Disadvantages Of IMRT And 3DCRT

IMRT and VMAT have many dosimetric and clinical benefits when compared to 3DCRT. IMRT and VMAT are techniques where the radiation dose can be delivered more precisely to the tumour. In comparison to 3DCRT, the dose can be escalated so that the tumour will receive a higher dose and normal tissues will receive a lower dose. Because 3DCRT does not modulate as precisely to the tumour, the patient can be at risk of a large amount of normal tissue receiving a higher dose of radiation. This will result in a lot more toxicities for the patient and conclude that the tumour will receive a lesser dose of radiation. It is our aim to deliver as high a dose as possible to the tumour and as small a dose as possible to normal tissue and organs. A disadvantage
As IMRT and VMAT are more modulated techniques in comparison to 3DCRT, with a higher dose treating the tumour, there is an increase in a lower dose of radiation dispersed throughout the body. IMRT is a longer technique which means that the patient’s monitor units delivered will be increased. An increase in monitor units being delivered to normal tissues and an increase in low dose radiation received by the volumes of tissues can cause secondary malignancies. However VMAT can compensate for this. As VMAT reduces the number of monitor units and the integral dose, the technique will prevent the occurrence of secondary malignancies. IMRT can reduce the mild to late toxicities such as urinary incontinence, chronic diarrhoea, and sexual function. A study comparing 3DCRT and IMRT for cervical cancer, showed significant DVH parameter differences for the small bowel, large bowel and pelvic bone. Patient’s whom received IMRT had a decrease in the volume of small bowel, bowel bag and large bag that received 40 and 45 GY when compared to the 3DCRT technique. The study also showed that the percentage of volume of the small bowel and bowel bag receiving 30Gy was also decreased. However with IMRT, the volume of pelvic bone receiving 40Gy increased. It is essential to ensure the DVH for the pelvic bone is within its dose constraint to prevent necrosis and a secondary malignancy. A study has shown that IMRT is more cost effective because it requires more training of expertise, physicans and radiation therapists. Although IMRT/VMAT is more cost worthy, the overall benefits for the patient will override this downfall as the patients late toxicities will be reduced. Less health care will be needed for the patient. However limited studies are available to support this as IMRT is a new concept and will require more years to determine the late effects of IMRT for