Computed Tomography (CT) Planning for Radiation Therapy

Computed Tomography (CT) Planning for Radiation Therapy Clinical Outcomes

The success of cancer treatment using radiotherapy (RT) is very dependent on the accuracy and quality of the design and delivery of the radiation beam. All radiation treatment plans depend on patient characteristics and need to be individualized. To improve on the targeting of the cancer and the avoidance of unnecessary irradiation to normal tissues, the initial design or planning of the RT is vital.

Improvements in digital technology have allowed us to utilise the images taken from diagnostic imaging (CT, magnetic resonance imaging [MRI], positron emission tomography [PET] scans) and incorporate them into the radiation therapy equipment. This allows accurate planning of RT and individualization of therapy for each patient¹.

Although some radiation treatments only require simple two-dimensional design (2D) planning, the majority of treatments will benefit by sophisticated 3D planning using CT simulation scans. In a busy radiation therapy department, this is more resource intensive, but it improves the quality of radiation therapy delivery.

CT Planning Rate as a Radiation Oncology Clinical Quality Indicator

The Australian Council of Healthcare Standards (ACHS)² has emphasised the importance of quality delivery of radiation therapy by implementing the rate of CT simulation as a national clinical quality indicator. ACHS recognizes that poor access to CT planning facilities will lead to delays and inferior treatment and this rate is audited across Australia. The indicator is a reflection of quality technique in radiation therapy and demonstrates that patients are managed with excellent standards.

At the National University Cancer Institute Singapore (NCIS), it is recognised that CT simulation should be undertaken for the majority of cancer sites especially in the curative treatment of head & neck, breast, lung, gastro-intestinal and central nervous system tumours. Although some patients with cancers involving the arm/leg or skin cancer will not require CT scan planning, they are generally in the minority.

Definition (ACHS 2002)

CT planning refers to the process where a patient undergoes simulation on a computed tomography simulator which is capable of scanning in the treatment position and interfacing with a radiotherapy treatment planning system. The final plan would incorporate all the 3-dimensional information obtained by the scan. The rate is defined as the percentage of treatment courses where CT planning was utilised compared to the total number of external beam treatment courses undertaken.

Figure 1 : CT Simulator; CT scan simulation of patient for radiation therapy; and 3D
radiation plan produced by CT Planning

3D CT Planning Rate at NCIS Radiation Oncology

Figure 2 : Percentage rate of 3D CT Planning compared with Aust ACHS data³.

Conclusion

In NUH, the rate of 3D CT cancer planning is 100%, which exceeds the Australian Council of Healthcare Standards (ACHS) outcomes for Australian units. This suggests that the quality of radiation therapy at the National University Cancer Institute Singapore (NCIS) is comparable to other major centres worldwide.

Information is correct as at November 2009

Footnotes

1. Aird E and Conway J. CT simulation for radiotherapy treatment planning British Journal of Radiology, 75 (2002), 937–949
2. ACHS Clinical Indicator Results for Australia and New Zealand 1998 – 2004: Determining the Potential to Improve Quality of Care 6th Edition. ACHS Ultimo NSW November 2005
3. Australasian Clinical Indicator Report, 2001-2008, 9th Edition

This material does not cover all information and is not intended as a substitute for professional care. Please consult your physician on any matters regarding your health.