Compare to Conventional Radiotherapy , the helical system of TomoTherapy allows a continuous spiral-ring delivery of radiation beams around the patient, providing higher flexibility of treatment angles, and by equipped with other modern radiation technologies, Tomotherapy gives a highly-precise radiotherapy treatment with reduced toxicity.
The TomoTherapy treatment system is mounted to a CT scanner-like ring gantry, which improves the flexibility and conformity of radiation treatment.
Helical type radiotherapy Improve Field-size limitation
Conventional radiotherapy is a linear accelerator, by it’s name implies, it delivers high energy X-ray in a linear manner. It takes longer time for changing the gantry angles from one field to another, and as the treatment field is limited within 40x40cm2, these constraining the treatment planning.
As a contrast, TomoTherapy allows a field coverage of up to 160cm , delivering radiation from head to feet in helical manner within a single treatment. So, unlike conventional therapy that requiring multiple fields set-up, it is advantageous for treating multiple regions and metastases within the body at the same time.
Intensity-Modulated Technology
Another advantage of TomoTherapy is that apart from more conforming to the shape and location of the tumor for greater precision; the intensity-modulated technology optimizes the contribution of each beamlets to the tumor and so a higher total tumor dose. Because of higher flexibility for radiation beam entry angles, radiation beams can be much divided and delivered to the tumor from more directions, and resulting in smaller dose received by the surrounding normal tissues. Not only reducing normal tissues toxicity and long term sequelaes , it is also keeping effective tumor dose with better tumor dose homogeneity; overall, providing a higher treatment quality.
Advantages of TomoTherapy for head and neck cancer
The advantage of TomoTherapy becomes more apparent when it is used for treating tumors of the head and neck nasopharynx,prostate, brainor spine.
For instance, Nasopharyngeal Carcinoma(NPC), it is common for this cancer affecting the lymphatics of the neck, and as nasopharynx is in close proximity to the base of skull where important cranial nerves situated. With this technology, it gives a highly-precise and effective tumor control treatment, and on the other hand, it also reduce normal tissues toxicity. Higher treatment conformity can reduce both short and long term side effects; it ameliorates acute oral, tongue and pharyngeal mucositis during therapy, besides, the toxicities to the salivary glands and the ears leading to dry mouth and hearing deficit are minimized, helps maintaining a good quality of life for patient.
Source: Dr Donna Chow Lee, Specialist in Clinical Oncology at Hong KongAdventist Hospital
