Question

Estimate the dose from CT for a prostate patient (total dose 78 Gy) who undergoes the following:

- 2 CT simulations

- 39 KVCT localization images

- 1 Midcourse Evaluation CT

- 1 Post Treatment CT

Please show all work.

Answer 1

ANSWER:

Patients with early-stage high-risk cancer are at high risk of recurrence following prostate cancer irradiation.

The use or application of radiation dose to the prostate may improve the condition of patient and survival rate also.

The increasing dose of radiation to the prostate may improve the local control and survival of these patients.

Intensity-modulated radiotherapy (IMRT) may increase survival rates of patients with high risk of prostate cancer.

They are two types of radiation therapy :

*EBRT (External beam radiation therapy)

*Brachytherapy (Internal radiation therapy)

*There are number of patients with prostate cancer have been treated with not only 3-dimensional conformal radiotherapy(3DCRT) but also with intensity - modulated radiotherapy.

*Pelvic CT is ordered in high-risk patients (= if PSA >20) or if symptoms indicate

#PSA -Serine protease produced by prostate acini and ductal cells

#The right half of each prostate image fusion is the reference kVCT(grayscale), and the left half is the daily MVCT image (yellow scale)

*The right half of each prostate image fusion is the reference kVCT(grayscale).

*Intrafraction motion attributable to respiration and bowel motion did not produce artifacts that rendered the images unusable.

*The volume the rectum receiving 78Gy chosen to track rectal doses from a kVCT scan

#The kVCT images provided the best contrast resolution, while the MVCT displayed the poorest

*kVCT clearly demonstrates that, in the absence of any special protocol that involves bowel preparation.

*Daily soft tissue imaging with the kVCT scan shows large variations in delivered dose to bladder and rectum with the confirmation that the dose delivered to the prostate is satisfactory.

*The bladder and rectum were assumed to be filled organs during recontouring on the MVCT and kVCT.

*Both kVCT and MVCT image guidance has shown the ability to track actual doses delivered to prostate, bladder, and rectum based on the anatomy of the day

*MVCT provides less soft tissue contrast due to the lower attenuation coefficients at high x-ray

#PET CT

PET-CT sensitivity and specificity are

greater than that for CT or MRI for many body sites.PET is considered to be superior for nodal involvement and distant metastases.

Midcourse TX chemotherapy -To evaluate disease site/size

Midcourse treatment radiation therapy- To evaluate lymphatics site/size

# For follow up of a patient with a clinical concern for residual or recurrent disease PRT with specialized agents are usually appropriate and are complementary modalities.

*There are currently two FDA- approved prostate specific Positron emission tomography agents for prostate cancer recurrence:carbon-11 choline and fluorine -q8 fluciclovine.

*The performance of choline PET showing its usefulness for nodal and bone lesion identification.

*Although prostate-specific PET agents have enhanced our understanding of prostate cancer recurrence and spread.