Set-up errors are the inherent features of the radiation treatment process. Coverage of
target volume is a direct function of set-up margins, which should be optimized to prevent
unintended irradiation of adjacent normal tissues. The aim of this study was to evaluate
three dimensional set-up errors and propose optimum margins for target volume coverage
in prostate cancer radiotherapy. 1620 Portal images were obtained for an average of 30
fractions per patient for 54 prostate cancer patients. Electronic Portal Image (EPI)
displacements obtained with iViewGTTM imaging software along the three major axes (X,
Y, Z) were analysed. Mean displacements, population systematic and random errors and
Three-dimensional vectors of displacements were calculated using StatPlus 2009
Professional 5.8.0 and Microsoft Excel (2013). Planning target margins were calculated
using three different published margin recipes; the International Commission on Radiation
Units and measurements (ICRU) 62, Stroom and van Herk. The random errors (σ) along
vertical, lateral and longitudinal were 3.19 mm, 4.13 mm and 3.83 mm respectively.
Similarly, the systematic errors (∑) were 1.81 mm, 2.83 mm and 2.51 mm along vertical,
lateral and longitudinal axes respectively. The population mean (Mpop) displacement in
vertical, lateral and longitudinal axes were -0.49 mm, 0.05 mm and -0.40 mm respectively
and standard deviation in vertical, lateral and longitudinal axes were 3.75 mm, 5.20 mm
and 4.76 mm respectively for the prostate cancer patients. Using ICRU report 62, the
clinical target volume to planning target volume margins (CTV-PTV) were 3.67 mm, 5.00
mm and 4.58 mm along vertical, lateral and longitudinal axes respectively. The
corresponding values were 5.85 mm, 8.54 mm and 7.69 mm with Stroom’s formula whiles
3.75 mm, 6.96 mm and 5.95 mm were with van Herk’s formula. The results suggest that
there is a significant difference within the three major axes. Hence, the need for local
departmental planning target margin protocol was recommended.
CDR, C (2021). PLANNING TARGET MARGIN CALCULATIONS BASED ON THE EVALUATION OF ELECTRONIC PORTAL IMAGING DURING PROSTATE CANCER RADIOTHERAPY. Afribary.com: Retrieved May 06, 2021, from https://afribary.com/works/planning-target-margin-calculations-based-on-the-evaluation-of-electronic-portal-imaging-during-prostate-cancer-radiotherapy
Coalition, CDR. "PLANNING TARGET MARGIN CALCULATIONS BASED ON THE EVALUATION OF ELECTRONIC PORTAL IMAGING DURING PROSTATE CANCER RADIOTHERAPY" Afribary.com. Afribary.com, 02 Apr. 2021, https://afribary.com/works/planning-target-margin-calculations-based-on-the-evaluation-of-electronic-portal-imaging-during-prostate-cancer-radiotherapy . Accessed 06 May. 2021.
Coalition, CDR. "PLANNING TARGET MARGIN CALCULATIONS BASED ON THE EVALUATION OF ELECTRONIC PORTAL IMAGING DURING PROSTATE CANCER RADIOTHERAPY". Afribary.com, Afribary.com, 02 Apr. 2021. Web. 06 May. 2021. < https://afribary.com/works/planning-target-margin-calculations-based-on-the-evaluation-of-electronic-portal-imaging-during-prostate-cancer-radiotherapy >.
Coalition, CDR. "PLANNING TARGET MARGIN CALCULATIONS BASED ON THE EVALUATION OF ELECTRONIC PORTAL IMAGING DURING PROSTATE CANCER RADIOTHERAPY" Afribary.com (2021). Accessed May 06, 2021. https://afribary.com/works/planning-target-margin-calculations-based-on-the-evaluation-of-electronic-portal-imaging-during-prostate-cancer-radiotherapy