Cancer treatment: the evaluation of the differences in the dose received by the OAR Essay

For this study the limitations were that, the V50 doses had to be manually measured with a cursor on the dose volume histograms. This made it difficult to place the cursor perfectly on 50%. Some plans for certain patients had a higher Dmax compared to other patients as the volumes for each patient differ due to anatomy differences and volume differences to get the 95% of the prescribed dose to cover the target volume. Each patients target volumes where drew in differently as the patients anatomy differs and different radiation oncologists drew volumes differently. Depending on how the PTVs were drawn in would affect the amount of dose to the OAR, as the OARs might fall into the volume. Each patients anatomy and tumour volume is different and bigger or smaller than the other, for some patients the tumour volumes or treatment volumes were bigger and overlapping into some OAR such as the bladder and rectum.

The energy chosen for the radiation therapy also determines the dose distribution and the dose to the volumes. 6MV was chosen for this study as it was suitable to cover the target volumes with 95% of the dose. All these factors would influence the dose each OAR would receive. With the planning 3DCRT and VMAT was the easiest to get the 95% to cover the PTVs, IMRT with certain patients were difficult to get the 95% to cover the target volumes. 3DCRT was the most challenging to get the dose to the OAR to stay within their tolerance doses.

16. CONCLUSIONS

The aim of this study was to evaluate the differences in the dose received by the OAR for all three treatment planning techniques for radical localised prostate cancer. The aim was also to determine which technique, namely 3DCRT plan, an IMRT plan and a VMAT is regarded as the optimal radiation treatment technique for radical prostate cancer with the least radiation dose to the critical organs around the prostate and the highest dose to the target volume. Results of this study confirmed that both IMRT and VMAT treatment techniques are both beneficial in of sparing OAR and delivering the highest prescribed dose to the target volumes. Both these techniques are suitable for prostate cancer treatment. More dose comparisons would make this study more accurate. Based on the data it was clear the 3DCRT is not an optimal treatment technique compared to IMRT and VMAT. Both the VMAT and IMRT produced clinically adequate treatment plan for prostate cancer. Based on the data in this study, VMAT delivered slightly favourable dosimetric results. However, the difference between IMRT and VMAT was minimal. VMAT produced more conformal dose distributions if compared with IMRT. Manually measuring the V50 with a cursor on the DVHs and differences in anatomy were some of the limitations involve in this study. Recommendation would be to increase the sample size and to include more dose comparisons. The more comparisons there are the more accurate and viable the results for this research