Nuclear Medicine & Radiation Therapy

Radiotherapy is a versatile tool used in the treatment of various types of benign and malignant neoplasms. However, conventional radiation therapy for cancerous conditions often results in collateral damage to healthy tissues due to involvement of oversized radiation fields. Over the last decade one type of precision based radiation treatment has developed. This new treatment, known as Stereotactic Radiosurgery (SRS), involves highly accurate beams of high-energy radiation that are used to destroy abnormal cells by permanently damaging their DNA. As technology progressed stereotactic cranial radiosurgery developed into a successful method for certain tumorous conditions of the head and skull. The success of stereotactic cranial radiosurgery led to further radiation application research to widen the spectrum of treatable conditions to include those located extracranially. The result of this continued research led to the development of stereotactic body radiation therapy (SBRT), a radiotherapy technique based upon principles of SRS that is used to treat small or moderate sized tumors of the body with a limited number of treatments. Stereotactic body radiation therapy combines the use of the latest tumor imaging technology as well as precision based radiation delivery mechanisms to overcome physiological barriers of normal radiation therapy such as movement of tumors in tissues. The net effect of SBRT is that a dose of radiation much larger than normal can be administered in a very precise manner, over smaller time frame, bringing about a dramatic tumor response. In this review the authors will attempt to briefly cover the subject of stereotactic body radiation therapy as well as its applications and effectiveness.

Evaluate the effect of lesion size and Sphere to Background Ratio (SBR) on the threshold used for PET tumor volume delineation. Evaluation the effect and the accuracy of Recovery Coefficient (RC) model on Standards Uptake Value (SUV) of different inner size diameters filled with different activity concentration and apply this model on small cohort of patients and construct Look Up Table (LUT) for different lesions with different sizes.
A cylindrical phantom equipped with different volume hollow spheres was used. Two different reconstruction algorithms were applied in this study; one of them modified with Point Spread Function (PSF), the other did not based on PSF. Partial volume effect (PVE) was highly dominant in low uptake spheres although it had large size i.e., not only small size object affecting by PVE but also low activity concentration object. For true volume measurements, practically TrueX algorithm was more accurate when activity measurements deal with true or measured volumes.
Also, the results showed using that phantom study had successfully provided a practical ‘‘Look Up Table’’ for the partial volume correction of spherical lesions at maximum measured activity ratios that were typically noted in human PET-CT imaging. The present study demonstrated that SBR did not have significant effect on the estimation of volumes from PET images in the different SBRs.
The only determining factor for the threshold for PET volume estimation was the size of the sphere. Superior percent accuracy was shown for OSEM algorithm when applying RC model to corrected SUV values and OSEM was more efficient and less error variation with respect to sphere volume, but in case of uncorrected data, no remarkable difference between TrueX and OSEM algorithm had been observed.

Preconception irradiation of either parent’s gonads has not result in increased cancer or malformation in their children. The radiation dose and gestational ages during X-rays is the yard stick for measuring whether it will have an effect on the embryo or foetus at the time of exposure. During X-rays, high dose of ionizing radiation on embryo or foetus may causes some effects such as miscarriage, restriction of fetal growth, congenital malformation (which include microcephaly), or lead to mental retardation sometimes can cause cancer during childhood.

The experimental observation showed that, radiation-induced of 100mGy equal to 10rads, may usually result to death of the embryo that may kill up to 20% of human embryos or fetuses. The radiation-induced of 5000 mGy equivalent to 500 rads also kill 100% of human embryos or fetuses before 18 weeks gestation. Therefore, it is recommended that during pregnancy or developmental stages X-rays of high dose is not advisable.

Radiation therapy (RT) is an important treatment modality for extra-nodal lymphoma (ENL) of the head and neck (H&N). Intensity Modulated radiation therapy (IMRT) has been shown to be associated with decrease in the incidence of late side effects in squamous cell carcinoma of the H&N region. The purpose of the study is to determine the treatment outcomes and late toxicities in 14 patients with ENL of H&N treated with two different RT techniques. Median age was 60 years (range: 42-95). Median follow up was 28 months (range: 1-52). Thirteen patients were treated with RT (8 with IMRT) while one patient with chemotherapy only. Majority of the patients had stage I disease (64%). Overall response rate after combined modality treatment was 100%. There were no local or neck node relapses and none with grade 3 or 4 toxicities. Radiation therapy following chemotherapy or used alone was associated with better local and distant disease control and IMRT is associated with less toxicity profile compared with conventional radiotherapy techniques.

Study background: The aim of this study was to measure radiation exposure including scatter radiation, resulting from CT of the scaphoid in different settings as used in daily practice and to calculate the effective dose (ED) using a wrist phantom.

Methods: The radiation exposure was quantified for five different CT protocols, all used in daily practice for the scaphoid CT. Two protocols concerned a CT of the scaphoid with a plaster cast of the hand and three protocols without. For all protocols the Computed Tomographic Dose Index weighted (CTDIw), the scatter dose to the brain and scatter dose to the torso were derived from the CT and measured externally with the Piranha dose meter.

Results: The average CTDIw was 2.18 mGy. The average scatter to the brain and torso was 0.011 mSv. The average estimated ED was 0.02 mSv (range 0.02 to 0.04) of which 0.0008 mSv (range 0.0003 to 0.0012) was due to the scatter radiation. The two CT protocols of the scaphoid performed with a plaster cast resulted in a 90% higher ED, although the power of the study was too low to demonstrate this statistically.

Conclusion: The CT protocols used for scaphoid analyses in a plaster cast immobilized hand may result in higher radiation exposure than without plaster cast. We therefore recommend, whenever possible, performing CT of the hand and wrist without a plaster cast.

Helium-neon (He-Ne) laser has been used in many clinical fields, and caught our interest on cancer treatment. We conducted the study of He-Ne laser in lung cancer for the sake of the most common cause of cancer deaths worldwide, and up to 50% of the patients with advanced non-small-cell lung cancers with brain metastases. In this study, we used two human lung cancer cell lines A549, H1299, bronchial epithelial cell line BEAS-2B to detect the effects of He-Ne laser on proliferation and migration capabilities by MTT, trypan blue exclusion and wound healing analysis, followed by Western blot analysis to identify the putative signaling pathway evoked by the He-Ne laser. Low-power He-Ne laser slowed H1299 migration by inhibiting Extracellular signal-regulated protein kinases (ERK) phosphorylation, and decreased A549 cell proliferation via p38 up-regulation. However, He-Ne laser increased NT2 cell proliferation and migration activities through ERK activation. The low-power He-Ne laser had diverse effects on different cells, possibly suppressive effect on malignant cells, but growth provocation on pluripotent cells. We proposed that the low-power He-Ne laser renders a beneficial alternative for cancer treatment and for tissue repair.

Graves' disease is usually diagnosed as a syndrome of clinical and biochemical features including ophthalmopathy (TAO); the latter occurring in up to 50% of patients with the syndrome. The incidence of TAO is higher in females than in males, as with the parent syndrome (16:2.9 cases per 100 000 people annually). Onset is later in males, who also tend to have more severe cases and poorer prognosis. A 34 year-old male patient initially presented at the Eye Clinic with a three-month history of right-sided proptosis. Main findings were right proptosis of 3 mm, with no lid retraction or lag, nor impairment of vision. He was subsequently referred to the Endocrinology Clinic; there he was diagnosed with Graves' disease and placed on antithyroid medication. Ocular manifestations may be the first signs of Graves' disease, as occurred with this patient.

Purpose: To determine the prognostic role of pretreatment F-18FDG PET/CT maximum standardized uptake value (SUVmax) in metastatic breast cancer (MBC) patients and its correlation with clinicopathological parameters.
Materials and Methods: The pretreatment 18FDG-PET-CT SUVmax in MBC patients was compared with clinicopathological parameters. The prognostic value of pretreatment SUVmax for progression free survival (PFS) and overall survival (OS) were assessed using log rank test and cox regression analysis.
Results: Overall, 100 patients (77%) had evidence of visceral metastases while 30 patients (23%) had oligometastatic disease confined to bones only. The receiver operator curve (ROC) demonstrated that SUVmax of 4.4 and 7.7 to be the cutoff value for predicting PFS in patients with oligometastasis to bones and multiple metastatic disease respectively. Patients with bone oligometastasis SUVmax of >4.4 had a significantly shorter OS [Hazard ratio (HR 3.2)] <4.4 (P<0.0001),whereas patients with SUV max of ≤4.4 had significantly longer PFS compared with those with SUVmax >4.4 (P<0.001). Consequently, multiple metastatic patients with SUVmax ≤ 7.7 had significant improvement in OS compared to those with SUV max >7.7.On Cox regression analysis, the SUVmax category was the only factor correlated with both PFS (HR=4.5, 95% C I 3-6.8, P<0. 0001) and OS (HR=3.2, 95% C I 2.2-4.9, P<0. 0001) in patients with multiple metastasis.
Conclusions: The pretreatment 18FDG-PET-CT SUVmax showed a statistically significant association with different clinicopathological prognostic factors. In addition, it may be considered as a potential independent prognostic indicator of clinical outcomes in metastatic breast cancer.

Keywords

¹⁸FDG PET/CT SUVmax; Metastatic breast cancer

Malignant Melanoma (MM) accounts only for 4% of all skin cancers, but is the most aggressive and lethal type of skin cancer. MM metastizes either to regional lymph nodes or to distant sites following predictable or unpredictable pathways. Nuclear Medicine (NM) plays a key role in nodal staging with the use of sentinel lymph node (SLN) mapping and guided sampling techniques. 18F-Fluorodeoxyglucose (18F-FDG) Positron Εmission Τomography (PET) has also a pivotal role in staging and restaging of MM and can alter significantly patient’s management. In today’s clinical practice, hybrid SPECT/CT and PET/CT scanners allow simultaneous assessment of both metabolic and anatomic characteristics of the primary tumor and its potential local, regional, and distant extension. More studies are required to determine the optimal surveillance schedules of PET/CT in patients with high-risk MM in order to maximize the detection of early relapse, as well as the role of PET/CT in the assessment of response to MM therapy.
In this paper, we review the clinical contribution of current nuclear medicine technologies to the management of MM.

Background:This study compared features of the Vero4DRT system with those of conventional systems, focusing on the total treatment time and patient safety.

Methods: Individual treatment times for brain stereotactic radiotherapy (SRT) and stereotactic body radiation therapy (SBRT) were compared among the Vero4DRT, Novalis, and Clinac iX systems. The mean total treatment time was calculated by summing the entire time required for the radiation treatment. The total treatment time for both brain SRT and SBRT with non-coplanar fields was markedly shorter with the Vero4DRT system than the others.

Results: For SBRT, the treatment time with the Vero4DRT system was reduced by 40%, compared with the time using a Clinac iX (13.8 vs. 20.3 min). For SRT, the treatment time with Vero4DRT was 20% shorter than with the Novalis system. With Vero4DRT, all treatments were completed within 14 min, with a significant reduction in the kV-image acquisition and image merging times.

Conclusion: The total treatment time using the Vero4DRT system was significantly shorter compared with conventional options in clinical settings; the shorter treatment time also offered the advantages of minimal intrafractional body movement, as well as better patient throughput.