RAJIV KUMAR SINGH RADIOTHERAPY TECHNOLOGIST

. MAZUMDAR SHAW CANCER CENTER

NARAYANA HRUDAYALAYA HOSPITAL

MANAGEMENT OF RESPIRATORY MOTION IN RADIATION THERAPY

INTRODUCTION

Intrafraction motion is becoming increasingly important in the era of image-guided Radiotherapy.

Intrafraction motion can be caused by the respiratory, skeletal muscular, cardiac and Gastrointestinal systems.

Of these four systems, most of the research and development to date has been directed towards accounting for respiratory motion.

PROBLEMS OF RESPIRATORY MOTION

DURING RADIOTHERAPY

A. Image acquisition limitations

B. Treatment planning limitations

C. Radiation delivery limitations

METHODS TO EXPLICITLY ACCOUNT FOR RESPIRATORY MOTION IN

RADIOTHERAPY A. Respiratory gating methods B. Breath-hold methods 1. Deep inspiration breath-hold 2. Active Breathing Control 3. Self-held breath-hold 4. Self-held breath-hold using an External

Marker C. Forced shallow breathing methods D. Real-time tumor tracking methods

What is ABC?

Active Breathing Coordinator (ABC) is a noninvasive, advanced technology that helps patients hold their breath while

they receive radiation therapy

The concept of ABC was developed by Dr John Wong at William Beaumont Hospital (WBH) in 1997.

• The basic theory behind the procedure is for the patient to perform short, repeated breath-holds (BH) so that CT imaging and treatment delivery can be achieved with the tumor in a stationary position.

• During an ABC procedure, a specifically designed device is utilized to reproducibly apply the same breath-holding level for each session.

How ABC works

The ABC consists of a turbine spirometer, which measures the relative airflow and displays a visual representation of the respiratory curve on a laptop computer.

The patient is connected to the system via a length of tubing and a bacterial filter, with a nose clip to prevent leakage and increase accuracy of the spirometry measurement.

How ABC works

How ABC works

After a predefined volume of air (threshold volume) has passed through the spirometer, a small balloon valve will inflate and occlude the tube, applying an assisted Breath Hold (BH).

How ABC works

At all times the patient is in control of the BH, via a patient control switch. This switch must be depressed to initiate an ABC procedure and if released will automatically open the balloon valve and allow the patient to breathe freely.

How ABC works

The system is configurable to each individual patient or procedure, with variable threshold levels and BH durations.

How ABC works

PROCESS

END OF 1 ST SEGMENT

AGAIN

WORKFLOW

Initial training session Appropriate threshold level BH duration possible has been reported as 15–

20 seconds

GOAL

To improve the accuracy of treatment delivery

STABILITY

Immobilizing the respiratory motion during specific breath-holds (intra-

breath hold)

VERSATILITIY

Shift the normal structures out of the high dose region

CONCLUSION

This has paved the way for alternative fractionation regimes, such as hypo fractionation, to be adopted in current clinical practice.

THANK YOU