Utility of pre-treatment 18 F-fluorodeoxyglucose PET radiomic analysis in assessing nodal involvement in cervical cancer.

OBJECTIVE: Intratumor heterogeneity has prognostic value in cervical cancer, which can be depicted on 18 F-fluorodeoxyglucose ( 18 F-FDG) PET/computed tomography (PET/CT) and then quantitatively characterized by texture features. This study aimed to evaluate the discriminative performance and predictive ability of the texture features in determining lymph node involvement in cervical cancer. METHODS: A total of 101 patients with newly diagnosed cervical cancer, who underwent pre-treatment whole-body 18 F-FDG PET/CT imaging were retrospectively recruited. Patients were categorized based on their nodal status. Thirty-five radiomic features together with the maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of the primary cervical tumors were extracted. Conventional indices were used to build logistic regression model and texture features were used to build random forest model. The performances for differentiating nodal status were assessed by receiver operating characteristic analysis. RESULTS: Conventional PET indices were significantly higher in patients with nodal involvement compared to those without: SUVmax = 14.22 vs. 10.05; MTV = 57.02 vs. 28.73; TLG = 492.8 vs. 188.8 ( P < 0.05). Nineteen radiomic features describing regional heterogeneity were significantly different between nodal involvements. Area under the curves of the models with conventional indices and PET texture features for discriminating nodal status were 0.72 and 0.76, respectively. CONCLUSION: PET-derived radiomic features had moderate performance in discriminating nodal involvement in cervical cancer; and they did not outperform model based on conventional indices.

Development of a prototype of the tele-localisation system in radiotherapy using personal digital assistant via wireless communication.

In localisation of radiotherapy treatment field, the oncologist is present at the simulator to approve treatment details produced by the therapist. Problems may arise if the oncologist is not available and the patient requires urgent treatment. The development of a tele-localisation system is a potential solution, where the oncologist uses a personal digital assistant (PDA) to localise the treatment field on the image sent from the simulator through wireless communication and returns the information to the therapist after his or her approval. Our team developed the first tele-localisation prototype, which consisted of a server workstation (simulator) for the administration of digital imaging and communication in medicine localisation images including viewing and communication with the PDA via a Wi-Fi network; a PDA (oncologist's site) installed with the custom-built programme that synchronises with the server workstation and performs treatment field editing. Trial tests on accuracy and speed of the prototype system were conducted on 30 subjects with the treatment regions covering the neck, skull, chest and pelvis. The average time required in performing the localisation using the PDA was less than 1.5 min, with the blocked field longer than the open field. The transmission speed of the four treatment regions was similar. The average physical distortion of the images was within 4.4% and the accuracy of field size indication was within 5.3%. Compared with the manual method, the tele-localisation system presented with an average deviation of 5.5%. The prototype system fulfilled the planned objectives of tele-localisation procedure with reasonable speed and accuracy.

Volumetric intensity-modulated arc therapy vs conventional intensity-modulated radiation therapy in nasopharyngeal carcinoma: a dosimetric study.

Dosimetric comparisons between RapidArc (RA) and conventional Intensity-Modulated Radiation Therapy (IMRT) techniques for nasopharyngeal carcinoma (NPC) were performed to address differences in dose coverage of the target, sparing of organs-at-risk (OARs), delivery of monitor units (MUs) and time, to assess whether the RA technique was more beneficial for treatment of NPC. Eight NPC patients (Stages I-IV), who had completed RA treatment, were selected for this study. Computed tomography data sets were re-planned using 7-fields fixed beam IMRT. Quantitative measurements of dose-endpoint values on the dose-volume histograms were carried out for evaluation of: (i) dose homogeneity (D5% - D(95%)); (ii) degree of conformity (CI9(5%)); (iii) tumor control probability (TCP); (iv) doses to OARs; (v) normal tissue complication probability (NTCP); (vi) treatment time; and (vii) MUs. RA plans achieved better dose conformity and TCP in planning target volumes (PTVs). Target dose homogeneity was not as high as for IMRT plans. Doses to tempero-mandibular joints, clavicles, parotid glands and posterior neck, and their NTCPs were significantly lower in RA plans (P < 0.05). Mean doses to the brainstem and spinal cord were slightly lower in IMRT plans. RA plans allowed for a mean reduction in MUs by 78% (P = 0.006), and a four-fold reduction in treatment delivery times, relative to IMRT plans. RA plans showed superior, or comparable, target coverage and dose conformity in PTVs, but at the expense of inferior dose homogeneity. RA plans also achieved significant improvements in dose reduction to OARs and healthy tissue sparing. A significant reduction in treatment delivery time for RA treatment technique was also noted.