SCLC)
SCLC accounts for 10-15% of all lung cancer, and they are typically treated by systemic
therapy.
2-non-small cell lung cancer (NSCLC)
which have an overall prognosis of 15% 5-year survival.Surgery is the most common
treatment for stages 1, 2 and 3.But your doctor may suggest that you have radiotherapy
instead of surgery to try to get rid of the cancer cells.

24. Lung cancer stages
*****Treatment guidelines have been developed by the National Cancer Care Network
(NCCN)depending on the stage of the disease at presentation*****
1-early stage lung cancer (I)
The cancer is located only in the lungs and has not spread to any lymph nodes.
Early stages IA and IB have 49% and 45% 5-year survival
2-locally advanced lung cancer (II)
The cancer is in the lung and nearby lymph nodes.
Stage IIA and IIB have about 30% 5-year survival
3-recurrent lung cancer (III)
Cancer is found in the lung and in the lymph nodes in the middle of the chest.
there is sharp decline in survival from stages IIIA (14%) to IIIB (5%)
4-Advanced(IV)
This is the most advanced stage of lung cancer. This is when the cancer has spread to both lungs, to fluid in the area
around the lungs, or to another part of the body.
o.s : Overall Survival

25. Proton therapy for early stage ( I ) lung cancer
Proton therapy has been found to be as effective as surgery in regards to primary tumor.
Since 1999 studies have reported an 80 to 90 percent rate of LC for patients with stage I NSCLC treated with
hypofractionated proton beam radiotherapy.
Bush et al. reported study from Loma Linda University for a group of 111 patients with NSCLC stage using a 2-
week course of hypofractionated proton therapy
-Peripherally located tumors were given 66 Gy over 10 fractions
-centrally located tumors were given 80 Gy over 25 fractions
with tolerable side effect
-no grade 3 pneumonitis
-no change in FEV1 or DLCO function.

26. Intensity modulation proton therapy (IMPT) was used to
treat this early stage non-small cell lung cancer (NSCLC)
-patient is set-up in supine position with both arms above the
head and immobilized with a vacuum bag and head holder
-4D CT scan was done using Varian RPM system to evaluate
tumor motion.
-If the tumor motion is 1 cm or less, then the ITV approach was
done. The GTV was contoured on lung window on inspiration
and expiration phases, GTV was expanded with 5 mm margin
for CTV (excluding chest wall or bronchus). The two CTV are
combined to form ITV. Setup uncertainty (5 mm) and range
uncertainty are added to form beam specific PTV