1. Indigenous Cobalt- 60 teletherapy technology- 4 years experience
Dr. Arun Chougule
Pro Vice Chancellor RUHS
Senior Professor and Head
Department of Radiological Physics,
SMS Medical College & Hospitals
Jaipur, Rajasthan

2. Cancer Incidence- Indian scenario
The reported cancer incidence in India is expected to increase from an estimated 1.1 million to 1.8 million by 2020 driven by a narrowing diagnosis gap.
As per the assessment by WHO & IAEA, developing countries like India need minimum one radiation therapy machine per million of population.
Accordingly, India needs at least 1300 – 1400 therapy machines for cancer treatment but has only about 400 units
The slow growth of radiotherapy facility is primarily attributed to the high cost of imported machines, combined with lack of indigenous technology in our country. The present availability of teletherapy machine in India is only about 0.3 per one million population, whereas, in developed nations like USA and UK, the availability is 8.2 and 3.4 per million respectively
There is a wide gap between the requirement and availability due to exorbitant cost of purchase (typically Rs 7-8 crore) and maintenance of imported machines. 

3. Scenario of Teletherapy units in India
Being the most cost-effective, teletherapy cobalt-60 unit is the most relevant method of cancer treatment in a developing country like India. The Cobalt-60 teletherapy unit is the workhorse of radiotherapy and cancer treatment
Many states and most of the districts in the country do not have any teletherapy machine.
Although, more than two-third of cancer patients need radiation therapy, only about one-third of them receive the therapy, due to the shortage of therapy units and urban-centric distribution of radiotherapy centers.
In view of the situation in India, Department of Atomic Energy, took up the development of radiotherapy machine indigenously for treatment of cancer patients under the name ‘Bhabhatron’. Currently Bhabhatron-II is most successful telecobalt unit of India, which is writing its success stories in India and outside India also.  

4. Inception of Bhabhatron by DAE, Govt of India
Bhabhatron, a high performance telecobalt machine at a much lower price, was developed to meet the growing demand for affordable high-performance telecobalt machine.
The first unit of Bhabhatron was installed at the Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Navi Mumbai in March 2005.
Later, BARC developed an improved version of the machine, Bhabhatron-II. More than 60 Bhabhatron telecobalt units are installed in many cancer hospitals in India and India donated the unit to many countries- Vietnam, Magnolia, Kenya…..

5. Installation Details
We are using Bhabhatron Co-60 teletherapy machine for over 4.5 years and treating more than 140 cancer patients daily. The machine is operated for about 14 hours daily and has uptime of 95% in last 4 years.
Model No.- Bhabhatron II TAW & 31
Performance tests performed as per AERB RPAD/Telecobalt/QA protocol
All components and parameters are found within acceptable limits
Ci [ 168 RMM]

6. Bhabhatron-II Cobalt-60 Teletherapy Unit
The first indigenous Telecobalt machine designed and
developed by D.A.E & B.A.R.C to manage the increasing
cancer incidence in the country
It has many advanced features over other imported
Telecobalt machines.
Specifically designed for rural areas; Can
provide 8 hrs battery backup even in case of of
the power failure
Majority of the motions are computer controlled
The facility of 0 x 0 filed size and asymmetric
Jaws differs this machine from other
imported machines.

7. Recent Advancements of Bhabhatron II
Source Head
Interlocks
/Indicator
Gantry
Software
Collimator
Functionality
Keypad
Couch
Aesthetic
Counter weight

9. BHABHATRON –II-TAW
The first indigenous Telecobalt machine designed and developed by DAE & BARC to manage the increasing cancer incidence in the country
Shielding vault composed of Tungsten alloy
Carbon Fiber Couch Top
maximum source capacity of 555 TBq (15000Ci) or 250 RMM of Co-60
Introducing asymmetric motion of collimator jaws & motorized wedge
The facility of 0 X 0 cm2 filed size and asymmetric Jaws differs this machine from other imported machines.
It can provide 8 hrs battery backup even in the absence of power failure
Majority of the motions are computer controlled
Potential to be attached with multileaf collimator (MLC) for 3D conformal treatment technique.

10. Accuracy of Field Sizes
A calibrated graph sheet paper was utilized to measure the field size accuracy.
After setting the jaw for X and Y the field light was checked at 80cm, SSD.
The graph paper was placed on the COUCH at 80 cm.
Tolerance :- within ± 2mm

11. ACCURACY OPTICAL DISTANCE INDICATOR
Plastic slab phantom on table surface put 100 cm SSD on its surface isocentre by adding blocks verified by reduction in ODI values and checked that should be in line with slab thickness and additional
We cross verify it by mechanical front pointer.

12. ALIGNMENT BETWEEN OPPOSING FIELDS: ROTATIONAL CHECKS OF GANTRY
laser alignment test tool was used
PATIENT TREATMENT TABLE AXIS OF ROTATION
Gantry positioning with the collimator axis of rotation pointed vertically downwards.
Millimeter graph paper is attached to the treatment table and the image of the cross-hair marked on this graph paper.
The cross-hair image should trace an arc with a radius of less than 1 mm.

13. RADIATION CHECKS CONGRUENCE Between LIGHT AND RADIATION FIELD
Checked by placing radiographic film perpendicularly to the collimator axis of rotation.
The edges of the light field are marked with radio-opaque objects (lead marker) and by pricking holes with a pin through the ready pack film at the corners of the light field.
A plastic slab phantom of .5mm is placed on the film to positioned film near zmax to yield an OD of between 1 and 2.
The light field edge should correspond to the radiation field edge within 2 mm.
RADIATION ISOCENTRE
three type of isocentre are verified
i. Collimator Rotation
ii. Gantry Angles
iii. Couch Position
Tolerance of ± 2.0 mm dia .
SSD 80 on Treatment Couch
Field Size 3cm X 30 cm .
the exposures was made by Rotating Collimator

14. S. No Wedge Filter Wedge Factor, WF Angle Field Size cm x cm Measured
S. No
Wedge Filter
Wedge Factor, WF
Angle
Field Size
cm x cm
Measured
Specified by
Manufacturer 1 15
15WX20
0.662
0.674 2 30
10WX16
0.572
0.580
0.584 3 45
0.498
0.499
0.444 4 60
0.405
0.365
0.340
0.331

15. COUCH TRANSMISSION FACTOR
 The average transmission factor of the treatment couch table is 96.67%.
Linearity Check
The linearity in time and dose is required for the delivery of prescription dose (Rx) to the patient.

16. RADIATION PROTECTION SURVEY
Head Leakage in Source OFF position
The sources OFF position leakage were measured at a distance of 5cm from the surface of the source Head and 1m from the center of the source.
The OFF position leakage should not exceed 20mR/hr at 5cm from the outer surface of the source Head and should be less than 2mR/hr at 1m from the center of the source
the maximum radiation leakage levels at 1 m from the source and at 5 cm from any accessible head surface was found to be mR/hr and mR/hr, respectively.
It is for maximum rated capacity of the source head. Thus the values are within the permissible limits of ≤2mR/hr at 1m from the source and ≤20mR/hr.

17. Collimator Transmission
Transmission of X JAWS
The X JAWS are completely closed and the Y Jaws are completely opened for maximum field size.
Points of measurement to check Collimator Transmission

18. Collimator Transmission : X JAWS
The transmission of collimators are measured as per the diagram shown.
The maximum field size 35 * 35 cm is considered. The hypotenuse R = cm was found by Pithogerous formula.
Keeping this as a Radius(24.75 cm) the outer circle is formed.
Other two inner circles are formed from 1/3 & 2/3 of the major radius which gives 16cm & 8cm radiuses respectively and the two circles are formed.
The transmission measurements done in the above points will give an overall detail of the Transmission of each Jaws .
Prior to that Average readings of 10 x 10 field size was measured to find the transmission factor.

19. Collimator Transmission : Y JAWS & Combined Jaws
Collimator Transmission Y Jaw
Points
pC/min
nC/min
% of Transmission
Tolerance 1
10.12
< 2 % of RMM of the loaded source 2
9.25 3
9.53 4
9.34 5
9.71 6
9.7
0.0097
0.025 7
9.68 8
9.81 9
10.38 10
9.67 11
9.85 12
10.37 13 14
10.05 15
0.01 16
10.43
Average Transmission
Combined Jaws Transmission
Points
pC/min
nC/min
% of Transmission
Tolerance 1
18.4
0.0184
< 2 % of RMM of the loaded source 2
1.12
0.0011 3
14.58
0.0145 4
5.95
0.0059 5
26.86
0.0268 6
19.43
0.0194 7 26
0.0260 8
14.48
0.0144 9
1.4194
0.0014 10
0.36 11
1.2835
0.0013 12
0.45
0.0004 13
5.3
0.0053 14
3.5
0.0035 15
2.8691
0.0028 16
5.24
0.0052
Average Transmission

20. CONCLUSION
All the Quality Assurances were under the recommended Tolerance limit. Bhabhatron-II being a computer controlled machine satisfies the necessary and basic safety requirements for Clinical usage
The plan parameters such as Field size, Collimator, Gantry and Couch parameters can be loaded for individual patients along with the Treatment time.
The source stays in ON Position till the programmed time and returns to OFF Position after delivering the Treatment. This ensures that the patient receives accurate Treatment when the patient setup is maintained.
Configuring this machine in the TPS and executing the Treatment through 3-D Planning will give a huge benefit to the patient.
Implementation of Multi leaf collimator in this advanced machine is expected.
The Bhabhatron II head can accommodate nearly 250RMM [15000Ci] source strength.
This unit has keypad attached at both sides of the couch that also has digital display.
The patient treatment is computer controlled. This machine has advanced features such as asymmetric
collimators, motorized wedge & integrated MLC etc.
Superior features in terms of safety, user-interface and security.
Implementation of computer controlled Treatment Delivery, Asymmetric Jaws, motorized wedge, Record of Patient History, Battery backup of Eight hours etc. has remarkably enhanced the Quality of treatment in the field of Radiotherapy.

22. Thank You