EVALUATION OF INTENSITY MODULATED RADIATION THERAPY (IMRT) DELIVERY ERROR DUE TO IMRT TREATMENT PLAN COMPLEXITY AND IMPROPERLY MATCHED DOSIMETRY DATA

Intensity modulated radiation therapy (IMRT) is a technique that delivers a highly conformal dose distribution to a target volume while attempting to maximally spare the surrounding normal tissues. IMRT is a common treatment modality used for treating head and neck (H&N) cancers, and the presence of many critical structures in this region requires accurate treatment delivery. The Radiological Physics Center (RPC) acts as both a remote and on-site quality assurance agency that credentials institutions participating in clinical trials. To date, about 30% of all IMRT participants have failed the RPC’s remote audit using the IMRT H&N phantom. The purpose of this project is to evaluate possible causes of H&N IMRT delivery errors observed by the RPC, specifically IMRT treatment plan complexity and the use of improper dosimetry data from machines that were thought to be matched but in reality were not. Eight H&N IMRT plans with a range of complexity defined by total MU (1460-3466), number of segments (54-225), and modulation complexity scores (MCS) (0.181-0.609) were created in Pinnacle v.8m. These plans were delivered to the RPC’s H&N phantom on a single Varian Clinac. One of the IMRT plans (1851 MU, 88 segments, and MCS=0.469) was equivalent to the median H&N plan from 130 previous RPC H&N phantom irradiations. This average IMRT plan was also delivered on four matched Varian Clinac machines and the dose distribution calculated using a different 6MV beam model. Radiochromic film and TLD within the phantom were used to analyze the dose profiles and absolute doses, respectively. The measured and calculated were compared to evaluate the dosimetric accuracy. All deliveries met the RPC acceptance criteria of ±7% absolute dose difference and 4 mm distance-to-agreement (DTA). Additionally, gamma index analysis was performed for all deliveries using a ±7%/4mm and ±5%/3mm criteria. Increasing the treatment plan complexity by varying the MU, number of segments, or varying the MCS resulted in no clear trend toward an increase in dosimetric error determined by the absolute dose difference, DTA, or gamma index. Varying the delivery machines as well as the beam model (use of a Clinac 6EX 6MV beam model vs. Clinac 21EX 6MV model), also did not show any clear trend towards an increased dosimetric error using the same criteria indicated above.

AN ASSESSMENT OF THE CURRENT STATUS OF MENTAL ILLNESS IN BENDEL STATE OF NIGERIA: IMPLICATIONS FOR PUBLIC MENTAL HEALTH POLICY AND EDUCATION

This descriptive study assesses the current status of mental illness in Bendel State of Nigeria to determine its implications for mental health policy and education. It is a study of the demographic characteristics of psychiatric patients in the only two modern western psychiatric facilities in Bendel State, the various treatment modalities utilized for mental illness, and the people's choice of therapeutic measures for mental illness in Bendel State.^ This study investigated ten aspects of mental illness in Bendel State (1) An increase of the prevalence of mental illness (psychiatric disorder) in Bendel State. (2) Unaided, unguided, and uncared for mentally ill people roaming about Bendel State. (3) Pluralistic Treatment Modalities for mentally ill patients in Bendel State. (4) Traditional Healers treating more mentally ill patients than the modern western psychiatric hospitals. (5) Inadequate modern western psychiatric facilities in Bendel State. (6) Controversy between Traditional Health and modern western trained doctors over the issue of possible cooperation between traditional and modern western medicine. (7) Evidence of mental illness in all ethnic groups in Bendel State. (8) More scientifically based and better organized modern western psychiatric hospitals than the traditional healing centers. (9) Traditional healers' level of approach with patients, and accessibility to patients' families compared with the modern western trained doctors. (10) An urgent need for an official action to institute a comprehensive mental health policy that will provide an optimum care for the mentally ill in Bendel State, and in Nigeria in general.^ Of the eight popular treatment modalities generally used in Bendel State for mental illness, 54% of the non-patient population sampled preferred the use of traditional healing, 26.5% preferred the use of modern western treatment, and 19.5% preferred religious healers.^ The investigator concluded at this time not to recommend the integration of Traditional Healing and modern western medicine in Nigeria. Rather, improvement of the existing modern western psychiatric facilities and a proposal to establish facilities to enable traditional healing and modern western medicine to exist side by side were highly recommended. ^