Núria Jornet1, Pablo Carrasco2, Mercè Beltrán3, Juan Francisco Calvo4, Lluís Escudé5, Victor Hernández6, Jaume Quera7, Jordi Sáez3. 1. Servei de Radiofísica i Radioprotecció, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain. Electronic address: njornet@santpau.cat. 2. Servei de Radiofísica i Radioprotecció, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain. 3. Servei de Física, Hospital Vall d'Hebró, Barcelona, Spain. 4. Servei d'Oncologia Radioteràpica, Hospital Quirón, Barcelona, Spain. 5. Servei d'Oncologia Radioteràpica, Clinica Teknon, Barcelona, Spain. 6. Servei de Física, Hospital Sant Joan, Reus, Spain. 7. Servei d'Oncologia Radioteràpica, Hospital de l'Esperança, Barcelona, Spain.
Abstract
BACKGROUND AND PURPOSE: We performed a multicentre intercomparison of IMRT optimisation and dose planning and IMRT pre-treatment verification methods and results. The aims were to check consistency between dose plans and to validate whether in-house pre-treatment verification results agreed with those of an external audit. MATERIALS AND METHODS: Participating centres used two mock cases (prostate and head and neck) for the intercomparison and audit. Compliance to dosimetric goals and total number of MU per plan were collected. A simple quality index to compare the different plans was proposed. We compared gamma index pass rates using the centre's equipment and methodology to those of an external audit. RESULTS: While for the prostate case, all centres fulfilled the dosimetric goals and plan quality was homogeneous, that was not the case for the head and neck case. The number of MU did not correlate with the plan quality index. Pre-treatment verifications results of the external audit did not agree with those of the in-house measurements for two centres: being within tolerance for in-house measurements and unacceptable for the audit or the other way round. CONCLUSIONS: Although all plans fulfilled dosimetric constraints, plan quality is highly dependent on the planner expertise. External audits are an excellent tool to detect errors in IMRT implementation and cannot be replaced by intercomparison using results obtained by centres.
BACKGROUND AND PURPOSE: We performed a multicentre intercomparison of IMRT optimisation and dose planning and IMRT pre-treatment verification methods and results. The aims were to check consistency between dose plans and to validate whether in-house pre-treatment verification results agreed with those of an external audit. MATERIALS AND METHODS: Participating centres used two mock cases (prostate and head and neck) for the intercomparison and audit. Compliance to dosimetric goals and total number of MU per plan were collected. A simple quality index to compare the different plans was proposed. We compared gamma index pass rates using the centre's equipment and methodology to those of an external audit. RESULTS: While for the prostate case, all centres fulfilled the dosimetric goals and plan quality was homogeneous, that was not the case for the head and neck case. The number of MU did not correlate with the plan quality index. Pre-treatment verifications results of the external audit did not agree with those of the in-house measurements for two centres: being within tolerance for in-house measurements and unacceptable for the audit or the other way round. CONCLUSIONS: Although all plans fulfilled dosimetric constraints, plan quality is highly dependent on the planner expertise. External audits are an excellent tool to detect errors in IMRT implementation and cannot be replaced by intercomparison using results obtained by centres.